top of page

What are lectins and should I avoid them?

Have you seen social media posts or read a book which tells you that lectins are the underlying cause of obesity, auto immune diseases or inflammation? Surely these dangerous components of some foods should be completely avoided?!

What is a lectin?

A lectin is defined as a protein which binds to a carbohydrate. They are found in all plants. However, the highest amount is found in raw legumes (peas, beans, lentils and peanuts) and in whole grains. They are known as an ‘anti-nutrient’ because they can block the absorption of minerals in food such as calcium, iron and zinc. They are stable in acidic environments (so won’t be broken down by stomach acid during digestion). They can also bind to the cells which line the gut and can affect the growth and reproduction of the gut bacteria.

What do lectins do?

Lectins can cause issues when eaten intheir raw state. Raw red kidney beans have been reported to cause severe adverse reactions such as nausea, vomiting, stomach upset, diarrhoea, bloating and gas. This is due to the raw or undercooked component phytohaemagglutinin. Note that this only occurs if you eat raw or undercooked red kidney beans. Fully cooked red kidney beans are absolutely safe and the lectins are no longer in an active state. Many people ask me how long they need to cook tinned kidney beans for. The answer is zero minutes. Tinned beans are already fully cooked and can be eaten straight from the tin, in a salad for example.

How can I avoid these issues?

Simple. Do not eat uncooked beans, lentils or peas. Cook your wholegrains. To be honest these foods are pretty unpalatable raw anyway! Lectins are water soluble and so when you soak them in water prior to cooking, or cook in water then the majority of lectins are rendered inactive. If you cook your beans in a slow cooker at a low heat then some lectins may still be active. Small amounts if active lectins are fine.

Our bodies do produce some enzymes which can degrade some lectins during the process of digestion. Sprouting grains and beans also deactivates them.

Maybe I should avoid them to be safe…?

Please don’t. Lectin containing foods are some of the cornerstones of a high fibre, healthy diet. Take out whole grains and legumes and you will be missing out on some very valuable foods which research shows are fantastic as prebiotics (food to encourage growth of beneficial bacteria in the gut), prevent constipation, can help in weight loss diets, reduce risk of colon cancer, are a valuable source of vegetarian protein and provide many of the B vitamins.

Lectins are also antioxidants, protecting the body from free radicals which cause cell damage and can lead to cancer.

Being hard to digest, lectin containing foods are more slowly digested and do not cause blood sugar spikes, making them useful for pre diabetics or those trying to lose weight.

The future of Lectins

Contrary to the scaremongering which has gone on around lectins, based on very little research, they could prove to have benefits beyond those which we already know about. Research is beginning into how lectins might play a part in anti cancer treatments since they can cause cancer cell death, and maybe also in treating patients who have not been able to eat for long periods, by stimulating the growth of new gut cells.

The take home message.

Lectins have been much maligned, yet they are found in some of the healthiest foods we know of, backed by massive amounts of reliable research. Soak and cook lectin containing foods well and you’ll have no issues whatsoever. In fact, you will be consuming a healthy, high fibre diet which will benefit your body in many ways.


bottom of page