Growing awareness of the link between diet and health, and by extension physical appearance, means that many consumers are receptive to the concept of 'beauty from within'.
Indeed, a recent Datamonitor report predicted the overall European cosmeceuticals market to grow to $4.4bn (€3.4bn) in 2009, up 5 per cent from today. This includes all cosmetic products containing at least one bio-active ingredient for the skin.
The new research from Germany that links skin health to cocoa flavanols could well be readily accepted by the female-dominated consumer base. The same Datamonitor report said that 63.7 per cent of women over the age of 50 are prepared to spend more on cosmeceuticals.
"This study demonstrates that the regular consumption of a beverage rich in flavanols can confer substantial photoprotection as well as help maintain skin health by improving skin structure and function," wrote the researchers in the new issue of the Journal of Nutrition (Vol 136, pp 1565-1569).
Led by Wilhelm Stahl from the Heinrich-Heine University in Dusseldorf, the researchers supplemented the regular diet of 24 female volunteers with healthy, normal skin with either a high flavanol (326 milligrams per day) or low flavanol (27 milligrams per day) cocoa powder drink (dissolved in water). Both flavanol powders were provided by Mars.
Women were advised to continue their normal dietary habits, while other dietary supplements were not to be taken during the 12-week intervention trial. Sunbathing and use of tanning beds was also forbidden.
On three separate occasions (weeks 0, 6, and 12), the skin of volunteers was exposed to 1.25 times the UV irradiation dose required to redden the skin (erythema) on the back and shoulder region.
The researchers found that the group receiving the high flavanol cocoa beverage had a reduction in skin response to the UV radiation of 15 per cent after week 6, and 25 per cent after week 12, compared to baseline. The low flavanol receiving group did not affect UV sensitivity.
"We showed here for the first time, to our knowledge, that dietary intervention with a cocoa beverage rich in flavanols decreased the sensitivity of human skin toward UV light, which was determined by the degree of erythema," wrote the researchers.
In addition to the reduction in sensitivity, the researchers also observed an increase in subcutaneous blood flow for the high flavanol group, as well as improving skin texture by increasing skin density (16 per cent), skin thickness (12 per cent), and skin hydration (28 per cent), compared to baseline. No significant changes were observed in the low flavanol group.
Polyphenols, such as the catechins found in cocoa, are reported to absorb UV light, which may contribute to the reduction in UV sensitivity. The compounds are also capable of scavenging reactive oxygen species (ROS) that are formed during photo-oxidation.
The main flavanols found in the high flavanol beverage were epicatechin (61 milligrams per day) and catechins (20 mg/d), while the low flavanol drink contained about one tenth these concentrations.
"These amounts [in the high flavanol beverage] are similar to those found in 100 grams of dark chocolate," explained the researchers.
The mechanisms by which the cocoa flavanols improve skin texture are not known, but Prof Stahl and his colleagues suggest that the flavanol-mediated rise in skin blood flow is likely to improve the appearance of the skin.
This research is in-line with previous animal studies that reported tea flavanols could inhibit UV-induced skin reddening, but Co-author Prof Helmut Sies, also from the Heinrich-Heine University, stressed to NutraIngredients.com that this is the first such study to show a benefit in a human trial, and said that research in this area was continuing.