Because of the intrinsic processes associated with skin ageing, as well as environmental factors, the skin is constantly changing. Stressful lifestyles and unbalanced diets make it impossible to provide all the essential nutrients that the skin requires to maintain its homeostasis and skin health.
Dietary supplements are, therefore, intended to supplement the normal daily food intake with nutrients that are not available in sufficient quantities in our regular diet. A number of dietary supplements have been highlighted in recent scientific publications that relate to specific indications and benefits:
Regular Supplementation. Vitamins A, B, C and E, micronutrients and fatty acids are the most commonly used compounds to supplement the skin.2
Photoprotection. Dietary carotenoids, vitamins E and C, and polyphenols are known to contribute to antioxidant-based skin defence and might enhance endogenous photoprotection. Acting by protecting molecular targets and scavenging reactive oxygen species, they modulating stress-dependent signalling and/or suppress cellular and tissue responses such as inflammation. Intervention studies with carotenoid-rich diets have demonstrated benefits related to photoprotection. Oral supplementation is a likely future strategy for photoprotection, even when the supplementation period required to achieve the benefit is 10 weeks.3
Antiageing. The first study to evaluate the effect of dietary supplements on facial wrinkles reported on key factors involved in skin ageing: skin inflammation, collagen synthesis and oxidative stress. A combination of a supplement drink containing soy isoflavones, lycopene, vitamin C and vitamin E, and a capsule containing fish oil, was trialled in post-menopausal women.
This combination of micronutrients has shown clinical as well as histological benefits. It has been reported to significantly reduce the depth of facial wrinkles and increase the deposition of new collagen fibres in the dermis. This was the first study to confirm that oral supplementation can induce a clinically measureable improvement; that is, a reduction of the depth of facial wrinkles and associated tissue changes following long-term use.4
Skin Barrier Function. Further evidence, in the form of systematic reviews and meta-analyses are required to advance our understanding of the true benefit of oral supplementation in skincare. A recent review suggested that there is some evidence to suggest that oral GLA supplements may improve skin health and barrier function.
A 6–31% reduction of trans-epidermal water loss (TEWL) has been reported in elderly, dry and sensitive skin populations. Even studies that observed no changes in TEWL reported other benefits induced by supplementation, including the improvement of dry skin texture and increased collagen deposition.
Future research requires a rigorous approach to reporting, including detailed population characteristics (baseline nutritional status, BMI and pro-inflammatory plasma markers) and measurement conditions, and a range of barrier function measurements (skin barrier challenge tests) in addition to TEWL.5
5. K. Steventon, et al., “Polyunsaturated Fatty Acid Supplementation and Skin Barrier Function Assessed by Trans-Epidermal Water Loss in Healthy Volunteers – A Critical Review,” in press.