Can Blood Type O Eat White Potatoes? Separating Fact from Fiction

December 3, 2025 •

3 min read

Despite the popular yet scientifically unproven Blood Type Diet suggesting otherwise, there is no clinical evidence to support the claim that those with blood type O should avoid white potatoes. This diet, developed by naturopath Peter D'Adamo, relies on theories that have been widely debunked by the medical and nutrition communities.

Quick Summary

The restriction of white potatoes for individuals with blood type O stems from the pseudoscientific Blood Type Diet and lacks support from credible research and clinical studies.

Key Points

Blood Type is Not a Guide: There is no scientific basis for the Blood Type Diet's claim that individuals with blood type O should avoid white potatoes.
Scientific Review Found No Evidence: A systematic review of the Blood Type Diet concluded there is no valid evidence to support its health claims.
Lectin Levels are Reduced by Cooking: The lectins in potatoes are mostly destroyed by proper cooking, making them safe for general consumption.
Inflammation is Not Blood Type-Specific: Any inflammatory response to nightshades is due to individual sensitivity, not your blood type.
Proper Storage and Preparation are Key: Avoid green or sprouted potatoes, as they contain higher levels of solanine, and peel older potatoes to reduce glycoalkaloids.
Dietary Improvements Are General: Any positive health outcomes from following the Blood Type Diet are likely from cutting out unhealthy processed foods, not adhering to blood type-specific rules.

The Origins of the 'Eat Right for Your Type' Myth

The idea that blood type should determine diet originated with naturopath Peter D'Adamo's Eat Right 4 Your Type book. His theory proposes that each blood type evolved differently, leading to varied digestive responses to certain foods. Type O individuals, labeled 'hunter-gatherers,' are advised a high-protein, meat-centric diet while avoiding foods like grains, dairy, and nightshades such as white potatoes, which are claimed to contain incompatible lectins. D'Adamo's theory suggests these lectins cause red blood cell clumping (agglutination), leading to various health issues.

Why Scientific Consensus Debunks the Blood Type Diet

While the Blood Type Diet has followers, it's largely rejected by mainstream medical and nutritional science. A major systematic review in The American Journal of Clinical Nutrition found no scientific evidence supporting the diet's health benefit claims. Other research indicates that observed health improvements are linked to generally healthier eating habits rather than blood type adherence. The proposed evolutionary timeline for blood types has also been questioned. Experts emphasize that overall diet and lifestyle are crucial for health, not blood type.

The Truth About Lectins and Potatoes

Potatoes contain naturally occurring lectins and glycoalkaloids like solanine. While the Blood Type Diet highlights lectins as harmful to type O, scientific understanding offers a different perspective.

Key points regarding potatoes and these compounds:

Cooking: Lectins in potatoes are significantly reduced or destroyed by cooking, particularly boiling. Raw potatoes are not recommended for anyone.
Storage: Glycoalkaloid levels increase in potatoes exposed to light (causing greening) or sprouting. Proper storage in a cool, dark place is vital, and green or sprouted potatoes should not be consumed.
Peeling: Glycoalkaloids are mostly concentrated in the potato's skin and outer layer, so peeling can reduce intake.

Blood Type Diet vs. Scientific Consensus on Potatoes


Feature	Blood Type Diet Claim	Scientific Consensus	Fact-Based Conclusion
Effect of Potatoes	Harmful for Type O due to incompatible lectins, causing agglutination and inflammation.	No evidence links blood type to potato consumption effects.	Potatoes are safe and nutritious for people of all blood types when prepared correctly.
Associated Health Risks	Increased risk of arthritis and other inflammatory issues for Type O.	Any inflammation sensitivity to nightshades is individual, not blood type dependent.	Genetic and lifestyle factors determine arthritis risk, not blood type.
The Role of Lectins	Lectins from potatoes are harmful to Type O blood cells.	Cooking destroys most plant lectins, and potential harm is not linked to blood type.	Proper cooking neutralizes most concerns related to potato lectins for everyone.

The Real Connection: Individual Sensitivity, Not Blood Type

Some individuals do report inflammatory reactions, such as arthritis flare-ups, after consuming nightshade vegetables like potatoes. However, this is attributed to individual sensitivity, not blood type. A person with any blood type could have such a sensitivity. Consulting a healthcare professional is recommended for suspected food sensitivities, rather than following a debunked diet.

In conclusion, the restriction of white potatoes for blood type O is a nutritional myth. A balanced, healthy diet is most important for well-being, and for most people, properly cooked potatoes are a nutritious component of that diet.

For further reading on the blood type diet and its controversies, consult this comprehensive review on WebMD.

How to Safely and Healthily Enjoy Potatoes

Choose Wisely: Select firm potatoes free of green spots or sprouts.
Prepare Properly: Cook potatoes thoroughly (boiling, baking, frying) to reduce lectins.
Consider Peeling: Peeling can lower glycoalkaloid levels, especially in older potatoes.
Portion Control: Manage portion sizes as part of a balanced diet.
Listen to Your Body: If you experience adverse reactions, consult a doctor; this is likely individual sensitivity, not blood type related.

Frequently Asked Questions

This idea originates from the popular but scientifically unproven Blood Type Diet created by naturopath Peter D'Adamo, who claimed that foods like potatoes are incompatible with blood type O.

No, extensive scientific reviews, including one in The American Journal of Clinical Nutrition, have concluded that there is no evidence to validate the health benefits purported by the Blood Type Diet.

The theory that lectins in white potatoes are specifically harmful to type O individuals is not supported by science. Proper cooking also effectively reduces lectin levels in potatoes for everyone.

No, there is no scientific basis for this claim. While some people may have an individual sensitivity to nightshades, it is not related to blood type.

Solanine is a natural glycoalkaloid found in potatoes. Levels are usually safe, but increase in green or sprouted potatoes. Avoiding green/sprouted potatoes and peeling older ones is a good practice for everyone.

The best diet for someone with blood type O is a balanced, healthy diet rich in whole foods, like vegetables, lean proteins, and fruits, just as it is for individuals of any other blood type.

Any health improvement is likely due to the diet's generally healthy components, such as reducing processed foods. These benefits are independent of blood type and would apply to anyone adopting healthier eating habits.