The O negative blood type diet is an eating plan tailored for individuals with type O positive or negative blood. Naturopath Peter D’Adamo popularized the concept that aligning one's diet with their blood type could enhance overall health and lower the risk of certain diseases. While anecdotal reports suggest health improvements with this diet, these benefits might stem from adopting a generally healthy eating pattern.
Scientific Evidence and the Blood Type Diet
Research into the blood type diet's effectiveness remains limited, and existing studies haven't substantiated its claims. A 2014 study concluded that their findings didn't support the purported benefits of a blood type diet. Similarly, a 2013 review of data on the blood type diet found no current evidence to confirm its advantages.
The Rationale Behind Blood Type Diets
The premise behind blood type diets is that different blood types may influence susceptibility to certain health conditions. A large 2019 genetic study revealed that individuals with type A and AB blood have a higher risk of gastric cancer. Another 2019 study in Croatia linked the AB blood type to an increased risk of psychiatric disorders.
D’Adamo suggests that a chemical reaction occurs when blood interacts with specific foods, particularly lectins, which are proteins. Lectins can directly affect the blood and digestive tract by binding to cells, causing them to clump together and potentially leading to hormonal disruptions. This reaction is likened to the presence of a foreign substance in the body.
According to D’Adamo, people with different blood types react differently to lectins in various foods, leading him to recommend specific diets for each blood type. However, current research doesn't support the idea that lectins affect people in specific blood groups differently.
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A 2014 study indicated that following the blood type O diet reduced triglyceride levels in the blood. However, the study's authors attributed this reduction to factors unrelated to blood type.
Foods to Eat and Avoid for Blood Type O Negative
Proponents of the blood type diet suggest that people with blood type O should consume and avoid specific foods. However, it's crucial to remember that there's limited reliable evidence to support this diet's effectiveness.
Beneficial Foods for Blood Type O Negative
Animal Proteins
The diet plan recommends that people with blood type O consume "beneficial" animal products, including:
- Beef
- Lamb
- Mutton
- Veal
- Venison
- Cod
- Herring
- Mackerel
People with type O blood can generally consume most meat products, including cold-water fish. Type O blood often signifies a physiology uniquely suited to processing animal proteins. As a result of this efficiency, the optimal diet for those with Type O blood features a lot of meat, poultry, and seafood. These high-quality proteins are efficiently processed and converted into nutrition for the body to provide energy and ensure the healthy function of the body’s many different systems.
Dairy
While the blood type O diet generally advises against dairy and eggs, occasional consumption of the following products is permitted:
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- Butter
- Cheeses (farmer, feta, mozzarella, and goat’s cheeses)
- Soy milk
Nuts and Seeds
Nuts are a good source of protein and healthful fats. People following the diet can typically consume most nuts, except those on the "foods to avoid" list. Suitable nuts and seeds include:
- Walnuts
- Hazelnuts
- Almonds
- Pumpkin seeds
Pumpkin seeds and walnuts are believed to provide the most benefits.
Beans
People with type O blood generally tolerate beans. The diet's proponents believe the most beneficial beans for these individuals are:
- Adzuki beans
- Pinto beans
- Black-eyed peas
Grains
While most grains should be avoided on the O positive and negative diet, a few can be included:
- Amaranth
- Buckwheat
- Rice
- Kamut
- Kasha
- Millet
Some individuals may also be able to tolerate gluten-containing grains, such as:
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- Barley
- Rye
- Spelt
- Oat
- Essene bread
- Ezekiel bread
Vegetables
With a few exceptions (listed in the "foods to avoid" section), people with type O blood can eat most vegetables, including:
- Tomatoes
- Artichoke
- Chicory
- Dandelion
- Garlic
- Horseradish
- Kale
- Okra
- Onions
- Parsley
- Parsnips
- Red peppers
- Sweet potatoes
- Pumpkin
- Seaweed
- Turnips
Fruits
Some of the recommended fruits for people with type O blood include:
- Plums
- Prunes
- Figs
- Grapefruit
- Most berries
Spices and Condiments
Spices that people following the diet can enjoy include:
- Kelp-based seasoning
- Iodized salt
- Parsley
- Curry
- Cayenne pepper
- Chocolate
- Cocoa
- Honey
Beverages
People following an O positive and negative diet can drink the following:
- Seltzer water
- Club soda
- Sparkling water
- Tea
- Wine
Foods to Avoid for Blood Type O Negative
Supporters of the diet suggest that people with type O blood may experience unwanted weight gain when they eat particular food groups, such as dairy. Specific products, like wheat-based foods containing gluten, may also lead to an inflammatory and autoimmune response. On the other hand, gluten in many grain products, can antagonize the body and throw a wrench in its works, creating stress on the body and creating imbalances.
Animal Proteins
The diet plan for people with type O blood excludes:
- Pork (including ham and bacon)
- Goose
- Barracuda
- Pickled herring
- Catfish
- Smoked salmon
- Caviar
- Octopus
- Conch
Dairy
People following the diet should avoid dairy products not on the "foods to eat" list, including yogurt.
Nuts
Particular nuts are not included in the diet plan, including:
- Brazil nuts
- Cashews
- Peanuts
- Pistachios
- Poppy seeds
Beans
Beans that proponents of the diet advise against include:
- Copper beans
- Kidney beans
- Tamarind beans
- Lentils (domestic, green, and red)
Grains
The diet also excludes the following grains:
- Corn
- Gluten
- Graham
- Bulgur
- Durum
- Sprouted
- White and whole wheat
- Wheat germ and bran
- Farinaseven grain
Vegetables
Although people in blood group O tolerate many vegetables well, the advice is that they should avoid:
- Vegetables belonging to the Brassica family (cabbage, Brussels sprouts, cauliflower, and mustard greens)
- Alfalfa sprouts
- Shiitake mushrooms
- Fermented olives
- Vegetables from the nightshade family (eggplant and potatoes)
- Corn
- Leek
Fruits
People following the O positive and negative diet should also avoid several specific fruits:
- Melons (cantaloupe and honeydew)
- Oranges
- Tangerines
- Strawberries and blackberries
- Rhubarb
- Avocado
- Coconut and products containing coconut
Spices and Condiments
Spices and condiments to avoid in the diet include:
- Pepper (white and black)
- Vinegar
- Capers
- Cornstarch and corn syrup
- Nutmeg
- Vanilla
- Ketchup
- Pickles
- Mayonnaise
- Relish
Beverages
People with type O blood should avoid drinking the following, according to the diet plan:
- Beer
- Coffee
- Distilled liquor
- Black tea
Blood Types and Their Significance
Blood consists of vital components, including plasma, red and white blood cells, and platelets. Blood also contains antigens, substances on the cell surface that trigger the immune system to attack foreign compounds and organisms. Antigens can also trigger the immune system to attack blood types with different antigens.
Doctors classify blood types as A, B, AB, and O, and label them as either rhesus (Rh) positive or Rh negative to denote the presence or absence of an antigen called Rh factor. For example, a person with O+ blood doesn't have A or B antigens but has Rh factor. O- blood has no A or B antigens and no Rh factor, making it a universal red cell donor type.