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

You can think of your immune system as your bodyguard, fighting off anyone who threatens your health. Now, imagine that your bodyguard begins attacking you instead—this is essentially what happens when you have an autoimmune disease.

An estimated 23.5 million Americans now struggle with an autoimmune disorder—a shocking 80% of whom are women1. We know that increasing rates of stress and exposure to toxins contribute to the growing prevalence of autoimmunity, but 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. All of these come with their 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 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.

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.

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

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.

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.