B+ is neither a good nor a bad blood type. It is a normal, healthy type, and what it changes is practical: whose blood you can safely receive, and who your donation can help. How rare it feels depends on where your family comes from, because B+ is uncommon in the US and Europe but one of the most common types across parts of Asia. Large studies link it to slightly higher average risks for a few conditions, but those are small shifts in odds, not a diagnosis.
What the B and the Plus Actually Mean
Your blood type names the markers that sit on the surface of your red blood cells. The B means your red cells carry the B marker and do not carry the A marker. The plus means your red cells also carry a marker called RhD, which is what doctors mean by Rh factor or Rh positive. Doctors know of more than 30 blood group systems, but ABO and Rh are the two that matter for everyday transfusions.1PubMed Central. Blood groups systems
On a lab report or donor card, your result may read “B Rh positive,” “B pos,” or “B+.” All of these mean the same thing. Your type is usually checked before surgery, during pregnancy, and when you give blood. It stays the same for life, except in rare cases such as after a bone marrow transplant.
B+ blood also naturally carries antibodies against the A marker. If A or AB red cells were given to you, those antibodies would attack the donated cells. That reaction can be dangerous, which is why hospitals test blood and cross-match every unit before a transfusion. The plus is simply one more marker on the cell. Being Rh positive doesn’t mean you are healthier or more protected. Unlike anti-A, anti-RhD antibodies are not present from birth in an Rh-negative person. They form only after exposure to Rh-positive blood, so a first exposure usually causes no reaction but can set up a stronger one later.
Who Can Give Blood to You, and Who You Can Help
For red cells, the matches work like this:
- You can receive from: B+ donors,2Brooklyn Cancer. Discover how blood type is determined B- donors,3Brooklyn Cancer. Discover how blood type is determined O+ donors,4Brooklyn Cancer. Discover how blood type is determined and O- donors.5Brooklyn Cancer. Discover how blood type is determined
- You can give to: B+ patients and AB+ patients.6American Red Cross. B Blood Type7NHS Blood Donation. B positive blood type
O- donors can help you because their red cells lack the A, B and RhD markers, so your antibodies have nothing to attack. Your own red cells carry B and RhD, so they can go only to patients who already carry the B marker.
The plus and minus matter most for red cells, because RhD sits on the red cell surface. As a B+ person you already carry RhD, so you can receive Rh-negative or Rh-positive red cells. A B- patient, though, should get Rh-negative red cells where possible, since exposure to RhD can lead to antibody formation. That means B- donors can help B- and AB- patients as well as Rh-positive ones.
In an emergency where your type isn’t yet known, staff may start with O- red cells. They switch to type-matched blood once testing confirms your type.
For plasma, the liquid part of blood, the rules are the reverse of those for red cells.8American Red Cross. Blood Types Plasma carries antibodies rather than red cells, so what matters is whether the recipient’s red cells have the marker those antibodies attack. Your B plasma holds anti-A antibodies, so it is safe for patients whose red cells lack the A marker, which means B and O patients, and it would attack the red cells of an A or AB patient. AB plasma has no anti-A or anti-B antibodies, which is why it is the most widely usable.
Hospitals also sometimes give blood products that are a slight mismatch, such as type O platelets to non-O patients, and judge this case by case.9PubMed Central. When is ABO-incompatible plasma safe to transfuse? Defining an empirical estimation of anti-A/anti-B in ABO incompatible plasma-containing blood products
How Common B+ Is Around the World
About 8.5% of people in the US are B+, compared with about 37% who are O+ and 36% who are A+.10Statista Daily Data. Infographic: How Blood Type Prevalence Varies Around the World B+ is about three times more common among Asian and Black American donors than among White or Hispanic donors.11bloodtypechart.com. Blood Type Distribution by Ethnicity and Country In parts of Western Europe, such as the Netherlands, Norway, Portugal and Switzerland, type B as a whole falls to single-digit percentages.12Wikipedia. Blood type distribution by country
Across Asia the picture flips. Pakistan and Bangladesh are among the few countries where B+ is the single most common type, and it is also common in India and China.13Statista Daily Data. Infographic: How Blood Type Prevalence Varies Around the World Across the Middle East, type B is unusually frequent.14Wikipedia. Blood type distribution by country Within China, some groups such as Manchu and Mongolian people are about one-third type B.15BMJ Open. Frequencies and ethnic distribution of ABO and RhD blood groups in China: a population-based cross-sectional study Type B is believed to have been absent among Native American and Aboriginal Australian peoples before European contact.16Wikipedia. Blood type distribution by country
Blood type follows ancestry, so B+ often clusters in families with South Asian, East Asian or Middle Eastern roots. That’s how a type that is rare in one country can be the most common one in another. Nobody is sure of all the reasons it became frequent in some places, so be wary of tidy explanations.
B- is a different story. It is far rarer, at under 2% even among White donors, because being Rh negative is mostly a European-ancestry trait.
Does B+ Affect Your Health
In a large study following people for more than 20 years, type B was linked with an 11% higher risk of heart disease than type O.17Penn Medicine. The connection between blood type and heart health A study of 1.5 million blood donors found that non-O types, including B, had more blood clots in both veins and arteries.18PubMed. ABO Blood Group and Risk of Thromboembolic and Arterial Disease: A Study of 1.5 Million Blood Donors
One proposed explanation is that blood type influences levels of a protein involved in clotting, and non-O types tend to have more of it. More of this protein can make blood slightly more likely to clot. That is one explanation, not a settled one.
In a large group of French women, type B carried a 21% higher risk of type 2 diabetes than type O.19PubMed. ABO and Rhesus blood groups and risk of type 2 diabetes: evidence from the large E3N cohort study In that same study, B+ specifically had the highest risk, about 35% higher than type O.20PubMed. ABO and Rhesus blood groups and risk of type 2 diabetes: evidence from the large E3N cohort study
In two large US groups, type B had about 46 new pancreatic cancer cases per 100,000 people each year, compared with 27 for type O.21PubMed Central. ABO Blood Group and the Risk of Pancreatic Cancer Even with type B, this cancer stays uncommon, at under 1 case in 2,000 people a year.
Some links are mixed or unclear. Links between blood type and COVID-19 have varied from study to study and place to place.22PubMed Central. A narrative review of the epidemiological and mechanistic associations between ABO blood groups and diseases: focusing on cardiovascular diseases, cancers, diabetes, malaria, COVID‑19 and rheumatic diseases A large Scandinavian study found no link between blood type and dementia.23PubMed Central. ABO Blood Group and Dementia Risk – A Scandinavian Record-Linkage Study One study did find a higher dementia risk in people who carry two B gene versions, so the picture remains unsettled.24PubMed Central. Association between ABO genotypes and risk of dementia and neuroimaging markers: roles of sex and APOE status
An 11% higher risk is 11% of a small starting number, not 11 out of every 100 people. If the starting risk is small, the extra risk stays small, so look for absolute numbers, like the pancreatic cancer rates above.
These studies also compare groups. They show that people with type B have more of a condition on average, not that blood type caused it in any one person. Differences in diet, age or ancestry between groups can blur results, although researchers try to adjust for them. Smoking, high blood pressure, high cholesterol, diabetes, inactivity and excess weight each shift heart risk far more than your blood type does.
You can’t change your blood type, so focus on the risk factors you can change. Get regular checks of blood pressure, cholesterol and blood sugar. And tell your doctor about any family history of blood clots before surgery, long flights or starting hormone medicines.
How You Inherited B+ and What You Can Pass On
You inherit one ABO gene version from each parent.25AI DiagMe. Blood Group B: Meaning, Traits, and Health Risks A and B both show up when you carry them, while O stays hidden behind them.26Medicover Genetics. Genetics of blood type: Inheritance and compatibility So a person with type B carries either two B versions (BB) or one B and one O (BO).27AI DiagMe. Blood Group B: Meaning, Traits, and Health Risks Rh works in a similar way: Rh positive masks Rh negative.28DNA Diagnostics Center. Blood Type Inheritance Chart That means a parent’s blood type doesn’t always reveal which versions they can pass on.29DNA Diagnostics Center. Blood Type Inheritance Chart
A standard blood test can’t tell the two apart, so you may not know which one you are. Genetic testing or family results can reveal it, but it rarely matters for your health.
Two BO parents can have a type O child, because each can pass on their hidden O. A B parent and an A parent can have a child of any ABO type: A, B, AB or O.
Rh is inherited separately from ABO, so your B and your plus come from different gene pairs. A B+ person can carry two Rh-positive versions or one positive and one negative. That is why two Rh-positive parents can have an Rh-negative child.
Your own type tells you a little about your parents. At least one had to carry a B version and at least one an Rh-positive version. One parent could be type A or AB, as long as the other carried B. An O parent can pass on only O, so with an O parent your B must have come from the other.
Pregnancy and the Plus Sign
An Rh-negative mother’s body can make antibodies against an Rh-positive baby’s blood. During pregnancy or birth, a small amount of the baby’s blood can cross into the mother’s circulation. If the baby’s red cells carry RhD and the mother’s do not, her immune system may see them as foreign and make anti-D antibodies.
Antibodies usually form after the first exposure, often around delivery, so the first baby is typically unaffected. In a later pregnancy with another Rh-positive baby, those antibodies can cross the placenta and attack the baby’s red cells, causing anemia. That is why prevention is given: Rh-negative mothers carrying an Rh-positive baby may need anti-D injections around 28 weeks, within 72 hours after birth, or after procedures where the mother’s and baby’s blood can mix.30PubMed Central. Distribution of ABO and Rh blood groups among pregnant women attending the obstetrics and gynecology clinic at the Jordan University Hospital
As a B+ mother, you do not need these injections. A B+ father can pass on Rh positive, though, so an Rh-negative partner should make sure her Rh status is known early in pregnancy.
The Blood Type Diet for B+
The type B diet says people with your blood type digest certain foods well, such as dairy, and should avoid others, such as chicken and corn. It was popularized in a book, not built from controlled testing, and its rules were set by blood type rather than by anything measured in a B person’s body.
A systematic review found no evidence that blood type diets deliver their claimed health benefits.31PubMed. Blood type diets lack supporting evidence: a systematic review When researchers checked people’s actual blood type genes, eating the Type-B diet showed no link to heart or metabolic health markers for type B people.32PubMed Central. ABO Genotype, ‘Blood-Type’ Diet and Cardiometabolic Risk Factors Its rules have no special value for a B+ person. Some people still feel better on it, because the plan cuts processed foods, which can help anyone regardless of blood type.
Healthy eating for B+ people is the same as for everyone else: plenty of vegetables, fruit and whole grains, and limited processed food. If you have a specific condition, such as diabetes or lactose intolerance, your diet should follow that, not your blood type. A dietitian can tailor advice to your health and tastes.
Why Your B+ Donation Counts
B+ plasma can be given to about 60% of people.33Australian Red Cross Lifeblood. What should I donate? Donating plasma can therefore stretch your contribution further than donating red cells, which only B+ and AB+ patients can receive. Ask your blood service which donation type it most needs from B+ donors.
Hospitals use plasma for patients who are bleeding heavily or have clotting problems. In an emergency with unknown type, AB plasma is usually used first.
Plasma donation is a bit different from giving whole blood. A machine draws your blood, separates out the plasma, and returns your red cells to you. It takes longer, often around an hour, but you can usually give plasma more often than whole blood.
Because B+ is more common among Asian and Black American donors,34bloodtypechart.com. Blood Type Distribution by Ethnicity and Country patients from these communities benefit from a diverse donor pool, especially those who need repeated transfusions and do better with closely matched blood.