Studies have found that people with Type A, B, or AB may have a slightly higher risk of heart disease compared to those with Type O.
One reason may be higher levels of blood-clotting proteins in non-O blood types, which can increase clot formation.

Type O individuals tend to have lower levels of these proteins, offering some protection—but lifestyle factors still matter far more.

2. Infections and Immune Response

Your blood type can influence how your body responds to certain infections:

  • Type O: More resistant to severe malaria, but more vulnerable to cholera

  • Type A: Higher susceptibility to smallpox and some viral infections

  • Type AB: Mixed immune traits due to having both A and B antigens

During the COVID-19 pandemic, research suggested that Type O individuals might have slightly lower risk of severe infection, though this is not absolute.

3. Digestive Health

People with Type A may produce less stomach acid, which could affect digestion and increase vulnerability to certain gut bacteria like H. pylori.
This has been linked to a higher risk of stomach ulcers and gastric cancer in some populations.

4. Cancer Risk

Some studies have observed: