Longevity Briefs: Can Microbes Keep Your Skin Young?

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Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

The problem:

Scientists are beginning to realise that the microbes living in our guts could play an important role in the ageing process. While most research focuses on gut microbes, humans also have a diverse skin microbiome. Given the size of the cosmetic industry, it’s surprising that more studies have not investigated whether targeting microbes on the surface of the skin can slow skin ageing.

We know that the populations of bacteria living in the gut become smaller and less diverse with increasing age. What’s more, the diversity of these gut microbes correlates with many aspects of health for a given age group. Animal models even show that health can be improved by transplanting microbes from the guts of young animals into the guts of older ones. Does the same apply to ageing skin?

The discovery:

In this paper, researchers review what we know so far about the importance of the skin microbes and their relationship with the ageing process. Here’s a summary of the key points:

• Just like in the gut, the composition of the skin microbiome changes with age, with certain types of bacteria and fungi becoming more common while others become less common.
• These changes vary between different areas of the body as well as in different parts of the world.
• These changes happen in part due to age-related changes in the skin, such as reduced blood supply and shrinkage of the sebaceous and sweat glands. This makes the surface of the skin dryer and more alkaline, which favours certain microorganisms over others.

In turn, the skin microbiome protects the skin itself in a number of ways:

• Skin microbes protect against pathogenic (disease-causing) microbes on the surface of the skin by competing with them.
• Skin microbes strengthen the physical barrier of the skin by boosting keratinocyte division and by secreting proteins and lipids that support the skin’s outer layer.
• Skin microbes help train the immune system, reduce inflammation and accelerate wound healing when the skin is damaged.
• Cyanobacteria on the skin produce mycosporine-like amino acids, which absorb ultraviolet light and may protect the skin against photoageing. Cyanobacteria have been found to decline with age.

The implications:

While unlikely to be as important for general ageing as the gut microbiome, the skin microbiome has potential as a target for slowing skin ageing. Even if you don’t care about the cosmetic aspects of skincare, skin does fulfil many vital functions and we should all do our best to look after it, which means looking after its microbes. It is suggested that slightly acidic moisturisers may be beneficial for older people, since the loss of both moisture and acidity seems to be a contributor to the decline of the microbiome. 

Supplying prebiotics (nutrients that support beneficial microbes) and probiotics (introducing beneficial microbes to the skin) are other avenues of research. To make full use of these approaches, we would need a better understanding of which microbes are beneficial.

Finally, it’s important to point out that since this seems to be a two-way relationship, anything that protects the skin is likely to benefit the skin microbiome. The most important factor is shielding the skin from ultraviolet light, since this remains the most significant environmental cause of skin ageing.