Blood Types And Autoimmune Diseases: The Connection

An autoimmune disease is when your body confuses its cells with foreign invaders and starts attacking them. Around 10 million people¹ in the United States live with different autoimmune diseases, including type 2 diabetes, rheumatoid arthritis, and psoriasis.

Your chances of developing certain autoimmune diseases may depend on your blood type. While we need more research in this area, knowing your blood type could alert you to specific risks and help your doctor schedule necessary screenings.

Let's look closely at the connection between blood types and autoimmune diseases.

Types of autoimmune diseases

Many different types of autoimmune diseases exist and range in severity. An autoimmune condition can significantly decrease your quality of life, especially if you don't receive due treatment. That's why it's imperative to get the right diagnosis.

The most common autoimmune diseases in the U.S. are lupus and types of inflammatory bowel disease (IBD) called Crohn's disease and ulcerative colitis. One million people live with lupus, while 1.4 million have IBD.

Here are examples of autoimmune diseases:

• Joint and muscle: Rheumatoid arthritis, lupus, Sjogren's syndrome

• Digestive tract: Crohn's disease, ulcerative colitis, celiac disease

• Endocrine system: Hashimoto's disease, Graves' disease, Addison's disease

• Skin: Psoriasis, dermatomyositis

• Nervous system: Multiple sclerosis, Guillain-Barre syndrome

• Others: Vasculitis, type 1 diabetes

It's possible to control many autoimmune conditions with medication and lifestyle changes. Others may require different treatment.

What are the symptoms of autoimmune diseases?

While all autoimmune conditions manifest differently, some common symptoms include:

• Unexplained fatigue

• Joint pain and swelling

• Stomach pain

• Digestion problems

• Recurring unexplained fever

• Swollen glands

What are different blood types?

Similar to eye or hair color, blood type is an inherited factor. Doctors need to know which blood type someone has when transfusions are necessary. If you don't know your blood type, you can identify it by using a home testing kit, asking the doctor to run a simple blood test, or becoming a blood donor.

Four main groups exist. The difference between them dictates the absence or presence of A and B antigens (protein molecules) on red blood cells:

• Type A only has A antigens

• Type B only has B antigens

• Type AB has A and B antigens

• Type O doesn't have either A or B antigens

Each blood group receives a further classification depending on the absence or presence of the Rhesus (Rh) factor. Blood types with Rh factor (another protein on the surface of a blood cell) are Rh-positive. Types without the Rh factor are negative. 

Accordingly, there can be eight blood types:

• A+ (universal recipients)

• A-

• B+

• B-

• AB+

• AB-

• O+

• O- (universal donors)

The most common blood type is O+. The need for donors with this type is high since 37%² of the population has it? O- blood is often necessary for emergencies when the patient’s blood type isn’t identifiable, as it carries the least risk of causing a reaction. Only 7% of the population is O-, meaning there’s a shortage of donors.

In total, there are 44 blood group systems, which have various antigens, and some are incredibly rare. NHS scientists discovered the Er group in September 2022.³ 

The connection between blood types and autoimmune diseases

The theory that people with certain blood types are more likely to develop certain autoimmune diseases still warrants more research. Several studies have connected blood types with specific conditions, but all of them are too small to make definite conclusions.

Here are several autoimmune diseases that may be related to blood type.

Type 2 diabetes

A recent case-control study⁴ tried to determine whether A, B, AB, or O blood groups increased the risk of developing type 2 diabetes. It looked at 300 people with and without diabetes. The researchers collected information by sending out an electronic questionnaire.  

The study found that people with blood group B had a higher risk of developing type 2 diabetes than others. Based on this study, researchers recommend people with blood group B get regular screenings for the condition.

Rheumatic diseases

Rheumatic autoimmune diseases cause pain in the joints, tendons, cartilage, and connective tissue. The most common ones are rheumatoid arthritis, Sjogren's Syndrome, and systemic lupus erythematosus.

A 2017 study⁵ looked at 823 patients with different blood types. Each of them had a common rheumatoid disease. The study connected specific blood types to the risk of specific conditions:

• O: Lupus, systemic sclerosis, and Sjogren's Syndrome

• AB: Least likely to have rheumatic diseases (possibly because it's a rare blood type and fewer study participants had it.)

In addition, 92.2% of the patients had a positive Rh factor. This could mean that positive Rh is a risk factor. However, the positive Rh factor is more common in general.

Hashimoto's disease

Hashimoto's disease causes the immune system to attack healthy thyroid cells. Eventually, cells die, and the thyroid gland stops functioning properly.

A 2019 study⁶ looked at 958 patients with Hashimoto's disease and non-Hashimoto's hypothyroidism, a condition where the thyroid gland is underactive.

The number of people with O blood was higher in the Hashimoto disease group than in the group with non-Hashimoto hypothyroidism. The number of patients with the AB blood group was the lowest.

Researchers concluded that the O blood group might be associated with a higher risk of developing Hashimoto's disease.

Multiple sclerosis

Multiple sclerosis (MS) is when the immune system attacks nerve fibers, leading to permanent nerve damage. This hinders communication between the brain and the body.

A 2019 study⁷ looked at 265 patients with multiple sclerosis. It found that people with blood groups without A and B antigens or Rh factors had the lowest chances of developing the disease. Meanwhile, those with A, B, and Rh+ may be at risk of developing MS.

Lupus

Lupus is a condition that involves your immune system attacking tissues and organs. This disease can affect the entire body, including the joints, kidneys, brain, heart, and lungs.

Since antigens play a major role in how lupus works, studies checked if the blood groups with antigens (A, B, and AB) are a risk factor.  

One study⁸ demonstrated that people with B+ blood type might have a higher risk of developing lupus.

Risk factors for autoimmune diseases

While researchers are yet to discover what causes your body to start attacking itself, numerous studies revealed certain risk factors. They are:

Sex

If you are a woman, you have a much higher chance of developing an autoimmune disease. According to statistics, 78%⁹ of people with these conditions are women.

Women may be more likely to develop autoimmune diseases because of the additional X chromosome, reproductive function, and differences in immune responses.

Genetics

Similar to the blood type, your chances of developing an autoimmune disease may depend on your family history. Conditions such as lupus and multiple sclerosis in the family could increase your risk.

Existing autoimmune disease

If you have one autoimmune disease, your chances of developing another one are higher.

Multiple autoimmune syndrome (MAS)¹⁰ is where you have three or more autoimmune diseases. This happens in about a quarter of patients with autoimmune conditions.

Today, researchers know three different types of MAS. Each type groups together different diseases. If you have one of the diseases from a particular group, you should consider getting a screening for others.

Obesity

Obesity affects around 41.9%¹¹ of American adults. It's a risk factor for many health problems, including autoimmune diseases. For example, it increases your chances of developing rheumatoid arthritis, type 2 diabetes, and psoriatic arthritis.

When people gain weight, they accumulate excess fat in and around the vital organs. This fat plays a major role in many functions of the body. When there is too much of it, fat tissue becomes dysfunctional. This could lead to inflammatory processes and affect the immune system.

Smoking

Smoking harms how your body functions. Researchers have found significant proof that it can lead to several serious conditions, including cancer.

Research¹² links smoking to autoimmune conditions such as lupus, MS, and rheumatoid arthritis. When people smoke, they inhale toxins that lead to inflammation, immune system suppression, and the development of autoantibodies.

Autoantibodies are antibodies that attack your proteins.

Blood type

As of today, we need more research to confirm that blood groups and types may affect your chances of developing autoimmune conditions. However, some studies already show the connection between blood types and autoimmune diseases:

• B: Type 2 diabetes

• O: Lupus, systemic sclerosis, Sjogren's syndrome, Hashimoto's disease

• A, B, and types with an Rh factor: Multiple sclerosis

• B positive: Lupus

Talk to your doctor about extra screenings based on your blood type.

Causes of autoimmune diseases

The exact cause of developing autoimmune diseases is currently unknown. However, knowing all the risk factors can help doctors determine your possibility of developing an autoimmune condition.

That's why sharing your medical and family history with your doctor is important. They can schedule screenings to find existing conditions and begin treatment.

Many people don't seek medical help when experiencing the first symptoms of autoimmune diseases. Waiting for any symptoms to subside without help isn't a good idea. This decreases your quality of life and delays treatment.

How to diagnose autoimmune diseases

If a doctor suspects you have an autoimmune disease, they may run a series of tests. The most common one is the antinuclear antibody (ANA) test. This test checks if you have antinuclear antibodies which attack healthy proteins.

If the ANA test comes back positive, it doesn't always mean you have an autoimmune condition. A doctor may order further tests.

You may still have an autoimmune disease if the ANA test is negative. If you continue having symptoms, a doctor may order additional tests. They may include:

• Complete blood count (CBC) 

• Comprehensive metabolic panel

• C-reactive protein (CRP)

• Erythrocyte sedimentation rate (ESR)

• Urinalysis

Your doctor may also order these tests if you are at a high risk of developing certain autoimmune conditions. The faster you identify the problem, the faster you can start controlling it.

Since symptoms of autoimmune diseases are often non-specific (can indicate several diseases), autoimmune conditions are hard to diagnose. According to a survey conducted by Autoimmune Diseases Association, it takes up to 4.6 years and five doctor visits¹³ to receive the diagnosis.

How to treat autoimmune diseases

Scientists are yet to discover why the immune system starts attacking healthy cells. However, they already know that we can manage autoimmune diseases. 

Currently, there isn't a cure for autoimmune diseases. However, you can manage the symptoms and improve your quality of life. Your doctor may prescribe:

• Painkillers

• Anti-inflammatory medications

• Insulin injections

• Sleep meds

• Corticosteroids

• Rash creams

• Immune system suppressors

The course of treatment depends on your individual needs and the disease you have. You may also improve your condition by making positive lifestyle changes. When your doctor determines the course of treatment, they can also give general lifestyle and diet recommendations.

The lowdown

Several studies demonstrate a certain connection between blood types and autoimmune diseases. However, researchers are yet to discover a direct relationship. Different blood types may increase the risk of developing different autoimmune conditions.

When determining your chances of developing an autoimmune disease, your doctor reviews your family and medical history, including the blood type. These may warrant specific screenings and determine the course of treatment.

Frequently Asked Questions  

Which blood type is most sensitive to diseases?

Different blood types may be more sensitive to different diseases. For example, people with the B blood group may be at a higher risk of developing diabetes. Meanwhile, people with A and B blood could likely develop multiple sclerosis.

What is the healthiest blood type to have?

People with the O blood group are generally less susceptible to certain diseases. However, they could be at a higher risk of developing autoimmune conditions.

What genes make you more prone to autoimmune diseases?

Human leukocyte antigen (HLA) genes may be responsible for a person developing an autoimmune disease.