9 secrets your blood type reveals about you

Unless you’ve recently given blood, you may not think much about your blood type. The presence or absence of certain molecules called A or B antigens, as well as a protein called the Rh factor, determine which of the eight common blood types you have coursing through your veins. (The Australia Red Cross notes that these blood types are: A+, A-, B+, B-, AB+, AB-, O+, or O-.) However, these antigens make a difference beyond just your blood, according to an article published in Blood Transfusion in 2013. They can influence other parts of your body, including blood vessels, neurons and platelets, and as a result, your blood type may be linked to your risk of developing certain diseases.

Non-O blood types have 25 to 30 percent higher levels of blood-clotting proteins known as von Willebrand factor and factor VIII. In part, because of that difference, these people also have a 15 per cent greater risk of dying from heart disease compared to people with other blood types, according to 2015 research from BMC Medicine.

Find out which are the worst foods for your heart.

Considering that type Os have lower quantities of the proteins that help blood coagulate, they’re also less likely to suffer from blood clots. (The downside is that blood clotting helps prevent excessive bleeding.) That said, there are many things that cause blood clots. “It shouldn’t be assumed that being an O blood type means an individual is ‘protected’ or an A blood type is at higher risk,” says haematologist Dr Terry B. Gernsheimer.

Read on for the reasons everyone should know their blood type.

Type O may be the most common blood type – and it may interfere with pregnancy. As research published in the journal Human Reproduction notes, O types were twice as likely to have levels of follicle-stimulating hormone (FSH); the levels were high enough to indicate low ovarian reserve – fewer egg cells for fertilisation. Another study published in the Journal of Assisted Reproduction and Genetics found that women with both O and A blood types were less likely to experience successful IVF (ie resulting in a live birth) than those with type B, whose odds were higher.

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Another interesting finding from the BMC Medicine study that linked certain blood types to a higher risk of heart disease: Non-O blood types (A, B, or AB) also had an increased risk of gastric cancers, possibly due to an inflammatory response to H. pylori bacteria. (The bacteria are a cause of gastric ulcers.)

Because of differences in clotting, A/B blood types are more likely to suffer from venous thromboembolism – a clot that forms in the deep veins of the leg, groin or arm (deep vein thrombosis, or DVT), and can break off travel to the lungs (pulmonary embolism) – compared to O types, according to research published in the journal Blood Transfusion. The study additionally found that non-O types with inherited thrombophilia, a condition in which blood coagulates abnormally, raised their risk threefold.

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Though AB is the least common blood type, research published in the journal Neurology in 2014 suggests that people with AB are 82 per cent more likely than people with other blood types to develop cognitive issues that could lead to dementia later in life. The study’s authors theorise that this may be because AB blood has higher levels of factor VIII.

Read on for the health reasons your short-term memory is getting worse.

People with a blood type of A or B have an up to 21 per cent greater risk of developing type 2 diabetes compared to those with type O, according to a study published in the journal Diabetologia. (Those who were B positive had the highest odds.) While researchers note that it’s not exactly known why, one thought is that the blood type may influence the GI microbiome, which can affect glucose metabolism and inflammation.

Read on to separate the diabetes myths from truths.

You may have heard people talk about the blood-type diet, in which eating and avoiding certain foods based on your blood type can boost your health and lower your risk of disease. However, a 2013 review in the American Journal of Clinical Nutrition concluded that there’s no evidence that proves these types of diets actually work. Another study published in PLOS ONE found that while following a diet like this may have a positive effect on some cardiometabolic risk factors, it has nothing to do with someone’s specific blood type.

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There’s a theory that your blood type can explain why you act the way you do. While that largely hasn’t been proven, one Japanese study published in PLOS ONE found that some personality traits differed between blood groups. People with type A, for instance, scored higher on persistence compared to types B or O. However, even the researchers note that there isn’t enough data to prove the connection. Until we know more, it looks like you can’t use your blood type as a scapegoat for your behaviour.