Lectins are a type of carbohydrate-binding protein that stick to cell membranes in the digestive tract.

They exist in most plant and animal foods. However, they’re found in the highest amounts in legumes, nightshade vegetables, dairy products, and grains, such as barley, quinoa, and rice.

Some types of lectins, such as ricin, are toxic, but others aren’t.

There is limited research on how lectins affect people. The lectin-free diet promotes reducing intake of or completely eliminating lectins from your diet. This may be beneficial for some people with food sensitivities. However, more research is still needed.

If you don’t include a variety of nutrients in your diet, it may negatively impact your health.

On the other hand, if you have food sensitivities or are prone to gastrointestinal distress, avoiding foods with lectins may be beneficial.

Lectins haven’t been studied extensively in humans. Currently, there is no evidence that concludes whether it’s good or bad for your health.

The lectin-free diet is restrictive and eliminates many foods — even those thought to be healthy.

It may benefit people with food sensitivities

Eating large amounts of food containing lectins may cause gas or gastric distress in some people. Lectins aren’t digestible. They bind to cell membranes lining the digestive tract. There, they may disrupt metabolism and cause damage.

It can help you to avoid potentially toxic foods

Cooking destroys most lectins in food. It’s important to avoid raw, soaked, or undercooked beans, such as kidney beans, which have been found to be toxic to people due to their lectin levels. One study reported that soaking beans isn’t enough to remove lectin content.

It might reduce peptic ulcers

An animal study showed the negative effects of lectins in rats. They spiked bacterial growth in the small intestine and stripped away the mucous defense layer. This increases the risk of peptic ulcers.

It may help you avoid damage in your digestive tract

Some research notes that lectins can disrupt digestion and cause intestinal damage if eaten in large quantities over a prolonged period of time.

Data from human studies is lacking

Research on lectins, and their effects on people, is currently sparse. Most of the studies have been conducted on animals, not humans. Research has been largely performed in vitro. This means it has been conducted with isolated lectins in laboratory dishes or in test tubes.

The claims may be biased

Approach your lectin research with a healthy dose of skepticism. Look for science-based evidence instead of inflated claims on websites that sell cookbooks or supplements geared toward helping you achieve lectin-free health. Some may be what they claim to be, but others may not.

For example, there are claims that lectins promote weight gain, but multiple studies, such as this one on pulse consumption, indicate a positive weight loss effect.

The diet is lacking in broad-based nutrition, including fiber

Many healthy foods are prohibited on the lectin-free diet, making it hard to stick to. This food plan lacks many of the nutrients needed for optimum health.

All plants and animal products contain some lectins. Fruits and vegetables on the low end of the lectin scale include:

  • apples
  • artichokes
  • arugula
  • asparagus
  • beets
  • blackberries
  • blueberries
  • bok choy
  • broccoli
  • Brussels sprouts
  • cabbage
  • carrots
  • cauliflower
  • celery
  • cherries
  • chives
  • collards
  • cranberries
  • kale
  • leafy greens
  • leeks
  • lemons
  • mushrooms
  • okra
  • onions
  • oranges
  • pumpkins
  • radishes
  • raspberries
  • scallions
  • strawberries
  • sweet potatoes
  • Swiss chard

You can also eat all forms of animal protein, such as fish, beef, chicken, and eggs. Fats, such as those found in avocados, butter, and olive oil, are allowed on the lectin-free diet, as are many types of nuts such as walnuts, pecans, pistachios, pine nuts, flax seeds, hemp seeds, sesame seeds, and Brazil nuts.

Foods highest in lectin include:

  • nightshade vegetables, such as tomatoes, potatoes, goji berries, peppers, and eggplant
  • all legumes, such as lentils, beans, peanuts, and chickpeas
  • peanut-based products, such as peanut butter and peanut oil
  • all grains and products made with grain or flour, including cakes, crackers, and bread
  • many dairy products, such as milk

  • If you feel that going lectin-free is for you, you’ll want to make sure to avoid foods high in lectins every day.
  • You can also prepare foods that contain lectins in a pressure cooker, which may help reduce levels.
  • Soaking and boiling beans can help reduce their lectin content.
  • Fermenting or sprouting grains and beans can also help to reduce their lectin content.
  • It may make sense to take a trial-and-error approach to see if you feel better or experience a reduction in gastric distress by removing some foods, but not others.
  • Many of the foods that are eliminated on this food plan are high in dietary fiber, which is beneficial to health. Make sure to eat enough fruits and vegetables to compensate, or take a fiber supplement.
  • It may help to discuss the diet with your doctor or dietitian prior to proceeding. This will help to ensure that you get the full range of nutrients you need every day.

The lectins found in raw beans is dangerous to humans and can be deadly. Most foods contain some lectins, but those highest in this carbohydrate-binding protein are nightshade vegetables, legumes, and grains.

Scientific research on lectins is lacking in humans, but there are some animal studies that indicate a lectin-free diet might be beneficial for some people, such as those with food intolerances.

Make sure to take a critical approach when researching this food plan — many websites that promote it are trying to sell products.