Thursday, October 11, 2018

"Fitness versus adiposity in cardiovascular disease risk"

"Having a low VO2max increased CVD mortality risk as much or more than traditional risk factors such as diabetes mellitus, high cholesterol levels, hyperension, or current cigarette smoking"

Wow.

New from Japan: Life Updates: I’m Back! (Hopefully)

From Grace Under Pressure

"Life Updates: I’m Back! (Hopefully)"

Read the whole thing!

Friday, October 5, 2018

"Muscle damage and inflammation biomarkers after two ultra-endurance mountain races..."

About what you'd expect: exercise is hard on the body.

Due to short follow-up, it doesn't look at how quickly these indicators return to normal, as other studies have.

Wednesday, September 19, 2018

"A Grand Unified Theory of Polyunsaturated Fatty Acid Misbehaviour in Inflammatory Disease"

LOL: "But another clue was supplied by Tucker Goodrich, the PUFA ninja..."

Very interesting piece, read the whole thing.

Link via The High-fat Hep C Diet

Wednesday, September 5, 2018

Monday, August 20, 2018

Thursday, August 9, 2018

Tuesday, August 7, 2018

Review: Jane Brody of the "New York Times" on the Paleo Diet

Ms. Brody (I presume it's Ms., since she does work at the Times) is the Times' august "personal health columnist, a position she has held since 1976," and as such, one would think she'd be well-suited to examine the details of a diet.

So let us see what she has to say about my own personal diet.
"Is the Paleo Diet Right for You?"
"In the Paleo era, people ran around all day and rarely lived past 40, so their risk of developing the so-called diseases of civilization is unknown."
That's not even the article, it's just the starting blurb, which ought to entice us to read further, not induce wincing, as is the case here.
  1. "...people ran around all day..."
This no doubt refers to the debunked calories-in, calories-out model, oft summarized as "east less, move more".  We now know that human movement appears to be largely constant, and the fact that paleo man ran around more doesn't per se have an impact on their weight, obesity being the primary current manifestation of the Diseases of Civilization. See here:
"Energy expenditure and activity among Hadza hunter-gatherers." [1]
  1. "...rarely lived past 40..."
This is a familiar trope, and indicates that Ms. Brody does not understand arithmetic. Forty would represent (assuming her number is correct) an average, not a max lifespan for a paleolithic person.
"Life expectancy is an average, and it fluctuates with age as the risks we face change throughout our lifetimes. Both those facts make it a frequently misunderstood statistic. High infant-mortality rates depress the figure substantially. This can lead contemporary observers to the false conclusion that most humans died quite young, even in the not-so-distant past."
That's from this article, "Who Lives Longest?" that appeared in the NYT in 2013. It includes a discussion of paleolithic lifespans. The max was higher than 40. Ms. Brody should read it.
  1. "...their risk of developing the so-called disease of civilization is unknown..."
Hard to know, but not unknown. Paleopathology is the field of determining ancient health, and what it tells us is clear: the diseases of civilization appeared at the end of the Paleolithic, and people got sick, fast. From Jared Diamonds 1987 article, "The Worst Mistake in the History of the Human Race":
"Skeletons from Greece and Turkey show that the average height of hunter-gatherers toward the end of the ice ages was a generous 5' 9'' for men, 5' 5'' for women. With the adoption of agriculture, height crashed, and by 3000 B. C. had reached a low of only 5' 3'' for men, 5' for women. By classical times heights were very slowly on the rise again, but modern Greeks and Turks have still not regained the average height of their distant ancestors... 
"...Compared to the hunter-gatherers who preceded them, the farmers had a nearly 50 per cent increase in enamel defects indicative of malnutrition, a fourfold increase in iron-deficiency anemia (evidenced by a bone condition called porotic hyperostosis), a theefold rise in bone lesions reflecting infectious disease in general, and an increase in degenerative conditions of the spine, probably reflecting a lot of hard physical labor. "Life expectancy at birth in the pre-agricultural community was about twenty-six years," says Armelagos, "but in the post-agricultural community it was nineteen years. So these episodes of nutritional stress and infectious disease were seriously affecting their ability to survive.""
I haven't even gotten out of the blurb yet, and we've discovered 81% of the words in the blurb are untrue or at least grossly questionable statements.

Welcome to the New York Times! And thus you see the problem with fake news. It takes me 469 words to debunk 21 bogus ones.

The article doesn't get any better from there, but having demonstrated the general tone (most of these points are repeated in the body) I'll just hit a couple of high points.

Ms. Brody observes:
"There have been no studies of large groups of people who have followed the currently popular versions of the Paleo diet for decades to assess their long-term health effects."
This is a nonsensical criticism, as there are no such long-term studies of ANY DIETS for their health effects, with the exception of the Dietary Guidelines we are all forced to follow. The Dietary Guidelines failed to show any benefits for the health problems they were purported to ameliorate. The few paleo diet studies (as she mentions at the very end) have shown greater benefits than almost every other diet studied, including the ability to reverse many of the diseases of civilization.
"Several short-term studies among small groups of people (often with no control groups) suggest that the Paleo diet is more effective than the Mediterranean approach..."
She nevertheless endorses the Mediterranean diet, while ignoring the fact that it also has no studies to assess its long-term health effects. Note the double standard.

She seems to be using the Paleo Diet as espoused by Loren Cordain, which is fine, although not my personal choice. It's rather odd that she doesn't look into other versions of the paleo diet, which address some of her criticisms. Some of them are fair, but couched in language that demonstrates a lack of basic knowledge of food and physiology. No, dairy is not a great source of Vitamin D, Ms. Brody, the sun is. "There is no such thing as “a” Paleo diet" she says. Which is true, and every single paleo diet book tells you that. It's a strawman argument, and could have been rectified in a few moments online.

She does go talk to one "expert", Dr. Marlene Zuk, who wrote a book called Paleofantasy [2], from which Ms. Brody apparently got the substance of her article. Dr. Zuk is an evolutionary biologist, but she studies insects, not people. Hence she's not familiar with the subject she criticizes. But don't take my word for it, here's a review, from the academic journal Evolutionary Psychology: "Throwing Out the Mismatch Baby with the Paleo-Bathwater" [3]:
"In sum, Zuk has written a wide-ranging, accessible, and stimulating book, but one that mainly triumphs in dispatching paleo-hucksters, anonymous bloggers, and scholarly straw men. In failing to acknowledge the successes of the mismatch perspective, Zuk has reached the wrong conclusion: The mismatch perspective has not been a failure; it has been tremendously fruitful."
Now what you need to understand is that Dr. Zuk's book was published in 2012, and Ms. Brody's NYT article was published on August 6, 2018. So it's six years out of date.

In the interim Prof. Daniel Lieberman, Chairman of the Department of Human Evolutionary Biology at Harvard wrote the masterful The Story of the Human Body: Evolution, Health, and Disease [4]. If there hadn't been a paleo diet already, this book would have spurred it. And if Ms. Brody had based her criticism on the paleo diet on that book, she might have realized there is much less to criticize. (Prof. Lieberman is not a fan of the paleo diet per se, but cites some of the early papers from the founders, and makes the same argument.)

What's entirely missing, of course, is any defense of the paleo diet from a supporter.

So the Times turns out to be not even news, just fake; simple fear, uncertainty, and doubt. This article is basically a tarted-up book review of a book six years old combined with a snarl.




[1] Pontzer, H. , Raichlen, D. A., Wood, B. M., Emery Thompson, M. , Racette, S. B., Mabulla, A. Z. and Marlowe, F. W. (2015), Energy expenditure and activity among Hadza hunter‐gatherers. Am. J. Hum. Biol., 27: 628-637. doi:10.1002/ajhb.22711

[2] Paleofantasy: What Evolution Really Tells Us about Sex, Diet,and How We Live. W. W. Norton & Company: NY. 2013. 255 pp., ISBN #978- 0393081374 (hardcover).

[3]  Robert O. Deaner and Benjamin M. Winegard; 2013; Book Review: Throwing Out the Mismatch Baby with the Paleo-Bathwater; Evolutionary Psychology; doi: 10.1177/147470491301100123

[4] The Story of the Human Body: Evolution, Health & Disease By Daniel Lieberman
Publishers: Pantheon Books, Random House, USA (2013) and Allen Lane (UK) 2013 ISBN: 978-1-846-14393-9

Thursday, July 12, 2018

Review: "Fitness Confidential" by Vinnie Tortorich

tl;dr: Recommended, fun and useful account of a top trainer. 
(The links on this page help support the blog!)

For those of us who participate in the health and fitness worlds in podcasts or twitter, Vinnie Tortorich has been a fixture for many years.

Vinnie is "Hollywood's go-to guy for celebrities and athletes looking to get fit fast." He's a "trainer", the guy you go to to lose some pounds and tone up before your next movie role, or for the rest of us, before summer arrives.

Formerly known as "America's Angriest Trainer", (he doesn't really push that line anymore) Vinnie seems to have mellowed in recent years, but you'll still get some of his attitude in this book, originally published in 2013. (You can see him in the photo on the cover, although it's unclear if he's angry about the dietary idiocy foisted on Americans, angry about a client not listening, or just in agony while on an ultra-length bicycle ride.)

Argh!
What you get in this book is Vinnie's biography, essentially, peppered with mostly anonymous stories of his experiences in his own life that shaped his approach to training people. Despite the subtitled tease "get the dirt", one of the things you won't find in this book is dirt on clients. Vinnie doesn't kiss and tell and name names, although there are a few names mentioned. Interestingly, one of the non-anonymous clients Vinnie discusses is his co-author, Dean Lorey, who fired Vinnie initially after finding his approach challenging.

Lorey came around, wound up thin and running a half-marathon, and then proceeded to nag and coach a reluctant Vinnie into writing this book together.

The result is a well-written and quick read. You won't find pages of recipes or workout routines, instead you'll find concise principles that (in my experience, independent of Vinnie) will work, and lots of entertaining stories to illustrate the principles and drive them home.

Of more value is Vinnie's advice on how to select a gym, and trainer, some real useful thoughts about what works and what doesn't, and tips on how to help people get motivated. Some of it is quite counter-intuitive.

I read this book on a flight from LA to NYC, and it kept pulling me along.

The surprising thing about this book, perhaps, is that he's not an angry guy, he's caring and thoughtful, and seems to be motivated to continue his career by a genuine desire to help people, both his clients and the rest of us.

N.B. When you reach the advertised "end" of the book, keep reading. The best part, I thought, was in the chapters after the story of the training and diet stuff is over. This is the story of Vinnie's battle with leukemia and his fight to conquer a 509.5-mile bicycle race through Death Valley. It's the best part of the book, in my opinion, and is not to be missed.

Overall, it's highly recommended. If you're looking for a simple and straightforward recipe for weight loss and fitness, this is a fun and entertaining way to get it, and you'll wind up with a better approach than most PhDs.

FITNESS CONFIDENTIAL: Adventures in the Weight-Loss Game

Thursday, June 28, 2018

What's Worse—Carbs or Seed Oils? Understanding a High-PUFA Diet.

tl;dr: The one study I'm aware of that shows conclusively that excess glucose acts as an accelerant for excess n-6, but it not nearly so harmful without the n-6, in vivo.

I had this study:

As my pinned tweet on Twitter for quite a while. (N-6 is short for omega-6 fats). The argument has gotten a little stronger since then, but the study is important to understand, as it best elucidates the mechanism behind the argument concentrated omega-6 fats and not carbohydrates alone are the best candidate for the root cause of the Diseases of Civilization.

This is the one study I'm aware of that shows conclusively that excess glucose acts as an accelerant for excess n-6, but it not nearly so harmful without the n-6, in vivo.

"Brief episode of STZ-induced hyperglycemia produces cardiac abnormalities in rats fed a diet rich in n-6 PUFA" (PDF) [1]

A title only an editor could love, as it buries the lead deeply enough so it could only be found by an archaeologist.

What are they trying to show here?
"Diabetic patients are particularly susceptible to cardiomyopathy independent of vascular disease, and recent evidence implicates cell death as a contributing factor. Given its protective role against apoptosis, we hypothesized that dietary n-6 polyunsaturated fatty acid (PUFA) may well decrease the incidence of this mode of cardiac cell death after diabetes." 
"...The majority of studies that have looked at the relations between lipotoxicity and cardiovascular complications of diabetes have utilized lard or other sources of saturated dietary fat rich in palmitic acid (7, 17, 26). However, in humans, increased awareness of obesity and its cardiovascular complications have led to an indiscriminate substitution of atherogenic saturated cooking fats with “heart-friendly” refined vegetable oils, such as sunflower oil, rich in n-6 polyunsaturated fatty acids (PUFA) (42). In several studies, n-6 PUFA conferred protection against arrhythmias (32) and coronary artery disease (12) and, at least in human primary fibroblasts and Leydig cells, prevented apoptosis (4, 31)."
Excellent, seed oils (a more precise term than vegetable oils) are the primary source of such fats, and they're what the Dietary Guidelines suggest we eat to stave off heart disease.

Cardiomyopathy is, basically, a failure of the muscles in the heart. They don't entirely fail, but it's progressive, and also leads to heart failure, which also doesn't indicate total failure, but is obviously not good.

It's not good, but it's also common, and one can find many articles with titles like:

"Heart failure: the cardiovascular epidemic of the 21st century" [2]

Or more alarmingly:

"Impact of Obesity and the Obesity Paradox on Prevalence and Prognosis in Heart Failure" [3]

Prevalence of heart failure in 5,881 Framingham participants according to obesity status.
So avoiding cardiomyopathy and heart failure is a hot topic.

So what, again, are they doing?
"We hypothesized that, given the role of saturated fatty acids in accelerating cardiac apoptosis after diabetes, switching to an n-6 PUFA-rich diet may well be protective against cell death."
They're trying to test what happens with the "indiscriminate" replacement of saturated animal fats with seed oils in diabetics, using a mouse model.

Since they have a control that is fed a high-carbohydrate diet, both with and without induced diabetes, this also serves as a comparison of the effects of carbohydrates and n-6 PUFA on these animals, although this was not the focus of the paper. As the effects are fairly dramatic, I will highlight those parts.

So here are the steps:
  1. Table 1. Composition of diets
    Determine diets. They picked two, and added sunflower to one as a PUFA source. Diet details are good, pretty well-controlled by the generally-abysmal standards of these studies, but they aren't perfectly matched diets like in this study. One has a fair bit more carbs, and the PUFA diet has 2X the monounsaturated fat, 9X the n-6 PUFA, and 1/3 the n-3. Saturated fat was about the same. (See table 1.)
  2. Table 2. About the recently-deceased rats
    Acquire rats, divide into 4 groups, divided by the traits: Diabetic (D), and Normal (N), and Control (C), and PUFA (P). This gives us Normal Control (NC) Normal Diabetic (ND), and PUFA Control (PC) and PUFA Diabetic (PD) rats. (See table 2.)
  3. Feed all the rats their diets for 4 weeks.
  4. Give the rats in ND and PD groups T1 diabetes by injecting enough STZ (streptozotocin) to kill half the beta cells in the pancreas.
  5. Let the now type 1 diabetic D-group rats eat for 4 days.
  6. Take serum blood samples, then kill all the rats for analysis.
The Good News
"...We hypothesized that dietary n-6 polyunsaturated fatty acid (PUFA) may well decrease the incidence of this mode of cardiac cell death after diabetes." 
Apoptosis is a process of controlled cell death, which allows the body to get rid of damaged cells before say, they become cancerous. While many in the online community get worked up about it, and pursue it through fasting, it's really just a basic house-keeping process, that probably goes on all the time. It's certainly plausible that too much apoptosis could be a bad thing, just as too much of anything could be bad. Clearly having too many heart cells (myocytes) die off could be problematic, and would explain much of heart failure.
"Recently, we demonstrated that feeding a 20% (wt/wt) palm oil diet (rich in palmitic acid) to diabetic rats enhances cardiac apoptosis in vivo..."
Fig. 2. Apoptosis protection from n-6 PUFA
They tracked "....caspase-3 activity, the prime effector of cardiomyocyte apoptosis..." and sure enough, apoptosis in the PUFA-fed diabetic rats (PD) was much lower than the non-PUFA fed diabetic rats (ND).  Apoptosis in PD was a bit higher than NC or PC, but as a treatment this appeared to be a very good thing. See the red-highlighted bars in Fig. 2 to compare ND to PD. N-6 PUFA for the win!

However, they also checked heart function by another method. They looked at necrosis, and at the heart muscle directly:
"To verify necrosis, serum LDH [lactate dehydrogenase] was estimated using an appropriate kit (Sigma). However, release of LDH does not necessarily imply cardiac necrosis. Thus, to verify cardiac necrosis, sections were evaluated histologically using Masson’s trichrome stain..."
The Bad News

Fig. 3. Necrosis via lactate dehydrogenase
Necrosis is a catastrophic cell death (they use the word "accidental", but it's a bit worse than that) that leads to uncontrolled release of cell contents into the body. Some of these are toxic, and some can induce auto-immune responses, which is why the body prefers to use the orderly process of apoptosis.

In Fig. 3 we can see that LDH skyrockets in the PD rats , those that showed a major benefit from n-6 "control" of apoptosis. It appears that what n-6 is actually doing is shifting the cells from controlled, apoptotic cell death to uncontrolled, necrotic cell death.
"In these hearts, a rise in linoleic acid and depleted cardiac glutathione could explain this “switch” to necrotic cell death."
But they did mention that it's not a sure-fire indicator, and so they had a visual check of heart cells as a backup method.

Fig. 3 A. Normal heart (NC) Fig. 3 D. Necrotic heart (PD)
"Black arrows, severe disruption of contractile apparatus (hypercontracted muscle and thickened fibers); white arrows, focal necrosis (gray discoloration) in... PD hearts (D, 600). Cardiac necrosis was absent in NC (A, 400)..."
Indeed it appears that the n-6 + diabetes rats have suffered a catastrophic onset of heart failure via necrosis. In just four days! N-6 did indeed "protect" them from apoptosis, by shifting to a worse outcome.

More Bad News: Cardiolipin Levels Collapsed, as Did Mitochondria

I've written three long posts on the role and impact of excess n-6 in the mitochondria as affects cardiolipin (CL):
  1. The Cause of Metabolic Syndrome: Excess Omega-6 Fats (Linoleic Acid) in Your Mitochondria
  2. How To Prevent Oxidative Damage In Your Mitochondria
  3. What Effect Does Linoleic Acid Have On Mitochondria?
So I won't bore you here. To summarize, CL is a key molecule in the mitochondria that preferentially takes up n-6, and then breaks down into toxins such as HNE, often destroying the mitochondria, and perhaps the cell, in the process.

Here we have an n-6 intervention, with resultant cell death via necrosis. Was CL in the mitochondria involved, as my posts above would predict?

Fig. 5. Cardiolipin
Luckily these researchers looked at it.

Figure 5 shows the catastrophic effect of n-6 on cardiolipin in both wings to which it is fed, and the much smaller, but still additive, effect of induced diabetes.
"Total cardiolipin decreased almost sixfold after n-6 PUFA feeding, with a significant drop of ATP only in PD hearts, which could have contributed to cardiac necrosis (40)." 
As CL is a crucial molecule in the mitochondria, one would expect that such a dramatic reduction in CL content would also have an effect on the mitochondria, since CL is required for ATP production. (ATP is the body's basic energy carrier.) The paper also looks at morphology, the shape of the mitochondria, both normal and n-6-fed.
"Figure 5A depicts a mitochondrion with a double membrane and lamellar cristae, which are typical in NC, ND, and PC hearts. A novel observation in this study was abnormal condensed mitochondria, but only in the PD group (Fig. 5B)." [Image A not shown]
Fig. 5 B. Normal mitochondria (orange), condensed (red)
Hence n-6 consumption has a catastrophic effect on mitochondria, and hyperglycemia induces even worse pathology.

Bad News Continues: Mitochondrial Function Reduced

The next question is the functional impact of these alterations of CL content and mitochondrial form.

The authors therefore look at the effect of these alterations on fuel use.

Fig. 6 B. Glucose (white) and palmitate (black) use
And sure enough, they were rather severe. The authors (details in the paper) take the hearts from the dead animals and run fuel through them, creating a controlled environment where they can see precisely what fuel is used and how much.
"To meet the energy demand at high afterload (135 mmHg), all except the PD group increased their glucose oxidation. With regard to fatty acid oxidation, only the NC group was able to increase palmitate oxidation, suggesting that, in the ND, PC, and PD groups, fatty acid oxidation was already operating at its maximum at low afterloads."
The lack of glucose oxidation (red circle, Fig. 6 B) indicates a near-total failure in mitochondrial Complex I, where glucose is burned. The study detailed in my post 3 notes a high production of reactive oxygen species (ROS) in complex I induced by n-6, and the results of this study suggest that n-6 induced ROS may terminally damage complex I and thus the cell's ability to utilize glucose.
"A novel observation in this study was that, analogous to Barth’s syndrome, n-6 PUFA feeding for 4 wk, together with 4 days of hyperglycemia, led to similar changes in some mitochondria. Interestingly, abnormal condensed mitochondria have been recently recognized in skeletal muscle and cardiac atrial neurons from diabetic patients (25)."
This is a notable finding, as excess ROS production and an inability to utilize glucose is a primary feature of Alzheimer's Disease, which is also referred to as Type III Diabetes and for  which n-6-induced damage is an oft-observed possible cause.

Mitochondrial Toxins Increased

Fig. 4 A GSH in Control (white), Diabetic (black)
In my post 2 above I noted that the breakdown of n-6 fat linoleic acid in CL produces a toxin, HNE. As production of some amount of HNE is a normal part of mitochondrial function, there's a detoxification mechanism, part of which is the antioxidant glutathione—inexplicably abbreviated everywhere as GSH. While the authors don't mention HNE directly—the mechanism for CL producing HNE wasn't found until 2012—they do look at GSH. Since GSH levels are often used as a proxy for HNE production, this is a useful measure.
"PUFA feeding was associated with a significant decrease in GSH. Interestingly, diabetes for 4 days in normal chow-fed rat hearts could not decrease cardiac GSH, whereas superimposition of diabetes in PUFA-fed animals led to a further decrease in cardiac GSH levels (Fig. 4A)"
In Fig. 4 A, one sees that GSH is indeed reduced, least in ND rats, most in PD rats. There is additional discussion in the paper about some further indicators, but I'm not going to discuss them as they don't add much to the point made here. 

HNE is the leading cause of genetic damage and also induces amyloid-beta plaque development in Alzheimer's, so it's something we want to minimize, and the implication of this data is that n-6 in these amounts overwhelms the body's ability to detoxify it.

This would explain one of the more inexplicable aspects of chronic diseases of civilization, that of mitochondrial dysfunction. Here it is shown how to induce it.

Worst News: Now They Have Heart Failure

The failure in energy production, as the mitochondria are the primary engines of the heart, has consequential effects on heart function. Function decreases, and the ability to respond to increased demands declines dramatically, as the semi-functional mitochondria are no longer able to meet those demands.
Fig. 8. Heart function
"At higher afterloads, glucose and fatty acid oxidation increased in the NC group. In ND and PC hearts, the only increase was that of glucose oxidation, inasmuch as, presumably, fatty acid oxidation was already operating at its maximum. The PD group alone failed to increase its glucose oxidation in response to a higher energy demand, an aspect that could have contributed to the drop in cardiac function."
Additionally, they have some spiffy pictures of the progression of cellular dysfunction from NC to the poor PD rats, who are clearly in a rough spot. I'll spare you those, as I presume by now the gist is clear.

This failure of the capacity to produce energy using fats causes a back-up of fats in the fat cells, as delivery is exceeding demand.
"In our study, n-6 PUFA feeding substantially increased cardiac fatty acid in the PC and PD groups, but only PD hearts demonstrated a considerable increase in lipid droplets."
They've replicated what's described in this paper [4], in the section entitled "Evidence that Human Cardiac Dysfunction Is Associated with Excess Lipid", where lipid droplets are seen in diabetic and/or failing human hearts.

N-6 Induced Obesity

The weight figures from Table 2 fail to tell an important story. The figures given are those when the rats were killed, but the highest weight in the D-groups was at STZ injection. See the chart (mine) to see what a significant increase n-6 caused in the rats' weights prior to STZ, which caused a dramatic decline only in the rats fed n-6.

Rat weight at STZ injection.
Red indicates weight lost after injection (4 days)
"Interestingly, in contrast to the ND group (361 ± 9 and 358 ± 9 g before and after STZ, respectively), diabetes in PUFA-fed animals was associated with a profound loss of body weight (450 ± 11 and 393 ± 11 g before and after STZ, respectively). This loss in body weight could not be attributed to any change in food or fluid intake but could be a result of excessive lipolysis and loss of adipose tissue mass with subsequent increases in serum free fatty acids and TG in the PD group."
This is consistent with Alvheim's series of papers starting in 2012 showing that n-6 linoleic acid uniquely induces obesity in rodents. [5]

A Bonus Bad-News Easter Egg: The Control Got Diabetes, Too 

"Thus, although promoted as being beneficial, excess n-6 PUFA, with its predisposition to induce obesity, insulin resistance, and ultimately diabetes, could accelerate myocardial abnormalities in diabetic patients... Circulating TG were higher in the PC than in the NC group, and serum insulin was increased in the PC group (likely as a consequence of insulin resistance) compared with the NC group, but there was no overt hyperglycemia in the PC group."
Table 2. PC is PUFA Control, not the intervention!
They don't really focus on this, but it's kind of a big deal. They had two variables they were testing, and this left them with four groups, as detailed in Table 2. Therefore they had one "control", NC, but the intervention was supposed to be the PD group. But let's look at the PC group, too. The quote above notes they didn't get "overt" hyperglycemia, but, compared to the full control, their:
  • Blood glucose +29%
  • Triglycerides (TG) +462%
  • Insulin +96%
  • Leptin* +59%
(* An hormone that is supposed to control fat accumulation.)

The D-groups had Type 1 diabetes induced, the PC group got Type 2 diabetes because of the intervention: n-6 induced it!

Back to "overt" hyperglycemia. The PC rats didn't get it because:
"In rodents fed high-fat diets, insulin resistance does not progress to hyperglycemia in the absence of genetic defects (36)."
So these rats seem to have gotten as close to Type 2 diabetes as it's possible for them to have gotten.

Conclusion
"In summary, chronic caloric excess of n-6 PUFA when coupled with acute diabetes of only 4 days precipitated mitochondrial abnormalities, a steep drop in GSH, altered substrate utilization, and myocardial TG deposition. Given that these hearts also demonstrated necrosis and extensive myocardial cell loss, a feature that is predominant only in chronic diabetes (1, 14, 16, 24), our data suggest that this mode of cell death in PUFA-fed diabetic hearts is an important factor in accelerating diabetic cardiomyopathy. Although these effects of n-6 PUFA in the diabetic animal would seem contrary to accepted belief as being beneficial, in countries such as Israel, with high dietary n-6 PUFA consumption, there is an excessive incidence of obesity, insulin resistance, hypertension, and type 2 diabetes (6).... Thus advocating diets rich in n-6 PUFA for diabetic patients could accelerate the impairment of myocardial contractility."
This also is the only study I know of that shows the effects of hyperglycemia to significantly accelerate the negative effects of n-6 PUFA feeding on an organism. The PC and PD groups can be seen as a model for the progression of obesity and insulin/leptin resistance to an advanced form of chronic Type 2 with advanced pancreatic beta-cell death, a condition that is becoming increasingly common in human children.

Combined with my previous post, "Hello, Can We Have Your Liver?": Understanding a High-PUFA Diet, we have evidence of n-6 involvement in two major chronic organ failures, and the hints of causation of diabetes, a disease impacting all organs.



(I'll also note that I've been told this paper was a Trojan horse, that the authors knew very well what the paper was going to show, but to get it published kow-towed to the Temple of Vegetable Oils, to make it look like another cheerleading pro-PUFA study. They feign surprise that this does not seem to be the case, but I think that in this sentence, with it's pejorative "indiscriminate" and scare quotes around "heart-friendly", they let the truth slip out. Luckily the editors and reviewers didn't catch it!
"However, in humans, increased awareness of obesity and its cardiovascular complications have led to an indiscriminate substitution of atherogenic saturated cooking fats with “heart-friendly” refined vegetable oils, such as sunflower oil, rich in n-6 polyunsaturated fatty acids (PUFA) (42)."
Good for them!)



[1] Ghosh, Sanjoy, Dake Qi, Ding An, Thomas Pulinilkunnil, Ashraf Abrahani, Kuo-Hsing Kuo, Richard B. Wambolt, Michael Allard, Sheila M. Innis, and Brian Rodrigues. Brief episode of STZ-induced hyperglycemia produces cardiac abnormalities in rats fed a diet rich in n-6 PUFAAm J Physiol Heart Circ Physiol 287: H2518 –H2527, 2004. First published July 29, 2004; doi:10.1152/ ajpheart.00480.2004

[2] Thomas F. Lüscher. Heart failure: the cardiovascular epidemic of the 21st century, European Heart Journal, Volume 36, Issue 7, 14 February 2015, Pages 395–397, https://doi.org/10.1093/eurheartj/ehv004
[3] Carl J. Lavie, Martin A. Alpert, Ross Arena, Mandeep R. Mehra, Richard V.Milani, Hector O. Ventura. Impact of Obesity and the Obesity Paradox on Prevalence and Prognosis in Heart Failure
JACC: Heart Failure Apr 2013, 1 (2) 93-102; DOI:10.1016/j.jchf.2013.01.006

[4] Goldberg, Ira J. et al. Lipid Metabolism and Toxicity in the Heart, Cell Metabolism, Volume 15 , Issue 6 , 805 - 812

[5] Alvheim, A. R., Malde, M. K., Osei‐Hyiaman, D. , Hong, Y. H., Pawlosky, R. J., Madsen, L. , Kristiansen, K. , Frøyland, L. and Hibbeln, J. R. (2012), Dietary Linoleic Acid Elevates Endogenous 2‐AG and Anandamide and Induces Obesity. Obesity, 20: 1984-1994. doi:10.1038/oby.2012.38

Wednesday, June 6, 2018

Thoughts on "Cardiolipin Synthesis in Brown and Beige Fat Mitochondria Is Essential for Systemic Energy Homeostasis"

Interesting confirmation of a core mitochondrial functional role for cardiolipin, and some interesting observations about cold-adaptation.

Get used to shivering! 
"However, the ability of adipose tissue to expend energy is a dynamic process that continues to increase with prolonged cold exposure, only reaching maximal capacity after several weeks (Cannon and Nedergaard, 2004)."
And clearly staying warm is overwhelmingly dependent on fat metabolism.
"However, the enrichment of lipid metabolism proteins far eclipsed that of proteins involved in all other metabolite pathways from 3 days to 3 weeks of cold exposure (Figure 1B)."
This likely explains why overweight people or inactive people have such a problem staying warm. Fat-burning capacity is dependent on stimulus, and while this doesn't show it, it likely atrophies like every other function of the body. Use it or lose it.

One of the key questions around cardiolipin and omega-6 fat intake is: what is a cardiolipin supposed to look like? This is more evidence that they're not supposed to be saturated with linoleic acid, leaving them uniquely susceptible to oxidizing and producing toxins like HNE as they damage mitocondrial function.
"Newly synthesized CL is characterized by shorter, more saturated acyl chains, which can be remodeled by phospholipases, and acyltransferases through monolysocardiolipin (monolysoCL) intermediates to generate a diverse pool of CLs."
It shouldn't surprise that CL is produced in an ideal state. Why it so readily takes up linoleic acid is an interesting question...

The paper also claims that energy production in brown-fat adipocytes (fat cells) controls systemic glucose homeostasis and therefore type 2 diabetes.

I'm a little more skeptical of that claim, as I looked into the connection between mitochondrial dysfunction and diabetes, and it's not as clear as I would like it to be. If this was a clear mechanism, then it would suggest that people living in warm climates that never experience a need for cold thermogenesis would be more susceptible to diabetes, and we really don't see that.

They get it when the industrial diet is introduced, same as everyone else on the planet.

Friday, April 27, 2018

LDL Cholesterol: You Aren't Always What You Eat, or Roundabout Ways to Improve Your Diet

Sometimes you read these papers and shake your head.

"Lowering Dietary Saturated Fat and Total Fat Reduces the Oxidative Susceptibility of LDL in Healthy Men and Women"

The troll who pointed me to this was trying to argue that this invalidated the claim that omega-6 polyunsaturated (n-6) fats are important in cardiovascular disease (I gather), since lowering saturated fat (see the title) lowered oxidation.

Oddly enough, he was almost right, but not quite.

Fat components
The intervention was to have fixed protein (15%), but a variable rate of saturated fat (SFA), to be replaced by carbohydrate (CHO), and fixed rates of monounsaturated and polyunsaturated fats (MUFA and PUFA, respectively). And they did a good job of detailing what the diet included, right down to the individual fats.

However you have to go to a different study to find all the details ("Effects of Reducing Dietary Saturated Fatty Acids on Plasma Lipids and Lipoproteins in Healthy Subjects")

To sum the variation, SFAs were 16%, 9%, and 5%; and CHO was therefore 48%, 55%, and 59%. MUFA was 14%, and PUFA was 7%.

The diet part of it seems to have been very well done, indeed. If you want some idea from where the food may have come, may I introduce you to their sponsors?
"The DELTA Investigators express thanks to the following contributors: AARHUS, Bertolli, USA., Best Foods, Campbell Soup Company, Del Monte Foods, General Mills, Hershey Foods Corp., Institute of Edible Oils and Shortenings, Kraft General Foods, Land O'Lakes, McCormick Incorporated, Nabisco Foods Group, Neomonde Baking Company, Palm Oil Research Institute, Park Corporation, Procter & Gamble, Quaker Oats, Ross Products Division/Abbott Laboratories, Swift-Armour and Eckrick, Van Den Bergh Foods, Cholestech, Lifelines Technology Incorporated."
Wow.

The troll was almost right because LDL oxidation did indeed go down in this study. But it went down for a reason that I wouldn't have expected, and which leaves me somewhat perplexed to explain mechanistically. 

The paper goes on ad nauseum along these lines:
"Convincing evidence suggests that oxidative modification of LDL plays an important role in the pathophysiology of atherogenesis (Steinberg 1997). In recent years, numerous molecular mechanisms have been proposed to explain the different oxidation pathways that lead to modification of LDL (Steinberg 1997). 
"One of the earliest steps in the generation of oxidatively modified LDL is the peroxidation of its polyunsaturated fatty acids (PUFA).3 The oxidative breakdown products of these fatty acids, such as malondialdehyde [MDA] and 4-hydroxynonenal [HNE], form covalent bonds with apolipoprotein B (apo B)..."
Yeah, yeah. Old news (the paper is from 2000), but here's where it gets odd:
"The results of the present study also show that LDL composition (LDL quality) affects susceptibility to oxidation. [It] was inversely correlated with the quantity of LDL oleic acid (r = −0.29, P < 0.01), and positively correlated with the quantity of LDL linoleic acid (r = 0.23, P = 0.04) and the 18:2-to-18:1 ratio (r = 0.52, P < 0.001). The oxidation rate was positively correlated with the 18:2-to-18:1 ratio (r = 0.24, P = 0.03)."
To lower n-6, cut SFA?

What?

So lowering SFA indeed made the LDL more resistant to oxidation. But it did so by lowering n-6 and raising MUFA in the LDL! SFA was basically unchanged.

A little Lipidology 101, MDA and HNE, mentioned above, aren't made from SFA, they're made from PUFA, and HNE is made exclusively from n-6. MDA and HNE pretty much are oxidized LDL. So you're not getting oxidized LDL from SFA in the body. It just won't happen.

Of course the authors don't mention that little fact. More below.

For some reason I am unable to explain, lowering SFA (16:0, palmitate in the chart) in the diet lowered n-6 (18:2, linoleate) in the LDL, and increased MUFA (18:2, oleate), protecting LDL from oxidation. SFA stayed  the same, basically.

My best guess is that it was the increased CHO in the diet (is this what's behind the Japanese diet, which is low in SFA and high in CHO?) but it is just a guess.
"In the present study, the ratios of 18:2 to 18:1 and PUFA to MUFA in the LDL from subjects when they consumed the Step-1 and Low-Sat diets were significantly lower than they were in the LDL from subjects when they consumed the AAD. Linoleic acid (n-6) in LDL from subjects when they consumed the Low-Sat diet also was significantly lower compared with those from subjects when they consumed the AAD. "
The first citation for this paper is:

"Oxidation of low-density lipoproteins: intraindividual variability and the effect of dietary linoleate supplementation"
"LDL oxidized faster after the linoleate diet than after the oleate diet... and produced more conjugated diene [that's bad] in proportion to the increase in LDL linoleate."
Here's where we get to the shaking my head part.

Why in blazes wouldn't you reduce the thing that is actually capable of causing the harm, as your first cite shows, and as your own study shows, is the source of the problem? Why keep n-6 flat and reduce something else, which through some round-about effect, lowers what you need to lower, the n-6?

Just lower the n-6 and you reduce the susceptibility for oxidation! They cite other papers that have done exactly that!

This study was done in 2000, did I mention that?

Think of the progress we would have made if they'd actually done what any engineer reading this paper would have told them to do. 
"N-6 converts to these toxins? You're proved that? Why not reduce the n-6?"
Let's not get too into conspiracies here, but on the face of it this study is clearly little more than a misleading advertisement for the sponsors listed above, who are forced to follow the United States Dietary Guidelines and replace saturated fats with the n-6 fat that their own research claims is harmful.




This post started with a twitter troll who cited the first-mentioned study:


Thursday, April 26, 2018

Breakfast with Low-Carb Dr. Tro Kalayjian

I'm the one with the bunny ears.

I had breakfast with Dr. Tro this morning in poverty-stricken Greenwich, Connecticut this morning, where I believe he treats gunshot wounds or stabbing victims, or something. Or maybe broken fingernails from Ferraris. Not too clear on that, actually...

He's a fascinating guy, he was morbidly obese (see pic below) until he decided to commit to a low-carb and then zero-carb (carnivore) diet. After initially thinking the whole notion of "fat adaption" was nonsense, he became a convert after discovering how it worked himself, with guidance from a bunch of folks, including (I hope) yours truly.

You'd never guess he was ever anything but lean and healthy. It's really quite remarkable.

He seems like he's got all the motivations to make an excellent, scientific doctor (which is not an easy thing!), and I hope he goes ahead and opens the practice we were discussing. He wants to help people with obesity, and show them how to "get off all their pills", so two thumbs up for that!

We also discussed training; if people can rebuild tendons and ligaments in the middle of life, which is a project we're both working on; and dreadful doctor-run blogs.

And a bunch of other stuff. See his post below and the replies, including my attempt to follow-up on some of our discussion points.


Wednesday, April 25, 2018

How Much Carbohydrates Should Humans Eat?

"Abstract: In the past, attempts have been made to estimate the carbohydrate contents of preagricultural human diets. Those estimations have primarily been based on interpretations of ethnographic data of modern hunter-gatherers. In this study, it was hypothesized that diets of modern hunter-gatherers vary in their carbohydrate content depending on ecoenvironments.

"Thus, using data of plant-to-animal subsistence ratios, we calculated the carbohydrate intake (percentage of the total energy) in 229 hunter-gatherer diets throughout the world and determined how differences in ecological environments altered carbohydrate intake. We found a wide range of carbohydrate intake (≈3%-50% of the total energy intake; median and mode, 16%-22% of the total energy). Hunter-gatherer diets were characterized by an identical carbohydrate intake (30%-35% of the total energy) over a wide range of latitude intervals (11°-40° north or south of the equator).

"However, with increasing latitude intervals from 41° to greater than 60°, carbohydrate intake decreased markedly from approximately equal to 20% to 9% or less of the total energy. Hunter-gatherers living in desert and tropical grasslands consumed the most carbohydrates (≈29%-34% of the total energy). Diets of hunter-gatherers living in northern areas (tundra and northern coniferous forest) contained a very low carbohydrate content (≤15% of the total energy).

"In conclusion, diets of hunter-gatherers showed substantial variation in their carbohydrate content. Independent of the local environment, however, the range of energy intake from carbohydrates in the diets of most hunter-gatherer societies was markedly different (lower) from the amounts currently recommended for healthy humans."
"Diets of modern hunter-gatherers vary substantially in their carbohydrate content depending on ecoenvironments: results from an ethnographic analysis"

Monday, April 16, 2018

"How fast can we run?"

"Marathon-ready Daniel Lieberman offers evolutionary perspective on Bannister 4-minute mile, human speed limits, and ‘Man Against Horse’".

"...He did talk about the kinds of shoes that he wore back in the day, and was fascinated by — and not particularly approving of — how running shoes had gotten so built up. He, like any fast miler, was a forefoot striker. We published a few years later the paper in which we made the argument that, essentially, prior to shoes pretty much everybody ran the way Bannister ran. He felt that was clearly the best way to run.

"I remember him describing how he had his shoes made by a cobbler in London. You couldn’t go to a shoe store back then and buy a pair of running shoes. He basically had to have his shoes custom made. I remember he discussed how hard it was to get the right kind of material — light but durable enough not to fall apart...."

Read the whole thing!

Saturday, March 31, 2018

"A Bunch of Running Nerds on Their Favorite Shoes"

Interesting list, with people like Magness, Dicharry, and Lieberman:

“I wear a variety of different shoes to mix it up, but all are zero drop, because I’m a forefoot striker and don’t need or want any cushioning on the heel, otherwise I end up running like a ballerina”...

Friday, March 30, 2018

"The Western Diet and Lifestyle and Diseases of Civilization"

Apparently a must-read paper, according to the interviewer of one of the authors:

"Do Traditional People Hold the Key to a Healthy Life? 15 Questions with Researcher Pedro Carrera Bastos"

Don't know how I missed this. The other authors: Maelan Fontes-Villalba, James H O’Keefe, Staffan Lindeberg, Loren Cordain.

"Regarding dietary changes, it should be mentioned
that, in the US, dairy products, cereal grains (especially the
refined form), refined sugars, refined vegetable oils, and
alcohol make up to 70% of the total daily energy consumed."

Tuesday, January 30, 2018

"My first podcast interview, over at Break Nutrition"

Great interview, of one of the smarter guys out there, with an amazing story.

Link via The High-fat Hep C Diet

Iron Overload: A Myth in Healthy People?

tl;dr: Oft-mentioned iron overload does not appear to be a problem in healthy humans, only in those with genetic defects. Iron is steadily lost through normal mechanisms and regained through dietary intake. Deficiency is the problem in healthy people.

So sometimes I get curious.


Now many people in the health communities I participate in get very concerned about iron overload—more below—but the basic concern has been that people keep eating iron in red meat, say; and there's no way to get rid of it, so at some point it will hit toxic levels and start to do damage. There are a number of genetic conditions where high iron levels do appear to cause damage, so this could be a reasonable concern. People even proactively give blood to lower their iron stores. But that all depends on the notion that you have no way of getting rid of excess iron.

I poked around half-heartedly, but didn't find anything.

Iron retention per year
Dumping iron

Today I got a little more curious about it, and found "Body iron excretion by healthy men and women" (Hunt 2009), which is an update of the last study done on the topic, in 1968 (Green 1968).
"On the basis of turnover rates, these subjects needed to replace as little as 2% and as much as 95% of their body iron annually!"
They used radioactive iron to measure iron turnover, which was the same method used as Green. Seems a reasonable way to do it.

Oddly, the primary mechanism for the body to shed iron is through shedding skin cells (!), exfoliation in the scientific jargon. There are also losses through bile (feces), urine, and shedding cells in the gut. Iron must be pretty hard to come by, as the body is mainly concerned with keeping it, and getting rid of it seems to be incidental to other body functions.

Hunt notes that shedding iron seems to be a somewhat random process, it's not homeostatically regulated like uptake is. (Although they saw a 40-fold variation in loss, so there may be some regulation process going on, it seems unlikely to me that such an important nutrient would be dumped randomly. But Hunt does not report a mechanism.)

One of the reasons Hunt did his study was because Green hadn't looked at women, so Hunt did. Obviously women (who menstruate) lose more iron than men do, and are more at risk from anemia (iron deficiency), consequently. I should mention that most of the iron in the body is contained in hemoglobin in the red blood cells, and the next biggest functional use of iron is in the mitochondria, in the cytochrome C molecule, which I have discussed before. There are also iron stores in the body.

Based on Hunt and Green, I think it's safe to say that the body is perfectly capable of getting rid of iron.

95% loss per annum would get the job done. 

Iron uptake

The known regulator of iron stores in the body is through uptake during digestion. That's sort of outside the scope of this, basically, but there's also a wide variation in iron uptake, depending on iron need and digestive capability.

The US RDA for iron was based on Green, which was a male-only study:
"Current US dietary recommendations for iron use the body weights and the daily iron losses of the subjects of Green et al (2) to derive an average estimated iron loss of 14 µg/kg...."
"This reduction, together with the tendency in the present study for the men to (nonsignificantly) increase their body iron in 3 y may mean that dietary recommendations for men in Western countries may best focus on preventing body iron accumulation rather than iron deficiency."
So that's where what I think the myth comes in. Are men in Western countries really at risk of iron overload?

Iron overload

Hunt noted that Green had measured a pretty wide variation of losses in his study—Green was in South Africa:
"Green et al... measured basal iron losses of 0.95 ± 0.30 mg/d for white men in the United States, 0.90 ± 0.31 mg/d for Mestizo men in Venezuela. and 1.02 ± 0.22 mg/d for Indian men in South Africa. Higher and more variable losses of 2.42 ± 1.09 and 2.01 ± 0.94 mg/d for Bantu men in Johannesburg and Durban, South Africa, respectively, were attributed to greater than normal body iron stores in the Bantu population."
From "Body iron excretion in man" (Green 1968), a rather important paper, as noted above.

So, if you're looking for evidence of iron overload, that seems to be the place to look for it. From Walker, 1953:
"Among the South African Bantu, the intake of iron is often very high—as much as 200 mg. per diem. This high intake is due mainly to the uptake of the element from iron utensils occuring during the preparation of their usual foods (particularly fermented cereal products)."
Dang, that's 100-fold what Green reported them losing per day! They must be like Tetsuo, The Iron Man!



[Don't watch that, it's really weird. Included for referential comprehensiveness.]

However, their high intake and status appears to have little effect:
"...there appears to be no evidence that iron overload per se is detrimental to well-being."
If the Bantu are eating that much iron and seeing no ill effects, then I think we in the West can worry less about it.

Genetic iron management diseases

The Bantu (and other Africans) do get a disease of iron overload, known as siderosis. However that appears to be genetic, and not from diet:
"Researchers originally believed that the popular, iron-rich beer caused cases of African iron overload. However, many individuals that drank the beer did not develop the disorder and some individuals that did not drink the beer did develop it. This led researchers to speculate that a mutation of a gene or genes involved in the transport or breakdown (metabolism) of iron must play a role in the development of African iron overload. Such a gene has not yet been identified."
That's from the Rare Diseases site, 2013. So it's similar to the iron overload disease that most are familiar with, hemochromatosis.

So just to wrap this up, I'm including two more links, from the CDC and from Merck.

CDC: Recommendations to Prevent and Control Iron Deficiency in the United States

Merck Manual: Secondary Iron Overload (Secondary Hemochromatosis)

As noted in those two links, virtually all instances of iron overload appear to be genetically caused. It's even possible to have iron overload (in storage) and be anemic (not enough iron in the blood) at the same time, interestingly as noted in the second link, but again from a genetic problem.

Conclusion

Hunt, again:
"Despite this substantial range in iron excretion, homeostatic control mechanisms were effective at maintaining body iron homeostasis for most subjects, with substantially impaired iron-status indexes in only one menstruating woman... These considerable differences in iron excretion and resulting requirements can generally be appropriately met by physiologic control of iron absorption, provided that dietary iron is accessible and reasonably bioavailahle."
Iron, like most important things, is tightly, homeostatically regulated by the body. As a creature that appears to have evolved on a diet of large amounts of heme-rich ruminant meat, we are unlikely to be susceptible to iron poisoning via that route, that is, via a diet far higher in heme iron than what most humans alive today eat. So unless you have an actual genetic problem, it's not necessary to manually regulate things like air, water, or your body's iron stores.

All that said, as I discuss in the cytochrome C link far above, iron is related to the diseases associated with the metabolic syndrome. But that's because it's a catalyst for the oxidation of omega-6 polyunsaturated fats. But the evidence for that beyond what I've already posted will have to be dealt with in another post.



Sunday, January 28, 2018

Meta-analysis of Oxidative Stress and Alzheimer's

No clear effect, little research. Did not look at focal analysis of specific regions or organelles.

"The field of oxidative stress as it relates to AD is large, with primary data coming from many different systems and supplemented by a large and rapidly growing narrative review literature. While this volume of data indicates intense interest in this topic, its utility is diminished by obfuscating or masking the complete picture of the oxidative changes in the AD brain. The purpose of this analysis was to quantitatively address this problem specifically for oxidative-stress related changes in the human AD brain. The pattern of oxidative changes identified in this analysis suggests that the antioxidant enzyme system in the brain is largely intact in AD and the global accumulation of oxidative damage is less substantial than has generally been reported."

And this:

"While this [brain malondialdehyde (MDA) level] is not the most specific or robust marker of lipid peroxidation, it is the most commonly studied marker of lipid peroxidation in AD brain..."

Sigh.

An excellent, comprehensive meta-analysis, well worth reading just to admire the work.

"Markers of oxidative damage to lipids, nucleic acids and proteins and antioxidant enzymes activities in Alzheimer's disease brain: A meta-analysis in human pathological specimens"

Tuesday, January 23, 2018

"Hello, Can We Have Your Liver?": Understanding a High-PUFA Diet.

tl;dr: A diet high in omega-6 and omega-3 polyunsaturated fatty acids has some positive effects on the body: lower weight gain, better preservation of lean mass, improved blood lipids, and increased brown adipose tissue; but also results in increased oxidative stress, mitochondrial dysfunction, and beginning of progressive liver failure.

This paper's a classic
"Fat Quality Influences the Obesogenic Effect of High Fat Diets [HFD]"
Sounds benign enough, right?  We all like quality fats...
"To investigate whether polyunsaturated fats could attenuate the above deleterious effects of high fat diets, energy balance and body composition were assessed after two weeks in rats fed isocaloric amounts of a high-fat diet (58.2% by energy) rich either in lard or safflower/linseed oil. Hepatic functionality, plasma parameters, and oxidative status were also measured. The results show that feeding on safflower/linseed oil diet attenuates the obesogenic effect of high fat diets and ameliorates the blood lipid profile...."
That's terrific!  So we just need to eat more omega-6 and omega-3 fats, and we'll be thinner with better blood cholesterol!

A nice example of a rat diet study

So these two sets of rats got two remarkably well-constructed diets, with 58.2% of fat from either lard (L) or safflower and linseed oil (S).  Lard is the classic bogeyman of rat diets. "Eat your carbohydrates, children, or Lard will get you!" Nice to see them adding in the omega-3 (n-3) fats from linseed oil—gold star. This accomplishes two things: First, it's well known that sufficient n-3 ameliorates the obesity often induced by high n-6 diets, so they're assuring the outcome. I don't know if they knew this, but I did and noticed it immediately. Second, they get around the n-3/n-6 ratio question, as the S diet actually has a better ratio than the lard diet does: the L diet has an omega-6 (n-6) to n-3 ratio of 12:1, which is pretty bad, and the S diet has a ratio of 4:1, which is pretty good, by lab-rat standards.

L S
Fat 58.20% 58.20%
LA 13.93% 59.13%
% E 8.11% 34.41%
ALA 1.12% 14.47%
% E 0.65% 8.42%

So the L rats got 8.11% of their daily bread (% E) from linoleic acid (LA), and just a smidge from the omega-3 fatty acid alpha-linolenic acid (ALA).  The lucky S rats, fed the healthy, anti-obesigenic, cholesterol-lowering high-PUFA diet got 34% (!) of their calories from LA, and a whopping 8.42% from ALA.

The full diet is in the following two images. By lab-diet standards, this is incredibly well done, as they even give the exact breakdown of the individual fatty acids (FA). They get a bit of a demerit for including "chow" as a line-item, and not breaking that out, but at least both arms are getting the same amount of chow, and both are getting the same 20.7%E from carbohydrates. We can infer this is not a high-sugar diet.



I'll say it again.  This is a lovely diet, they're really doing a neat job of controlling their variables here. Lots of heart-healthy PUFAs, and a big dose of plant-based n-3 fats to balance the somewhat troublesome omega-6 fats.

How to make lab rats fat

Now we know that 8% E of LA is plenty to induce obesity in rodents.  See here:

"Dietary linoleic acid elevates endogenous 2-AG and anandamide and induces obesity."

And sure enough, these rats got fat.  Interestingly, the L rats got fatter than the S rats, despite eating much less LA.
"After two weeks of isocaloric high fat feeding, obesity development was evident both in L and S rats, since their percentage of body lipids about doubled compared to initial value, although the final value was significantly lower in S rats than in L rats (Figure 1A)."
Rats don't do very well on HFDs with LA, as the above paper shows, so it's not surprising that these rats all got fat. It's also been shown that adding n-3 fats helps prevent obesity in rats, so that added linseed oil seems to benefit the rats, although it clearly didn't prevent obesity here.

Benefits of a high-PUFA diet, versus lard

What's worse, the L rats got worse fat than the S rats did; visceral (abdominal) and epididymal (the man parts) fat.
"In addition, the percent of epididymal and visceral white adipose tissue (WAT) increased during dietary treatment, reaching a final value that was significantly lower in S rats than in L rats (Figure 1C,D)."
Not only that, but the L rats lost more lean mass than the S rats did, so they're going to have to go to the gym more often.  
"Therefore, it appears clear that L rats exhibit an impaired metabolic flexibility that exacerbates obesity development."
So far, it appears that lard is an unhealthy fat, and that the safflower/linseed combination is far superior. The higher-PUFA diet is also in line with the dietary recommendations, so that's also a benefit.

Brown Adipose Tissue
There were a number of other benefits to the high-PUFA HFD, including better fuel burning, and increased brown adipose tissue (BAT), which is used to turn fuel into heat to keep the animal warm, and also helps with disposing of excess calories. Cholesterol also went down, and for those who like the current dietary guidelines, that's also a plus

Unfortunately those blood lipids went somewhere...

The Catch

Oh, wait a minute...
"Plasma metabolic characterization evidenced lower cholesterol but higher lipid peroxidation and ALT activity in S rats compared to L rats (Table 3). At variance with plasma lipid profile, livers from S rats had higher lipids, triglycerides, and cholesterol, as well as higher lipid peroxidation..."
And...
"...Conversely, hepatic steatosis and mitochondrial oxidative stress appear to be negatively affected by a diet rich in unsaturated fatty acids."
Oh, darn.  "Negatively affected"? Here's where things go off the rails. One expects a lard-based diet to be bad for rats, who reliably get fat on such diets. But swapping out the MUFA and SFA for PUFA is supposed to make things better, and it has so far in this study.

Until we get to the mitochondria and the liver.

They've come for your liver
TBARS is a test looking for a marker of lipid peroxidation (LPO), which is the oxidation of PUFAs, essentially; see in table 3 in the image above. TBARS are notably higher in the S diet. It's not surprising, I suppose, that the oxidation of PUFAs should be much higher on a higher-PUFA diet. But LPO is not a good thing, as the products of LPO are toxic. TBARS is a marker of malondialdehyde (MDA) one of the worst such LPO products. They should have also tested for 4-hydroxynonenal (HNE), in my opinion, but such is life.

LPO has very negative effects on mitochondria and the liver, and sure enough that's exactly what is seen in these rats. A paler liver indicates a fattier liver, and non-alcoholic liver disease (NAFLD) is a major problem in both rats and humans fed a HFD. Here we see that NAFLD is far worse (the paler colors) in the bottom row of images, from rats fed the supposedly-healthy S diet. What's really notable, and a particularly brilliant part of this paper, is these are rats with a high n-6 diet, but a low n-6/n-3 ratio. Which doesn't seem to have helped their livers at all.

Liver n-6 concentrations change:
"...there was a significant increase in the omega 6 fatty acids linoleic, gamma-linolenic, eicosadienoic, and dihomo-gamma linolenic and in the omega 3 fatty acid docosapentaenoic (Figure 5B), in S rats compared to L rats."
Except the liver mitochondria was altered:
"However, some differences were evident in the content of specific fatty acids, such as the monounsaturated fatty acid oleic acid and the omega 6 fatty acids gamma linolenic, arachidonic, and docosapentaenoic, that were found to be significantly decreased, while the omega 3 fatty acids alpha linolenic, eicosapentaenoic, and docosapantaenoic were found to be significantly higher, in S rats compared to L rats (Figure 5A)."
This might confirm a post of mine:
How To Prevent Oxidative Damage In Your Mitochondria
"These reactive oxygen species readily attack the polyunsaturated fatty acids of the fatty acid membrane, initiating a self-propagating chain reaction."
In that post I discussed how a high n-6 diet affects tissue composition, and how the mitochondria could be damaged by such a concentration. In this study we get to see it in action. Increased TBARS suggests that the n-6 membranes are undergoing the reaction described in the post above, and the n-6 fats have been replaced by non-peroxidizable SFA and MUFA fats. It's the same process described in this study:
"...patients with ARDS decrease their percentage plasma concentrations of total plasma linoleic acid, but increase their percentage concentrations of oleic and palmitoleic acids. As plasma linoleic acid concentrations decreased, there was usually an increase in plasma 4-hydroxy-2-nonenal [HNE] values, one of its specific peroxidation products, suggestive of severe oxidative stress leading to molecular damage to lipids. 
"Plasma fatty acid changes and increased lipid peroxidation in patients with adult respiratory distress syndrome."
I won't go into it here, but these seems to confound much research into negative effects of omega-6 fats: the simple n-6 fat level alone does not tell you about the pathological process, as less can mean it's further along.

Conclusion

This is one of the neater studies I've seen, and it seems to have been created as a refutation of the premise, stated in the paper:
"In fact, some authors have hypothesized that HFDs rich in unsaturated fatty acids are less deleterious for human health than those rich in saturated fat [12–15]...."
They successfully illustrate that higher PUFA in the diet do have the effect they surmise:
"...However, polyunsaturated fatty acids exhibit the highest sensitivity to reactive oxygen species (ROS)-induced damage, their sensitivity to oxidation exponentially increasing as a function of the number of double bonds per fatty acid molecule [16]. As a consequence, if antioxidant defense systems are unchanged, a higher degree of fatty acid unsaturation in cellular membranes may increase their sensitivity to lipid peroxidation and would also expose other molecules to lipoxidation-derived damage."
The effect on the liver alone is enough to demonstrate that this higher PUFA diet is unhealthy. However they also manage to demonstrate, in the process, that some of the often-touted benefits of higher-PUFA diets are in fact parts of the pathological process.

(Title is from one of the more bizarre Monty Python skits.)