Nearly 80% Of Autoimmune Cases Affect Women — But Why?

Imagine your immune system as your personal bodyguard, always ready to defend you against threats to your health. Now, picture that bodyguard turning against you—this is the essence of an autoimmune disease.

In the United States, approximately 23.5 million people are affected by autoimmune disorders, with a staggering 80% being women1.

While rising stress levels and increased exposure to toxins are known factors in the growing prevalence of these diseases, the question remains: Why are women so disproportionately affected?

There are more than 80 types of autoimmune diseases, including Type I diabetes, arthritis, multiple sclerosis (also known as MS), and Graves' disease. Each of these comes with its own unique symptoms.

However, "The most common autoimmune disorder symptoms are fatigue, joint swelling and pain, skin issues, abdominal pain or digestive issues, and swollen glands," explains board-certified regenerative medicine doctor Seema Bonney, M.D.

Given the broad nature of these symptoms, it's often difficult to spot an autoimmune disease from the start. "There isn't just one test to take that tells you which one you have or if you have one at all," Bonney says.

She adds, "These symptoms are also linked to many other conditions, and diagnosing an autoimmune disorder [requires] having the right symptoms, blood markers, and even tissue biopsies in some cases." 

The diagnostic process can be especially challenging for women, considering that symptoms like acne, digestive problems, and lethargy are commonly considered just another part of the experience of being a modern-day woman.

We don't yet have a clear understanding of why women are disproportionately affected by autoimmune diseases, but experts say it could be partially due to the following factors:

Chromosomes

"The X chromosome has been associated with certain autoimmune disorders2, and since women have two X chromosomes compared to men (XY), this may potentially be a reason why females are more prone to autoimmune disorder," says board-certified lifestyle physician Poonam Desai, D.O.

Hormones

Many autoimmune disorders (like MS and lupus) are driven by estrogen, Bonney says. Increased estrogen can cause inflammation in the body3, so when women go through puberty4 and pregnancy5 (and their estrogen levels rise), they may be at a higher risk of developing an autoimmune disease.

In one 2017 systematic research review6, there was an association between hormonal contraceptive use and increased risk of autoimmune diseases like MS, Crohn's disease, lupus, ulcerative colitis, autoimmune thyroid disease (hypothyroidism), immune skin diseases, and rheumatoid arthritis (RA).

There's less research about HRT and autoimmune disease risk, which makes sense given HRT includes significantly less estrogen than traditional oral contraceptives. Still, one study did find that those using HRT did have a higher rate of lupus7.

This isn't to say taking oral contraceptives, or HRT will cause an autoimmune disease—the current research is all associated data, not a display of cause and effect. There could be plenty of other contributing factors.

Immune response

Plenty of research shows that women have a higher immune reactivity8, making them better at fighting off infections than men. 

While this may be a benefit in many ways, it also raises the risk for hyperimmune responses, which can lead to autoimmune disease predisposition. 

Chronic stress

We know that chronic stress can harm the immune system and cause inflammation, making it another risk factor for many things, including autoimmune diseases.

While both men and women experience psychological stress, the effect it has on the brain is different—some research7 suggests the different responses have to do with testosterone, which can buffer the negative effects of stress on mental health. These are animal studies, so more research is needed.

Even so, women also tend to face certain stressors in their personal and professional lives that men just don't. 

There are plenty of other risk factors for autoimmunity that are unrelated to sex, such as smoking, exposure to toxins, and infections. Genetics can also play a role.

Not every autoimmune disease has a genetic component, but many do, says Bonney. "Two examples of this are lupus and multiple sclerosis, which run in families."

There's no guarantee that you can fully prevent the onset of an autoimmune disease (or any disease, really), given many of the factors above aren't directly in your control. 

While there's more research on autoimmune disease today than there was even three or four years ago, there's still much we don't know.

When I asked Desai how the medical industry can advance the current knowledge of autoimmune diseases, she pointed to financing endeavors for both diagnostics and treatment. 

Autoimmune diseases disproportionately affect women. Some of the prevalence in women can be attributed to chromosomal, hormonal, and immune system differences, while others are more related to lifestyle factors like increased stress.

We need more research on how women can protect themselves from autoimmune diseases. In the meantime, the best we can do is prioritize some basic pillars of health and well-being: eat a balanced diet, exercise regularly, manage stress, and get high-quality sleep.