By Rory Linehan
Key Messages:
- More than three out of every four people with autoimmune disease are women
- The reasons for the ‘gender bias’ in autoimmune disease are still not well understood but can be grouped broadly into three categories; Immune Response, Hormones and Genetics
- Women are able to mount a stronger immune response than men which may make them more likely to develop autoimmune disease
- Some male predominant hormones reduce autoimmune disease while some female predominant hormones increase autoantibody production
- Women carry two X Chromosomes, while men only carry one. X Chromosomes carry a number of genes which relate to immunity.
You may have heard that autoimmune disease is now the third most prevalent type of disease in the US and affects up to 8% of the population[1]. But this is not unique to the US. Right across the world the prevalence of autoimmune disease is increasing, including in my neck of the woods, Australia and New Zealand, where approximately 5% of the population is affected by the condition[2].
What you might not know is that autoimmune disease disproportionately affects women. In fact, conservative estimates indicate that 78% of the population affected by autoimmune disease are women. Or put another way, more than three out of every four people with an autoimmune disease are women!
FEMALE:MALE RATIOS IN AUTOIMMUNE DISEASE
Graphic from the American Autoimmune Disease Related Disease Association Inc.
But why is it that women suffer from this condition to a far greater degree than men? As a man with a number of very important women in my life, I was particularly interested as to why my mum, my sisters and my best mates are more likely to have to deal with the stress of an autoimmune disease than me.
What Causes Gender Differences in Autoimmune Disease?
Unfortunately, the literature reveals that reasons for this “gender bias” in autoimmune disease are still not well understood. There have been a number of studies on the subject, yielding slightly different results and hypotheses. I’ve broken the results down into three key areas in an effort to better understand the phenomenon, including; Immune Response, Hormones and Genetics.
THE WHYS BEHIND GENDER DIFFERENCES IN AUTOIMMUNE DISEASE
*Graphic from Gender differences in autoimmune disease by S.T. Ngo, F.J. Steyn and P.A. McCombe
- Immune Response:
According to several studies[3][4], the gender difference in autoimmunity may be driven by differences between the male and female immune systems. Women’s immune systems have heightened immune reactivity when compared to men’s immune systems, meaning that women can mount more powerful immune responses than men[5].
This means that women was have greater resilience to infections and diseases (maybe man-flu is real?!) but on the flip side, it is possible that this greater immune reactivity makes women more prone to developing autoimmune disease.
- Hormones:
Sex hormones, such as estrogen, testosterone, and progesterone account for much of the difference in the prevalence of autoimmune disease between men and women.
The precise interaction between hormones and the immune system is just beginning to be understood. Several studies show that male-predominate hormones, such as androgens, reduce autoimmune disease while some female-predominate hormones, such as estrogen, stimulate antibody (autoantibody) production[6], which can lead to autoimmune disease.
What the literature shows is that the science on the role of sex hormones in autoimmune disease is still very nascent and more research needs to be done before firm conclusions can be made.
- Genetics:
Men carry an X and Y chromosome while women carry two X chromosomes. Although most of the second X chromosome in women is deactivated during fetal development, some of its genes remain. As a result, women may express more genes from the X chromosome than men do, and a number of these play a major role in immunity[7]. Some researchers believe this difference might explain at least some of the sex-bias in autoimmune disease[8].
A final word…
The gender bias in autoimmune disease is still not well understood. However, it is clear that the interaction of immune response, hormones and genetics, among other factors, make women more susceptible to autoimmune disease than men.
And while I personally have no influence over the prevalence of autoimmune disease among the important women in my life, my experience from over three years on the Paleo Autoimmune Protocol shows that regardless of sex, Nutrition, Lifestyle and Mindset are crucial to reversing and even stopping autoimmune disease before it presents itself.
Want to find out more about the Paleo Autoimmune Protocol? Check out the Simple Guide to the Paleo Autoimmune Protocol by Eileen Laird. In upcoming weeks, I’ll be giving away two copies to two lucky readers. But if you can’t wait until then, you can find it at the link below.
[1] http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2527069/
[2] http://www.allergy.org.au/patients/autoimmunity/autoimmune-diseases
[3] http://www.ncbi.nlm.nih.gov/pubmed/19747114
[4] http://www.ncbi.nlm.nih.gov/pubmed/17537382
[5] https://www.sciencedaily.com/releases/2013/08/130822122801.htm
[6] http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2527069/
[7] http://www.sciencedirect.com/science/article/pii/S089684110900050X
[8] http://www.sciencedirect.com/science/article/pii/S0091302214000466
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