5 Crucial and Surprising Secrets Your Blood Type Can Tell You About Your Health

Doctor holding tube of specific blood type

The average adult has between 1.2 and 1.5 gallons of blood in their body, accounting for roughly 10% of their weight. Despite it being such a large, and critical, part of human anatomy, many people don’t know what their blood type even is.

Why is it worth it to know? Your blood type can tell you some important insider info (no pun intended) about your health, including if you are more at risk for certain types of medical conditions. Keep reading to learn five secrets your blood type can tell you about your health.

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What Determines Blood Type?

There are four main blood types: A, B, AB and O. Board-certified family physician Dr. Amber Robins, MD, MBA, explains that blood type is determined by one’s genes; it’s passed down from one’s biological parents.

Dr. Laura Purdy, MD, MBA, a board-certified family medicine physician and the medical director and co-founder of SWELL Medical, adds to this, explaining that the presence of specific antigens in your blood determines someone's blood type. Antigens are protein molecules found on the surface of red blood cells. Whether or not certain antigens are on your red blood cells determines what your blood type is.

“The times when [doctors] check blood type is usually when someone is either donating your blood or have the potential of receiving blood. For those who are preparing for surgery or having a baby, many times we do check for your blood type. However, this is not a routine blood test that is done when you get a regular check-up at your doctor’s office,” Dr. Robins says.

To this point, if you don’t know your blood type and want to find out what it is, one way is to donate blood. Dr. Purdy says you can also simply ask your doctor for a blood test to find out what your blood type is or do an at-home blood test.

Related: This Is the #1 Most Important Blood Test To Get Every Year if You Want To Live to 100, According to a Geriatrician 

5 Secrets Your Blood Type Can Tell You About Your Health

Making the effort to get a blood test at your doctor’s office or doing an at-home blood test to learn what your blood type is has several key benefits. Below are five secrets your blood type can tell you about your health and why knowing what your blood type is can be so beneficial.

1. You’ll know what type of blood you need in case of emergency

Both Dr. Purdy and Dr. Robins say that one big reason why it’s beneficial to know your blood type is because you’ll know what type of blood you need in case of an emergency and need a blood transfusion. However, even if you communicate your blood type to emergency responders or doctors, rest assured that doctors will still confirm your blood type through a test called an ABO determination. If emergency responders or doctors don’t have the 45 minutes it takes to figure out your blood type and you need a transfusion quickly, they will give you type O blood, which is safe for individuals of any blood type to receive.

2. If you’re pregnant, knowing your blood type can keep you and your baby safe

There’s an important reason why Dr. Purdy says that knowing your blood type can be helpful if you are pregnant. During pregnancy, having Rh-negative blood can be dangerous if the baby’s blood is Rh-positive. If the two types of blood mix, it could cause the baby to become anemic or it could cause the mother’s body to attack the baby’s blood. Rh factor is a type of protein on the surface of red blood cells. Rh-negative blood is not something that typically is an issue, except during pregnancy if the baby’s blood is Rh-positive.

Since it’s so important for Rh-negative and Rh-positive blood not to mix, doctors will perform blood tests at prenatal appointments to check for the Rh antigen.

Related: This Is the #1 Most Important Screening To Get Every Year If You're 50 or Older

3. It can tell you if you’re more at risk for ulcers and pancreatic cancer

Certain blood types are more at risk for certain health conditions impacting the digestive system. For example, scientific studies show that people with type O blood are more likely to experience ulcers. Scientific research also shows a link between blood types A, B and AB and an increased risk of pancreatic cancer. Having one of these blood types does not mean you are destined to experience ulcers or get cancer. However, it may serve as guidance to take extra precautions to lower your risk through diet and lifestyle habits.

4. It can tell you if you are more at risk for heart disease

Scientific studies show that people with type O blood type are at a lower risk for developing heart disease than all the other blood types. Again, this doesn’t mean that if you have type A, B or AB blood you will definitely get heart disease—or if you have type O blood you definitely won’t. But it’s still helpful intel to have and if your blood type is A, B or AB, it might inspire you to take extra care of your heart through healthy diet and lifestyle habits.

5. It’s helpful to know if you want to donate blood

Every two seconds in the U.S., someone needs blood. A single blood donation can save up to three lives. Despite this crucial importance, only 3% of Americans who are eligible donate blood each year. Dr. Robins says that it can be helpful to know what your blood type is if you want to donate. Some blood donation centers will send text blasts to past donors when there is a crucial need. If you have type O blood, you are an especially valuable donor because all blood types are compatible with yours. However, if you don’t know your blood type, don’t let it stop you from donating. By doing so, you will be saving lives.

While it’s not dangerous to not know your blood type, knowing what it is can offer helpful clues about your health. After all, the more you know about your body, the better you can take care of it.

Next up, here's everything you need to know about at-home medical tests, including which ones are the most accurate.

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