Lectins are proteins present in all plants and many animal products (e.g. dairy); they are erroneously dubbed ‘anti-nutrients’ and frequently blamed for health damage they did not cause, whilst their clear health benefits are ignored.
What are Lectins?
Lectins are proteins, which possess the ability to bind to carbohydrates. Mass-market media, fad diet books and poor understanding, have linked lectins to be a major cause for everything from chronic inflammation and obesity to autoimmune disease – the illnesses that are not easily explained or too embarrassing to accept.
Which foods contain Lectins?
Unfortunately, the doom scenario starts to unravel from the outset. Lectins are present, at some level, in virtually all plants and even some animal products.
Foods with the highest levels of Lectins are:
- Grains (quinoa, wheat, corn)
- Pulses, or legumes (beans, soy, red kidney, lentils, cashews, peanuts)
- Nuts and seeds
- Nightshades (tomatoes, aubergines, peppers, potatoes, goji berries)
The problem with Lectins?
Lectins are plant defenders in nature, being stable in acid environments. The argument then runs that this stability also prevents them being broken down in your acid gut. This argument is propagated by many people selling dietary and gut aids.
It is true that lectins are known to bind to cells in the digestive tract wall and it is believed this can restrict absorption and alter the microbiome make up.
Since this binding may be long-term, ‘experts’ talk of this causing chronic inflammation and auto-immune disease – rheumatoid arthritis and chronic fatigue syndrome can thus be explained. You ate too much wheat!
It is also true from Laboratory cell studies that lectins can interfere with mineral absorption, especially iron, zinc, phosphorus and calcium.
This is, to some degree, an odd finding since the very foods that contain lectins – for example, lentils – are often high in those minerals.
Lectins and the gut
Perhaps the most infamous lectin is gluten in wheat. If it cannot be broken down in the gut, it can ‘turn on’ the gut wall enzyme Zonulin, and worsen weak patches or holes in the gut wall.
Approximately, 40% of adults are technically gluten-intolerant, and almost 100% are Lactose-intolerant. Fortunately we have our friends in the microbiome to help us.
Lactic Acid bacteria can break down dairy products and lactose for us, leaving perhaps 40% of the World’s population Lactose intolerant. Why? They don’t have the necessary bacteria.
For gluten the figure starts at 40%, but our friends reduce that to about 1%.
But it is not Lectins that caused the problem here – antibiotics, drugs, poor diet, parasites, yeasts, viruses, smoking, alcohol, stress and more can all cause the loss of commensal bacteria reducing our ability to break down lactose or gluten. People often tell me that since they ‘had the operation’, or ‘developed that bout of food poisoning’ they have become gluten or lactose intolerant.
It is perfectly true that there have been cases, for example, of people eating undercooked red kidney beans and developing chronic stomach pains, diarrhoea and even clumped red cells due to a type of lectin, phytohaemagglutinin (1); some people have nut intolerances, others nightshade intolerances; but these are all known to stem from commensal bacteria loss in the microbiome.
If you already have IBS, eating lectins may make it worse. That doesn’t mean to say that Lectins caused the IBS in the first place.
Auto-immune disease – little to do with lectins
Our understanding of auto-immune disease has now moved to another level. Lectins can cause thyroid cells to talk to the immune system and cause Hashimoto’s disease, says one Thyroid site. Really? Hashimoto’s is caused by an overgrowth of bacteria in the small intestine: SIBO. This prompts an immune attack – the bacteria shouldn’t be there. That attack simultaneously targets the thyroid.
Alzheimer’s is linked to gluten argues American nutritionist David Perimutter; but that doesn’t appear to be the case either. E coli and food poisoning bacteria bind to each other and the gut wall producing ‘curli fibres’. These happen to resemble amyloid plaque and are attacked by the immune system, which also attacks the amyloid plaque in the brain because it appears to be the same thing. Gluten has nothing to do with curli fibres.
So are Lectins really a health threat?
Well, firstly, what we are seeing is “is it chicken or egg?” Did the lectins damage the gut, or was the gut damaged before the lectin intolerance?
Secondly, look at how you eat the foods – the majority of lectin foods, you cook. Raw potatoes anyone? Lectins are broken down by cooking.
Next, the storing of pulses (legumes) to provide food for people through the winters was in a dry form, and lentils were usually soaked overnight before cooking; some people suggest you soak nuts too but I have no evidence of that being traditionally the case in the Mediterranean diet. False nuts like peanuts (they are vegetables), maybe. The Thais do soak them and have done for centuries.
But this brings us to another important point. If Lectins are so bad for us how have all the people living along the Mediterranean coast from Naples to Barcelona survived? How have the people of Sardinia with their whole grain pasta, tomatoes, peppers, aubergines, lentils, nuts, seeds, olives, grapes thrived? This diet and lifestyle produces the greatest numbers of 80, 90 and 100 year-old people per head of population in the World? Soaking walnuts? Avoiding whole grain pasta?
Pull the chairs up to the table and we will eat our fresh tomatoes, olives, red peppers and mozzarella with big chunks of whole wheat bread. Lectins, gut problems? Really?
Lectins have huge health benefits!
Lectins are antioxidants, which protect human cells from free-radical damage.
Their action actually slows down the absorption of carbohydrate, preventing dramatic increases in blood sugar and insulin levels and thus restricting diabetes and cardiovascular disease risk.
Lectins also cause cancer cell death(2).
They are now being used to stimulated gut digestive action after colorectal cancer surgery and the use of ileostomy bags and poor diets. There is good research that fresh nut consumption prevents colorectal cancer and especially its recurrence(3).
These foods are high sources of fibre, especially soluble fibre. They increase the numbers of commensal gut bacteria and boost the immune system. They have been shown to reduce weight because they more easily ‘fill people up’ and thus can overturn the obesity epidemic caused by poor and excessive sugar-rich diets.
Lectin foods have been shown(4) to improve T-cell production – your first line of immune defence – and thus to improve immunotherapy drug performance.
Lectins contain B vitamins, often in short supply in the modern diet. And 120 years ago, they were our prime source of protein by a big measure.
We have lived with these foods for thousands of years. They provided our natural good health. It is quite ludicrous to even suggest they are a major source of modern illness.
Modern illness starts with drugs, poor lifestyle and poor diet. It renders people incomplete, their microbiome damaged.
And only then do complications with foods arise, just as they might with alcohol or drugs. Due you really think the people in the mountains of Sardinia have auto-immune diseases?
- Vasconcelos et al.’Anti-nutritional properties of plant lectins’, Toxicom 2004
- Liu et al; Could plant lectins become promising anti-tumour drugs?
- Eating nuts reduces colorectal cancer recurrence and increases survival.
- Increasing fibre intake improves immunotherapy outcomes.