My new shower gel proclaims: 鈥淣ew! Stimulates skin flora.鈥� Is there any benefit in this?
It sounds like advertising hype to me. Your 鈥渘ormal鈥� flora don鈥檛 need any extra nutrition if your skin is in a generally healthy condition. Each distinct zone of healthy skin has its own stable, dominant flora and meddling with it is risky.
The ideal flora for each zone form an even, adherent coating of a particular combination of strains that perform all sorts of different functions, such as tuning your personal and family varieties of body odour. It also crowds out or repels rival strains that might threaten your health. Over large areas of skin your normal beneficial flora form what amounts to a protective non-stick coating.
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Growing too vigorously does no good because overcrowding might cause them either to harm your skin or flake off, leaving footholds for alien pathogens. Furthermore, in microbial ecology one of the most important competitive weapons is the denial of food to rivals. Leukocytes in pus, for example, inhibit germs partly by absorbing iron, and therefore denying it to invasive bacteria and fungi. If your shower gel supplies excess nutrients to your skin, that surplus might fuel an alien invasion.
鈥淚f your shower gel supplies excess nutrients to your skin, that surplus might fuel an alien invasion鈥�
Jon Richfield, Somerset West, South Africa