TLDR Polyphenols may help treat skin conditions like warts, hair loss, acne, and dark spots, but more research is needed.
The 2014 systematic review analyzed 17 clinical trials to evaluate the effectiveness of polyphenol-based treatments in dermatology, with a focus on conditions such as anogenital warts, alopecia, acne vulgaris, hyperpigmentation, and photoaged skin. The trials included a range of 12 to 503 participants and lasted from 4 weeks to 2 years. Green tea polyphenols were supported by high-quality evidence for treating anogenital warts, while other polyphenols showed potential benefits for alopecia, acne, and hyperpigmentation. For example, a study with 43 men demonstrated significant hair growth over 12 months, and another with 60 women showed reduced melanin content over 8 weeks. Adverse events were generally mild, with no serious adverse events reported. However, the review noted limitations such as small sample sizes and short follow-up times and called for more rigorous trials to establish evidence-based guidelines for polyphenol use in dermatology.
14 citations,
January 2006 in “Skin pharmacology and physiology” Procyanidin compounds from apples and barley promote hair growth and prevent hair cell death.
28 citations,
December 2005 in “Journal of cosmetic dermatology” Apple procyanidin applied to the scalp may help grow hair without side effects.
190 citations,
October 2002 in “The FASEB journal” Androgens may cause hair loss by increasing TGF-beta1 from scalp cells, which inhibits hair cell growth.
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37 citations,
January 2002 in “British journal of dermatology/British journal of dermatology, Supplement” Apple extract called procyanidin B-2 was found to greatly increase hair growth.
32 citations,
December 2000 in “Phytomedicine” Apple-derived procyanidin B-2 can safely promote hair growth in men.
January 2019 in “ARC journal of pharmaceutical sciences” Acne can be managed with various treatments and requires psychological support due to its emotional impact.
1 citations,
January 2013 in “Springer eBooks” Cosmeceuticals may benefit skin health but need more research for efficacy and safety confirmation.
18 citations,
June 2019 in “Clinical research in dermatology” Acne can't be cured but can be managed with treatments like benzoyl peroxide and diet changes; it's costly and can lead to scarring and mental health issues.
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434 citations,
October 2003 in “PTR. Phytotherapy research/Phytotherapy research” Natural products in cosmetics are beneficial for skin and hair care with low toxicity.
8 citations,
January 2017 in “Elsevier eBooks” Certain nutrients can help keep skin healthy as we age.
