The review, published in Nutrition Bulletin, finds that while a healthy, balanced diet, containing essential vitamins and minerals, is required for healthy skin, nutraceutical products that claim to help the skin may not add further benefit to the effects already obtained from a healthy diet.
“As consumers can spend hundreds of pounds a year on oral beauty supplements, we felt it was important to investigate the association between the ingredients in these products, and the signs that we associate with skin ageing, such as wrinkles, loss of elasticity and moisture,” said review co-author Ayela Spiro, nutrition science manager at the BNF.
“While there is a body of research on the science of skin ageing, evidence for the benefit of nutraceuticals to skin appearance is currently not strong enough to draw firm conclusions.”
Writing in the review, Spiro and colleagues note the ‘striking’ rise of the nutraceutical market, specifically in oral nutrition supplements claiming to improve skin appearance. They note that while some of the commonly used ingredients in such formulations have authorised skin-related health claims, many do not.
The BNF authors added that vitamins A, C, B2, B3, B7, and the minerals iodine and zinc, are proven to contribute to the maintenance of normal skin – noting that a deficiency of these essential micronutrients can result in skin abnormalities.
However there is a wide variety of other ingredients used in oral beauty nutraceuticals.
Limited evidence
As a result, the team focused on reviewing the current scientific evidence for a group of commonly used nutraceutical ingredients without existing authorised claims. These included green tea extract, pomegranate extract, carotenoids, evening primrose oil, borage oil, fish oil, collagen and co-enzyme Q10.
“Evidence from high quality human trials demonstrating clear benefit is required by regulatory authorities in order for foods and nutrition supplements to carry a health or beauty claim,” said the team. “To date, the evidence for many ingredients in relation to skin appearance is limited, not sufficiently robust and/or inconsistent.”
Indeed, they noted that although there are a small number of human studies suggesting potential benefits and some plausible biological mechanisms, much of the current evidence stems from animal data and in vitro cell line studies.
However, these results cannot automatically be assumed to be relevant beyond the laboratory, said the BNF team.
Indeed in its review, the BNF was only able to identify a limited number of well-conducted human trials, it said – noting that findings of these were ‘inconsistent.’
“There are simply not enough good quality randomised controlled trials in this area to draw firm conclusions about the benefit of nutraceuticals to skin appearance,” they said.
Source: Nutrition Bulletin
Volume 43, Issue 1, pages 10–45, March 2018, doi: 10.1111/nbu.12304
“Nutraceuticals and skin appearance: Is there any evidence to support this growing trend?”
Authors: A. Spiro, S. Lockyer