With echoes of the gluten-free craze, lectins are being wrongly vilified with a glut of questionable health claims, says Anthony Warner
By Anthony Warner
Just in case there was not enough fear and misinformation about food, the latest restrictive fad sent to cure us of all ills is the lectin-free diet. Lectins, a family of proteins found in many foods, have been described as “the new gluten”, and if that refers to them being wrongly demonised, it might not be far from the truth.
A lot of their bad press stems from overblown claims in a recent book, The Plant Paradox, by US heart surgeon Steven Gundry. In it, he outlines his belief that lectins are toxins driving obesity and a host of other conditions. The resulting diet vilifies a long list of foods, including grains, legumes, pulses, beans, peas, corn, soy, tomatoes, peppers, squashes, courgettes and even quinoa, usually the darling of new-age health writers.
The main focus of the book is weight management, and in this area Gundry might just be on to something. When speaking of the clients he treats in his exclusive California clinics, he notes that “the more supposedly healthy foods that I eliminated, the more their health improved”.
If we substitute the words “their health improved” with “they lost weight”, then the apparent paradox is perhaps not so surprising. It is not hard to imagine that you will almost inevitably lose weight by cutting out staple foods after a doctor tells you they contain toxins that are tearing holes in your gut.
The later chapters of Gundry’s book outline the many nutritional substitutes that anyone embarking on strict lectin avoidance will need to take. Cutting out all lectin-containing foods could lead to nutritional deficiencies, and although one might question the wisdom of a diet that fails to provide adequate nutrition, at least Gundry recognises this. He directs dieters to the online shop section of his website, which sells his supplements – a selection of prebiotics, polyphenols and specially designed “lectin shields”, with the products priced up to $99.99.
Weighing the evidence
But Gundry’s theories on the damaging effects of lectins are not supported by mainstream nutritional science, and any lectin-free diet is a long way from what any qualified dietician might recommend as healthy.
It is true, and has been known for decades, that in some cases, lectins can be harmful, especially those in raw or undercooked kidney beans, lentils or other dried pulses. However, in properly prepared food in the quantities that most of us experience in our diets, they do us no harm. As with many substances, the dose makes the poison.
There is also some evidence that lectins of various types might be beneficial. What is true is that when consumed in a normal diet, any potential injurious effects they may have are hugely outweighed by other beneficial nutrients.
The overwhelming evidence of benefit from a diet high in lectin-containing fruits, vegetables, seafood, pulses and wholegrains is so overwhelming as to render Gundry’s arguments laughable.
Fear about lectins is easy to create, because it relies on a misunderstanding about the nature of food, a belief that all constituent parts have to be just right for us. In reality, no whole food is perfect, and everything contains a wide spectrum of components with different effects on the body.
Those effects are often nuanced and complex, and sometimes poorly understood. This can be hard for our certainty-craving brains to accept – which sadly leaves the door open for those who claim to offer definitive answers in the absence of solid evidence.