An article published in the November 28, 2017 Proceedings of the National Academy of Sciences (PNAS) claims that Americans would get nutrient deficiencies if they go vegan. Yet the authors are not experts on human nutrition or public health. Instead, they are experts on how to feed livestock. Their conclusions were not based on any studies of the health of vegan human beings.
Admitting Some Truths
The study’s authors do admit that plant-based diets have several important advantages:
- Shifting to a plant-based diet would increase the amount of food available for human beings.
- A plant-based diet requires people to eat a greater volume of food, to maintain the same weight. [That is why a vegan diet is the solution to our epidemics of obesity and type 2 diabetes.]
- The 2015 Dietary Guidelines Advisory Committee concluded that plant-based diets would improve health and improve long-term sustainability of the US food supply.
Spreading Big Lies
The authors of the PNAS article claimed that the plant-based diet would be deficient in several important nutrients. However, they did not back up this claim with any studies of nutrient deficiencies among vegans. The authors 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.
The Truth About Vegan Nutrition
You do need to get some calcium from your diet. But it is practically impossible to find anyone who got sick from a low-calcium diet. Instead, problems with calcium balance in the body usually result from lack of vitamin D or from high-protein diets.
Do not worry about getting arachidonic acid, eicosapentaenoic acid, or docosahexaenoic acid from your food. The Food and Nutrition Board of the National Academy of Sciences says that they are not essential. In other words, you do not need to get them from your food. There are two fatty acids that you do need to get from your food.
- Linoleic acid is an omega-6 fatty acid. You can easily get it from grains, nuts, and seeds.
- Alpha-linoleic acid is an omega-3 fatty acid. It comes from the chloroplasts in green plants and is plentiful in fresh vegetables.
Human beings need very little of these essential fatty acids. Our need for them was not discovered until hospital patients were being fed nothing but fat-free intravenous solutions for a long time. Even then, the problem could be solved by rubbing a little bit of vegetable oil on the patient’s skin.
Human beings can easily meet their requirements for vitamin A by eating orange, yellow, or dark-green vegetables. These vegetables contain beta-carotene, which your body can convert to vitamin A.
Vitamin B12 is the only true vitamin that is likely to be missing from a balanced plant-based diet. Vitamin B12 is made by bacteria, not by animals. It can be obtained from a cheap supplement.
Vitamin D is not a true vitamin. It is a hormone that your body makes if you get sunshine on your skin. You don’t need to get “the sunshine vitamin” from your food.
Good for People, Bad for Industry
The PNAS article warns us that a shift to a vegan diet would cause big changes to the economy. In particular, it would be disastrous for the livestock industry. The authors of the PNAS article have devoted their careers to serving the livestock industry, not to studying human health. This explains why they know so little about human nutrition and nutritional epidemiology.
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.
Even Good Journals Sometimes Publish Nonsense
PNAS is a prestigious journal. Yet like other prestigious journals, it occasionally publishes nonsense. Likewise, I imagine that PNAS probably also rejects some good articles for stupid reasons. I have worked for peer-reviewed journals. I have also submitted articles to peer-reviewed journals. So I have seen the problem from both sides, as I explain in this blog post. The editors of PNAS made a mistake in this case. They failed to have this article reviewed by a genuine expert in human nutrition and nutritional epidemiology. As a result, PNAS ended up spreading livestock industry propaganda.