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The Effect of Blood Group on Diet

There has been a lot of interest lately in the effect that a person's blood group may have on their diet.

In fact, a whole new diet program has evolved around the theory that certain foods are metabolized differently by people with different blood groups.

This is an interesting idea and one that is based on certain historical and ancestral facts.

Blood Type O

hunter gatherersIt is known that the oldest blood group, Type O was prevalent when our oldest cave dwelling ancestors kept themselves alive but hunting and gathering their food. The bulk of their regular diet was made up of meat, berries and fruits so their metabolism was optimized to cope with large amounts of animal fats, meat protein and fruit sugars to obtain the maximum nutrition from these sources.

Come up to today's modern human physical makeup and notice how people with blood type O tend to be able to happily eat a diet predominantly made up of meats and meat protein with high levels of fruit sugars without unduly gaining weight. As soon as you add high carbohydrate wheat or other grain based products to that diet, the person's weight increases when they don't do enough exercise each day.

This makes a lot of sense when you consider that the ancestral type O blooded hunter gatherers did not eat any wheat or grain based foods and got all their carbohydrates from the fruits they could gather. Their metabolism would not have been able to cope very well with this type of food because it simply was not available. Therefore the cave-dweller's digestive system was best suited to processing a variety of animal products, fruits and berries.

Blood Type A

harvest by handLater on in the evolutionary process of humans, we emerged from our caves and learned how to grow our own food. This change didn't happen overnight, but happened gradually over many thousands of years.

As we evolved, the blood type A also appeared. Our digestive systems gradually evolved to cope with the newer form of nutrition, made up primarily of vegetable crops, some grains, seeds and dairy products. It still featured animal products, but the balance shifted to a greater reliance on what we could grow, store and make into food without the need for hunting or gathering.

Modern humans with the Type A blood group are better at metabolizing and obtaining the maximum amount of nutrition from vegetable crops, fruits and seeds while relying less on animal products.

Blood Type B

traditional farmerBlood type B is the the most recent evolutionary step in human makeup and stems from the ancestral period when our early farmer ancestors started farming dairy cattle and creating a wide range of dairy products.

Farming settlements had become firmly established as a way of life and families grew into small communities that relied on each other to produce food, clothing and tools necessary for the day to day running of those communities.

The ancestral diet from this period therefore was made up of more dairy products and of course farmed vegetables, fruits and other products.

What does all this mean to modern dieters?

Well, the Blood Type Diet is optimized for the three main blood types according to the way in which their bodies metabolize food and the way they handle the agglutinating lectins in certain foods.

Each blood type handles these lectins differently and when the wrong foods are eaten, these lectins can cause problems with their metabolizing, from increasing the risk of illnesses, allergies and health conditions to weight gain.

Dieting with Blood Type O

Those with blood type O actually thrive on a diet of high protein meats coupled with a vigorous exercise regime. They don't get on so well with dairy products but do very well on a diet rich in lean meats, fish and poultry.

blood type o meat eatersBody weight can be maintained at the correct levels by avoiding grain-based products such as breads, cakes and pasta as well as legumes and especially beans. The gluten in wheat germ and other grains lowers the metabolism by interfering with insulin efficiency, which leads to weight gain.

It is also true that thyroid function problems tend to be more prevalent in people with blood type O, so it is best to avoid foods that interfere with thyroid function, such as vegetables of the brassica family (cabbage, Brussels sprouts, cauliflower, mustard) while increasing consumption of iodine rich foods to boost hormone production such as kelp and seafood.

From a health perspective, it has been shown that foods from the nightshade group of vegetables (tomatoes, capsicum, potatoes, peppers and chilies, eggplant etc) can cause lectin deposits in the tissue surrounding the joints.

Type O's also tend to have higher stomach acid levels and so should avoid high acid fruits such as oranges, while increasing the amount of alkali forming fruits and berries. Dairy products such as cheese, butter, full fat milk, full fat yogurts etc should also be kept to a minimum as the digestive system does not metabolize these very well.

Dieting with Blood Type A

blood type a vegetable eatersIt has been shown in the Blood Type Diet for Type A's that they can eat a diet made up primarily of certain vegetables and lower levels of meats and animal products. Or in fact they can be completely vegetarian and maintain a healthy weight.

Introducing high levels of red meats and food products high in animal fats leads to weight gain as the metabolism is not optimized for processing meats and meat protein very well.

Avoiding most meats can result in weight loss, which makes it an important factor for those with Type A. It is also important to get more natural foods in the diet with the emphasis on organically grown crops.

The lower stomach acid levels in Type A's is another factor in reducing their ability to digest meats.

Therefore animal proteins should be substituted with nuts, seeds and soy protein based foods such as tofu. Dairy products are also badly metabolized and should be avoided where possible or kept to a minimum.

Type A's can metabolize most legumes and beans (apart from a few exceptions, such as red kidney and Lima beans) very well and these should form a staple part of the diet. A diet high in vegetables is vital to incorporate the right enzymes, nutrients and antioxidants.

Most fruits can be eaten in larger proportions and aid weight maintenance and health balance. However, there is sensitivity to the lectins found in nightshade vegetables (see above) as well as some fruits such as mango, papaya and oranges.

Dieting with Blood Type B

The modern diet recommended for blood type B is low in meat protein and actually prescribes avoiding eating chicken, corn, lentils, peanuts and sesame seeds. blood type b dairy eatersType Bs are better able to resist many of the more severe illnesses that are common to modern life, such as heart disease and cancer as long as they follow the right diet.

However, they are more prone to immune-system disorders that include multiple sclerosis, lupus and chronic fatigue syndrome, so it is important to avoid any foods that might aggravate these conditions.

Type B is actually the only blood type where people can fully enjoy a wide variety of dairy foods.

Their metabolism is best geared up for processing dairy products and they gain the most nutrition from them. However, the nuts and seeds that better suit Types O and A should be avoided by B's as the lectins they contain interfere with insulin production.

Most Type B's do not tolerate wheat products very well as they contain a lectin that reduces insulin efficiency and fails to stimulate the burning of fat. Rye should also be avoided as it contains a lectin that settles in the vascular system, causing blood disorders and can potentially lead to strokes.

Major factors in Type B weight gain include corn and buckwheat. These contribute to a sluggish metabolism, insulin irregularity, fluid retention and fatigue.


While these are only guidelines of what should be eaten and what should be avoided according to a person's blood type, there is a lot of truth in this system as it relies on known metabolic and digestive data taken from a wide spectrum of the populace.

Certainly, health improvements can be had from improving your diet no matter what blood type you happen to be, by reducing your intake of processed foods, junk foods and switching to home prepared and cooked meals made from more natural and fresh ingredients.

- Terry Didcott


Posted on Sun, 29 Apr 2012 in Diet | 0 Comments

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