Eating for Beautiful, Healthy Skin
The skin is the largest organ of the human body and a barrier that protects the body from microbial pathogens and other damaging elements. The health of the skin is a reflection of one’s overall health, and the skin’s resilience to sun exposure and outward appearance can be enhanced with high-nutrient foods.
Skin cancer is the most common cancer in the U.S., affecting one out of every five Americans.1 Ultraviolet radiation from the sun promotes aging and carcinogenesis via oxidative stress, inflammation, and damage to DNA. Ultraviolet (UV) exposure also leads to alteration of the skin’s structural proteins, causing sagging and wrinkling. Taking proactive measures such as using a safe mineral sunscreen and limiting mid-day sun exposure are crucial to protecting your skin from the sun’s UV rays. Phytochemicals from natural foods can provide an extra source of protection, by enhancing the body’s natural defenses to help prevent sunburn, and its associated dangers, and by slowing the aging of the skin.
Carotenoids are one class of phytochemicals that offer photoprotection. After we consume carotenoid-rich foods, carotenoids accumulate in the skin, where they oppose UV-induced oxidative stress. Individual carotenoids, mixed carotenoids, and carotenoid-rich whole foods have been shown to have photo-protective qualities that prevent or repair DNA damage to the skin caused by the sun.2,3 Lycopene-rich tomato paste, for example, was given to healthy women daily for twelve weeks, and their skin’s sunburn response to UV light was measured at the beginning and end of the study. After twelve weeks of tomato supplementation, the skin’s resistance to UV-induced reddening was enhanced. The tomato paste supplementation also reduced the DNA damage caused by the UV exposure.4 Tomatoes are the most familiar source of lycopene, but lycopene is also found in pink fruits such as watermelon, grapefruit, and papaya. Supplementation with lutein and zeaxanthin, found primarily in leafy green vegetables, was also found to provide photoprotection and improve several measures of skin quality, such as elasticity.2 Beta-carotene has been shown to interfere with UVA-induced oxidative damage in skin cells, and—similar to lycopene, lutein, and zeaxanthin—reduced UV-induced redness compared to placebo.2,5 Because of the potential dangers of isolated carotenoid supplements, we should supply our skin with carotenoids by eating leafy greens, yellow and orange vegetables, tomatoes, and pink fruits.
In addition to carotenoids, another class of antioxidant nutrients—polyphenols—has been investigated for photoprotective actions. Polyphenols are a large family of antioxidants that include subfamilies phenolic acids, flavonoids (abundant in berries), lignans (in flax, chia, and sesame seeds) and stilbenes (such as resveratrol, the signature antioxidant of grapes and red wine). There are hundreds of polyphenols, and they are present in most whole plant foods.6 Polyphenols from cocoa and green tea, for example, have been shown to counteract UV-induced skin damage in human studies.7,8
Wrinkles and other signs of skin aging are related to chronological age but also strongly influenced by UV rays. It is estimated that 80% of the visible aging in a woman’s face is due to sun exposure.9 So the phytochemical-rich foods that offer sun protection also offer some protection against wrinkles. In one study of older adults, higher intakes of vegetables and legumes and lower intake of dairy and sugar were associated with less visible sun damage.10 Another study assessed skin aging in middle-aged American women, and found that higher dietary vitamin C intake was associated with fewer wrinkles.11 In a study of Japanese women that related dietary variables to “crow’s feet” wrinkling, higher intake of green and yellow vegetables was associated with fewer wrinkles.12 In studies on green tea and cocoa polyphenols, in addition to UV protection, these interventions improved appearance factors such as elasticity, hydration, and softness.7,8
Structural proteins in the connective tissue of the skin are also affected by diet. There is preliminary evidence that beta-carotene reduces the levels of one such protein that promotes skin wrinkling.13 Also, tomato paste supplementation was found to reduce the activity of an enzyme known to degrade structural proteins in the skin, presumably slowing skin aging.4
In spite of the well-known damaging effects of the sun on our skin, many of us still perceive a suntan as healthy-looking. Food-derived carotenoids can also affect our skin coloration, and new research has shown that carotenoid-colored skin is perceived as healthier and more attractive. In the wild, carotenoids are responsible for the bright feather colors of male birds, which make them more attractive to potential mates.14 There is a much more subtle, but similar phenomenon in humans. An increase in carotenoid-produced skin coloration was consistently found to be perceived as healthier in people of Caucasian, African, and Asian descent.15 One interesting study found that people preferred the skin color caused by eating carotenoids over the skin color from a suntan.16 Another study investigated skin carotenoid coloration changes in response to increased fruit and vegetable consumption. They found that photos of individuals a few weeks after increasing fruit and vegetable intake by three serving per day received higher ratings of health and attractiveness than “before” photos.17 Furthermore, the improvement in appearance has been shown to be a motivating factor for increasing fruit and vegetable consumption, as reported in the journal Health Psychology.18
Maintain skin antioxidants with consistent healthful eating
Each time the skin is exposed to the sun, some carotenoids are “used up” for their antioxidant, so they must be constantly replenished by the diet to maintain the protective effects (smoking and alcohol also deplete additional carotenoids from skin).2,19 Consistently consuming antioxidant-rich plant foods will build up the stores of these protective phytochemicals in the skin. You can even quantify your skin carotenoid levels using a specialized scanner to confirm the accumulation of dietary carotenoids in your skin.20,21 I use one of these scanners in my medical practice to confirm that these beneficial phytochemicals have accumulated in the skin of patients as they increase their consumption of carotenoid-rich foods. A Nutritarian diet is designed to be rich in antioxidant phytochemicals and promotes health inside and out, protecting against chronic disease and sun damage while giving the skin a natural, healthy-looking glow.
1. Skin Cancer Foundation: Skin Cancer Facts [http://www.skincancer.org/skin-cancer-information/skin-cancer-facts]
2. Evans JA, Johnson EJ: The role of phytonutrients in skin health. Nutrients 2010;2:903-928.
3. Stahl W, Sies H: beta-Carotene and other carotenoids in protection from sunlight. Am J Clin Nutr 2012.
4. Rizwan M, Rodriguez-Blanco I, Harbottle A, et al: Tomato paste rich in lycopene protects against cutaneous photodamage in humans in vivo. Br J Dermatol 2010.
5. Kopcke W, Krutmann J: Protection from sunburn with beta-Carotene--a meta-analysis. Photochem Photobiol 2008;84:284-288.
6. Manach C, Scalbert A, Morand C, et al: Polyphenols: food sources and bioavailability. Am J Clin Nutr 2004;79:727-747.
7. Heinrich U, Moore CE, De Spirt S, et al: Green tea polyphenols provide photoprotection, increase microcirculation, and modulate skin properties of women. J Nutr 2011;141:1202-1208.
8. Heinrich U, Neukam K, Tronnier H, et al: Long-term ingestion of high flavanol cocoa provides photoprotection against UV-induced erythema and improves skin condition in women. J Nutr 2006;136:1565-1569.
9. Flament F, Bazin R, Laquieze S, et al: Effect of the sun on visible clinical signs of aging in Caucasian skin. Clin Cosmet Investig Dermatol 2013;6:221-232.
10. Purba MB, Kouris-Blazos A, Wattanapenpaiboon N, et al: Skin wrinkling: can food make a difference? J Am Coll Nutr 2001;20:71-80.
11. Cosgrove MC, Franco OH, Granger SP, et al: Dietary nutrient intakes and skin-aging appearance among middle-aged American women. Am J Clin Nutr 2007;86:1225-1231.
12. Nagata C, Nakamura K, Wada K, et al: Association of dietary fat, vegetables and antioxidant micronutrients with skin ageing in Japanese women. Br J Nutr 2010;103:1493-1498.
13. Terao J, Minami Y, Bando N: Singlet molecular oxygen-quenching activity of carotenoids: relevance to protection of the skin from photoaging. J Clin Biochem Nutr 2011;48:57-62.
14. Carotenoids Are Cornerstone of Bird's Vitality. 2009. ScienceDaily. http://www.sciencedaily.com/releases/2009/02/090213114154.htm. Accessed
15. Whitehead RD, Coetzee V, Ozakinci G, et al: Cross-cultural effects of fruit and vegetable consumption on skin color. Am J Public Health 2012;102:212-213.
16. Stephen ID, Coetzee, V., Perrett, D.I.: Carotenoid and melanin pigment coloration affect perceived human health. Evolution and Human Behavior 2010.
17. Whitehead RD, Re D, Xiao D, et al: You are what you eat: within-subject increases in fruit and vegetable consumption confer beneficial skin-color changes. PLoS One 2012;7:e32988.
18. Whitehead RD, Ozakinci G, Perrett DI: A randomized controlled trial of an appearance-based dietary intervention. Health Psychol 2014;33:99-102.
19. Lademann J, Meinke MC, Sterry W, et al: Carotenoids in human skin. Exp Dermatol 2011;20:377-382.
20. Ermakov IV, Gellermann W: Validation model for Raman based skin carotenoid detection. Arch Biochem Biophys 2010;504:40-49.
21. Ermakov IV, Sharifzadeh M, Ermakova M, et al: Resonance Raman detection of carotenoid antioxidants in living human tissue. J Biomed Opt 2005;10:064028.