Yet Another Silly Study About White Rice!

If you look at arti­cles about East Asian coun­tries in issues of Nation­al Geo­graph­ic from the ear­ly 20th cen­tu­ry, you will notice two things. One is that many of the peo­ple in East Asia were eat­ing a lot of white rice. The oth­er is that only the rich peo­ple and the sumo wrestlers were over­weight. That’s because the rich peo­ple and the sumo wrestlers were eat­ing some­thing besides rice and veg­eta­bles.

Back in the 1930s, Dr. Wal­ter Kemp­n­er real­ized that pop­u­la­tions that ate a rice-based diet were slim and remark­ably free of degen­er­a­tive dis­ease. After he start­ed teach­ing his patients at Duke Uni­ver­si­ty in North Car­oli­na in the Unit­ed States to eat a diet con­sist­ing of white rice and fruit, they lost weight and reversed their type 2 dia­betes. Many of his patients with type 1 dia­betes were even able to cut their insulin dos­es. So why am I see­ing stud­ies that are try­ing to prove that white rice caus­es dia­betes? The lat­est was just pub­lished in the British Med­ical Jour­nal (BMJ).

One prob­lem with the BMJ study is that it ana­lyzed how much white rice peo­ple were eat­ing, but it didn’t account for how much food they were eat­ing and what oth­er kinds of food they were eat­ing. It just looked at a dose effect between serv­ings of rice and health out­comes. That approach is poten­tial­ly mis­lead­ing. For exam­ple, some­one who is in train­ing to become a sumo wrestler prob­a­bly eats a lot more rice than the aver­age Japan­ese per­son does. How­ev­er, he also eats a lot more meat and drinks a lot more beer. Because of their train­ing diet, sumo wrestlers gain weight and often get type 2 dia­betes. Yet it would be extreme­ly dif­fi­cult for some­one to gain enough weight to become a sumo wrestler or even stay over­weight on a diet of white rice and veg­eta­bles. It would there­fore be sil­ly to blame white rice for a sumo wrestler’s weight and blood sug­ar prob­lems.

The BMJ study pro­vides a clas­sic exam­ple of a recur­ring prob­lem I see in the sci­en­tif­ic lit­er­a­ture on nutri­tion. The researchers want to answer a question—in this case, whether white rice makes peo­ple fat and con­tributes to type 2 dia­betes. The sen­si­ble way to answer that ques­tion would be to sur­vey all of the avail­able evi­dence and then see how it relates to Hill’s con­sid­er­a­tions for estab­lish­ing cause and effect in epi­demi­ol­o­gy. Instead, the BMJ study took a very biased view of only one kind of evi­dence and then did some fan­cy math. Then, they came up with a mis­lead­ing result.

The researchers want­ed to know whether con­sump­tion of white rice is linked to obe­si­ty and dia­betes. So they gath­ered a bunch of stud­ies that asked peo­ple about their rice con­sump­tion and that fol­lowed up to see which peo­ple gained weight and got type 2 dia­betes. Then the researchers used a math­e­mat­i­cal approach called meta-analy­sis to com­bine the results of the stud­ies. The biggest prob­lem with this approach is that the researchers chose only one kind of study for their analy­sis: cohort stud­ies of peo­ple who weren’t dia­bet­ic at base­line and who were eat­ing what­ev­er they felt like eat­ing. This means that the researchers sys­tem­at­i­cal­ly left out stud­ies that com­pared rice-eat­ing pop­u­la­tions to oth­er pop­u­la­tions, as well as the clin­i­cal stud­ies of peo­ple who lost weight and reversed their dia­betes after being taught to eat as much as they want­ed of a diet based heav­i­ly on rice and veg­eta­bles.

We’ve known since the ear­ly 20th cen­tu­ry that a high-fat diet pro­motes insulin resis­tance, which is the under­ly­ing prob­lem in type 2 dia­betes. In the ear­ly 1930s, a British researcher named H.P. Himsworth found that he could cause insulin resis­tance in healthy young men in a week by feed­ing them a diet that was 80% fat by calo­rie. As he replaced fat with starch in his test diet, his sub­jects’ glu­cose tol­er­ance improved. He got the best glu­cose tol­er­ance with the starchi­est diet he test­ed: 80% car­bo­hy­drate by calo­rie.

Start­ing in 1939, Dr. Wal­ter Kemp­n­er found that he got great results by teach­ing his patients to eat a diet based on white rice, fruit, and fruit juice—plus some added sug­ar for patients who were los­ing too much weight on that low-fat diet. Kemp­n­er designed this extreme­ly low-fat, low-salt, low-pro­tein diet because many of his patients had kid­ney prob­lems and high blood pres­sure. That was back in the days before blood pres­sure med­ica­tions. The high car­bo­hy­drate con­tent of this diet (>90% by calo­rie) and cor­re­spond­ing­ly low fat con­tent helped to improve his patients’ sen­si­tiv­i­ty to insulin. The Rice Diet Pro­gram that Dr. Kemp­n­er found­ed is still help­ing peo­ple lose weight and reverse their chron­ic ill­ness­es, but now they do empha­size whole grains.

Pho­to by Iqbal Osman1

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