Nutrition Diet: Debunking the Myth About What Blood Type Should Not Eat Beans?

October 19, 2025 •

4 min read

Despite a popular yet unproven diet claiming certain blood types, particularly Type O, should avoid beans, scientific consensus reveals no link between blood type and dietary needs. This article investigates the origins of the myth, exposes the lack of evidence behind the claim what blood type should not eat beans, and highlights the significant health benefits of legumes for everyone.

Quick Summary

The unproven Blood Type Diet claims certain blood types, such as Type O, must avoid beans due to lectin incompatibility, but a review of scientific literature found no evidence supporting this theory. Experts affirm that properly prepared beans are a valuable and healthy part of nearly any diet.

Key Points

Blood Type Diet Myth: The claim that what blood type should not eat beans is based on the unproven and scientifically unsupported Blood Type Diet theory.
Type O and Beans: The Blood Type Diet controversially recommends that individuals with Type O blood avoid beans like kidney and navy beans.
Beans Are Healthy: Evidence-based nutrition shows beans are a powerhouse of fiber, protein, and minerals, benefiting everyone for heart health, digestion, and weight management.
Lectins Aren't a Threat: While raw beans contain lectins, proper soaking and cooking effectively neutralize them, making beans safe and nutritious for consumption by all.
Focus on Evidence-Based Nutrition: Rather than following restrictive blood type diets, prioritize a balanced, varied diet based on scientific evidence for long-term health benefits.
Individual Sensitivity Over Blood Type: Some people may have a genuine sensitivity to lectins or other compounds in beans, but this is a personal intolerance, not tied to their blood type.

The Pseudoscience of the Blood Type Diet

The idea that one's diet should be dictated by their blood type, a theory proposed by Peter D'Adamo in his 1996 book Eat Right 4 Your Type, lacks robust scientific support. This theory, often referred to as the Blood Type Diet, claims that different blood types reflect evolutionary stages and therefore require distinct dietary approaches. For example, it suggests that individuals with Type O blood, supposedly the oldest blood type, should follow a high-protein, meat-heavy diet similar to 'hunter-gatherers'. Conversely, it recommends a vegetarian-style diet for Type A blood, based on an agrarian ancestry.

Central to the Blood Type Diet is the assertion that specific food components, particularly proteins called lectins, can be harmful to people with certain blood types. According to D'Adamo's theory, lectins in some foods can bind to blood group antigens, causing cellular damage and various health problems. Based on this premise, the diet advises individuals with Type O blood to limit or avoid certain grains, dairy, and beans, including kidney and navy beans. People with Type A blood are advised to avoid kidney beans, while Type AB is told to skip kidney and fava beans.

Scientific Rejection of the Blood Type Diet

Despite the diet's popular appeal, the scientific community has consistently refuted its claims. A comprehensive systematic review published in the American Journal of Clinical Nutrition analyzed over 1,400 scientific articles and concluded there is no evidence to validate the purported health benefits of blood type diets. Another study found no significant association between blood type-specific diets and cardiovascular risk factors. In essence, the theory that blood type determines how one's body digests and reacts to food contradicts fundamental principles of human physiology and metabolism.

Any positive health outcomes experienced by followers of the Blood Type Diet are most likely due to the elimination of processed foods, refined sugars, and excessive calories, which are common recommendations in many healthy eating plans. The restrictive nature of the diet may lead to a healthier eating pattern overall, but this benefit has nothing to do with blood type.

The Overwhelming Evidence for Bean Consumption

In stark contrast to the unproven Blood Type Diet, a vast body of evidence supports the consumption of beans and other legumes as a vital component of a healthy diet. Beans are nutritional powerhouses, packed with plant-based protein, dietary fiber, vitamins, and minerals. Regular consumption is linked to numerous health benefits, including lower cholesterol, improved blood sugar control, and better digestive health.

Lectins and Proper Preparation

It is true that raw beans contain lectins, and some are more potent than others. However, the vast majority of dietary lectins are effectively neutralized by proper cooking methods, such as soaking and boiling. Raw or undercooked kidney beans, for example, contain a toxic lectin, but thorough cooking renders them perfectly safe to eat. While some individuals may have a genuine sensitivity to lectins, causing digestive issues, this is not determined by blood type and can be managed by ensuring proper food preparation. For most people, the health benefits of properly cooked beans far outweigh any minor risks associated with their naturally occurring lectin content.

Blood Type Diet vs. Evidence-Based Nutrition

This table summarizes the core differences between the unsubstantiated Blood Type Diet and widely accepted, evidence-based nutritional science regarding bean consumption.


Feature	Blood Type Diet Claims	Evidence-Based Nutrition Consensus
Core Principle	Optimal diet is determined by blood type, reflecting evolutionary heritage.	Optimal diet is based on individual needs, balanced intake, and general health guidelines.
Beans & Type O	Discourages or restricts beans (especially kidney, navy) for Type O blood.	Recommends beans as a key component of a healthy diet for all blood types.
Scientific Basis	Lacks supporting scientific evidence; debunked by major reviews.	Supported by extensive research showing significant health benefits.
Mechanism	Lectins in certain foods cause negative reactions based on blood type.	Lectin sensitivity is not linked to blood type; proper cooking neutralizes most lectins.
Health Focus	Narrow focus on blood type-specific 'harmful' foods.	Broad focus on nutrient density, fiber, and overall balanced intake.

Prioritizing Evidence for Long-Term Health

For a healthy and sustainable diet, it is best to rely on evidence-based nutrition principles rather than restrictive and unproven theories. Mainstream dietary guidelines, such as those from the World Health Organization and the NHS, consistently recommend legumes, including beans, as a staple food. These guidelines emphasize a varied diet rich in fruits, vegetables, whole grains, and lean proteins, which provides a wide spectrum of nutrients and promotes overall well-being. The notion that a specific blood type, such as Type O, should not eat beans is a myth that overlooks decades of sound nutritional science. Rather than focusing on a speculative connection between blood type and diet, individuals should prioritize a diverse and balanced eating pattern, ensuring all foods, especially legumes, are prepared safely to unlock their full nutritional potential.

Sources:

Conclusion

In conclusion, the idea that a specific blood type, such as Type O, should avoid beans is rooted in the scientifically debunked Blood Type Diet. Mainstream nutrition science has found no credible evidence to support this restrictive approach. Beans are a valuable source of nutrients, and when properly prepared through soaking and cooking, they are a healthy addition to the diet for most people, regardless of their blood type. Instead of following unproven dietary fads, individuals should prioritize a balanced, varied diet based on established nutritional principles to achieve and maintain optimal health.

Frequently Asked Questions

According to the unproven Blood Type Diet, individuals with Type O blood are advised to limit or avoid certain beans, such as kidney and navy beans, because of alleged incompatibility with their blood type.

No, there is no credible scientific evidence to support the Blood Type Diet. A systematic review published in the American Journal of Clinical Nutrition found no studies validating its purported health benefits.

Some people may experience digestive issues like gas or bloating from eating beans due to their high fiber content or individual sensitivities to compounds like lectins. These issues are not related to blood type.

While raw beans contain lectins that can be harmful, proper cooking methods like soaking and boiling neutralize them, making the beans safe and healthy to eat for most people.

Yes, beans are an incredibly healthy food choice. They are rich in fiber, plant-based protein, vitamins, and minerals, and are linked to improved heart health, better blood sugar control, and weight management.

To reduce lectins, dried beans should be soaked for several hours before cooking and then boiled thoroughly. This process deactivates most of the lectins, making the beans safer to consume.

No, you should not follow a diet based on your blood type. It is a discredited theory. For optimal health, focus on a balanced, varied diet recommended by established nutritional guidelines, prioritizing whole foods like beans, fruits, and vegetables.