As the largest and most exposed organ in the body, the skin experiences trauma from both extrinsic and intrinsic aging factors, resulting in loss of elasticity, increased laxity, wrinkling, and rough-textured appearance.1 Chronologically aged skin appears dry, thin, and finely wrinkled; photoaged skin appears leathery with coarse wrinkles and uneven pigmentation.2 In recent years, numerous systemic nutrients have been proposed to improve skin appearance. This article reviews the efficacy of these vitamins and supplements.
Carotenoids
Carotenoids are a group of lipophilic molecules derived from vitamin A.3,4 Ingestion of carotenoids may play a role in photoprotection against UV radiation (UVR) by acting as acceptors of reactive oxygen species.4-6 Stahl et al7 investigated lycopene’s usefulness in protection against UVR-induced erythema. Over 10 weeks, 9 volunteers received 40 g of tomato paste containing 16 mg daily of lycopene while 10 controls received placebo. A solar simulator was used to induce erythema of the skin at weeks 0, 4, and 10. At week 10, erythema formation was 40% lower in the lycopene group compared to controls (P=.02).7
In another study assessing the photoprotective effects of a novel nutritional and phytonutrient blend of carotenoids, 36 women with Fitzpatrick skin types I and II were treated for 8 weeks.8 Presupplementation, UVR-induced erythema, and skin carotenoid concentrations were determined along with facial skin attributes and characteristics. Results showed protection against UVR-induced skin damage, with reductions in erythema at 3 minimal erythema doses (MEDs)(P=.01). Additionally, significant improvements were noted in facial skin elasticity, radiance, and overall appearance (all P<.05).8
In 2013, Meinke et al9 conducted an 8-week, double-blind, placebo-controlled study on 24 volunteers whose diets were supplemented with moderate amounts of carotenoids, including lutein, beta-carotene, and lycopene. Utilizing novel techniques to measure the skin’s ability to scavenge free radicals, they discovered that dietary carotenoids provided notable protection against stress-induced radical formation and increased baseline radical scavenging activity of the skin by 34%. The authors concluded that dietary supplementation could avoid premature skin aging.9
Vitamins C and E
Vitamin C is an essential vitamin that must be obtained through dietary sources.10 It functions as a free radical scavenger and is a necessary cofactor for the synthesis and stabilization of collagen.
A study evaluated the effect of UVR-induced oxidative stress and the association with vitamin C supplementation among 20 white patients with Fitzpatrick skin types II or III.11 The volunteers were treated with UVR on two 1-cm sites on the buttock. Six punch biopsies of these sites and 2 control biopsies from nonexposed skin were taken. Volunteers took vitamin C supplements (500 mg) for 8 weeks, and the exposure and biopsy were repeated. Researchers concluded that supplementation with vitamin C had no effect on the MED, with identical concentrations at baseline and after 8 weeks of supplementation. Additionally, there was no evidence that vitamin C affects UVR-induced oxidative stress.11
In 2007, Cosgrove et al12 conducted a study to assess the associations between nutrient intake and skin aging in more than 4000 women aged 40 to 74 years. Higher dietary vitamin C intakes were associated with a significantly lower likelihood of senile xerosis and wrinkled appearance (P<.009).12
Vitamin E is a lipid-soluble, membrane-bound vitamin, and its most active form is α-tocopherol.11,13 Vitamin E functions as an antioxidant and protects cellular membranes from lipid peroxidation by free radicals.13-15 Once oxidized, vitamin E can be regenerated to its reduced form by vitamin C.11 Their synergistic effects on skin protection have been studied extensively. A double-blind, placebo-controlled study of 10 patients compared 2 g of vitamin C combined with 1000 IU of vitamin E vs placebo.16 The patients’ skin reaction before and after 8 days of treatment were assessed by determination of MED and the cutaneous blood flow of skin irradiated with UV light. Results showed that the median MED of those taking vitamins increased from 80 to 96.5 mJ/cm2 (P<.01) and decreased for the placebo group. Investigators concluded that the combination of vitamins C and E reduces the sunburn reaction and leads to a reduction in the sequelae of UV-induced skin damage.16 A prospective, randomized, placebo-controlled study by Fuchs and Kern17 replicated these findings, also concluding that combinations of vitamins C and E provide improved photoprotective effects than either vitamin alone.