As I explain in Where Do Gorillas Get Their Protein?, a low-fat vegan diet is good for people and good for the environment. However, an article in the Proceedings of the National Academy of Sciences (PNAS) disagrees. It claims that vegan diets would be a disaster for public health. Yet the authors are not experts on human nutrition or public health. Instead, they are experts on how to feed livestock. Their did not base their conclusions on any studies of human nutrition. As a result, they give bad dietary advice.
The authors of the PNAS article even freely admit that plant-based diets have several important advantages:
- A plant-based diet would increase the amount of food available for human beings.
- Vegans have to eat a huge amount of food to keep from losing weight [That’s why they tend to be thin and free of type 2 diabetes ]
- The 2015 Dietary Guidelines Advisory Committee supported plant-based diets. They noted that plant-based diets would improve health and make our food supply more sustainable.
False claims about vegan diet
The PNAS article claims that the vegan diets would be deficient in several important nutrients. Yet the authors did not show that vegans were getting sick. Instead, they just wrote, “However, without animal-derived foods, domestic supplies of Ca [calcium]; arachidonic, eicosapentaenoic, and docosahexaenoic fatty acids; and vitamins A and B12 were insufficient to meet the requirements of the US population.” That claim is absolutely ridiculous, for the following reasons:
- You do need to get some calcium from your diet. However, nobody gets sick from eating low-calcium diets. Some problems with calcium balance result from a lack of vitamin D (sunshine deficiency). Others result from high-protein, high-calcium diets.
- You don’t need to get arachidonic acid, eicosapentaenoic acid, or docosahexaenoic acid from your food. We do not need to get small amounts of two essential fatty acids from our diet. However, we can easily get enough of both from practically any plant-based diet.
- Human beings can easily get vitamin A from orange, yellow, or dark-green fruit and vegetables.
- Vitamin B12 is the only true vitamin that is lacking from plant-based diets. Vitamin B12 is made by bacteria, not by animals. You can get it from a cheap supplement.
- The article also warns about vitamin D deficiency. Yet vitamin D is not a true vitamin. You can make your own vitamin D if you go outside in the sunshine. You don’t need to get “the sunshine vitamin” from your food.
Concern for industry, not for human health
The PNAS article warns us that a shift to a vegan diet would cause big changes to the economy. These changes would be disastrous for the livestock industry. (The authors of the PNAS article have devoted their careers to serving the livestock industry. They have not studied human health. That is why they know so little about human nutrition.)
A switch to a vegan diet would also be a disaster for the pharmaceutical industry. Many people who shift to a low-fat, plant-based diet can stop taking most or all of their prescription medications. These changes would be good for public health, though bad for industry.
PNAS is a prestigious journal. Yet like other prestigious journals, it sometimes publishes articles that are nonsense. Likewise, PNAS probably also rejects some good articles for stupid reasons. I have worked for peer-reviewed journals. I have also submitted articles to other peer-reviewed journals. Thus, I have seen the problem from both sides, as I explain here. The editors of PNAS failed to send their article to a genuine expert in human nutrition. As a result, they ended up spreading livestock industry propaganda.