Diets 101 – The Bloodtype Diet

In the 1950s and 60s, medical studies linking blood types to common diseases such as cancers and heart disease gained in popularity, but it’s only recently that blood type has been used to as a strategy for optimising what kinds of foods people should eat (or avoid) to improve their energy, lose weight, and ward off disease. Intrigued by the fact that one-size-fits-all diets inevitably never worked for everyone, US-based naturopathic physician, Peter D’Adamo took over this line of enquiry from his father. Based on their laboratory experimentation with multiple common foods and their specific chemical reactions with various bodily fluids, including blood, they were able to generalise which foods reacted negatively with which blood types. This offered an attractive entry to the diet industry, posing the appeal of a biochemical angle, which, at the time, was becoming an increasingly mainstream way of thinking about health and illness.

The research was compiled in D’Adamo’s first publication, Eat Right for Your Type, published in 2001, which has now sold over 7 million copies world-wide. The book categorises people by the four common blood-types (A, O, B, AB) and correlates each type to a specific diet. According to D’Adamo, 85% percent of people are either Type A or O. Although the book highlights quite specific details regarding the best foods to eat or avoid by type, generally, Type As function best on a plant-based Mediterranean or Asian-style diet, and Type O’s thrive on a low-carbohydrate, high-protein diet. D’Adamo has further linked blood-type to predisposition for different illnesses, dominant personality traits, and susceptibility to stress. In conjunction with the suggested dietary changes which are said to minimise the chance of illness, weight gain and fatigue, D’Adamo also offers guidelines for lifestyle habits including the best types of exercise and stress-reducing activities for each type. Generally, Type A’s, prone to stress and fatigue, respond well to gentle, calming exercises such as yoga and walking, whereas Type O’s benefit from brisk aerobic exercise such as jogging. For a more detailed explanation, see the official Eat Right For Your Type website and listen to a thirty minute podcast interview with D’Adamo and Australia’s ‘Wellness Guys’.

As someone who isn’t a nautropath or traditional medical practitioner, hasn’t tried this diet or read D’Adamo’s book, I’m ill-equipped to provide a professional or personal account of the usefulness of the blood-type diet or to promote its claims to support weight-loss and improve levels of immunity and energy. However, as a researcher, I can point out the critiques, so you can make a more informed decision should you decide to experiment with this approach. Aside from opponents who explicitly argue the blood-type diet reduces the human body and all its complex individual variations to a sort of ‘blood type astrology’, there’s also very little support from the traditional scientific community. According to a 2013 systematic review in PubMed, a database for the life and biomedical sciences, there has been no published scientific evidence to validate the advertised health benefits of blood type diets. What this translates to is a lack of comparative studies which explore the health outcomes between participants adhering to a particular blood-type diet and those continuing a standard diet. This doesn’t necessarily debunk the beneficial claims of the blood-type diet, but it suggests an element of hype.

With thousands of advertised diet regimes and a plethora of conflicting advice and so-called experts vying for consumer’s money in what has now become a million dollar dieting industry, it’s never an easy task to sift through the competing claims. But, one thing most dietary advice has in common is a focus on eating more nutritious, fresh foods and increasing exercise. In all likelihood, it’s these simple changes which in fact make the biggest difference, rather than following the latest gimmick.