Dr Ivan Petyaev, a former Cambridge University researcher, and the founder of biotech firm Lycotec behind the product, said: "We're using the same antioxidant that keeps goldfish gold and flamingos pink. In clinical trials we saw that inflammation in the skin starting to go down and the tissues began to benefit.
"We used people in their 50s and 60s and in terms of skin biomarkers we found it had brought skin back to the levels of a 20 or 30-year-old. So we've improved the skin's physiology.
"People claimed that their skin was better, and we can see that the product is working to slow down ageing." As the bar contains just 38 calories, its makers say it is even safe for diabetics.
The confectionery, which is also called Cambridge Beauty Chocolate, comes boxed as a three-week supply, individually wrapped, and will be available in high-end retailers from next month.
It is also likely to come with a hefty price tag, although its makers were unwilling to reveal the cost before its launch at the Global Food Innovation Summit in London next month.
According to the company brochure, its target market is "elegant, educated and affluent" city-dwelling women in their 30s and businessmen "to support their appearance in a stressful environment and on their business travels".
However, health experts were careful to reserve judgment. Naveed Sattar, a professor of metabolic medicine at Glasgow University, said more robust clinical trials would be needed to validate the "ridiculously strong" claims made by the company.
"Some of the compounds may benefit some processes linked to ageing. But eating too much chocolate means more calories, which means obesity," he said.
Dr George Grimble, a nutritionist at University College London, said: "There is a potentially sound scientific base to this, although it is obviously early days.
"There needs to be further clinical trials to show that it is safe, but astaxanthin has been shown to have antioxidant effects and low toxicity, so from that respect, it seems promising.
"In my humble opinion, it would be necessary for the company's in-house trial to be submitted for publication in a peer-reviewed journal in order for their health claims to be substantiated. It is too early to say what the long-term benefits might be."
Nutrition experts at UCL also warned that previous trials showed that astaxanthin worked better when applied directly to the face rather than ingested.
