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  • Dr. Whitney Mostafiz

Exploring the Blood-Type Diet: Part One

Healthy Steak

Just a few months ago I ate steak for the first time in about 10 years AND I didn't get sick. It was a lean cut, well-proportioned and surprisingly sat well in my stomach. With less than one week left of winter, I have also noticed that this is the first winter in at least 7-8 years that I did NOT get sick, despite flu being on the rise this year. I started to wonder if my own health marvel went hand-in-hand with the small shift I made in my diet. And I’m sure you’re wondering, why the 180 - why did I start eating meat out of the blue?

Do you know what your blood type is? I’ve started asking my patients and friends alike, and I am surprised when I hear so few people know. I'm Type O+. A few months ago a health-coach friend of mine discussed how she transformed her own health by adhering to a blood type-specific diet and offered me a book to read entitled “Eat Right for Your Type.” Having perused Dr. Peter D’Adamo’s updated book ( is a great resource), I was surprised to learn the scientific relevance of blood types in relation to diet, survival and disease correlation. I’ve never adhered to a “diet,” but I am curious and open to broadening my dietary horizons.

First, here is a quick definition of what I mean in describing the 4 blood types (A, B, O, and AB). My purpose is not to go into the biology and science, and I will keep this very basic. There are different immune system markers on blood that are called antigens, which is coded in our genetics. Type A has the A antigen, Type B has the B antigen, and Type O has neither antigen present. Meanwhile, type AB has both A and B antigen markers present on its surface. Rh factor is an additional antigen that is either present or not and termed as positive or negative when labeling a blood type. Therefore, all of the possible blood types include A+/A-, B+/B-, O+/O-, AB+/AB-.

Another quick definition is the term “lectin.” Dr. D’adamo mentions that there is a chemical reaction between blood and the food we eat. This reaction is caused by lectins, which are proteins found in each food. If a food possesses a lectin that conflicts with your blood type, the lectin proteins will target an organ (such as the liver, kidney, gut, stomach) or body system and agglutinate (AKA clump) blood cells in this area. This clumping will cause an inflammatory response. Generally speaking, our immune system protects us from about 95% of these lectins. Meanwhile 5% are filtered into our blood and can lead to unfavorable bodily reactions. The clumping of blood cells can lead to symptoms of IBS, bloating, joint/muscle aches, acne, fatigue, liver cirrhosis, or blocked blood flow to the kidneys, and accelerate the aging process.

Breaking Bad Ricin

An example of a toxic lectin is ricin (think Breaking Bad), which is derived from castor beans. Ricin causes large blood clots and almost instantly kills. It is one of the most potent agglutinins. Most foods are not high in lectins, fortunately. Many people with joint problems may avoid nightshade foods (tomatoes, eggplant, white potatoes), because they are high in lectins.

Normal versus Agglutinated Blood

(normal versus agglutinated blood)

Here is a quick breakdown of the evolutionary anthropology relating to blood types:

  • Type O: our hunter-gatherers, based on survival. Our oldest blood type, most robust and currently comprises approximately 45% of our population. Type O (Rh negative) is the “universal donor” blood type, since it has no markers on it for bodies to reject. Fun fact: Type O blood types were susceptible to the Bubonic Plague, and led to a drastic drop-off in this blood type during the Middle Ages.

  • Type A: the first adaptors to an agrarian and domesticated society; a blood type that disappeared and then reappeared 300k years ago. Represents approximately 34% of the population. Resistant to infection in urban regions and were survivors of the Plague.

  • Type B: migrated north in cold/harsh environments, and was a mutation of Type O. In total, Type B comprises about 11% of the population.

  • Type AB: a modern adaptation 1000-2000 years ago. Type A and B antigen adaptations are co-dominant. Type AB (Rh positive) is the “universal acceptor” blood type since it has all markers present and therefore no blood would be rejected. These types are the least susceptible to allergies and autoimmune diseases; however, have increased predisposition to certain cancers. Type AB is the rarest blood type, totaling 4% of the population.

Here are a few soundbites: Type O blood-types are predisposed to stomach ulcers as they often have increased stomach acids, while Type A -types are predisposed to stomach cancers, which interestingly is linked to lower acid production. Type O blood types thrive on high protein diets, as they have the stomach acids to support protein breakdown, while conversely Type A blood types fare well with a low protein, high vegetable diets. I will delve into more detail over a course of a few posts, as I was captivated by these concepts.

Blood Type Diet Breakdown

Dr. D’Adamo suggests that blood type diets are constructive towards weight loss. Here is a very abridged version of the foods to eat and avoid, based on blood types:

Blood Type Weight Loss

In terms of building a diet in relation to blood type, this book also emphasizes the importance of eating so that one is prepared to have a proper physiologic “stress” response (aka fight/flight reaction for survival). For the sake of brevity, I will only share Blood Type O in this post.

Blood Type O: "the hunter"

Lean red meat

Type O’s thrive on intense exercise and animal protein. According to Dr. Lam (, Type O’s muscle tissue should be slightly acidic. Type O has a hardy digestive tract that can tolerate meats, and possesses an overactive immune system that best responds to stress during intense physical activity. Meats such as beef or lamb, should be grass-fed, antibiotic/ hormone/ pesticide-free, which will be more rich with omega-3 fatty acids. Pork should be always avoided, as it contains toxins. Poultry is neutral in terms of benefits. Make sure to balance meats with vegetables and fruits for fiber, antioxidants and nutrients.

Omega 3 Fish

The authors also recommend fish that are rich with omega-3s and fresh caught; best fish include bass, cod, halibut, mackerel, snapper, sole and trout. Dairy should be heavily restricted, as O blood types have trouble metabolizing dairy – it can cause inflammation and weight gain as a result. Dr. Lam mentions that if you are Type O and of African descent to eliminate dairy and eggs, altogether. Free-range eggs, rich with DHA fatty acid, offers the most nutritional value. In terms of cheese, pecorino and urda are best metabolized. The best oils to use are flax-seed, camelina and olive oil.

Wheat products are not well-tolerated and should be completely eliminated from one’s diet. Especially true for those who have Crohn’s, colitis, and irritable bowl (IBS). Wheat may make you feel sluggish; artichoke flour is a recommended alternative and in addition 100% sprouted breads destroy gluten lectins. Dr. Lam similarly suggests that Type O’s should restrict grains, breads, legumes and beans particularly to assist in weight loss. Neutral grains include amaranth, buckwheat, millet, quinoa, whole oats and rice.

Onto the veggies. Nightshade vegetables should be avoided and may induce inflammation around joints (eggplants and white potatoes). Corn products may induce insulin insensitivity and diabetes/obesity. Meanwhile, dark leafy vegetables are beneficial. In terms of fruit, bananas, mango, and dark pigmented berries or plums may cause an alkaline reaction when digested. It’s important to avoid coconut, melons and oranges as they cause bacterial overgrowth. Blackberries are the only berry to avoid as they have an inflammatory response. Some great spices and herbs include parsley, curry and cayenne, which balance the microbiome; while black pepper and pickled foods should be avoided.


Dr. Lam mentions that Type O's tend to have lower levels of thyroid hormone, which may affect metabolism. He recommends avoiding foods that include cabbage, Brussels sprouts, cauliflower, mustard greens. Meanwhile kelp, seafood and iodized salt increase the hormone production. Eating foods rich in Vitamin K will assist in clotting factors, which are weak in Type O.

Intense exercise

The best dietary supplements include B complex vitamins, calcium, magnesium, iodine, licorice, rhodiola, bladderwrack, and N-acetyl-glucosamine. Avoid St. John’s Wort and excessive Vitamin C.

In terms of lifestyle, high intensity/aerobic exercises work best. Some exercises may include, aerobics, swimming, jogging and weight training. Ideally, the authors recommend reaching 70% maximal heart rate for 30 minutes, three times a week.

Blood Type O diet

Type O Summary:

  • Thrive on intense exercise and animal protein

  • Avoid grains and dairy

  • Gluten causes weight gain

  • Hardy digestive tract, with higher proportion of stomach acids

  • Watch out for ulcers

  • Lower thyroid hormone levels, generally speaking

Stay tuned to check in on Blood Types A, B and AB's diet/lifestyle next!

Blood Type Diet Cartoon
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