May 18, 2017

The next gluten? What you need to know about 'lectins'

Daily Briefing

    A controversial book and a flashy infomercial alleging that plant proteins called lectins cause of obesity and poor health prompted The Atlantic's James Hamblin to take a close look at the ethics of selling dubious health claims.

    Are you leading an evidence-based organization?

    Hamblin says he received a book last month called "The Plant Paradox" by a physician named Steven Gundry. The book, among other things, argues that certain plants—including tomatoes, peanuts, wheat, and beans—contain dangerous compounds which incite inflammation and can lead to "weight gain and serious health conditions."

    The publisher, a division of HarperCollins called Harper Wave, said the book contains diet advice that can help readers who are struggling with "cravings, digestive issues, headaches, brain fog, lack of energy, aching joints, morning stiffness, adult acne, or a host of other conditions you just can't shake."

    But as Hamblin notes, the idea of avoiding plant-based foods is far out of the nutritional mainstream, which argues that "soaring rates of obesity and diabetes that … are clearly linked to an abundance of low-nutrient, low-fiber, sugar-enhanced, heavily processed foods"—not an abundance of fruits and vegetables.

    A kernel of  truth?

    "The common factor among foods on the book's list is a broad category of proteins called lectins," Hamblin writes, which Gundry on his websites claims are the "#1 Biggest Danger in the American Diet." Hamblin says the book is filled with similar assertions and "clichés that confer a sense of superiority upon believers—a promise of being privy to life-altering secrets."

    But Hamblin writes that there is a kernel of truth to Gundry's apocalyptic preoccupation with lectins: As early as 1999, medical journals began recording instances in which lectin-heavy foods—such as red kidney beans—made people sick with diarrhea and other symptoms, especially when the foods are uncooked.

    Red kidney beans are high in the lectin phytohaemagglutinin, which is "known to be dangerous," Hamblin writes. However, according to Penn State University's Home Food Preservation advice site, kidney beans are dangerous only when eaten raw, because lectins are inactivated through cooking.

    Lectins, according to Hamblin, are sometimes called an "anti-nutrient," a term which usually refers to "foods that aren't nutrients, and whose role in human health is unclear, but may have evolved in plants to dissuade predators."

    Legumes, such as black and lima beans, are especially high in lectins, but in such foods lectins typically bind to carbohydrates and "pass through the human digestive tract" without any problem. However, Hamblin adds, "when the starches in the above plants haven't begun to be hydrolyzed by cooking, unbound lectins are free to interact with cells in our intestines" and can sometimes cause symptoms of food poisoning.

    A conflict of interest?

    In addition to selling books about his nutritional theories, Gundry also sells expensive supplements to help readers follow his advice, claiming, "Getting all of the nutrients you need simply cannot be done without supplements."

    Hamblin asked Gundry whether there was a conflict of interest in him pushing a dieting theory that calls for people to buy his supplements. "Unlike a lot of other books I've seen which are basically hawking products, this book is hawking getting yourself healthy with basically correct food choices," Gundry argued, adding, "Now, if they want to buy my products, that's fine. You know, I'll certainly tell people what they are."

    However, mainstream nutritionists and researchers say Gundry isn't selling "basically correct" food choices. For instance, "some research suggests that certain lectins could actually be beneficial in activating elements of the immune system," Hamblin writes. And "the much stronger evidence is that the longest-lived, healthiest people in the world tend to subsist largely on plant-based diets" (that "include lectins, often in abundance"), such as the typically Mediterranean Diet.

    How incentives encourage scientists to do bad science

    Gundry dismisses that evidence. "Grains and beans are negative aspects of the Mediterranean Diet that are countered by the large amounts of olive-oil polyphenols, large amounts of red-wine polyphenols, and fish," he said.

    However, Jenkins of the University of Toronto notes that if lectins were the cause of modern health epidemics like obesity, it wouldn't make much sense that such problems would be getting worse even as people eat fewer and fewer plants—including fewer and fewer beans.

    A broader point

    Hamblin isn't so much worried by one doctor, selling one book, based on one questionable health claim. Instead, he closes with a question about how health information is passed along in a consumer-centric market, leading to recurring fads such as the "gluten-free" craze. (The benefits of eating gluten-free are unproven for those without celiac disease, but many Americans have adopted the diet anyway).

    "Book publishing remains one of the industries that drives health trends," Hamblin writes, and calling yourself a doctor can get you instant credibility to sell your health solution—even if it is based on dubious science. And—worryingly—"for some publishers, conflicts of interest like Gundry's don't seem to preclude an author from being sold as the definitive expert on the pathology whose existence necessitates purchase of products sold by the author," Hamblin writes.

    "This is a problem much bigger than any plant protein," Hamblin concludes. "Cycles of fad dieting and insidious misinformation undermine both public health and understanding of how science works, giving way to a sense of chaos" (Hamblin, The Atlantic, 4/24).

    Are you leading an evidence-based organization?

    Despite the shift toward broad acceptance of evidence-based practice (EBP) among medical staff, over half of physicians report not actually using guidelines day-to-day when they are available. As a result, organizations continue to see tremendous variation in clinical practice—as well as in costs and outcomes.

    Our infographic outlines four principles you can use to support EBP at your organization, along with action steps to implement each one and pitfalls to avoid along the way.

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