Can dietary intake influence perception of and measured appearance? A systematic review.

Appearance-based interventions have had some success in reducing smoking and sun exposure. Appearance may also motivate dietary behavior change if it was established that dietary improvement had a positive impact on appearance. The aims of this review are to evaluate the current evidence examining the relationship between dietary intake and appearance and to determine the effectiveness of dietary interventions on perceived or actual appearance. An electronic search of English-language studies up to August 2012 was conducted using Cochrane, MEDLINE, Embase, CINAHL, Web of Science, SCOPUS, and PsycINFO databases. Studies that included participants aged at least 18 years, that observed or altered dietary intake from actual food or dietary supplement use, and assessed appearance-related outcomes were considered eligible. Data from 27 studies were extracted and assessed for quality using standardized tools. Nineteen studies were assessed as being of "positive" and 4 of "neutral" quality. All observational studies (n = 4741 participants) indicated that there was a significant association between various aspects of dietary intake and skin coloration and skin aging. The majority (16 studies, 769 participants) evaluated the effect of dietary supplements on skin appearance among women. Only 1 study examined the effect of actual food intake on appearance. Significant improvements in at least 1 actual or perceived appearance-related outcome (facial wrinkling, skin elasticity, roughness, and skin color) following dietary intervention were shown as a result of supplementation. Further studies are needed in representative populations that examine actual food intake on appearance, using validated tools in well-designed high-quality randomized control trials.