Blood Type Diet

The blood type diet was popularized by the book Eat Right 4 Your Type – The Individualized Diet Solution for Staying Healthy, Living Longer & Achieving Your Ideal Weight, written by naturopath Peter J. D'Adamo and published in 1996. This book won the New York Times Bestseller award for diet books and has sold more than a million copies. The blood type diet remains popular today, 25 years later, and many people have asked for my opinion on it, which is why I decided to write this article.

The idea behind the blood type diet is based on the assumption that people with different blood types digest certain proteins in food differently. Because of this, eating food that is not aligned with their blood type could cause health problems, while consuming suitable food could lead to a longer and healthier life.

According to the blood type diet hypothesis, all people sharing a common blood type also share a common evolutionary origin—meaning common ancestors who consumed similar food. From this, it follows that people with the same blood type will thrive on the same or a similar type of diet, as they are evolutionarily prepared to digest that kind of food.

Blood types and what they should eat are:

• Type O (The Hunters) – Considered the oldest group of people, they should follow a diet that mimics the earliest diet of prehistoric hunter-gatherer societies. Therefore, the diet for this group should be rich in animal proteins from meat and fish, supplemented with berries and vegetables, but without dairy products and milk, legumes, and grains.
• Type A (The Cultivators) – It is assumed that this blood type emerged when active farming and agriculture began, so a plant-based diet including fruits, vegetables, and whole grains is suggested for these people, while avoiding red meat is advised.
• Type B (The Nomads) – It is speculated that this blood type evolved among nomadic tribes, so a diet rich in dairy products and milk is proposed, which also includes fruits, grains, green vegetables, eggs, and meat, but not pork or chicken. Additionally, avoiding corn, wheat, peanuts, lentils, tomatoes, and a few other plants is advised.
• Type AB (The Mixed) – Supposedly formed by the blending of types A and B, they have the advantages and challenges of both groups. The best source of protein for this group is seafood, and they are also encouraged to consume eggs, tofu, vegetables, yogurt, and kefir. They are advised to avoid caffeine, alcohol, and processed meats.

Does a Blood Type Diet Make Sense?

If you want a simple answer – absolutely and unequivocally NO.

ABO blood types were discovered over a hundred years ago and have been intensively studied ever since. Differences in susceptibility to certain diseases have been established for different blood types, but a connection to differing dietary responses has never been scientifically proven.

While the idea of different diets based on different evolutionary origins makes perfect sense, human genetics is far more complex than a simple division into four groups. Furthermore, the assumption that the same blood type indicates the same evolutionary origin is not backed by any evidence. For instance, some scientists believe that blood type O developed independently at least four times in human history. This not only disproves the idea of a common ancestor, but also the theory that type O originated before other blood types and that we should mimic the diet of the first humans.

The blood type diet made it onto the British Dietetic Association's list of the Top 5 Celeb Diets to Avoid in 2019, taking a prominent first place. The association states that the blood type diet is entirely based on pseudo-science and warns of the danger of cutting out entire food groups due to the potential risk of malnutrition. Other practices found on this list include: consuming one's own urine, detox teas and weight-loss coffees, alkaline water, and slimming sachets.

Research

One study investigated the impact of the blood type diet on human health, involving 1,455 participants of different sexes, ages, and ethnicities. The study concluded that the diet did have positive effects on some health parameters, but there was no correlation between an individual's blood type and their optimal diet. Since it generally includes healthy options and bans processed foods, each of the four variants of this diet is healthier than what most people eat daily. The study found no discoveries to support the blood type hypothesis.

A smaller study, published in 2021, took a different approach. Sixty-eight overweight patients were given an identical low-fat, plant-based diet. The participants followed this regimen for 16 weeks and achieved similar results—losing around 7 kilograms—regardless of their blood type. The scientists concluded that blood type is not associated with the effects of a plant-based diet on body weight loss, body fat percentage, blood lipid levels, or glycemic control.

What Actually Makes Sense?

A diet based on ancestry can have a valid foundation. An example of this is lactose tolerance, which is highly prevalent in regions with a historical culture of milk and dairy consumption. On the other hand, residents of African and Asian countries, where milk consumption past early childhood is not traditional, very frequently exhibit lactose intolerance. This indicates a variance in the body's ability to produce digestive enzymes based on geographic origin and what our ancestors consumed. It follows that people from specific regions will possess the enzymes to digest foods historically eaten there, such as bread, grains, meat, radishes, onions, local mushrooms, pears, apples, blueberries, plums, figs, cherries, peaches, eggs, milk, and dairy products.

Even though a diet based on blood type makes no sense, different foods really do trouble different people. This can relate to geographic or ethnic origin, but it is more often individual and linked to childhood and upbringing. The discomfort can range from severe, like allergic reactions, to very mild ones that are impossible to spot immediately. If you think a certain food doesn't suit you or that you have an intolerance, most biochemical laboratories offer food intolerance testing. These tests are somewhat expensive, but they provide you with clear and reliable data on which ingredients to avoid.

A moderate and varied diet is, according to a vast number of studies, the best and healthiest way to eat. Additionally, a plant-based diet has shown the best results across almost all health parameters, and you can read more about this type of eating and its effects in my article on the Mediterranean diet.

If you are thinking about making changes to your diet to improve your health or reach your desired weight, don't hesitate to contact me, whether through the website, phone, or social media.

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