In my last post, I discussed the “gut-brain-skin” axis theory—which suggests that what we eat, what lives in our gut, our mood and the health of our skin are all intimately related.
In the 1930’s it was popular to treat acne internally with the use of L. acidophilus and L. acidophilus –fermented milk products, though there was little research into this approach and interest waned despite its apparent effectiveness. More recently, studies have shown that many patients with acne vulgaris and acne rosacea have low stomach acid (hypochlorhydria), small intestinal bacterial overgrowth (SIBO) and disturbances in normal gastrointestinal microflora. In 1961, a physician by the name of Robert Silver conducted a study in which he orally administered L. acidophilus and L. bulgaricus—and showed that 80% of the 300 patients studied had some degree of clinical improvement in their acne. Since that time, advances in molecular biology have shown that probiotics can regulate the release of inflammatory cytokines within the skin, including substance P—which may be a primary mediator of inflammation and sebum production in acne. Both Bifidobacterium longum and Lactobacillus paracasei can reduce the inflammation mediated by substance P. Certain bacterial strains such as Streptococcus salivarius secrete substances with antimicrobial properties, which limit the growth of Propionibacterium acnes, thought to play a major role in the development of acne lesions.
Probiotics may also act in the “gut-brain-skin” axis via glycemic control. New research shows that gut flora contribute to glucose tolerance—for example, Bifidobacterium lactis improved fasting insulin levels and glucose turnover rates.
Of note, milk may play a role in acne development via insulin-like growth factor 1 (IGF-1), which is absorbed across colonic mucosa but reduced in fermented dairy products. Thus, avoidance of milk (and substituting fermented milk products such as cheese, yogurt, kefir) may help improve acne in some patients.
More research is forthcoming with regard to the specific molecular mechanisms at play, but so far the evidence is quite compelling that dietary changes and modification of gut microflora can have an impact on skin inflammation and acne.
TIP: A topically applied yogurt mask (which contains the lactic acid bacteria Streptococcus thermophilus) can increase ceramide production—which have activity against P. acnes and a direct anti-inflammatory effect.
BOTTOM LINE: Acne may respond to changes in diet (increased fermented dairy consumption and nutrient rich foods; reduce sugar, carbohydrates, processed foods) as a result of normalization of gut microbiota.