Vitamin E has long been used in cosmetic applications to help the skin combat oxidative stress from the environment that lead to damage and ageing.
However although some vitamin E supplements have been positioned for beauty and skin health, scientific data to support their benefit has been lacking.
The new study, funded by vitamin maker BASF and first reported at a major conference on vitamin E last year, reveals for the first time a potential delivery mechanism for dietary vitamin E reaching the skin via sebaceous gland secretion.
It will open up new opportunities for supplement makers to tap the lucrative skincare market, currently seeing significantly stronger growth than the traditional vitamins sector.
"Most vitamin E supplements are just marketed as regular vitamin E but consumer awareness of the idea that nutrition can influence beauty is growing. Now we can offer customers scientific support for this concept," Simon Gauch, global product manager for fat-soluble vitamins at BASF, told NutraIngredients.com.
Skincare markets in Europe have seen growth above 20 per cent in recent years. France, which has some 40 per cent of the western European skincare market and sales of €2.2 billion in 2004, is expected to grow by 17 per cent over the next five years, according to Mintel, while less developed markets such as Italy will grow faster at 26 per cent over 2004 figures.
The UK market is also going to perform particularly well over this period, growing some 24 per cent to almost €1 billion, according to the market research firm.
"Consumer interest in beauty is often stronger than their interest in health," noted Gauch, adding that BASF are the first to study vitamin E's potential in this field.
Researchers led by Professor Jens Thiele at the Northwestern University Medical School in Chicago had previously shown that sebum contains the highest concentrations of alpha-tocopherol found in human skin and accounts for the high levels of vitamin E found in the outermost layers of the skin and in skin surface lipids.
They hypothesized that take-up of oral vitamin E in the skin is largely dependent on sebaceous gland secretion.
The theory was tested on 24 healthy volunteers, randomized to receive a daily supplement of either 400 mg synthetic alpha-tocopherol or natural source alpha-tocopherol for two weeks.
Fasting blood samples, facial sebum samples, and skin surface lipid extractions from a site with low density of sebaceous glands (the forearm) were taken between baseline and 21 days.
Serum alpha-tocopherol levels were significantly increased as early as 12 hours after the first supplements were taken, peaking on day seven, with an average increase of 76 per cent and 79 per cent, respectively.
Sebum levels remained unchanged during the first 14 days of supplementation but after two weeks, both vitamin E groups saw alpha-tocopherol levels in sebum increase by 87 per cent and 92 per cent, respectively.
No significant changes were observed in lower arm skin surface lipids at any time point.
"The results suggest that sebaceous gland secretion is amajor mechanism leading to site-specific differences," write the researchers in a special issue of the Annals of the New York Academy of Sciences (2004; 1031: 184).
They note that the bioavailability of both vitamin types is comparable but that possible protective effects in the skin will not be achieved before a supplementation period of two to three weeks.
"In view of the recently identified susceptibility of sebaceous lipids to solar photo-oxidation, dietary vitamin E supplementation may help to protect human skin barrier lipids from environmental oxidative stress," conclude the authors.
Further studies should compare test sites with different density and activity of sebaceous glands, they said, but added that other pathways of vitamin E delivery to the skin should not be ruled out.
The findings will also give vitamin makers new potential to grow the vitamin E market. The leading suppliers of synthetic vitamin E, BASF and DSM, have both expanded capacity recently, to a combined 45,000 tons, and need to grow the market.
While animal nutrition accounts for the biggest share of demand for this vitamin, both firms will be keen to push vitamin E products to higher value segments such as human nutrition and cosmetics, or indeed, the crossover -and least developed - area of cosmeceuticals.
The findings were presented by Dr Swarna Ekanayake Mudiyanselage from Friedrich Schiller University in Germany at the Vitamin E and Health conference organized by the New York Academy of Sciences in May last year.