Lectins are carbohydrate binding proteins that are widely distributed in nature and occur in a variety of foods. Largely present in plants, they are consumed almost daily in inappreciable amounts. Many studies have shown that lectins can interfere with nutrient absorption and with this effect it is considered to be an ‘antinutrient’. As “anti-nutrients”, they have received much attention due to popular media and fad diet books citing lectins as a major cause for numerous health issues. It is also being referred to as the ‘new gluten’.
Sources of Lectins
The food we consume is either derived from plants or animals. Plants offer an enormous variety of macro- and micronutrients if we can absorb them. As lectins are present in the most commonly edible plant foods, your exposure to functionally active lectins is a common event
Foods rich in Lectins are
Tomato, Potato, Lentils, Soyabean, Kidney beans, Peas, Carrots, Cherries, Blackberries, Wheat germ, Rice, Corn, Garlic, Peanuts, Mushrooms, Avocado, Beetroot, Leek, Cabbage, Tea, Parsley, Oregano , Almonds, Cashew nuts.
Health impacts
Significant amounts of lectins are found in fresh and processed foods and there is lack of public knowledge concerning the deleterious effects of dietary lectins on health. Along with their presence in most edible foods, lectins are- (a) toxic, inflammatory, or both; (b) resistant to cooking and digestive enzymes.
It is thus no surprise that they sometimes cause food poisoning. In fact in a study, food poisoning in 43 people was attributed to toxins present in uncooked or partially cooked kidney beans. No pathogens were present in the food, but it contained phytohaemagglutinin, a type of lectin that can cause red blood cells to clump together. It can also produce nausea, vomiting, stomach upset, and diarrhea. Milder side effects include bloating and gas. It can also disrupt the intestinal microflora.
Animal studies have reported that active lectins can interfere with the absorption of minerals, especially calcium, iron, phosphorus, and zinc. Legumes and cereals often contain these minerals and the presence of lectins may prevent the absorption and use of these minerals in the body.
Lectins are also capable of causing kidney disorders leading to nephropathy and proteinuria. Of particular interest is the health implication for autoimmune diseases because lectin proteins can bind to cells for long periods of time.
Another suspected lectin disease is rheumatoid arthritis (RA). Lectin found in wheat is one of the most common food triggers for RA patients.
Lectins block mucosa, which is the natural barrier and protector against bacteria and viruses not only in the intestine, but also in the throat. This creates a prolonged state of inflammation which can re-program the immune system and lead to autoimmune condition(Eg., Hashimoto’s)
Many lectins are powerful allergens, and prohevein, the principal allergen of rubber latex, is one. It has been engineered into transgenic tomatoes for its fungistatic properties, so we can expect an outbreak of tomato allergy in the near future among latex sensitive individuals and others.
Ways to reduce Lectin content from foods
Lectins are most toxic in their raw state, however, foods containing them are not typically eaten raw. Cooking processes including high-heat methods like boiling or stewing can inactivate most lectins. These plant antinutrients are water-soluble and typically found on the outer surface of a food, so exposure to water removes them. Simmering at low temperatures such as in a slow-cooker or undercooking lectin containing foods will not remove all the lectins.
Some lectins get destroyed during digestion as a result of enzymes produced by your body. Other processes that deactivate the compounds are sprouting grains and beans, and mechanically removing the outer hull that contains the most lectins.
Lectins are found in a whole variety of commonly consumed foods. It seems likely that the exclusion of lectins from the diet could become the next ‘food fashion’ for Nutritionists to promote, especially as there is evidence to suggest that certain lectins may be harmful to health.
We at iThrive recommend keeping yourself away from lectin containing foods if you are already facing health problems. To find out if lectins are at the root of your health problems, set up a consultation with us and we’ll help you out
References-
- https://sci-hub.tw/10.1016/j.toxicon.2004.05.005
- https://www.hsph.harvard.edu/nutritionsource/anti-nutrients/lectins/#:~:text=The%20problem%20with%20lectins&text=They%20contain%20phytohaemagglutinin%2C%20a%20type,effects%20include%20bloating%20and%20gas.
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1115436/
- https://www.boostthyroid.com/blog/2018/4/12/why-lectins-are-important-for-your-thyroid#:~:text=Nuts%20such%20as%20almonds%2C%20cashew,case%20for%20lectins%20from%20nuts.
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6603809/#:~:text=It%20seems%20likely%20that%20the,may%20be%20harmful%20to%20health.
