Recently a publication noted that your blood group can be a factor for developing an early ischemic stroke (before the age of 60). The majority of ischemic strokes develop after the age of 60.
But another research group found that your blood group can also be the reason why you may develop a heart attack earlier. Specifically, a blood group different from blood group 0 gives you a 9% risk increase for a heart attack.
During the Covid epidemic researchers found that the immune system is stronger in patients with blood group 0: They have less Covid infections and if they get it, they have better survival rates. The common denominator in all of this seems that blood group 0 functions like a genetic marker. It codes for less blood clotting in those with blood group 0 in comparison with people who have other blood groups. At the same time blood group 0 people have a stronger immune system than those with other blood groups.
Evidence for importance of blood group for developing stroke before age 60
Strokes are rare in adults below the age of 60. A University of Maryland School of Medicine study found that different blood group types have different rates of strokes.
The study was a meta-analysis of 48 studies on genetics and ischemic stroke. It included 17,000 stroke patients and nearly 600,000 healthy controls. They never had a stroke. Those with blood type A had a 16 percent higher risk of having an early stroke than people with other blood types. In contrast those with a blood type 0 had a 12% lower risk of getting an early stroke than people with other blood types. Steven J. Kittner, MD, Professor of Neurology at the University of Maryland School of Medicine was a principal co-author of the study.
Comment by Professor Kittner
He said: “We still don’t know why blood type A would confer a higher risk, but it likely has something to do with blood-clotting factors like platelets and cells that line the blood vessels as well as other circulating proteins, all of which play a role in the development of blood clots. We clearly need more follow-up studies to clarify the mechanisms of increased stroke risk.”
Another study showing that blood groups play a role in heart attacks
A 2017 study showed that non-0 blood groups (A, B, AB) had a higher risk to get a heart attack than 0 blood group patients. The meta-analysis of 1,362,569 subjects from 11 prospective cohorts had a total of 23,154 cardiovascular events. There were 9% more non-0 blood group patients who developed a heart attack in comparison to 0 blood group patients.
The lead author was Ms. Tessa Kole, a Master’s degree student at the University Medical Centre Groningen, the Netherlands. She said: “In future, blood group should be considered in risk assessment for cardiovascular prevention, together with cholesterol, age, sex and systolic blood pressure. It could be that people with an A blood group should have a lower treatment threshold for dyslipidemia or hypertension, for example. We need further studies to validate if the excess cardiovascular risk in non-0 blood group carriers may be amenable to treatment.”
Milder Covid infections in blood group 0 patients
Blood group 0 patients had a milder course of Covid than other blood group patients did. Both research in Denmark and in Canada confirmed that blood group 0 had less coronavirus infections. In the Denmark study there were 13% less severe Covid-19 cases in people with the blood group 0 than in negative controls. In the Canadian study of 95 patients with severe Covid-19 needed admission into the ICU. They noted that 84% of blood group AB patients in the ICU required intubation. In contrast, only 35% of 0 group patients required intubation. With regard to kidney support, 32% of AB patients, but only 5% of 0 patients required this during their ICU stay.
Researchers believe that the genetic locus that codes for blood groups is not far from blood clotting genes. This explains that group 0 patients have both less heart attacks and less early strokes. This finding is in contrast to group A, B or AB blood group patients. There may be some blood clotting factor that is produced more in the non-0 blood group patients. This could account for the difference.
The improved immune system in group 0 blood group patients may be another factor that is genetically coded and gives group 0 blood group patients yet another advantage. At the present time we just know that there are the above-described differences. However, we do not have the answers as to why this is so.
Blood 0 patients seem to have an advantage over non-0 blood group patients. They get less strokes below the age of 60 and get 9% less heart attacks. In addition, they have a stronger immune system to fight Covid. It may be that the genetic locus for group 0 and the genetic locus for better outcomes with respect to strokes and heart attacks are close to each other. The same is likely true in terms of proximity between the genetic locus for a strong immune system and the locus for the 0-blood group.
More research needed to find out why blood group 0 has less complications
At the present time researchers just noted an association between blood groups and risk for strokes and heart attacks. The same is true for blood groups and the ability to fight Covid easier or have a harder time. One has to look at all the risk factors and avoid what is detrimental. Included in this is cigarette smoking and drinking too much alcohol. Regular exercise also strengthens the body. Future research likely will explain how blood groups influence the clotting mechanism and the immune system.