For many of us, skin issues such as a pimple or a rash often follow an upset stomach and this is no coincidence. While our gut and skin may seem completely unrelated, these two organs are intrinsically linked. They are our first defense from the environment and what we ingest. They are also home to trillions of microbes of different species which ensure we are protected.
Our gut and our skin are constantly in touch with the environment. While our skin is constantly in touch with the external environment, the inside of our digestive tract is the interface between the foods we consume and our bodies. Our gut is home to trillions of microbes (bacteria, fungi and viruses) that can influence our health, and our skin is also home to its own unique microbial population. These microbial populations are constantly influenced by the environment.
How the gut microbiome affects the skin
The association between the gut microbiome and skin involves a complex interaction between our hormones, nervous system and our immune system:
Interactions via hormones and the nervous system
The neuroendocrine system is a chemical messenger system that involves our hormones and our nervous system. Both the gut and skin engage in this messaging system and are affected by it, as it allows us to sense and respond to our internal and external environment.
Studies suggest that the bacteria in the gut produce messaging molecules called neurotransmitters and hormones. Skin cells can also produce them. Together they function to strengthen barriers, regulate temperature and participate in the defense against microorganisms in the environment.
Interactions with external factors through the environment or the food we eat can cause changes to the levels of these molecules, causing changes to organs affected by them. For example, an upset stomach can increase levels of a neurotransmitter or hormone which can have an effect on our skin.
Interactions via the immune system
Our body uses inflammation to trigger the immune system against foreign invaders, toxins or injury. In the context of our skin, this is often seen in the form of swelling, rashes or sensitivity. Immune cells infiltrate the affected area and begin to manage the threat, after which inflammation subsides. Imbalances in our body’s ability to regulate inflammation can lead to chronic inflammation and unnecessary tissue damage.
Additionally, a healthy gut produces short-chain fatty acids and other metabolites that can help modulate inflammation.
There is mounting evidence linking skin disorders to gut health and alterations in the gut microbiome. Here are a few examples:
- Irregular bowel movements have been linked to dry skin problems.
- Celiac disease is associated with skin manifestations such as dermatitis herpetiformis, alopecia, vitiligo and oral mucosal lesions.
- Inflammatory bowel disease (IBD) is also associated with a higher risk of developing an inflammatory skin condition, such as psoriasis, atopic dermatitis, and rosacea.
- Small intestine bacterial overgrowth (SIBO), a condition with excessive growth of bacteria in the small intestine, is 10 times more prevalent in people with acne rosacea. Interestingly, the resolution of SIBO showed marked clinical improvement in acne.
- Dysbiosis has been seen in inflammatory skin conditions such as atopic dermatitis.
While these may be associations and we still have much to learn about the mechanisms behind them, taken together, there is sufficient evidence to say that our digestive health and skin health are indeed linked.
Making sure we have a healthy digestive tract by keeping our gut microbiome in check is almost entirely in our control and can go a long way in keeping our gut and skin healthy.
We can improve our digestive health by:
1. Including probiotic foods or supplements:
Probiotic supplements or fermented foods such as yogurt, sauerkraut, kefir, pickles and idli can be used to introduce healthy bacteria into our diet.
Research about the skin health benefits of probiotics indicates that oral consumption might reduce skin sensitivity and protect the skin. Remarkably, studies that found relief for certain chronic skin conditions (like atopic dermatitis and eczema) with oral probiotics, also showed a change in the gut microbiome rather than that of the skin.
One study of probiotic supplementation for acne showed an improvement in 80% of subjects, especially in those with inflammatory lesions. This was thought to be due to the production of an antibacterial protein produced by the probiotic bacteria, which can suppress the overgrowth of the bacteria that causes acne (Propionibacterium acnes).
2. Eating fibre-rich foods:
Dietary fibre feeds the good bacteria in our gut and is therefore called ‘prebiotic’. Sources include legumes, whole grains, beans, vegetables and fruits.
Dietary fibre has been shown to reduce the incidence of atopic dermatitis. Researches have revealed that prebiotics help to balance the composition of the skin’s microflora by inhibiting the growth of P. acnes while preserving the growth of the beneficial bacteria that serve to protect our skin from infections.
3. By increasing the intake of anti-inflammatory food:
Plant foods contain antioxidants that promote the growth of certain beneficial bacteria. These prebiotic antioxidants, like grape seed extract, also help lower inflammation. Similarly, omega-3 fatty acids are probiotic and anti-inflammatory. They can be found in foods like fish, walnuts, flax seeds and chia seeds.
4. By consuming foods that improve gut health:
Certain nutrients assist in repairing any damage to the gut cell lining. These include zinc, Vitamin D and an amino acid called glutamine. The use of collagen supplements has also been hypothesized to improve gut health.
5. By avoiding harmful foods:
Allergenic foods can cause unnecessary inflammation and trigger an immune response in the gut. Artificial sweeteners have been shown to be detrimental to the gut microbiome which can promote digestive issues.
Other lifestyle factors like exercise, sleep and stress also have a bearing on our gut microbiome and are therefore related to skin health.
Regulating our gut microbiome can help us improve the health of distant organs like the skin. A better understanding of its mechanisms can further allow us to develop novel strategies for improving our health with food.