Students at the Schools of Psychology and Bioscience at the University of Nottingham Malaysia Campus led by researcher Dr Ian Stephen are comparing the effects on skin and perceived attractiveness of a smoothie made from carrots and Malaysian fruits, against a control of mineral water.
“There is some previous research on carotenoids’ effects on skin,” Stephen, who is an assistant professor of psychology, told BeverageDaily.com today. “However, our study takes two new angles on the research.
“First, we are interested in looking at the effects of eating carotenoid rich foods (the smoothie), whereas most previous research has used carotenoid supplement pills.
“Second, we are particularly interested in the effects of carotenoids from smoothies on the appearance of the skin, rather than the specific physiological mechanisms.”
Gives you that golden glow…
Stephen found in his own research from 2011 that people who ate more fruit and vegetables daily had a more golden skin colour which, in perceptual studies, made them look healthier and more attractive.
Carotenoids are natural lipophilic orange and yellow pigments present in most fruit and vegetables and beta-carotene is one of the most studied – known for its function as pro-vitamin A and dietary antioxidant.
Stephen’s study – he is using a Southeast Asian population – involved serving 80 student volunteers a smoothie a day or the equivalent water volume for six weeks, and he claims initial data suggests ‘significant’ results that nonetheless require scoring by independent experts.
The academic told us that perceived attractiveness, clearly, is a subjective trait, so the study involves using further participants to judge any changes in levels via two techniques.
The first involves showing people before and after supplementation pictures of participants’ faces, and asking them which they think is more healthy looking or attractive.
However, this technique is limited since participants may have, for instance, lost or gained weight, began feeling happier or started to exercise more between the photos, which risks biasing results.
Cracking the secret carotenoid formula
Thus Stephen said the team will use ‘before’ pictures but using computer software, transform only skin appearance to simulate the measured change in skin appearance over the court of the supplementation, without any changes in weight or facial expression.
Judges will then be able to manipulate facial appearance over time – in terms of carotenoid appearance in the skin – by moving the mouse over the screen and choosing the healthiest instance of each face.
Seven smoothie recipes were used, each containing up to 50% of local Malaysian fruits – chiku, kedondong, pulasan, dragon fruit and star fruit – and during the trial measurements were taken of body composition, dietary intake, skin color and brightness
Nutrition scientist Dr Brigitte Graf designed the smoothies, and said that ensuring the survival of bioactive dietary compounds (carotenoids in this case) was key, especially given their sensitivity to UV light, high temperatures and oxidation.
“It is not a given that bioactive compounds in food are easily or completely absorbed in the gut,” she said.
“For example, the bioavailability of carotenoids from raw carrot is less than 10%. However, if the carrot is cooked (disruption of cell walls) and a little oil is added (induction of formation of dietary mixed micelles), the bioavailability of carotenoids can be as high as 90%.”
Research was ongoing into which amount of lipid ensured the optimal absorption of carotenoids, Graf added, noting that in a health drink “it is essential that the lipid fraction in the drink is as small as possible”.