Should we be afraid of lectins? What the science actually says

What do we really know about lectins, oats, cashews, and brown rice?

Lectins lowdown 

Lectins are a large family of carbohydrate‑binding proteins naturally present in many plants, including beans, grains, nuts, and some vegetables​ (source). Lectins are also classified as antinutrients - natural compounds that are found in plants and some animal foods. Antinutrients can interfere with the absorption of nutrients; however, this risk is usually mitigated by cooking, soaking, sprouting or fermenting foods.

In high amounts and in inadequately prepared foods (for example, undercooked red kidney beans), certain lectins can cause acute gastrointestinal symptoms such as nausea, vomiting, and diarrhea, which is well documented in case reports and risk assessments​ (source).

However:

• Food‑safety bodies note that when plant foods are properly cooked and eaten in moderation, lectins are not expected to have negative health effects for the general population.​
• A scientific review of wheat lectins concluded that, under typical conditions of cooking and processing, current data “do not support negative health effects in humans”​ (source).

Some lectins may also have beneficial properties, including possible roles in helping protect against certain cancers and infections, and supporting gut health. Research has also explored their potential links to lower risk of type 2 diabetes and obesity, showing that it is a lot more nuanced than “lectins are bad”​ (source).

Do lectins “poke holes” in the gut and cause leaky gut?

Health and wellness influencers’ claims often describe lectins as physically “poking holes” in the intestinal wall, causing “leaky gut” and a cascade of chronic disease.​​

What research shows:

• In vitro and animal work indicates that high doses of certain raw lectins can alter intestinal cell turnover, increase permeability, and affect immune responses (source).
• A risk assessment from Germany’s Federal Institute for Risk Assessment (BfR) concludes that these effects are mainly seen with high, non‑dietary exposures or improperly processed foods and that most lectins, as normally consumed, are not expected to harm gut health​ (source).
• Based on the current human data, there is no direct, clinically meaningful link between intake of cooked-food lectins and "leaky gut" or autoimmune disease (source).

Bottom line: In other words, concerns from high‑dose or raw exposures cannot simply be translated into “cooked oatmeal, cashews, and brown rice routinely damage your gut.”

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Claim 1: “Oatmeal is loaded with glyphosate, other pesticides and herbicides and loaded with lectins. It feeds horses - not you”

Fact check: Assertions that oats are unsafe because of lectins or pesticide residues oversimplify and misrepresent the evidence; processing reduces lectin activity, regulatory limits exist to keep residues within safe levels, and oats are associated with cardiovascular benefits when eaten as part of a balanced diet.

Oats, lectins, and preparation

Oats do contain lectins, but:

• Oats are almost always heat‑processed (steamed, rolled, or otherwise heated) before reaching the consumer, which substantially reduces lectin activity.​
• Reviews of cereal lectins indicate that typical processing (cooking, baking, extrusion) significantly diminishes lectin content and biological activity​ (source).

Observational studies consistently associate higher intake of whole grains, including oats, with lower risk of cardiovascular disease and all‑cause mortality, suggesting no obvious harm at population level, although these specific observations are not primarily about lectins.​ (source) (source). While research focusing on oats, specifically, also concludes that a higher oat intake is associated with lower risk of type 2 diabetes and reduced all-cause mortality (source).

Glyphosate and pesticide residues in oats

Residues of glyphosate and other pesticides can be detected in some oat products, especially when glyphosate is used as a pre‑harvest desiccant.​

However, here are some key points from regulators on this subject:

• EFSA’s (The European Food Safety Authority) latest glyphosate risk assessment includes cereals such as oats, and current EU regulations are based on the conclusion that dietary exposure to glyphosate is unlikely to pose a health risk at typical intake levels​ (source).
• The 2023 EU pesticide residue report found that the vast majority of foods tested, including cereals, were within legally allowed maximum residue levels (MRLs), with dietary exposure remaining below toxicological reference values (source).

This does not necessarily mean “zero exposure,” but it does mean that, under current regulations, glyphosate residues in oat products are considered unlikely to pose a health risk at typical intake levels.​ In addition, it’s important to also note that organic standards ban glyphosate use, and surveillance data show markedly lower pesticide residues in organic foods in general (source) (source).

“Horse feed, not human food”

Calling oats “horse feed” ignores extensive human data:

• Oats are widely recognised in clinical and public‑health guidance as a source of beta‑glucan fibre, which can help reduce LDL cholesterol and support glycemic control​ (source).
• No major health authority recommends avoiding oats because of lectins; instead, they are often recommended as part of a balanced, fibre-rich diet.​

The claim that oatmeal is one of the “worst foods you can put in your body” due to lectins and glyphosate is therefore not supported by current evidence when oats are prepared and consumed in typical ways.

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Claim 2: “Cashews are loaded with lectins, hard on your stomach and poke holes in your gut”

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Fact check: Claims that cashews are harmful due to lectins or antinutrients oversimplify the evidence; in reality, typical processing mitigates these compounds, and moderate consumption fits safely into a heart-healthy diet.

Cashews do contain antinutrients (like many nuts and seeds), but the context again matters.​

Key points:

• Cashews sold for consumption are heat‑treated to remove toxic components in the shell (such as urushiol‑like compounds). More broadly, this heat processing also denatures proteins, including lectins, reducing their biological activity (source).
• Human studies and dietary patterns frequently associate nut consumption (including tree nuts) with reduced risk of cardiovascular disease and improved overall diet quality, not increased gut damage, when eaten in moderate amounts (source).

Lectins and other antinutrients can theoretically contribute to digestive discomfort in some sensitive individuals, especially in large quantities.​ However, there is no robust body of human clinical evidence showing that normally prepared cashews “poke holes” in the gut or are uniquely damaging compared with other nuts.​ For most people without specific allergies or intolerances, cashews can reasonably fit into a varied, plant‑rich diet.​ In fact, some research shows that cashew nuts have been associated with reduced gut permeability.

If someone notices consistent gastrointestinal symptoms after eating cashews, individualised avoidance is reasonable, but that is very different from a blanket claim that cashews are broadly harmful due to lectins.

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Claim 3: “Brown rice is loaded with lectins”

Fact-check: Although brown rice does contain slightly higher levels of lectins, claims that it is harmful because of this are not supported by human evidence. In fact, brown rice remains a widely accessible, fibre-rich whole grain recommended in public-health guidelines.

Brown rice retains the bran and germ, which means:

• Slightly higher levels of certain antinutrients, including lectins and phytic acid, compared to white rice.​ 
• Higher amounts of fibre, vitamins, minerals, and bioactive compounds.​

Important context:

• A large proportion of the world’s population consumes rice daily, and many public‑health guidelines encourage whole‑grain options like brown rice for added fibre.​
• Reviews of cereal lectins again emphasise that, when grains are cooked or processed as normally eaten, evidence does not demonstrate clear adverse health outcomes in humans (source). In fact, the evidence consistently shows that regular consumption of brown rice and other whole grains is associated with a lower risk of type 2 diabetes and improved cardiometabolic health (source). The advantages of the extra nutrients and fibre clearly outweigh any effect of antinutrients.

Dr Gundry acknowledges that many cultures traditionally remove the hull (choosing white rice), but this observation alone does not establish that brown rice is harmful; it reflects culinary, taste, and storage preferences, not controlled trials on lectin toxicity in humans.​

For individuals with specific digestive issues, experimenting with different grains (including white rice) can make sense, but labelling all brown rice as “scary” because of lectins oversimplifies the evidence.