6 July 2020

Change diet to help adult acne

Dermatology Nutrition

It’s been a controversial issue, but now new evidence supports the theory that acne is made worse by sugary and fatty foods.

Results from a large prospective cohort study which compared a relatively intensive analysis of the diet of almost 25,000 adults aged over 25 with the presence or absence of acne has concluded that what you eat is important when it comes to your skin.

“The results of our study appear to support the hypothesis that the Western diet (rich in animal products and fatty and sugary foods) is associated with the presence of acne in adulthood,” the French researchers said in JAMA Dermatology.

According to their analysis, researchers found diets high in fatty and sugary products increased the likelihood of current acne by 50%. Diets high in sugary beverages increased the risk by 18% and a high milk intake was associated with a 12% increased likelihood of having the inflammatory skin condition. It’s important to note that the sample population were all aged 25 and over so one might expect acne not to be quite so prevalent as in teenagers even though, the study authors say, previous research has estimated about 50% of people in this older age bracket report experiencing acne on occasion, with a predominance in women.

Of course the link between high glycaemic load and acne has been mooted before, especially the link between high milk consumption and acne. But the problem has been, previous studies have had conflicting results and even the positive ones have been small. A Cochrane review in 2015 found there was insufficient evidence to support a low glycaemic-load diet for the management of acne.

But this study is a little different. For a start it has a large sample size – almost 25,000. They were all participants in the ongoing web-based NutriNet-Sante study, which was started back in 2009 and involves six-monthly online extensive dietary assessments. At these assessments the study participants need to submit 24-hour diet diaries from three non-consecutive days over the course of a week.

For this particular investigation, researchers sent out an additional questionnaire over an eight month period in 2018, specifically asking about acne. To be included in the study, the participants needed to have had completed the acne questionnaire (naturally enough) and to have completed at least three of the six-monthly dietary assessments. It was the detailed dietary phenotyping that enabled the researchers to determine the link.

And there are good scientific reasons such diets with a lot of sugar and fat could cause acne. The study authors explain that high GI diets are known to cause a rise in circulating levels of IGF-1 and insulin, these set off a cascade of effects that ultimately leads to increased level of oxidative stress and inflammation both of which promote acne. In addition, increased levels of IGF-1 stimulates androgen production which is a well-known cause of acne.

But before we start banning the hot chips and chocolate milk, both the study authors and the author of a linked editorial suggest we exercise caution in putting the study findings into clinical practice. It is an observational study, and as with all observational studies you cannot be certain that just because A is associated with B, that A causes B. They also point out that overall, the effect size of diet on acne was relatively small. They both highlight the need for randomised controlled studies to prove the link found in this trial.

Nonetheless, despite the limitations of the research, the dietary advice that is supported by the findings of this study is in keeping with dietary advice for general health regardless of whether the patient has acne or not. While we may not be able to rely on diet alone to treat acne, we can at least recommend it as a useful addition to current therapies.

“Given the uncertainty surrounding both causal inference as well as the magnitude of the association between diet and acne, dietary interventions may be better thought of as adjunctive strategies rather than primary treatment options,” the US editorial author concluded.

References:

  1. JAMA Dermatol. Doi: 10.1001/jamadermatol.2020.1602
  2. JAMA Dermatol. Doi: 10.1001/jamadermatol.2020.1601

This content first appeared on www.healthed.com.au

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