Acne

Ali Shields et al. (2023) · JAMA dermatology

Many people with acne turn to over-the-counter vitamins, minerals, herbal extracts, and probiotics hoping for a gentler alternative to prescription treatments -- but how well do these actually work? This systematic review pooled 42 randomized trials (3,346 participants total) testing oral nutraceuticals for acne, following a pre-registered research protocol and searching four major databases through January 2023. The interventions ranged from zinc and vitamins to green tea extract, fenugreek, probiotics, fish oil, and a traditional Korean herbal formula, giving a rare side-by-side look at how these popular supplements stack up against placebo. Reviewers independently screened thousands of records down to 42 qualifying randomized trials and rated each one's quality using a standard bias-assessment tool. Most trials (27 of 42) were rated poor quality, 11 fair, and only 4 good -- a reminder that supplement research overall is thinner than for prescription acne treatments. Outcomes tracked included clinician-rated improvement, lesion counts, patient-reported satisfaction, and side effects. Results varied widely by supplement. Zinc, the most-studied option, worked in only about half its trials and caused the most stomach-related side effects of anything tested, though higher doses (600 mg/day) tended to work better than lower ones. Vitamin D (1,000 IU/day) meaningfully reduced inflamed acne lesions in people who were vitamin D-deficient. Green tea extract cut inflammatory lesion counts but did not improve people's reported quality of life. Probiotics -- especially certain Lactobacillus strains -- showed the most consistently positive results across several small trials and were well tolerated. Omega-3 and omega-6 fatty acids reduced both inflamed and non-inflamed lesions after about 10 weeks. Pantothenic acid (vitamin B5) helped, but only at a dose far above typical nutritional intake. Fenugreek seed extract underperformed compared with an antibiotic in one small study. Four options -- vitamin D, green tea extract, probiotics, and the herbal formula cheongsangbangpoong-tang -- had the strongest (though still limited) supporting evidence. Vitamin D and omega-3/6 fatty acids carried the lowest risk in these trials, since their effective doses are close to normal nutritional intake, while zinc showed mixed results and a higher side-effect rate. Overall, most of this evidence comes from small, lower-quality trials; none of these supplements was tested as a replacement for proven acne treatments — the trials studied them as possible add-ons.