A healthy-looking glow may be more than a cosmetic ideal. Research from the University of St Andrews suggests that subtle changes in skin colour associated with carotenoids can influence how healthy and attractive a face appears.
Carotenoids are naturally occurring yellow, orange and red pigments found in many fruits and vegetables. Beta-carotene, lycopene and related compounds are familiar examples. When carotenoids are consumed, some accumulate in the skin, where they can contribute to a subtle yellow-golden coloration. Research suggests that humans are sensitive to these differences in facial appearance.
Researchers Ian Stephen, Vinet Coetzee and David Perrett investigated this phenomenon in a series of studies published in Evolution and Human Behavior. They found that people with greater dietary intake of carotenoids and fruits and vegetables showed increased skin yellowness, with skin measurements consistent with greater carotenoid pigmentation.
But the particularly interesting finding concerned perception.
When participants were allowed to manipulate photographs of faces to make them appear as healthy as possible, they increased carotenoid-associated skin coloration. The researchers found that this carotenoid coloration contributed more to the preferred healthy appearance than equivalent changes associated with melanin pigmentation. The results supported the idea that carotenoid coloration can function as a visible cue associated with diet and perceived health.
Subsequent research from St Andrews examined attractiveness more directly. Carmen Lefevre and David Perrett compared facial coloration associated with carotenoids with coloration associated with melanin. Increased levels of both were judged more attractive than lower levels, but when the amount of colour change was matched, participants consistently preferred carotenoid coloration over melanin coloration.
In other words, the desirable “golden glow” isn't necessarily the same thing as simply having a darker tan.
There may be an evolutionary explanation. In many animal species, carotenoid-based coloration acts as a visible signal involved in mate selection. Carotenoids also have antioxidant functions, and in humans their skin coloration is associated with fruit and vegetable consumption. Researchers have therefore proposed that human sensitivity to carotenoid-rich skin could represent a perceptual signal related to condition and health.
Intriguingly, another St Andrews study tested whether people simply preferred the colour itself. Researchers compared normal faces with scrambled images containing comparable colours. Increasing carotenoid coloration improved the attractiveness of the faces, but did not produce the same attractiveness effect in the scrambled images. This suggests that the preference is specifically connected with how colour appears in human facial skin, rather than merely being a general preference for golden-yellow colours.
The research therefore points toward an interesting principle of human appearance: what we perceive as a vibrant, healthy complexion can partly reflect biological pigments derived from diet.
The familiar idea of someone looking as though they are “glowing” may have more science behind it than we realize.