Science journal spreads false rumors about vegan diet

PNAS November 28 2017

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.

Fatty Acids

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.

Vitamin A

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

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

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.

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