Despite worldwide campaigns to increase fruit and vegetable consumption, intake is commonly inadequate, precipitating an estimated 2.6 million premature deaths per year worldwide. A British Academy Wolfson Research Professorship awarded to David Perrett has provided support to explore a new basis of motivating dietary change, essentially by appealing to vanity. With that support we found that eating carotenoid-rich fruit and vegetables leads to an attractive looking skin colour, and that showing people these appearance benefits can encourage dietary improvement.https://www.thebritishacademy.ac.uk/documents/668/BAR21-02-Perrett.pd

Ozakinci, Gozde

Perrett, David I

Whitehead, Ross D

Despite worldwide campaigns to increase fruit and vegetable consumption, intake is commonly inadequate, precipitating an estimated 2.6 million premature deaths per year worldwide. A British Academy Wolfson Research Professorship awarded to David Perrett has provided support to explore a new basis of motivating dietary change, essentially by appealing to vanity. With that support we found that eating carotenoid-rich fruit and vegetables leads to an attractive looking skin colour, and that showing people these appearance benefits can encourage dietary improvement

Perrett, David Ian

Whitehead, Ross David

University of St. Andrews - Pure

Eating fruit and vegetables gives your skin a golden glow

Stirling Online Research Repository

2 British Academy Review, issue 21 (January 2013). © The British AcademyESPITE WORLDWIDE CAMPAIGNS to increase fruit and vegetable consumption, intake is commonly inadequate, precipitating an estimated 2.6 millionpremature deaths per year worldwide.1 A British AcademyWolfson Research Professorship awarded to David Perretthas provided support to explore a new basis of motivatingdietary change, essentially by appealing to vanity. Withthat support we found that eating carotenoid-rich fruitand vegetables leads to an attractive looking skin colour,and that showing people these appearance benefits canencourage dietary improvement.The health problem: knowledge is not enough Insufficient fruit and vegetable consumption is associatedwith higher incidence of cardiovascular disorders, stroke,diabetes, some cancers and obesity.2 The ramifications ofthese diseases are widely felt. Not only are theredebilitating consequences for personal well-being, but alsoillness overburdens health-care systems, and adds tocountries’ financial woes through the lost productivity ofsufferers and their supporters. Fruit and vegetable consumption is particularly poor inparts of the United Kingdom. For example, only one infive Scottish adults meet the World Health Organization’srecommended intake of five fruit and vegetable portionsper day.3 Amongst younger adults the situation is evenworse, with more than 20% of 16- to 24-year-oldsreporting eating no fruit or vegetables at all. Sinceadolescent habits are likely to last, the poor diet of today’syouth is likely to magnify the already substantial burdenof chronic disease in the coming decades. There is a clearneed for dietary improvement, particularly amongst theyoung and those living in deprived areas, but there is roomfor substantial improvement in diet throughout the wholepopulation.Current attempts to encourage dietary change at apopulation level, such as the high profile ‘5-a-day’campaign, provide individuals with information on whata healthy diet is and how it benefits health in guardingagainst chronic diseases.4 Yet the provision of healthinformation alone does not seem sufficient to motivateadherence to recommendations. Two decades after theinception of 5-a-day campaigns, diet remains a keydeterminant of preventable sickness and death.5 There isall too often a discrepancy between good dietaryintentions and what people actually eat:6 most individualsare aware of what constitutes a healthy diet but fail to acton this knowledge.The question is: how do we get people to act onknowledge and good intentions? Inspiration may comefrom considering sex and the role of diet in colouredornaments in the animal kingdom. For many species,bright ornaments are pivotal in gaining the attention ofsexual partners. Humans go to extraordinary lengths toimprove their chances of finding a suitable partner, sopeople may take on a better diet if they know it improvestheir sex life. Of birds and fishMany animals wear a health badge in the form of acolourful ornament. Examples in the United Kingdom arethe yellow breast of great tits, yellow bills of blackbirds, red comb of grouse, and the red belly of male sticklebackfish. All these ornaments are brighter in individuals whoare healthy and duller in individuals with infections.Perhaps understandably the individuals with brighterornaments in these species are more attractive to potentialmates. We might assume red ornaments are a sign of goodblood supply, but the colour in many animal ornaments isbased not on blood supply but on a large family of (600+)carotenoid plant pigments that are obtained through diet.Carotenoids are a family of red-yellow chemicals that areabundant in coloured fruit and vegetables. Examplesinclude lycopene that makes tomatoes red, carotene thatmakes carrots orange, and lutein that can impart yellowEating fruit and vegetablesgives your skin a golden glowDAVID I. PERRETT, ROSS D. WHITEHEAD and GOZDE OZAKINCI1 K. Lock, J. Pomerleau, L. Causer, D.R. Altmann and M. McKee, ‘Theglobal burden of disease attributable to low consumption of fruit andvegetables: implications for the global strategy on diet’, Bulletin of theWorld Health Organization, 83:2 (2005), 100-108.2 World Health Organization, Global Strategy on Diet, Physical Activity andHealth (2004), available atwww.who.int/dietphysicalactivity/strategy/eb11344/strategy_english_web.pdf  (accessed June 2012).3 The Scottish Government. Scottish Health Survey. April 2012, availableat www.scotland.gov.uk/topics/statistics/browse/health/scottish-health-survey (accessed June 2012).4 World Health Organization, Diet, Nutrition and the Prevention of ChronicDiseases: Report of a WHO Study Group (Technical Report Series, 797;Geneva, World Health Organization, 1990), available viawww.who.int/dietphysicalactivity/publications/trs916/intro/en (accessedApril 2011).5 World Health Organization, World Health Statistics 2011, available atwww.who.int/gho/publications/world_health_statistics/EN_WHS2011_Full.pdf (accessed April 2012).6 Foods Standards Agency, Consumer Attitudes to Food Standards, Wave 6:UK Report, 2005, (February 2006), available at www.food.gov.uk/multi-media/pdfs/casuk05.pdf (accessed June 2012).DEATING FRUIT AND VEGETABLES GIVES YOUR SKIN A GOLDEN GLOW3Figure 1. Fruit and vegetables contain a range of nutrients including carotenoids – a large class of red and yellow pigments.coloration to peppers. Note: green fruit and vegetablesoften contain the same amount of carotenoids as orangeyellow and red ones, but chlorophyll in these foods maskstheir outward appearance. The appeal of coloured fruit andvegetables (Figure 1) is fitting to the benefits that theirconsumption can bring.Carotenoids do more than produce pretty colours inanimals and plants. They help neutralise reactive oxidisingchemicals formed as an unfortunate by-product of normalliving and obtaining energy from carbohydrates. Thesedangerously reactive chemicals are also produced by thefrontline agents of the immune system, the white bloodcells, when destroying bacteria and virus-infected cells.The carotenoids are antioxidants and help protect cellmembranes, enzymes and DNA from oxidising damage;but the carotenoids are expended in this neutralising role,so carotenoid levels in the blood fall during an infection.The only way they can be replenished is through diet –eating more of the right kind of food. Hence, thecarotenoids can act as an ‘honest’ cue to the bearer’shealth. Since healthy individuals do not get infected often,they don’t use their carotenoids in the war againstinfections, and can deploy them in showy ornaments. In the animal kingdom, choosing a mate withextravagantly coloured ornaments has both short-termand long-term benefits. Long-term benefits take the formof healthy offspring. More immediate benefits come fromthe fact that a partner who is fit and well can executeduties, provisioning and defence of the family, and isunlikely to be a source of contagious disease.Carotenoids and human skin colourCarotenoid pigments are found in all layers of humanskin. Therefore, we wondered whether diet would have ameasureable impact on human appearance as happens inmany animal species. Mammals in general have poorcolour vision and don’t generally have colouredornaments. In an evolutionary timescale, it is onlyrecently that primates evolved good colour vision (basedon three colour photoreceptors). Like birds and fish, thissets the scene for the development of colour signalling andraises the question whether humans (with their threecolour vision) convey signal health status to one anotherthrough colour. To find out, we asked European studentsto record how frequently they ate different types of food,4Figure 2. Skin colouration associated with diet. Images on the left represent a decrease in fruit and vegetable consumption of 8 portions a day, images on the right represent an increase in consumption of 8 portions day. NB: colours may vary with printreproduction. Under natural lighting conditions, images simulating increased consumption were seen as healthy and attractive.EATING FRUIT AND VEGETABLES GIVES YOUR SKIN A GOLDEN GLOW5and measured the colour of their skin. The results wereclear: the more fruit and vegetables a person ate, theyellower his or her skin was. The way the skin reflectedlight of different wavelengths showed that this was due topeople’s consumption of the colourful carotenoid plantpigments, rather than them getting sun-tanned. While this set the scene, we did not know how quicklythe skin changed in response to diet change, or whetherthe colour made a difference to perception. In our newwork, we found that, if people made consistent changes totheir diet, then within six weeks their skin colour changed.When people ate more fruit and vegetables their skincolour took on a redder and yellower tint. Conversely, ifpeople stopped eating as much fruit and vegetables, thentheir colour literally faded.7But does the colour matter? Recent experiments revealjust how much skin colour does impact on attractiveness.Indeed, the variation in skin colour across a populationhas a bigger impact on judgements of men’s attractivenessthan how masculine a man’s face shape is.8 Therefore, ournext step was to determine if people could see diet-relatedskin colour differences. We showed students faces thatvaried in the amount of colour from fruit and vegetables,and asked them to adjust each face until it looked mosthealthy and attractive. Virtually all the faces became betterlooking when the amount of plant-pigment colour wasincreased (see Figure 2). The evaluators did not go to excessand turn the faces into a tangerine colour – that did notlook healthy – but they did raise the level of fruit andvegetable pigmentation for an optimal appearance.The dietary pigment colour effect is evident acrossdifferent cultures: Asian and African faces are adjusted foryellow colour in the same way as European Caucasianfaces, and this doesn’t depend on the nationality and skincolour of the people doing the evaluation. Across all thecultures we’ve tested, people raise the amount of yellow inthe face in order to maximise apparent health.9 While theassociation between skin lightness and beauty does changeacross culture, the association between health and slightlyraised skin yellowness generalises across cultures.It is equally important to note that observers are able todetect skin colour differences associated with modestincreases in fruit and vegetable consumption, suggestingthat humans are very sensitive at discriminating subtledifferences in skin carotenoid pigmentation. Our latestestimate is that the skin colour changes associated withtwo extra portions a day or just one extra portion visiblyimprove skin appearance.Moreover, for Europeans, the colour associated with agood diet seems far more important than anything thatcan be achieved through altering the level of suntan.When given the choice of altering both tan and skindietary coloration in European faces, evaluators alterdietary pigmentation but barely adjust tan levels. Tooptimise skin colour, pigmentation from diet was three tofour times as important as pigmentation from suntan.10Intervention studiesWe are now well armed to start a campaign to persuadepeople to change their behaviour. Consider the facts: (a)diet can improve skin colour; (b) the change in dietrequired is small – an increase of one or two portions offruit and vegetables per day is sufficient; and (c) thebenefits are relatively quick to realise – six weeks shouldsee an improvement. All this comes with a generalagreement from health professionals that the change indiet improves long-term health. The carotenoids in fruit and vegetables shouldcontribute to health by providing antioxidants, but thereare a whole raft of benefits from eating fruit andvegetables. They contain multiple sources of antioxidants,vitamins, trace elements and fibre that can have importanteffects. Consuming more vegetables is likely to decreasethe appetite for less healthy foods – those energy densefoods that make it so easy for us to increase in girth.We conducted two intervention studies,11 in whichuniversity student participants were given leafletscontaining National Health Service information about thenature and benefits of a balanced diet. In the studies wealso showed one set of participants their own facial imageand how their skin colour could be affected by changingwhat they ate. This experience of seeing the moreattractive skin colour associated with a high fruit andvegetable diet was effective in triggering a change ofbehaviour and the adoption of a more healthy diet. Wetracked the eating habits of the groups of participants whohad seen their own face colour manipulated, and those in the control group who had received only NHSinformation. The NHS information alone had no effect on diet whatsoever (perhaps because people already knowwhat they should be doing). By contrast, those seeing their own appearance changed at the outset of the study reported an increased fruit and vegetableconsumption that was sustained for the 10-week studyperiod. 7 R.D. Whitehead, D. Re, D-K. Xiao, G. Ozakinci and D.I. Perrett, ‘Youare what you eat: Within-subject increases in fruit and vegetable con-sumption confer beneficial skin-color changes’, PLoS ONE, 7 (2012),e32988.8 I.M.L. Scott, N. Pound, I.D. Stephen, A.P. Clark and I.S. Penton-Voak,‘Does masculinity matter? The contribution of masculine face shape tomale attractiveness in humans’, PLoS ONE, 5 (2010), e13585. I.D.Stephen, I.M.L. Scott, V. Coetzee, N. Pound, D.I. Perrett and I. Penton-Voak, ‘Cross-cultural effects of color, but not morphological masculinity,on perceived attractiveness of men’s faces’, Evolution and HumanBehavior, 33 (2012), 260-7.9 I.D. Stephen, M.J. Law Smith, M.R. Stirrat and D.I. Perrett, ‘Facial skincoloration affects perceived health of faces’, International Journal ofPrimatology, 30 (2009), 845-857. I.D. Stephen, V. Coetzee and D.I.Perrett, ‘Carotenoid and melanin pigment coloration affect perceivedhuman health’, Evolution and Human Behavior, 32 (2011), 216-27.10 R.D. Whitehead, G. Ozakinci and D.I. Perrett, ‘Attractive skin col-oration: harnessing sexual selection to improve diet and health’,Evolutionary Psychology, 10:5 (2012), 842-54. I.D. Stephen, V. Coetzeeand D.I. Perrett, ‘Carotenoid and melanin pigment coloration affect per-ceived human health’, Evolution and Human Behavior, 32 (2011), 216-227.11 R.D. Whitehead, D.I. Perrett and G. Ozakinci, ‘Appealing to vanity:does seeing the potential appearance-benefits of fruit and vegetable con-sumption motivate dietary change?’, Annals of Behavioral Medicine, 41(2011), s214. R.D. Whitehead, G. Ozakinci and D.I. Perrett, ‘Brief report:a randomised controlled trial of an appearance-based dietary interven-tion’, Health Psychology (in press).EATING FRUIT AND VEGETABLES GIVES YOUR SKIN A GOLDEN GLOWAlthough our results are encouraging, they arepreliminary; one wants a dietary improvement to last yearsnot just months. We worked with young adults and thisgroup may have greater concern over appearance thanother age groups.12 Nonetheless, appearance-basedinterventions at an early age could be important inestablishing life-long beneficial dietary habits. Further, oursample was largely European. Hopefully the interventioncan be rolled out in larger clinical trials to establish theefficacy across people from all walks of life.We do not know the ingredients of a successfulcampaign, but there are several aspects of our approachthat are novel and might prove persuasive. We can stressthe short-term benefits that can be made. Avoidance ofillness later in life is a threat that may not be particularlymotivating. Our intervention stresses positives, betterlooks and achievable goals that are attainable withinrelatively short time frame (six weeks). One doesn’t haveto wait decades to cash in on good dietary behaviour. On the technological side we are able to personalise theinformation and this may make it salient. Each participantcan see how their own appearance is affected by a highfruit and vegetable diet. In future studies we hope to testwhether or not seeing images of another person can bepersuasive. If so, images demonstrating appearancebenefits would be an immensely cost-effective means ofhealth education. Even if the major benefits derive fromthe personalisation of images, with some developmentand care it should be possible to perform realistictransformations across the internet. Such possibilitysupplies health educators with persuasive tools, andprovides the internet-savvy public with the means for self-motivation.David I. Perrett is a Professor of Psychology at the Universityof St Andrews, and a Fellow of the British Academy. He helda British Academy Wolfson Research Professorship, 2009-2012.Ross D. Whitehead is a Research Fellow in the Child andAdolescent Health Research Unit in the School of Medicineat the University of St Andrews. Dr Gozde Ozakinci is a Lecturer in Health Psychology in theSchool of Medicine at the University of St Andrews. 12 S.J. Chung, S. Hoerr, R. Levine and G. Coleman, ‘Processes underlyingyoung women’s decisions to eat fruits and vegetables’, Journal of HumanNutrition and Dietetics, 19 (2006), 287-98.6

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Eating fruit and vegetables gives your skin a golden glow

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University of St. Andrews - Pure

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University of St. Andrews - Pure

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