In our daily lives we routinely “dose” ourselves with an innumerable variety of different chemicals. Our food, drink, air quality and all environmental chemicals we use or are exposed to have to be processed, circulated through or trafficked out of our bodies. As such the types of chemicals that reach us from our environments have the ability to affect our health in many different ways. Even in a diet or skincare regimen free from additives, everyday foods are highly complex chemical mixtures, and so the quality of our food choices guide the quality of repeated “chemical inputs” that our meals provide our bodies with. Whereas a healthy body processes the dietary or skincare chemicals from wholesome sources as welcome nutrition, industrial and post-industrialised lifestyles have introduced innumerable chemicals into our environments that are either unnatural or unnaturally abundant. Despite the valid short and medium-term testing in place in most countries to establish the safety of new skincare (and their ingredients), some of these synthetic compounds have been repeatedly linked to damaging our immune system, especially with long-term exposure. At a time where many have gained a renewed respect for health and wellness, this article explores the scientific link between our daily skincare choices and our immune system.
The physical presence of the skin, as the body’s continuous outer surface, provides a “basic” protective barrier to unwanted microbes. Far from basic protection, the skin provides microscopic spaces for good bacteria to live, and some chemical deterrents against bad bacteria. Moreover, different “immune cells” are resident deep in the skin, and other immune cells can be recruited if there is a lot of “heavy lifting to do”. With this terrain described, it may be easier to see how skincare products applied at the surface can have deeper, and even body-wide effects. A significant amount of evidence shows that disruption of the skin’s microbial community with inappropriate skincare permits pathogenic skin microbes to cause more damage: “When the chemical composition (pH, pathological sweat secretion) of host epidermis is disrupted, Malassezia spp. gains in pathogenicity and releases lipases, phospholipases, and an array of bioactive indoles. These molecules alter the function of the epithelial barrier resulting in immune deregulation and diseases.” (1). Similar issues are observed in inflammatory skin diseases like atopic dermatitis, where typically skin-resident microbes or microbes atypical to healthy skin abnormally increase their prevalence within the skin’s microbe population during disease, and effective treatments manage to increase and restore the skin’s microbial diversity (2). Important to note is that chemically-induced dermatitis is created by the skin’s immune cells identifying and becoming sensitive to an offending substance, which highlights how interfaced the immune system is with the skin (3).
The Skin's Interface with Skincare Chemicals.
Just beneath the skin's surface (and near many organs in the body), our fatty tissue (or “adipose” tissue) is found. A fat tissue receptor protein called “PPAR-gamma” (i.e. Peroxisome proliferator-activated receptor gamma) is a well-studied, unintended route for phthalates (and other PPAR-gamma inhibitors) to impact on the health of people (4). Inhibition of PPAR-gamma by environmental chemicals has been linked to obesity and childhood obesity (5), diabetes (6), both male (7) and female (8) reproductive system issues and many other endemic diseases of the industrialised world. Phthalates are just one class of many synthetic compounds called Endocrine Disrupting Chemicals (EDCs) that negatively impact our health on a daily basis, and have been added to “… food, cosmetics, plastic packages, and children’s toys and have thus become an integral part of the human environment” (9).
“…EDCs modulate the immune system through an impact on development, cellular and humoral responses [antibody production], cytokine synthesis, and lifespan” (9)
However PPAR-gamma activators (i.e. agonists that have the opposite effect of phthalates above), both natural and synthesised, have been recently highlighted as possible methods to address COVID-19 and stop patients from deteriorating (10). PPAR-gamma is highly researched for its potential role to mediate diabetes therapies, but PPAR-gamma also works as a strong anti-inflammatory agent in the body by regulating and suppressing the production of cytokines, immune signalling molecules that can be abnormally activated and produce the “cytokine storms” that cause the worst outcomes in COVID-19 patients (11). It has become apparent that, alongside the pharmaceuticals glitazones and NSAIDs, several plant foods such as turmeric, hot pepper, pomegranate and omega-3-rich oils are effective activators of PPAR-gamma (10).
Turmeric has an opposite effect of EDCs on PPAR-gamma… (credit: stevepb)