Your blood type can affect your overall health, but does that mean it should determine your diet?
Your blood type matters in ways that might surprise you: It's tied to your risk of heart disease, how much you get bit by mosquitoes and more. There's even a diet based on blood type, which proposes that people with type O blood should focus on eating different foods than, say, those with type A or B. For example, people with blood type A are advised to avoid eating red meat, and those with type O are advised to do the opposite.
But whether or not the Blood Type Diet is safe or healthy is another story. I asked registered dietitian nutritionist Anna Rios about the potential benefits (or complications) associated with eating based on blood type.
Here's what the Blood Type Diet is, how it is supposed to make you healthier, and what health scientists have discovered about its efficacy.
The Blood Type Diet originally comes from the 1996 book Eat Right 4 Your Type, by naturopathic physician Dr. Peter D'Adamo, and has been kicking around various health forums for nearly three decades.
The general thrust of the diet is that there are optimal foods for people with various blood types O, A, B and AB. Part of the claim hinges on the idea that blood types serve as maps of our ancestral history and genetics, and that the foods commonly eaten by our ancestors are better suited for our bodies, even in the modern day.
Below is a snapshot of the four main blood types and what D'Adamo posits is the best type of diet for each.
Type A: The agrarian or cultivator. According to D'Adamo, those with type A blood should avoid meat -- specifically red meat -- and eat a plant-based diet rich in fresh fruits, vegetables, legumes and whole grains. Because of more "sensitive immune systems," they should also avoid processed foods and opt for organic foods whenever possible.
Read more: Where to Buy Affordable Organic Groceries Online
Type B: People with blood type B are dubbed "nomads" by D'Adamo. Folks with type B are encouraged to eat plants but also most meats (except chicken). The diet also cautions against eating corn, wheat, tomatoes, peanuts and certain seeds.
Type AB: People with type AB blood, or "enigmas" as D'Adamo calls them, are a mix between types A and B. The Blood Type Diet encourages these people to eat seafood, tofu, dairy, beans, greens and grains but to avoid corn, beef and chicken. D'Adamo contends type ABs also have lower levels of stomach acid and thus should avoid caffeine and alcohol.
Type O: Also known as the "hunter," D'Adamo purports that people with this blood type should eat a high protein diet rich in red meat, fish, poultry and some fruits and vegetables. This precursor to the paleo diet cautions type Os against eating grains, legumes and dairy products.
To date, there is very little evidence that adhering to strict blood type-based diet recommendations will improve health outcomes. "The blood type diet has been debunked multiple times by new and improved research," Rios says. "People who claim to start feeling better on this diet typically do so because they start cooking at home more and eating more whole foods and less processed foods which can improve anyone's health."
The most comprehensive study was done in 2013 by the American Journal of Clinical Nutrition and found "no evidence to validate the purported health benefits of blood type diets." That said, most of the nutrition plans laid out in D'Adamo's book may be healthier than your current eating habits since they do focus on natural, whole and unprocessed foods.
Blood type isn't something dietitians take into consideration when providing medical nutrition therapy, Rios says. "As dietitians, we focus on the patient as an individual," she adds. "Important things to consider include health history, chronic illnesses, current lifestyle, food allergies, food intolerances, sensitivities, stress and digestion."
Following the Blood Type Diet can be "extremely restricting," Rios says, and, if you aren't being guided by a registered dietitian, it could lead to other health issues. There are lots of things to consider before excluding certain food groups from your diet.
If you have or are at risk for high blood pressure or heart disease, for instance, eating a diet high in red meat (as the type O diet suggests) could lead to problems. Diabetics, on the other hand, are often advised to avoid eating cheese, dairy and other foods in large amounts. Other health conditions including IBS and iron deficiency can be exacerbated by meticulously consuming or avoiding certain categories of foods.
If you're looking for a nutrition plan or diet to follow for increased overall health, the Mediterranean Diet has been ranked the No. 1 healthiest diet by US News and World Report for five straight years. Based largely on typical Mediterranean-style cooking, this nutrition plan includes lots of lean fish, fruits, vegetables, whole grains, beans and seeds. It also encourages limited sugar and salt intake and prioritizes healthy fats like olive oil.
While trying a nutrition plan outlined for your blood type shouldn't have any drastic negative consequences (at least not for those without underlying health conditions), there is also very little evidence that doing so will improve your health in any significant way.
Most nutrition experts suggest balance in the diet overall, including a mix of lean proteins and vitamin-rich vegetables along with whole grains, nuts and seeds. For losing weight, diets such as the keto and paleo plans have been known to garner fast results, but if the goal is overall improved health, including heart health, restrictive fad diets often get failing grades from nutritionists, dietitians and other health professionals.
For more help keeping your nutrition on track, learn about the best food sources for every vitamin and mineral and the best healthy meal delivery services. Plus, why you should stop counting calories and start counting macronutrients.