Blood Type Diet: What You Need to Know

With so many eating plans out there, it can be hard to determine which method of building a more healthy lifestyle is best for you. One diet trend that’s been around since the late 1990s is called the Blood Type Diet.

While scientific evidence is lacking, some have continued to look into the potential health benefits of eating foods based on your specific blood type.

How Does the Blood Type Diet Claim to Work?

D’Adamo traces the evolution of blood types through early civilizations that had different eating patterns.

What Can You Eat on the Blood Type Diet?

• Type O: This type is theorized to be the oldest, beginning somewhere around 40,000 B.C., the time of hunter-gatherers.
• Type A: The theory states that this type surfaced around 25,000 B.C., when people began farming.
• Type B: This is believed to have origins around 15,000 B.C. in people who were nomadic herders.
• Type AB: D’Adamo holds that this is the most recent blood type, developing less than 1,000 years ago as a result of farmers and herders coexisting.

Foods to Include

• Type O: Seafood, red meat, fruit, olive oil, and vegetables
• Type A: Soy (including tofu), whole grains, vegetables, seafood, olive oil
• Type B: Meat, eggs, seafood, fruits, green vegetables, dairy, grains
• Type AB: Dairy, tofu, lamb, seafood, grains, fruit, green vegetables (including kelp)

Foods to Avoid

• Type O: Wheat, corn, dairy
• Type A: Beef, pork, wheat, kidney beans
• Type B: Chicken, corn, peanuts, wheat
• Type AB: Chicken, corn, buckwheat, kidney beans

Potential Benefits of the Blood Type Diet

“When anyone jumps into a new diet, we’re usually getting rid of processed foods, cutting down on sugar and sodas, and eating more fruits and vegetables. That’s typically the baseline of a lot of diets out there,” says Janelle Connell, RDN, a researcher with the at-home diagnostics company Viome Life Sciences.

“When we do that, a lot of us will probably see some benefit, but not necessarily in connection to your blood type,” she says.

Potential Risks of the Blood Type Diet

The Blood Type Diet isn’t inherently unsafe, just potentially unhelpful. “The greatest risk would just be wasting your time and effort — you’re guessing [what your body needs] and it can be frustrating when you don’t see the results that you’re expecting,” says Connell.

However, it does lack an evidence base, and depending on your personal dietary needs, it has the potential to leave you lacking in some areas.

Nutrient Deficiencies

Connell says this is a risk with the Blood Type Diet. “Some of the diet types eliminate food groups, and Type O eliminates dairy altogether, so you could possibly get into an issue if you’re not supplementing,” she says.

As your body changes, so do your needs, and this plan doesn’t account for that. “Our blood type is something that never changes. But yet, from your twenties to your forties, you may go from being healthy to being overweight with diabetes,” Connell says.

“A woman who is in her twenties compared to a woman who’s maybe postmenopausal in her sixties are going to have not only different needs in terms of their calories and their metabolism, but different needs for calcium and vitamin D and iron during those stages of life,” she says.

Lack of Scientific Evidence

Is the Blood Type Diet Right for You?

As with most fad diets, the Blood Type Diet calls for a swift change in eating habits that may not fit your individual needs. Connell suggests taking a more tailored approach to dietary changes. “Baseline, we look at the individual for the basics: age, sex, and activity level,” she says.

She lists other factors to consider, including:

• Chronic conditions, such as diabetes
• Overall health goals; for example, are you hoping to gain muscle or to lose fat?
• Food sensitivities and intolerances

“Sometimes we just want to follow what our friend, neighbor, or family member has had success with. But dive in and look at what evidence is there to support [the choice] and make an informed decision for yourself based on your goals and your needs at that time,” Connell says.

The Takeaway

• The Blood Type Diet was developed 30 years ago with claims that certain foods are better for certain blood types.
• Researchers have not found validity in the principles behind the theory.
• Unless you have specific, preexisting dietary needs, intolerances, or deficiencies, any of the versions of this diet could support your goals.
• It’s important to do your own research as well as speak with your doctor before making any major changes to your diet.