Lectins

What are lectins?

Lectins are proteins from plants that can bind to sugars on the outside of body cells. Almost all plants contain lectins, but the concentration is higher in seeds, grains and legumes. For the plant, lectins are part of a defense system against predation and infections.

In humans, lectins in high, unprocessed doses can irritate the intestinal wall. With normal preparation, such as soaking and thorough cooking, lectins are largely broken down and the burden is much lower.

Where are lectins mainly found?

Relatively high lectin content in:

Unprocessed or barely heated grains: wheat, rye, barley, oats, rice
Legumes: beans, lentils, chickpeas, soy, peanuts
Some nuts and seeds: including cashews, peanuts
Skin and seeds of some vegetables: such as tomato and pepper

What do lectins do in the body?

In laboratory research, some lectins have been seen to attach to fat cells and receptors and give signals there that somewhat resemble those of insulin. This is called insulinomimetic. In these experiments, high concentrations of lectins are used and isolated cell cultures are examined.

In humans, it involves a much more complex system: gut barrier, immune system, hormones, liver, muscles and fat tissue all work together. The translation of laboratory data to practice is therefore limited.

Are lectins the main cause of obesity and metabolic dysfunction?

No. Obesity and metabolic conditions almost always arise from a combination of factors:

Long-term intake of more energy than is used
Many ultra-processed, energy-dense foods
Little exercise and loss of muscle mass
Disrupted sleep and chronic stress
Individual predisposition and medication

Insulin and insulin resistance play a central role here. For lectins, the evidence is limited. There are no large clinical studies showing that specifically reducing lectins, separate from energy and carbohydrate restriction, leads to clear improvement in weight and metabolic health on its own.

Lectins in the context of therapeutic carbohydrate restriction (TCR)

With a carbohydrate-restricted or ketogenic eating pattern, total carbohydrate intake is reduced. As a result, the diet often automatically shifts toward fewer grains and legumes and more vegetables, proteins and fats.

This has multiple consequences:

Total carbohydrate and insulin load decreases
Intake of lectin-rich products from grains and legumes often decreases
Emphasis shifts to unprocessed food, which is favorable for metabolism

In practice, it’s difficult to separate exactly which part of the effect comes from fewer carbohydrates, which part from less ultra-processing and which part from fewer lectins.

The core of TCR remains: reducing carbohydrate load and normalizing energy intake within a complete eating pattern.

When can it be useful to additionally restrict lectins?

For some people, an additional low-lectin approach may be useful, particularly:

For known celiac disease or clear wheat sensitivity
For inflammatory bowel diseases or severe irritable bowel complaints
For active autoimmune diseases, where a role of gut barrier and food is suspected
For clear, repeatable complaints after legumes, certain grains or nuts, despite correct preparation

Temporary approach (preferably with guidance)

Restrict grains and legumes (further) or choose carefully
Temporarily omit skin and seeds of nightshades (tomato, pepper)
Focus strongly on well-tolerated vegetables, animal proteins, eggs and fats

Practical advice about lectins and TCR

1. Choose mainly unprocessed products

The less industrially processed, the better for gut, hormones and metabolism. This is more important than just avoiding lectins.

2. Prepare grains and legumes well, if used

Always soak and rinse thoroughly where possible
Cook for a long time or pressure cook until really done
Don’t use raw or undercooked beans

Within stricter TCR, grains and legumes often fit only in small amounts or temporarily not at all. If they are used, proper preparation is essential.

3. Observe your own reaction

Pay attention for several weeks to abdominal complaints, bloating, bowel movements, energy, skin, weight and possibly glucose. If complaints clearly correlate with certain lectin-rich products, further restriction may be useful.

4. Lay the foundation with TCR principles

Limit sugars, fruit juices, soft drinks and sweet snacks
Limit white bread, white rice, pasta and other refined carbohydrates
Use plenty of non-starchy vegetables
Ensure sufficient protein (fish, meat, eggs, dairy as tolerated)
Add healthy fats (olive oil, butter, full-fat dairy, nuts if tolerated)

5. Lifestyle pillars besides nutrition

Daily exercise, strength training, good sleep and stress reduction strengthen the effect of TCR and are at least as important as whether or not to restrict lectins.

Key message

Lectins are plant proteins that in some sensitive people can contribute to gut and inflammation complaints. In laboratory research, certain lectins appear to be able to promote fat storage, but in humans it has not been demonstrated that lectins by themselves play the main role in obesity or metabolic dysfunction.

The most important lever for metabolism remains a sustainable healthy eating pattern with few ultra-processed, carbohydrate-rich products, combined with sufficient exercise, good sleep and stress reduction.

A therapeutic carbohydrate restriction (TCR) can be a powerful tool to reduce insulin load and improve metabolic health. Additional restriction of lectins can be a useful addition with individual sensitivity, but is not a standard requirement to become metabolically healthy.

Veelgestelde vragen

What are lectins?

Lectins are proteins from plants that can bind to sugars on the outside of body cells. They are mainly found in seeds, grains and legumes and are part of the plant's defense system.

Are lectins the cause of obesity?

No. Obesity arises from a combination of factors: excessive energy intake, ultra-processed food, little exercise, poor sleep and stress. There is no evidence that lectins play a major role in obesity when food is properly prepared.

How do I make lectins harmless?

Through traditional preparation: soaking in water, prolonged boiling or pressure cooking, fermenting, and removing skin and seeds where necessary. Raw or undercooked legumes and grains contain the most active lectins.

When is additional lectin restriction useful?

For celiac disease or wheat sensitivity, inflammatory bowel diseases, active autoimmune diseases, or with clear repeatable complaints after legumes or grains despite correct preparation. It is not a standard requirement for metabolic health.

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Medical Disclaimer: The information provided by Stichting Je Leefstijl Als Medicijn regarding lifestyle, diseases, and disorders should not be construed as medical advice. Under no circumstances do we advise people to alter their existing treatment. We recommend that people with chronic conditions seek advice regarding their treatment from qualified medical professionals.