It is a widely reported fact that women are far more likely to fall prey to almost every type of autoimmune disease, but the reasons for this are not clearly understood. This article examines the evidence regarding the incidence rates of autoimmune disease among different age, gender, and socio-economic groups, and the possible causes explaining the differences.
What is autoimmune disease?
An autoimmune disorder occurs when the body’s immune system incorrectly attacks and destroys healthy body tissue. A healthy immune system produces a special type of white blood cell called T lymphocytes, or T cells, that target and remove harmful substances that enter the body. These harmful substances, collectively referred to as antigens, commonly take the form of bacteria, viruses, cancer cells, or other toxic foreign material introduced from the environment. The immune system produces specialized antibodies that destroy the different types of antigens that enters the body. A dysfunctional immune system fails to distinguish between healthy tissue vs. antigens, and consequently attacks all suspect tissue, even healthy tissue.
Types of autoimmune disease
There are more than 80 different kinds of health disorders that are now classified as autoimmune diseases. Below is a partial list:
Variations in autoimmune prevalence between men and women
Of these 80 some-odd types of autoimmune disease only three have been documented to have a higher incidence rate in men: myocarditis, ankylosing spondylitis, and idiopathic pulmonary fibrosis. As shown in the table below, the ratio of female to male incidence varies widely among these diseases:
The mechanisms of autoimmune response in women vs. men
What accounts for these disparities between men and women? Researchers have discovered some key differences in the way male vs. female bodies respond to infection and tissue damage. Specifically, women respond to infections with increased antibody production in the form of Th2 T-lymphocyte cells, whereas men respond more frequently with production of Th1 T cells. How does this manifest differently in women vs. men, as it pertains to autoimmune disorders? Th2 cells, which respond more slowly and systematically, are designed to send out natural antibodies to tackle and remove toxic antigens that enter the body and bind to healthy cells. Th1 cells on the other hand, respond much more quickly with an acute and targeted inflammatory response.
The reasons for this different immune response in women vs. men are not entirely clear. One possibility is that from an evolutionary perspective, a rapid inflammatory response promotes quicker wound healing, which until fairly recently in our evolutionary life cycle men needed to keep themselves alive long enough to fight off attackers and protect their brood (and thereby pass on their genes to the next generation of well-adapted fighters). Women’s bodies on the other hand, were more concerned about staying around longer so they could successfully raise their young (who would in turn pass on these strong survival genes to the next generation.) Indeed, there is considerable evidence indicating that males have stronger short-term injury survival mechanisms, whereas women have much stronger long-term survival oriented immune systems.
The hormone connection
There is a clear hormone connection behind these differing sex responses to tissue damage and invasion. Women have much higher estrogen levels than men, and men have much higher androgen (testosterone) levels than women. These different hormone levels and their associated immune responses align closely with the male to female ratio of the different autoimmune disorders listed above. For instance, autoimmune diseases that are more prevalent in males, including myocarditis and ankylosing spondylitis are characterized by acute inflammation. Conversely, autoimmune disorders that are most prevalent in women, including lupus, Sjörgren syndrome, and Hashimotos thyroiditis are characterized by much higher levels of antigen-specific autoimmune antibodies.
The vast majority of autoimmune disorders affecting women begin in the peak hormone-expressing years between puberty and menopause, further reinforcing the connection between immune disorders and hormones. Estrogen plays a dominant role in the regulation of the thyroid gland, which has the highest ratio of female to male autoimmune disparity among all the autoimmune diseases. Male lupus patients also have higher estrogen to androgen levels and lower levels of testosterone. Furthermore, clinical studies have demonstrated that manipulating estrogen levels in test subjects elicits a significant change in the autoimmune reactivity of cells. Adding estrogen boosted the level of immune response in all study samples, but the reactivity of cells from women was almost two times greater than that of cells of men.
The environmental link
So if women have a fundamentally stronger immune response than men, which is driven by their uniquely high estrogen levels, why are they generally more prone to autoimmune disease? This is where the epidemiological data showing socio-economic differences come into play. Several studies have demonstrated a strong positive correlation between socio-economic status and the incidence of autoimmune disease. There is a positive correlation between gross national product and the incidence of asthma, Type 1 diabetes and multiple sclerosis in Europe. This is not only true at the country level but also for smaller regions such as Northern Ireland, where the low incidence of Type 1 diabetes is correlated with lower average socio-economic indicators. The incidence of diabetes is sixfold higher in Finland compared to the much less affluent adjacent Karelian republic of Russia, even though the genetic background is virtually identical. Similar results have been obtained in the province of Manitoba in Canada for Crohn’s disease. Additionally, migration studies have shown that offspring of immigrants coming from a country with a low autoimmune incidence acquire the same incidence as the host country, as rapidly as the first generation for Type 1 diabetes and multiple sclerosis.
So what is different about wealthy countries compared to less developed countries as it relates to autoimmune disease? According to the ‘hygiene theory’ of autoimmune disease, there are two primary factors at work. First, more developed countries have better public health protocols protecting the public from infectious agents. These take the form of clean drinkable water supplies, sanitary sewage systems that carry toxic wastes away from public sources, more sanitized healthcare service environments, etc. In underdeveloped African countries where infection rates are much higher, autoimmune disorders are very low. The other factor contributing to low infection rates involves the prevalent use of vaccines and antibiotics to quickly eradicate and prevent serious infections before they can spread both within the individual or the general population.
All of these forces add up to an exceptionally ‘sanitized’ environment in which our immune systems are underutilized and unprepared to deal with a new generation of 21st century toxins. From genetically modified corn and soy crops, highly hybridized wheat, industrial pollution, chemicals in processed food, etc., our largely defenceless bodies are being bombarded with new highly toxic antigens that our immune systems are ill-equipped to defend against. A number of studies support this hypothesis. One recent study revealed significantly fewer allergies are experienced among children in dishwasher-free homes. The natural extrapolation is that children who are regularly exposed to germs by hand-washing dirty dishes build up a natural immunity to various common infectious agents. Another study showed that eating peanut products as a baby reduces the risk of subsequent nut allergy by 80%.
The bottom line
The fundamental reason why autoimmune disease is higher among women appears to be a heightened and underutilized immune system, particularly among those living in the unusually sanitized environments of more developed countries. This lowers their immune response threshold and leaves their super-sensitive systems unprepared and confused as to how to fight a new generation of toxic agents. Each anatomical system that reacts with any of the 80+ autoimmune disorders has a unique underlying causative toxic agent, which creates a correspondingly unique antibody fingerprint. The nature of this antibody, and thus the identity of the unique toxin creating the autoimmune response, can normally be revealed by blood tests. The key to stopping each autoimmune disorder therefore lies in identifying the toxic causative agent creating the dysfunctional response, and removing it from the afflicted person’s environment. (See examples of specific case studies analyzed in this manner in other posts on this blog.)
Prevention against autoimmune disease requires systemic change
But that only corrects the specific autoimmune disorder of the moment, one at a time. Years ago, I used to teach problem solving workshops in various cities all across North America. This required me to get on an airplane almost every week and be locked in a closed cabin with two hundred other not entirely healthy people. For almost twenty years, I rarely got so much as a head cold as my natural immunity to all manner of germs became highly tuned. After a three year hiatus, I recently started traveling again and sure enough, one trip with a few sneezing and coughing passengers was enough for me to come down with the flu for the first time in my life. Just as other organs such as your muscles or heart wither and atrophy from lack of use and exercise, so it is with your immune system: exercise it (gently but regularly), or lose it. As always, the best medicine is preventive medicine: for long-term protection against all autoimmune disorders, the best solution lies in recharging your natural immune system by keeping it regularly exercised and ready to fight any external threat.
[Feel free to share your own experience with autoimmune disease and how you have managed it in the comment section below this post. Sharing of learnings and successes with each individual case can help many others.]