Science journal spreads false rumors about vegan diet

An arti­cle pub­lished this week in the Pro­ceed­ings of the Nation­al Acad­e­my of Sci­ences (PNAS) claims that it would be a dis­as­ter for pub­lic health if the pop­u­la­tion of the Unit­ed States sud­den­ly went 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 actu­al stud­ies of the health of veg­an human beings. The study’s authors even freely 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. [As I have explained in two of my books, this is why a veg­an diet is the key to solv­ing 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.

Nev­er­the­less, the authors of the PNAS arti­cle claimed that the plant-based diet would be defi­cient in sev­er­al impor­tant nutri­ents. Yet they did not back up this claim with any stud­ies that showed that veg­ans are real­ly like­ly to have health prob­lems as a result of nutri­ent defi­cien­cies. 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, for the fol­low­ing rea­sons:

    • Although you do need to get some cal­ci­um from your diet, it is prac­ti­cal­ly impos­si­ble to find actu­al cas­es of peo­ple who did not get enough cal­ci­um from their food. Prob­lems with cal­ci­um bal­ance in the body usu­al­ly result from lack of vit­a­min D or from long-term con­sump­tion of high-pro­tein, high-cal­ci­um diets.
    • The Food and Nutri­tion Board of the Nation­al Acad­e­my of Sci­ences does not con­sid­er arachi­don­ic acid, eicos­apen­taenoic acid, or docosa­hexaenoic acid to be essen­tial in human nutri­tion. In oth­er words, human beings do not need to get them from their food. The only essen­tial fat­ty acids are an omega-6 fat­ty acid called linole­ic acid and an omega-3 fat­ty acid called alpha-linolenic acid. Linole­ic acid is plen­ti­ful in grains, nuts, and seeds. Alpha-linole­ic acid comes from the chloro­plas­ts in green plants and is plen­ti­ful in fresh veg­eta­bles. The require­ment for both of these essen­tial fat­ty acids is so small that it was not even dis­cov­ered until hos­pi­tal­ized patients were being fed noth­ing but fat-free intra­venous solu­tions for a long time.
    • Human beings can eas­i­ly meet their require­ments for vit­a­min A by eat­ing beta-carotene, which is plen­ti­ful in dark green, orange, or yel­low veg­eta­bles.
    • Vit­a­min B12 is the only true vit­a­min that is like­ly to be defi­cient in plant-based diets. Vit­a­min B12 is made by bac­te­ria, not by ani­mals, and can be obtained from a cheap sup­ple­ment.
    • The arti­cle also warns about dietary defi­cien­cy of vit­a­min D. Yet vit­a­min D is not a true vit­a­min. It is a hor­mone that your body can make for itself, for free, if you expose your skin to sun­shine. You don’t need to get “the sun­shine vit­a­min” from your food.

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. (Note that the authors of the PNAS arti­cle are aca­d­e­mics who 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.

PNAS is a pres­ti­gious jour­nal. Yet like oth­er pres­ti­gious jour­nals, it occa­sion­al­ly pub­lish­es arti­cles that are full of non­sense. Like­wise, I imag­ine that PNAS prob­a­bly also rejects some good arti­cles for stu­pid rea­sons. I have worked for peer-reviewed jour­nals, and I have also sub­mit­ted arti­cles to oth­er peer-reviewed jour­nals, so I have seen the prob­lem from both sides, as I explain in this blog post. The mis­take that the edi­tors of PNAS made in this case was to fail to have this arti­cle reviewed by some­one who is a gen­uine expert in human nutri­tion and nutri­tion­al epi­demi­ol­o­gy. As a result, they end­ed up spread­ing live­stock indus­try pro­pa­gan­da.

Is Coconut Oil Good for You?

Late­ly, food fad­dists have been claim­ing that coconut oil is a health food. They claim that it will help you lose weight. In real­i­ty, coconut oil is as fat­ten­ing as any oth­er fat. Some peo­ple even claim that coconut oil can cure Alzheimer’s dis­ease. In real­i­ty, coconut oil can pro­mote ath­er­o­scle­ro­sis, which is an impor­tant cause of vas­cu­lar demen­tia. Also, fats of any kind, includ­ing coconut oil, tend to make your body less sen­si­tive to insulin. For this rea­son, eat­ing coconut oil would prob­a­bly make type 2 dia­betes worse. Coconut oil could even make Alzheimer’s dis­ease worse, since Alzheimer’s dis­ease seems to be relat­ed to insulin resis­tance in the brain. So why are peo­ple pro­mot­ing coconut oil for brain health? The idea that coconut oil is good for your brain came out of the fact that some of the fat­ty acids from coconut oil are use­ful as part of a diet for chil­dren with severe epilep­sy.

Epilep­sy is a con­di­tion in which peo­ple suf­fer from seizures. A seizure is an elec­tri­cal storm with­in the brain. In ancient times, epilep­sy was called “the falling sick­ness” because it often caus­es peo­ple to lose con­scious­ness sud­den­ly. How­ev­er, “par­tial” seizures may sim­ply cause altered men­tal states or uncon­trolled move­ments of the body. Many ancient peo­ple thought that epilep­sy was caused by the gods or by evil spir­its. How­ev­er, the ancient Greek physi­cian Hip­pocrates explained that epilep­sy was an ordi­nary phys­i­cal dis­ease, with phys­i­cal caus­es. The ancient Greeks knew that some peo­ple with epilep­sy did not have seizures while they were fast­ing. Of course, you can­not fast for­ev­er. You have to eat some­thing even­tu­al­ly, or you will starve to death. Once the per­son with epilep­sy resumed eat­ing food, the seizures would start up again.

By the 1920s, physi­cians were look­ing for a way to mim­ic some of the effects of fast­ing, with­out starv­ing the patient to death. They knew that fast­ing caus­es keto­sis, which is the buildup of chem­i­cals called ketone bod­ies in the blood­stream. But they knew that you could also get keto­sis from eat­ing an extreme­ly low-car­bo­hy­drate diet. For rea­sons that are still unclear, keto­sis sup­press­es seizures in many peo­ple with epilep­sy. For this rea­son, an extreme­ly high-fat, low-car­bo­hy­drate “keto­genic” diet has been used since the ear­ly 1920s for the man­age­ment of treat­ment-resis­tant epilep­sy in chil­dren.

Why does an extreme­ly low-carb diet cause keto­sis? Even in the 1920s, it was obvi­ous that keto­sis meant that the liv­er was mak­ing huge amounts of sug­ar. Much of the sug­ar in the blood­stream of some­one with untreat­ed dia­betes does not come from the starch or sug­ar in the food. Instead, it has been made out of pro­tein from the food and from the body’s tis­sues. If the insulin-pro­duc­ing beta cells in the pan­creas stop mak­ing insulin, the alpha cells in the pan­creas assume that the blood sug­ar lev­el must be low. As a result, the alpha cells will make huge amounts of a hor­mone called glucagon. Glucagon tells the liv­er to make glu­cose, to bring blood sug­ar lev­els back up to nor­mal. An over­dose of insulin kills peo­ple by pre­vent­ing their pan­creas from releas­ing glucagon, which would tell the liv­er to release glu­cose to cor­rect the low blood sug­ar. That’s why glucagon is used as an anti­dote to insulin over­dose.

The liv­er makes a lot of glu­cose out of its stores of a starch called glyco­gen. How­ev­er, the liv­er can also make glu­cose out of amino acids (the build­ing blocks of pro­tein) and oth­er non­car­bo­hy­drates. When the liv­er is mak­ing a lot of glu­cose, it may start to use up one of the mate­ri­als that it needs for break­ing fat down com­plete­ly into car­bon diox­ide and water. As a result, more of the fat is processed through an alter­na­tive path­way that pro­duces ketone bod­ies as byprod­ucts.

If you are fast­ing, a lit­tle bit of keto­sis is a good thing. Some of your brain cells can use some of the ketone bod­ies as an alter­na­tive fuel source. But the severe keto­sis that goes along with severe­ly high blood sug­ar in some­one with untreat­ed type 1 dia­betes is a life-threat­en­ing emer­gency.
You can get keto­sis from fast­ing, but you can also get it from an extreme­ly low-car­bo­hy­drate diet. That is why chil­dren with severe epilep­sy are some­times fed an extreme­ly low-car­bo­hy­drate (keto­genic) diet. This keto­genic diet has some impor­tant draw­backs. For one thing, it tends to stunt children’s growth, and it can lead to some severe side effects, includ­ing inflam­ma­tion of the pan­creas. Anoth­er draw­back is that chil­dren do not like the diet, main­ly because their food choic­es are lim­it­ed. Eat­ing even a lit­tle bit of car­bo­hy­drate stops the keto­sis. For this rea­son, it is hard to get chil­dren to stick to the diet well enough to get ben­e­fits.

Most of the fats in our food con­tain main­ly long-chain fat­ty acids. How­ev­er, nutri­tion researchers real­ized that short- and medi­um-chain fat­ty acids are bet­ter at pro­duc­ing keto­sis. Per­haps it is because the short­er-chain fat­ty acids go straight to the liv­er from the intes­tine. The longer fat­ty acids are absorbed through a dif­fer­ent path­way, which does not go through the liv­er before it reach­es the gen­er­al cir­cu­la­tion. Coconut oil is a rel­a­tive­ly rich source of medi­um-chain fat­ty acids. So if you feed an epilep­tic child coconut oil, you can let them eat a bit more car­bo­hy­drate and pro­tein, while still keep­ing them in keto­sis.

Since coconut oil is so good at gen­er­at­ing ketone bod­ies, there has been some inter­est in it for patients with Alzheimer’s dis­ease. In Alzheimer’s dis­ease, the brain is hav­ing some trou­ble with using glu­cose for ener­gy. For this rea­son, some researchers sus­pect that the brain of some­one with Alzheimer’s dis­ease might work bet­ter if some ketone bod­ies were avail­able. Yet this the­o­ry remains unproven.

The keto­genic diet is use­ful in cas­es of child­hood epilep­sy that do not respond to any oth­er treat­ment. How­ev­er, it is not a health-pro­mot­ing diet for the gen­er­al pub­lic. No soci­ety on earth has ever sub­sist­ed on a keto­genic diet for any length of time. Even Inu­it (Eski­mo) peo­ple, who lived on noth­ing but fat­ty meats and fish dur­ing the win­ter, did not go into keto­sis unless they were fast­ing. Also, there is plen­ty of evi­dence that high-fat, low-car­bo­hy­drate diets lead to rapid aging and ear­ly death, even if they do not pro­duce keto­sis.

Like anti­seizure drugs, a keto­genic diet may be good for some chil­dren with epilep­sy but should not be rou­tine­ly giv­en to peo­ple who do not have epilep­sy. Unless you have treat­ment-resis­tant epilep­sy, you would be bet­ter off eat­ing an extreme­ly low-fat, high-car­bo­hy­drate diet based on starch­es and veg­eta­bles. The soci­eties that have tra­di­tion­al­ly used coconut oil tend to have low rates of heart dis­ease. How­ev­er, that is usu­al­ly because their over­all intake of fat and cho­les­terol is low. Most of their calo­ries came from car­bo­hy­drates (starch­es and sug­ars) in the rice and starchy veg­eta­bles (such as sweet pota­toes and poi) that made up the bulk of their diet. Since these peo­ple lived in the trop­ics, they also ate a lot of fruit and veg­eta­bles. Some Poly­ne­sians eat a lot of coconut. How­ev­er, they are gen­er­al­ly eat­ing whole coconut, rather than coconut oil. As a result, they get a lot of pro­tec­tion from the fiber con­tent of the coconut. In the intes­tine, fiber binds to the cho­les­terol that the liv­er pro­duces to help you digest fat. As a result, the cho­les­terol can leave the body with the feces, rather than being reab­sorbed into the blood­stream.

If you want to lose weight and pro­tect your heart and brain, don’t add coconut oil to your diet. Instead, remove oils and ani­mal-source foods from your diet. The pop­u­la­tions that eat a starchy, high-fiber diet based on low-fat plant-source foods have the clean­est arter­ies and the best chance at a long and healthy life.