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Wednesday
Aug062014

The Secret Ingredient to a Great Summer Tan: Carotenoids

The summer is heating up, and for many of us that means it’s time to hit the beach and soak up the rays. Bikini fashions may change year on year, but one look that’s as popular as ever is bronzed, tanned skin.

But why? By this point, we all know that tanning is bad for us, yet many refuse to slop on the sunscreen and seek shade.

Every summer, doctors trot out the same warnings. Exposure to ultraviolet (UV) radiation causes skin cancer, tanned skin is damaged skin, and tanning at a young age is extra dangerous. Research suggests that indoor tanning isn’t any safer. One third of White American women under 35 visit the tanning salon at least once a year, increasing their risk of melanoma by as much as 75%.1

These warnings are serious but barely make a dent on behaviour. We want a ‘healthy’ tan. We think it looks attractive.2 And many of us have decided it’s worth the risk.

So if you’re packing your bag for the beach (or the tanning booth), how can I hope to stop you in your tracks? What if I said that there’s a way you can tan that is (a) cheaper than a trip to the tanning salon (much less a holiday at the beach!), (b) is not only free of health risks, but will actually improve your well-being, and (c) results in more attractive and healthier-looking skin than UV exposure could ever achieve? And here’s the kicker: there’s scientific research to back all these claims up.

Carmen Lefevre of the Centre for Decision Research at Leeds University (UK) used a spectrophotometer to measure the skin color of people who were exposed to a lot of sun, or hardly any sun.3 The bronzed skin color we get from sun-exposure is due to ramped-up production of the pigment melanin, so Lefevre’s measurements captured the real effects of this pigment on skin color.

Using her skin measurements, and a specialist computer graphics program, Lefevre adjusted the skin color in photographs of men and women’s faces. She made two versions of each face: one was given a rich tan, and the other was given the paler, bluer skin tone of someone who shuns the sun. The faces were otherwise identical. Lefevre showed her face pairs to volunteers, who chose which face they found more attractive: 79% chose the high melanin (i.e., tanned) face. No surprise there.

For her next experiment, Lefevre tweaked the skin color of her face pairs based on another type of pigment: carotenoids. These pigments are also found in the skin, but they’re not generated by UV exposure. Rather, we ingest them in the form of carotenoid-rich foods, such as carrots, cantaloupe, and kale. The carotenoids in these fruits and vegetables are laid down in our skin, and give us a glowing, golden complexion.

Researchers have measured the skin color of people who eat a lot of fruit and veggies, or who fail to get their 5 a day.4 Lefevre applied these differences in color to her face pairs. She found that 86% of her volunteers preferred a face with this yellow, carotenoid-based skin color to a paler, carotenoid-free face. Her results back up earlier research showing that eating carotenoid-rich foods makes a person’s skin color appear healthier and more beautiful.3,5

Finally, Lefevre pitched melanin and carotenoid coloration against each other. Which did participants perceive as most attractive? You guessed it: carotenoids trumped melanin 75% of the time. In both male and female faces, the skin color associated with eating your greens was more appealing than a UV-based tan.6

If I’ve convinced you to ditch the beach for the farmers’ market, you might be wondering how many fruit and veggies you have to eat to see a benefit. Fewer than you might think. Research indicates that eating 2.9 extra portions of carotenoid-rich foods per day will make you appear healthier. That’s a totally manageable daily regime of 3 tablespoons of sliced carrot, a handful of dried apricots, and half a red bell pepper.

Looking healthier is great, but if you’re after a summer romance you’ll want to appear more attractive too. In which case, you’ll need to eat slightly more: 3.3 rather than 2.9 extra portions of fruit and veggies per day will noticeably boost your beauty.5 Still, an extra butternut squash in your shopping bag won’t hit your bank balance as hard as the cost of a flight to Acapulco.

And it’s not only Caucasians who stand to gain by chowing down on sweet potatoes and red peppers. Research on Black South Africans shows that carotenoids have the same effect on dark skin, too.3 We all benefit from a carotenoid-rich diet.

Why is a yellow, carotenoid-based skin color so appealing? Carotenoids are powerful antioxidants that increase immunity to disease.7 A bright golden hue probably advertises a healthy body. That seems to be why other animals, including fish and birds, are also drawn to carotenoid-coloration in potential mates.8

There’s also the added bonus that carotenoid-deposition in the skin protects against UV damage.9 It’s a natural sunblock! So even if you insist on a vacation to a sun-drenched tropical island, remember to pack a carrot or three. Your skin will thank you.

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1Guy, G. P., Berkowitz, Z., Watson, M., Holman, D. M., & Richardson, L. C. (2013). Indoor tanning among young non-Hispanic White females. JAMA Internal Medicine, 173(20), 1920-1922. doi: 10.1001/jamainternmed.2013.10013

2Smith, K. L., Cornelissen, P. L., & Tovée, M. J. (2007). Color 3D bodies and judgements of human female attractiveness. Evolution and Human Behavior, 28, 48-54. doi: 10.1016/j.evolhumbehav.2006.05.007

3Stephen, I. D., Coetzee, V., & Perrett, D. I. (2011). Carotenoid and melanin pigment coloration affect perceived human health. Evolution and Human Behavior, 32(3), 216-217. doi: 10.1016/j.evolhumbehav.2010.09.003

4Stephen, I.D., Law Smith, M.J., Stirrat, M.R., & Perrett, D.I. (2009). Facial skin coloration affects perceived health of human faces. International Journal of Primatology, 30(6), 845-857. doi: 10.1007/s10764-009-9380-z

5Whitehead, R.D., Re, D., Xiao, D., Ozakinci, G., & Perrett, D.I. (2012). You are what you eat: within-subject increases in fruit and vegetable consumption confer beneficial skin-color changes. PLoS One, 7(3), e32988. doi: 10.1371/journal.pone.0032988

6Lefevre, C.E. & Perrett, D.I. (in press). Fruit over sunbed: Carotenoid skin coloration is found more attractive than melanin coloration. The Quarterly Journal of Experimental Psychology. doi: 10.1080/17470218.2014.944194

7Alexander, M., Newmark, H., & Miller, R.G. (1985). Oral β-carotene can increase the number of OKT4+ cells in human blood. Immunology Letters, 9, 221-224.

8Lozano, G.A. (1994). Carotenoids, parasites, and sexual selection. Oikos, 70(2), 309-311.

9Bouilly-Gauthier, D., Jeannes, C., Maubert, Y., Duteil, L., Queille-Roussel, C., Piccardi, N., . . . Ortonne, J.P. (2010). Clinical evidence of benefits of a dietary supplement containing probiotic and carotenoids on ultraviolet-induced skin damage. British Journal of Dermatology, 163(3), 536-543. doi: 10.1111/j.1365-2133.2010.09888.x

Dr. Robert Burriss - Science of Relationships articles | Website
Rob is an evolutionary psychologist who researches what we find attractive in potential partners. He is most interested in how female behavior and appearance is influenced by menstrual cycle phase and hormonal contraceptive use.

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