Can O+ Eat Tomatoes? The Truth About the Blood Type Diet

January 10, 2026 •

3 min read

The Blood Type Diet, which often suggests O+ individuals avoid certain foods like tomatoes, has been widely debunked by the scientific community. This article explores the origins of these claims and presents the compelling evidence that your blood type does not dictate your food choices.

Quick Summary

The blood type diet's claim that O+ individuals should avoid tomatoes due to lectins lacks scientific evidence. Tomatoes are a nutritious food that most can safely enjoy, with personal tolerance being the primary consideration, not blood type.

Key Points

Blood Type Diet Lacks Evidence: The theory that O+ blood types should avoid tomatoes due to lectins or evolutionary factors is not supported by scientific research.
Tomatoes are Nutritious: Tomatoes are rich in beneficial antioxidants like lycopene, along with vitamin C, potassium, and other essential nutrients valuable for overall health.
Lectin Concerns are Overblown: While some lectins exist in raw nightshades, cooking often deactivates them, and the amount consumed in a typical diet is not a health concern for most people.
Listen to Your Body: Personal food intolerances and sensitivities are real, but they are not determined by your blood type. If you have a specific issue with tomatoes, consult a medical professional.
Focus on a Balanced Diet: A healthy, varied diet with lots of fruits and vegetables is beneficial for everyone, regardless of blood type, and this is where true health gains are found.
Seek Professional Advice: For personalized dietary recommendations, rely on a registered dietitian or doctor rather than unproven fad diets.

Understanding the Blood Type Diet and the O+ Connection

The Blood Type Diet, developed by naturopath Peter D'Adamo, proposes that dietary needs are tied to blood type. For O+ individuals, it often recommends a high-protein diet similar to that of hunter-gatherers, suggesting restrictions on grains, legumes, and certain vegetables, including tomatoes, sometimes due to concerns about lectins or their status as a nightshade.

The Lectin Theory and its Flaws

The diet's rationale often centers on the idea that food lectins can cause blood cell clumping in specific blood types. D'Adamo claims tomato lectins are incompatible with O+ blood. However, scientific evidence does not support this; many lectins affect all blood types and are neutralized by cooking. Furthermore, lab studies using high lectin concentrations don't reflect normal dietary intake.

The Absence of Scientific Validation

The Blood Type Diet lacks scientific backing. A systematic review in The American Journal of Clinical Nutrition found no evidence supporting its effectiveness. Any perceived health benefits are likely from generally healthier eating habits rather than blood-type-specific restrictions.

Can O+ Individuals Safely Eat Tomatoes?

Yes, O+ individuals can safely eat tomatoes. Tomatoes are highly nutritious and beneficial.

Nutritional Benefits: Rich in lycopene (a powerful antioxidant), vitamins C and K1, folate, and potassium, tomatoes support heart health and may reduce cancer risk. They are also hydrating and low in calories.

Blood Type Diet vs. Scientific Consensus on Tomatoes


Feature	Blood Type Diet Claims (often contradictory)	Scientific/Nutritional Consensus	Personal Health Approach
Tomatoes for O+	Some sources say 'Avoid' due to lectins/nightshades; others say 'Eat'.	No evidence suggests O+ individuals should avoid tomatoes.	Individual tolerance is key. Listen to your body, not a fad diet.
Lectin Concerns	Suggests lectins cause agglutination and health issues in specific blood types.	Cooking and processing significantly reduce lectin activity; most lectins are harmless in normal amounts.	Focus on balanced cooking techniques to minimize potential lectin impact from all foods.
Overall Validity	Based on evolutionary speculation and unproven theories.	Widely rejected by medical and scientific communities.	Follow evidence-based dietary guidelines and consult healthcare professionals.
Primary Driver	Blood type is the primary determinant of food compatibility.	Genetic makeup, lifestyle, and individual health conditions are far more significant factors.	Customize your diet based on your personal health needs and goals.

A Balanced Perspective: Focus on What Matters

Instead of adhering to unproven blood type diets, focus on established nutritional advice: a balanced diet rich in whole foods, diverse fruits, and vegetables benefits everyone. Tomatoes are an excellent part of this. Personal food intolerances are distinct from blood type restrictions. Consult a registered dietitian or healthcare provider for personalized advice based on your health history and needs. The notion that blood type dictates diet is a myth. Enjoy the nutritional benefits of tomatoes unless you have a diagnosed intolerance. Further evidence against blood type diets can be found in this systematic review: Blood type diets lack supporting evidence: a systematic review.

Conclusion: Eat Your Tomatoes with Confidence

Scientific evidence does not support avoiding tomatoes based on O+ blood type. The Blood Type Diet's lectin theory is scientifically unfounded. Tomatoes are a nutritious food suitable for all blood types as part of a balanced diet. There's no reason to exclude them unless you have a specific, diagnosed intolerance.

Practical Steps for a Healthy Diet

Prioritize whole foods.
Focus on variety.
Cook foods appropriately.
Listen to your body.
Consult a professional.

Frequently Asked Questions

No, the blood type diet is considered a fad diet and lacks scientific evidence to support its claims. A 2013 systematic review confirmed that no studies have validated the supposed health benefits.

The theory, proposed by Peter D'Adamo, claims that lectins in tomatoes are incompatible with the O+ blood type and can cause health issues. This is not supported by scientific evidence.

Yes, tomatoes are a very healthy food. They are low in calories and rich in vitamins C and K, potassium, folate, and the antioxidant lycopene, which is linked to heart health and cancer prevention.

While high concentrations of lectins in raw or undercooked legumes can be harmful, the amount of lectins in most cooked foods is minimal and not a concern for the average person. Cooking and processing significantly reduce their activity.

For most people, nightshades like tomatoes do not cause inflammation. Some individuals with arthritis or other inflammatory conditions report sensitivity, but this is a personal intolerance, not a universal rule based on blood type.

A more effective approach is to follow evidence-based dietary guidelines, such as eating a balanced diet rich in whole foods, and consulting a healthcare professional for personalized advice. Individual health history and personal needs are more important than blood type.

You should not worry about eating foods simply because a blood type diet suggests avoiding them, as these claims are not scientifically sound. Base your diet on overall health principles and your personal well-being.