You Are What You Eat: Within-Subject Increases in Fruit and Vegetable Consumption Confer Beneficial Skin-Color Changes

Abstract

BackgroundFruit and vegetable consumption and ingestion of carotenoids have been found to be associated with human skin-color (yellowness) in a recent cross-sectional study. This carotenoid-based coloration contributes beneficially to the appearance of health in humans and is held to be a sexually selected cue of condition in other species.Methodology and Principal FindingsHere we investigate the effects of fruit and vegetable consumption on skin-color longitudinally to determine the magnitude and duration of diet change required to change skin-color perceptibly. Diet and skin-color were recorded at baseline and after three and six weeks, in a group of 35 individuals who were without makeup, self-tanning agents and/or recent intensive UV exposure. Six-week changes in fruit and vegetable consumption were significantly correlated with changes in skin redness and yellowness over this period, and diet-linked skin reflectance changes were significantly associated with the spectral absorption of carotenoids and not melanin. We also used psychophysical methods to investigate the minimum color change required to confer perceptibly healthier and more attractive skin-coloration. Modest dietary changes are required to enhance apparent health (2.91 portions per day) and attractiveness (3.30 portions).ConclusionsIncreased fruit and vegetable consumption confers measurable and perceptibly beneficial effects on Caucasian skin appearance within six weeks. This effect could potentially be used as a motivational tool in dietary intervention.

Perception of health from facial cues

“…Although the effect of colour was weaker than that of mouth curvature, faces with more yellow coloration were judged as looking healthier. This is consistent with prior work demonstrating a reliable preference for yellowness in faces [38,45,47,61], but additionally illustrates that yellowness acts independently of adiposity and mouth curvature as a cue to health in unaltered facial images. Our findings in 2D faces highlight the influence of colour and mouth curvatures (which is likely to be perceived as subtle expression) in judgements of health in a sample of young Caucasian adults.…”

It is all in the face: carotenoid skin coloration loses attractiveness outside the face

“…Following colour calibration according to a GretagMacbeth Mini ColorChecker included in each photograph [4], images were transformed in skin colour. The transform was performed according to an approximation of carotenoid coloration determined as the difference between high and low fruit and vegetable intake [10]. Previous work indicates that this manipulation increases health and attractiveness perceptions [4,5,10].…”

“…The transform was performed according to an approximation of carotenoid coloration determined as the difference between high and low fruit and vegetable intake [10]. Previous work indicates that this manipulation increases health and attractiveness perceptions [4,5,10]. To simulate healthy skin colour, following a pilot study assessing optimal health-colour levels (see the electronic supplementary material), we altered colour by 9.4 (DE) units along the carotenoid axis by adding 8.7 units of yellowness (b* in CIELab colour-space; [4]), subtracting 2.2 units of lightness (L*) and adding 2.8 units of redness (a*) to all faces.…”

Fruit over sunbed: Carotenoid skin colouration is found more attractive than melanin colouration

“…First, although we 344 matched the amount of transform between carotenoid and melanin images in delta E units, 345 recent work has suggested that humans may be more attuned to seeing differences in 346 yellowness compared to luminance (Tan & Stephen, 2013). While it is possible then that the 347 high and low melanin images are perceptually more similar than the high and low carotenoid 348 images, both of our skin colour transforms are clearly distinguishable, considering research 349 indicates that differences as small as 0.9 delta E are enough to accurately distinguish 350 attractiveness of two facial images (Whitehead et al, 2012b) and the differences reported …”

“…yellowness or redness axis in isolation), other 85 research has linked health perception to naturally occurring skin pigments: for skin redness, 86 participants increased the amount of oxygenated blood colour more than deoxygenated blood 87 colour, to maximise the appearance of health in faces (Stephen et al, 2009b been shown to increase T-lymphocyte counts in healthy adults (Alexander et al, 1985) and 115 has beneficial effects for thymus gland growth in children (Seifter, et al, 1981 The two groups did not differ on gender, age, BMI, or exercise behaviour. Skin colour was 157 measured on the forearm using spectrophotometry (for details see Whitehead et al, 2012b).…”