Dr. David Katz, Preventative Medicine: Do we dare to eat lectins

Dr. David Katz. (contributed photo)
Dr. David Katz. (contributed photo)Journal Register Co.

Lectins are a family of proteins found in many plants, dairy, yeast, eggs, and seafood that can bind to other molecules, notably sugar and carbohydrate molecules, that are present both in foods, and in the membranes of our cells. The case made in the The Plant Paradox, a current best-seller, is that the binding of lectins from plant foods to our cells is a major cause of ill health, and thus we must all fear and avoid lectins, and the rather dire foods, such as berries and beans, that sinisterly serve as their delivery vehicles. This, of course, is utter nonsense.

For starters, the reality of lectins is far more nuanced than the sound bites, scapegoats, and silver bullets of formulaic best sellers in the diet category. The scientific literature raises theoretical concerns about the potential toxicity of lectins in certain contexts, but also suggests the possibility of unique health benefits related to cancer prevention, and gastrointestinal metabolism. Lectins are far more active in binding to our cells when consumed at high concentration and in isolation, as they are in experiments, than when consumed in food — as they generally are by actual humans. Cooking often attenuates the binding action of lectins, or causes them to bind to other compounds in food.

This is not the first time we have been warned away from fruits and vegetables, beans and legumes, nuts and grains. Both low-carb and gluten-free diet advocacy foreswear whole grains, despite overwhelming evidence of the health benefits they consistently confer on all but the constitutionally intolerant. Both low-GI and fructose-is-toxic dietary platforms have caused people, intentionally in the first case and perhaps unintentionally in the second, to abandon fruit, despite overwhelming evidence of its role in defending us even against the very concerns associated with high-glycemic foods and excess fructose, notably type 2 diabetes. We abandoned nuts in the throes of misguided applications of advice to reduce dietary fat intake, somehow reaching the conclusion that Snackwells were good for us, while almonds were not.

This decades-long parade of dietary fads and fashions, an incessant sequence of nutritional misadventures demonstrate one thing above all others: there is more than one way to eat badly, and we the people of the United States seem committed to exploring them all. If you have a new version of dietary nonsense to sell, put it in a book — and we will buy it.

The new contention that we should avoid all of the most nutritious plant foods, including many vegetables, nearly all fruits, all beans, and all legumes because they contain lectins, takes nutritional nonsense to a whole new level. Following this advice will decimate the quality of your diet, and for anyone who actually sticks with such silliness over time (an unlikely eventuality with any diet) — your health.

The case being made against most of the foods most reliably linked to vitality and longevity suffers from several fallacies common to all manner of nutritional nonsense. One is to prioritize a theoretical concern (or hope) over the prevailing pattern of outcomes among actual people. As I recently noted to a colleague, oxygen is not a theoretical toxin with theoretical harms in people; it is a known toxic with established harms. The atmosphere of our planet is thus analogous to the dietary sources of lectins: both contain compounds with potentially toxic effects, but net benefit is overwhelming both from eating plants, and breathing.

Another is the conflation of a change in the dialogue about some threat with a change in the threat itself. In 2015, for instance, the International Agency for Research on Cancer, a subsidiary of the World Health Organization, declared processed meat, bacon, pepperoni, and such, a class I carcinogen. There was widespread media coverage, the customary hyperbole, and something nearing panic among the “I have never met a slice of bacon I didn’t like” crowd.

But, of course, such a response made no real sense. Yes, processed meat is bad for you, and yes, you’d be better off not eating it. And yes, eating it is rather bad for our fellow creatures and the planet, too.

But the risk from one day to the next changed not at all. Whatever your risk for cancer had been all along, it remained exactly the same the day after the IARC determination was announced. All that had changed was the official position on the matter of that risk. Similarly, the lectins that are in your hummus this week were there last week, too.

So, do you need to fear lectins now? Dr. Steven Gundry, the author, who reportedly will be happy to sell you supplements to replace the nutrients present in the foods he is telling you not to eat, says: yes. I say: hold your breath, and count to a thousand while contemplating the theoretical toxicities of oxygen. Long before you finish, the truth will surely come to you in a gasp.
