Advantages & Disadvantages of the Blood Type Diet

The key to weight loss and better health is not a low-fat plan that includes a wide variety of produce, whole grains, calcium-rich foods and lean protein, argues naturopath Peter J. D'Adamo. Instead, the key is to eat in a way that mirrors the diet of your prehistoric ancestors. D'Adamo claims your blood type indicates from whom you are descended.

Type-O people should supposedly eat as the hunter-gatherers did, type B's as ancient nomads, type-A individuals as agrarian farmers and type-AB people as a combination of A and B. All have different recommended and restricted foods. Ask your doctor if the plan advised for your blood type is a healthy, balanced choice.

Despite the differences D'Adamo recommends for each blood type, all followers are encouraged to eliminate processed foods and to purchase all meat, poultry, seafood and produce as close to its natural state as possible. For example, type-A individuals are advised to base their diets on fresh, organic fruits and vegetables, while those with type AB should not eat cured meats. In addition, refined grains and white sugar are discouraged for all blood types. Eating fewer processed and refined foods will lower your intake of fat, sodium and empty calories while giving you more fiber, vitamins and minerals, says the Harvard School of Public Health.

The Physicians Committee for Responsible Medicine praises the blood type diet for encouraging people who have type-A blood to follow a primarily plant-based diet. In addition, specific fruits and vegetables are recommended as regular fare for all blood types. A study published in 2012 in the "Archives of Internal Medicine" reported that people who obtain more of their protein from plant foods than animal foods are less likely to die from cancer or heart disease.

Type-O people following the blood type diet are instructed to avoid whole grains, while type-A individuals are told not to consume most types of dairy products. The New York University Langone Medical Center argues that advocating the elimination of whole categories of food may increase the likelihood of nutrient deficiencies. Dr. David L. Katz, the director of the Yale-Griffin Prevention Research Center, agrees, saying the blood type diet's restrictions may result in followers not getting enough fiber or calcium.

D'Adamo recommends that each blood type take a wide variety of dietary supplements. In addition, he specifically advises blood type diet followers to purchase their supplements exclusively from the line of products sold on his site. These are, allegedly, designed to meet the health needs unique to each individual's blood type. These supplements are expensive and have not been checked by the U.S. Food and Drug Administration -- there is no guarantee they contain what the label lists or that they will do what is promised.

In 2013, a review article in the "American Journal of Clinical Nutrition" concluded that scientific studies do not support the blood type diet. A later study conducted by University of Toronto researchers and published in 2014 in the medical journal "Plos One" confirms that conclusion. In this study, data collected from more than 1,400 subjects did not support the blood type diet's premise that people who have a specific blood type will be healthier if they follow the plan's rules.