Essentially the mother was so vitamin deficient that she couldn't produce milk that would sustain her child.
Here's another account:
"...He said they also have a 13-year-old daughter who has never suffered any serious health problems.
"Mr Daquo said both Mr and Mrs Le Moaligou were also opposed to traditional medicines, and used alternative therapies instead.
"Mr Daquo said: ‘The couple did not follow doctor’s advice to take their baby to hospital when she was suffering from bronchitis and was losing weight when they went for the nine-month check-up.
"‘They preferred applying clay or cabbage poultices whose recipes they found in their books. These are people who read the wrong thing at the wrong time.’
"Mr Le Moaligou’s lawyer, Patrick Quenel, said the couple remained committed vegans and were ‘wholly aware of the mistake they made’, but pleaded not guilty.
"The Le Moaligous were formally charged with ‘neglect and food deprivation followed by death’ which carries a maximum sentence of 30 years.
"The Le Moaligou case is believed to be the first time that a couple have faced a prison sentence for a crime directly linked to a vegan lifestyle.
"It will rekindle the fierce debate about the health benefits of veganism – a term first coined by Englishman Donald Watson, who founded the Vegan Society in 1944..."
Well it should. I will note however that vitamin B12 deficiency is a well-known shortcoming of a vegan diet. These two were grossly negligent to not supplement B12, in my opinion.
See here for Chris Masterjohn's excellent article on the nutrional deficits of a vegetarian/vegan diet.
Or see here for Richard Nikoley's take, titled, appropriately: "Stop the Madness: Vegans Keep Killing Their Kids."
P.S. I'm not a fan of a vegan diet, I don't think it's optimally healthy in the long-term, but this is not the expected outcome for a kid on that diet.. There were some other vegans who killed their kid by only feeding it apple juice. Feeding *anyone* only apple juice is going to kill them.
This is a from a similar case from Arizona, where luckily the kids survived:
"'Vegan children who are fed properly grow,' said Deputy County Attorney Frankie Grimsman.
"And in fact, when the children were placed in foster homes, they immediately began to gain weight - while still maintaining vegan diets."
Vegans have pretty typical patterns of malnutrition, but you can survive on this diet.