The Blood Type Diet which focuses on eating right according to each individuals blood type has been found popular for quite some time now. Upholders of this diet suggest that the blood type determines which foods are best for an individuals health.

There are many people who swear by this diet including Dr K J Yesudas, the eminent singer par excellence, and claim that it has saved their lives. But naturally several questions are bound to rise for most people about the details of the blood type diet, and if it is based on any solid evidence. Lets have a brief analysis here.

What is the Blood Type Diet?

The blood type diet, also known as the blood group diet, was popularized by a naturopathic physician, Dr. Peter D'Adamo in the year 1996; through his book titled Eat Right For Your Blood Type. He described in the book, how people could be healthier, live longer, and achieve their ideal weight by eating according to their blood type. Ones choice of condiments, spices, and even exercise should depend on ones blood type according to him.

The book which went on to become a best seller claimed that the optimal diet for any individual depends on the person's ABO blood type. It also states that each blood type represents genetic traits of our ancestors, including which diet they evolved to thrive on.

Recommended diet plans for each blood group

Type A: Called the agrarian, or cultivator. People who are type A have sensitive immune system; should eat a diet rich in plants, and completely free of red meat. This closely resembles a vegetarian diet.

Type B: Called the nomad. These people can eat plants and most meats except chicken and pork, and can also eat some dairy. However, they should avoid foods like wheat, corn, lentils, tomatoes.

Type AB: Called the enigma. Described as a mix between types A and B. Foods to eat include seafood, tofu, dairy, beans and grains. They should avoid kidney beans, corn, beef and chicken.

Type O: Called the hunter. This is a high-protein diet based largely on meat, fish, poultry, certain fruits and vegetables, but limited in grains, legumes and dairy. It closely resembles the paleo diet.

Proposed Link of Lectins between diet and blood type

One of the central theories of the blood type diet involves lectins, which are a diverse family of proteins that can bind sugar molecules. These substances are considered to be antinutrients, and may have negative effects on the lining of the gut.

According to the blood type diet theory, there are many lectins in the diet that specifically target different ABO blood types. It is claimed that eating the wrong types of lectins could lead to agglutination of red blood cells.

There may be evidence that a small percentage of lectins in raw, uncooked legumes, can have agglutinating activity specific to a certain blood type, like raw lima beans may interact only with the red blood cells in people with blood type A. However, it appears that the majority of agglutinating lectins react with all ABO blood types.

In other words, according to studies, lectins in the diet are not blood-type specific, with the exception of a few varieties of raw legumes. This may not even have any real-world relevance, because most legumes are soaked and/or cooked before consumption, which eliminates the harmful effect.

Is there a scientific evidence behind the Blood Type Diet?

Research on ABO blood types has advanced rapidly in the past few years. There is now strong evidence that people with certain blood types can have a higher or lower risk of some diseases. However, there are no studies showing this to have anything to do with diet.

In a large observational study of 1,455 young adults, eating a type A diet was associated with better health markers. But this effect was seen in everyone following the type A diet, not just individuals with type A blood.

In a major 2013 review study where researchers examined the data from over a thousand studies, they did not find a single well-designed study looking at the health effects of the blood type diet. They concluded: "No evidence currently exists to validate the purported health benefits of blood type diets."

Of the 4 studies identified as somewhat related to ABO blood type diets, they were all poorly designed. One of the studies that found a relationship between blood types and food allergies actually contradicted the blood type diet's recommendations.

Limitations

Restrictions: Depending on the blood type, one might need to severely restrict the foods he eats. Since the diet dictates that you eat very specific types of food based on your blood type, it doesn't allow much for personal tastes. Your blood type will determine your shopping list and your choices when eating out.

There are even recommendations about the types of spices and condiments you can use which might cause more inconvenience. Another interesting fact is that this diet doesn't ban gluten.

Exercise: The Blood Type Diet recommends specific exercises based on your blood type. For instance, it suggests yoga or tai chi for type A, and vigorous aerobic exercises like jogging or biking for up to an hour a day for type O.

Cost: D'Adamo recommends a lot of speciality and organic foods, which can be pricey. Vitamin and herbal supplements are also part of the diet which may be costly and difficult to find.

Is it good for certain health conditions?

The Blood Type Diet makes recommendations based solely on the blood type. So, if you have a chronic condition say, diabetes, you may be told to eat high protein, while another person with diabetes may have to avoid dairy or chicken. This may conflict with your diabetes treatment plan.

The American Diabetes Association recommends a more practical approach to a persons day-to-day eating. It also cautions against focusing on specific foods. In most cases it doesn't recommend cutting out any major food groups.

The Blood Type Diet also fails to address other conditions such as heart disease, high blood pressure or cholesterol. Any needed weight loss achieved by following this diet is sure to have a positive impact on these conditions though. But no matter what your blood type is, it is highly recommended to strictly adhere to medical advice before starting a new diet plan.

Bottom Line

A reasonable conclusion from these is that not a single well designed study has been conducted to either confirm or refute the benefits of the blood type diet.

Different diets work for different people. Some people do well with a lot of plants and little meat like the type A diet, while others thrive on plenty of high-protein animal foods like the type O diet.

If one could find great results from the blood type diet, then chances are that he has simply found a diet that happens to be appropriate for his metabolism. It may not have anything to do with his blood type. Also, since this diet removes the majority of unhealthy processed foods from a persons diet, he shifts automatically to a healthy lifestyle. Perhaps that is the single biggest reason that it works, without any regard to the different blood types.

Advocates of blood type diets say that while the ideal study has not yet been performed, the absence of evidence doesnt prove the theory is ineffective. And theres also no proof that these diets are harmful unless there exists a medical condition.

Also, on The Blood Type Diet, when processed food and simple carbs are avoided, that may be enough to help you lose some weight. But any weight loss on this diet has not been linked to the blood type in any of the studies. Theres also no research proving that this diet can aid in digestion or provide more energy. Though welcoming the positive effects of the diet may not cause harm but actually benefit an individual, it is worth remembering that science is stacked behind traditional recommendations for healthy eating- not restrictions based on the type of blood.

(The author is the Director -TGL Foundation, Chairperson CSA, Editor- The Intl Journal, Sr Director FWO)

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Eat according to your blood type - Mathrubhumi English