Wellness Wednesday: The Blood Type Diet Myth and the Truth About Healthy Eating
In a world overflowing with nutrition trends and quick-fix diet plans, it’s easy to feel overwhelmed and uncertain about what truly supports your health. As a nutrition scientist, educator, and health coach, I work with clients every day who are trying to make the best choices for their bodies but are constantly bombarded with conflicting advice. Misinformation—especially when it comes to food—can be incredibly harmful, leading to unnecessary fear, restriction, and confusion.
One of the most persistent myths in nutrition is the Blood Type Diet. Promising to optimize digestion, boost energy, and prevent disease based on your blood type, this diet has captivated many people searching for answers. But here’s the truth: there is no scientific evidence to support these claims. Unfortunately, when misinformation like this spreads, it complicates health for the very people who are trying to improve it.
I've seen clients cut out entire food groups based on blood type recommendations, only to develop nutritional deficiencies, struggle with low energy, or experience unnecessary stress around eating. The pressure to follow rigid, pseudoscientific guidelines often leads to frustration, guilt, and, ultimately, an unhealthy relationship with food. Instead of making health easier, diets like this make it harder.
So, let’s break it down. What does the Blood Type Diet claim? What does science actually say? And how can we shift the focus away from restrictive, unfounded diets toward evidence-based habits that promote real, sustainable health?
The Blood Type Diet: What It Claims
Popularized in the late 1990s by naturopath Peter D’Adamo in his book Eat Right for Your Type, the Blood Type Diet suggests that people should eat according to their blood type (A, B, AB, or O) to optimize digestion, maintain a healthy weight, and prevent disease. The recommendations are as follows:
Blood Type O: A high-protein diet similar to a hunter-gatherer’s, emphasizing lean meats, fish, and poultry while avoiding grains, legumes, and dairy.
Blood Type A: A plant-based, vegetarian-style diet with an emphasis on fruits, vegetables, and grains while avoiding meat and dairy.
Blood Type B: A balanced diet that includes meat, dairy, grains, and vegetables, but avoids specific foods like corn, wheat, and lentils.
Blood Type AB: A combination of A and B, allowing lean proteins, dairy, grains, and vegetables while limiting processed meats.
While this approach may sound logical, it lacks scientific validation. The idea that blood type influences digestion and metabolism in this way has not been supported by human clinical trials.
The Science: What Research Actually Shows
Several studies have examined the Blood Type Diet, and the consensus is clear—it is not backed by credible science.
A 2013 systematic review published in The American Journal of Clinical Nutrition found no evidence to support the claims made by the Blood Type Diet. The researchers concluded that no randomized controlled trials (RCTs) validate the diet’s premise.
A 2014 study by Wang et al., published in PLOS ONE, analyzed over 1,400 participants and their adherence to blood type-specific diets. It found no significant association between following a diet based on blood type and improved cardiometabolic health. Any health benefits experienced by participants were linked to overall diet quality, not blood type specificity.
In other words, people may feel better on these diets not because of their blood type but because they are consuming more whole, nutrient-dense foods and reducing processed food intake.
The Issue of Diet Adherence and Restriction
One of the biggest problems with the Blood Type Diet is that it imposes unnecessary food restrictions, making it harder for people to sustain long-term.
The Type O diet, which is high in protein and lower in processed carbohydrates, is easier to adhere to than others. Many people already benefit from eating fewer refined grains and added sugars.
The Type A diet eliminates animal protein, which could lead to deficiencies in iron and B12 if not properly planned.
The Type B and AB diets involve eliminating entire food groups arbitrarily, making meal planning and nutritional balance more complex.
Restrictive diets often result in frustration, nutritional gaps, and cycles of weight loss and regain—commonly known as yo-yo dieting. When a plan is difficult to follow, long-term success becomes unlikely.
Why the Blood Type Diet Falls Short
While some of the Blood Type Diet’s recommendations encourage healthy habits (such as eating more vegetables and whole foods), its disadvantages outweigh any potential benefits:
Lack of Scientific Basis: No credible evidence supports the claim that blood type determines optimal nutrition.
Nutritional Deficiencies: By eliminating entire food groups, the diet may lead to imbalances in essential nutrients like fiber, healthy fats, and protein.
Overly Restrictive Approach: Complexity and limitations make adherence difficult, reducing long-term success.
No Proven Long-Term Benefits: Studies show no connection between blood type and improved health outcomes from this diet.
What Science Supports: A Balanced, Sustainable Approach
Rather than following restrictive, unproven diets, a well-rounded approach to nutrition provides the best long-term results. Research consistently supports these key dietary principles:
Lean Proteins: Essential for muscle repair, immune function, and overall health. Sources include poultry, fish, beans, tofu, and lean meats.
Fiber-Rich Foods: Whole grains, fruits, vegetables, and legumes support digestion, regulate blood sugar, and reduce heart disease risk.
Healthy Fats: Found in nuts, seeds, avocados, and olive oil, healthy fats promote brain function and heart health.
Fruits and Vegetables: Packed with vitamins, minerals, and antioxidants, they help protect against chronic diseases like diabetes, heart disease, and cancer.
Stress Management & Sleep: Lifestyle factors like stress and sleep have profound effects on digestion, metabolism, and long-term health. Managing stress and prioritizing rest complement a nutritious diet.
The Bottom Line: No Quick Fix, Just Evidence-Based Nutrition
The Blood Type Diet may sound appealing due to its individualized approach, but it is not supported by science. Any health improvements seen from following this diet likely come from eating healthier foods overall—not from blood type specificity. A balanced diet, rich in whole foods, lean proteins, healthy fats, fiber, and a sustainable approach, remains the best way to achieve lasting health.
Before considering any restrictive eating plan, consult with a registered dietitian, nutritionist, or healthcare professional who can help tailor a nutrition strategy based on real science—not diet fads. By focusing on sustainable, evidence-based nutrition, you can achieve long-term wellness without unnecessary food restrictions or stress.
