Dr. Jonathan Wright has been thinking a lot about how . . .
… with the oral use of supplemental nutrients found to be
photoprotective, along with the topical use of sunscreens
Is it safe to swim in the ocean? Or does the movie Jaws continue to bias your judgment? In actuality, shark attacks are largely a myth, with only 2251 confirmed attacks in the last 428 years (from 1580 to 2008) on the entire planet.* Even in the United States, the world’s riskiest country (with more attacks than any other), there have been only 1032 incidents (including those of Hawaii) in the last 338 years (from 1670 to 2008). That works out to about 3 attacks per year, and only 50 have resulted in fatalities. That’s one fatality every 6.8 years. You have more reason to worry about death from a venomous spider bite (about 5/year), and certainly from exposure to the sun, which is virtually unavoidable. Even if you stay out of its direct rays, there is still a sizeable risk from reflected sunlight.
*Florida Museum of Natural History. International Shark Attack File. http://www.flmnh.ufl.edu/fish/sharks/statistics/gattack/mapusa.htm. Last updated July 9, 2009. Accessed April 22, 2010.
Skin cancer is the most common
form of cancer in the United States,
with more than 3.5 million cases in
two million people
Skin Cancer Death Toll Mounts
Skin cancer is the most common form of cancer in the United States, with more than 3.5 million cases in two million people diagnosed annually, for the most recent data available year.1 Did you know that each year there are more new cases of skin cancer than the combined incidence of breast, prostate, lung, and colon cancer?2 And that one in five Americans (20%) will develop skin cancer in the course of a lifetime?3 Consider basal cell carcinoma, the most common form of skin cancer, for example. There are an estimated 2.8 million cases annually diagnosed in the US.4 While basal cell is rarely fatal, it can cause significant disfiguring if ignored and allowed to grow. Then there’s squamous cell carcinoma, the second most common forms of skin cancer. As many as 700,000 cases are diagnosed each year,4 resulting in approximately 2500 deaths.5
Together, basal cell carcinoma and squamous cell carcinoma are the major forms of non-melanoma skin cancer. Startling as it may seem, between 40 and 50 percent of Americans who live at least 65 years will have either skin cancer at least once.6 And the cost is staggering. Just for the treatment for non-melanoma skin cancers in 2004, the direct cost was more than $1 billion.7 It is shocking to know that approximately 90 percent of these skin cancers are directly connected with exposure to ultraviolet radiation from the sun.8 Moreover, up to 90 percent of the visible changes commonly attributed to aging are caused by the sun.9 It is a major myth that most damage occurs before the age of 18. While 80 percent of a person’s lifetime sun exposure is acquired before age 18, the damage occurs later in life with continued exposure.10
The Skin’s Nightmare
At the end of the road is melanoma, the vast majority of which is caused by ultraviolet radiation.11 While the incidence of many common cancers is falling, that is not so with melanoma. It continues to rise sharply, faster than that of any of the seven most common cancers.12 All told, as many as 69,000 melanomas are expected to be diagnosed in 2010, with over 8,600 deaths resulting.13
While melanoma accounts for only about three percent of skin cancer cases,14 it causes a whopping 75 percent of skin cancer deaths.15 Of interest, melanoma mortality increased by about 33 percent from 1975–90, but has remained relatively stable since 1990 and survival increased from 49 percent in the early 1950s to 92 percent between 1996 and 2003.12 The hard truth is that 20 Americans die each day from skin cancer, primarily melanoma and that one person dies of melanoma almost every hour (every 62 minutes).13
If melanoma is detected early, the survival rate is about 99 percent.16 The survival rate falls to 15 percent for those with advanced disease. Other important facts are that melanoma is the fifth most common cancer for males and sixth most common for females, and that women 39 and under in age have a higher probability of developing melanoma than any other cancer except breast cancer. Melanoma is the most common form of cancer for young adults 25–29 years old and the second most common form of cancer for adolescents and young adults 15–29 years old.17
One blistering sunburn in childhood or adolescence more than doubles a person’s chances of developing melanoma later in life.18 Also, a person’s risk for melanoma doubles if he or she has had five or more sunburns at any age.19
Help is On the Way
With data like this, most people want to give up, especially when you consider that skin cancer is increasing despite the use of topical sun protection strategies. But there is something else you can do and research is showing that nutrients reduce photo-oxidative damage, suggesting that nutritional approaches could be heroic for preventing skin cancer.
The hard truth is that 20 Americans
die each day from skin cancer,
primarily melanoma and that one
person dies of melanoma almost every
hour (every 62 minutes).
It is sad to say that photo-oxidative ultraviolet A radiation reduces skin and blood antioxidants and damages cell components, not to mention DNA. However, it is good news that antioxidant vitamins, minerals, and phytochemicals, in addition to omega-3 fatty acids, have demonstrated protective properties. The Mediterranean diet contains many of these and is attributed with lowering the rates of melanoma in the region despite fairly high levels of solar radiation. From these observations, we can surmise that the study of dietary/nutritional supplementation for internal support of sun-protection mechanisms, could very well complement external strategies.
The Concerns of a Physician
Dr. Jonathan Wright has been thinking about the importance of protection from the sun using an internal approach along with the usual external (i.e., topical) route. In this pursuit, he has recently unearthed several reviews of what can be done to make the most of the available mechanisms.20-21 Reading the papers referenced, what he found is that there are quite a number of antioxidants and other nutrients that can have a protective effect. Some are vitamins, others trace minerals, yet others herbs, and some are food extracts. Finally there are fatty acids along with an amino acid.
Antioxidants Reduce Sunburn
When UV radiation is absorbed by skin, free radicals are generated in the damaged cells. This effect may be partly neutralized by antioxidant substances such as vitamin Cand vitamin E which are reported to scavenge reactive oxygen species. In a single-blind controlled clinical trial, 45 healthy volunteers were divided into three groups: one group consuming 1200 IU of vitamin E daily; another taking 2 g of vitamin C daily; and a third group taking 2 g of vitamin C plus 1200 IU of vitamin E daily.22 Treatment went on for one week. Before and after treatment, the researchers measured the number of damaged cells by determining the minimal erythema dose (MED) in all participants (erythema is redness of the skin, caused by increased blood flow in the lower layers of the skin in response to any skin injury, infection, or inflammation). The combination of vitamin E and vitamin C produced the best photoprotective effect, with MED increasing.
In a clinical trial conducted at J.W. Goethe University, Frankfurt, Germany, researchers studied the effects of oral supplementation with vitamin E, vitamin C, or the two vitamins together to determine their influence on solar simulated radiation induced skin inflammation in 40 healthy volunteers.23 The study was prospective, randomized, and placebo controlled with vitamin E given at 2 g/day, vitamin C at 3 g/day, or the vitamin E dose combined with the vitamin C dose, or placebo. Levels of the two vitamins were measured before and after 50 days of supplementation for concentrations in keratinocytes as was MED by visual grading before and after supplementation. After 50 days after supplementation, vitamin E levels were found to have increased in both groups taking it, as was the case with the group taking vitamin C. The dose response curve of UV radiation induced erythema showed a significant flattening and the MED increased by 80% after supplementation in the group taking both vitamin E and C. This meant that it took 80% more UVR to produce reddening. The researchers concluded that the 2 vitamins acted synergistically in suppression of the sunburn reaction.
The researchers concluded that
vitamins C and E acted
synergistically in suppression of the
In addition to sunburn, UV radiation causes other acute adverse effects such as photosensitivity reactions, or immunologic suppression, as well as photoaging or malignant skin tumors (these last two are long-term sequelae). As we know, UV produces reactive oxygen species, along with eicosanoids and cytokines. In another study, conducted at Ludwig Maximilian University of Munich, Germany, researchers assessed the protective effect of vitamins C and E against sunburn in human beings.24Using a double-blind placebo-controlled study, each of two 10-subject groups took either 2 gm of vitamin C combined with 1000 IU of vitamin E daily or placebo. Before and after 8 days of treatment the threshold UV dose for eliciting sunburn (MED) was measured along with the cutaneous blood flow of skin irradiated with incremental UV doses against that of nonirradiated skin.
The median MED of those taking the vitamins increased by about 21% whereas it declined by about 14% in the placebo group. Cutaneous blood flow decreased in those given vitamins while increasing in the placebo group. It is again clear that the combination of vitamins C and E reduces sunburn, and that this might indicate reduced risk for later UV-induced skin damage.
Carotenoids Help Scavenge Free Radicals in Skin
Carotenoids (vitamin As) and tocopherols (vitamin Es) are known to be efficient antioxidants and capable of scavenging reactive oxygen species generated during photooxidative stress. Consequently, they may protect the skin from UV light-induced erythema. While beta-carotene is frequently used as an oral sun protectant, there have been few studies about this aspect. In a study conducted at Heinrich-Heine-University in Düsseldorf, Germany, the protective effects of orally given carotenoids and a combination of carotenoids and vitamin E against the development of erythema in 20 healthy subjects was investigated.25 A supplement containing 25 mg of total carotenoids/day and a combination of the carotenoid supplement and 335 mg (500 IU) of vitamin E/day were given to healthy volunteers for 12 weeks. The mix of carotenoids included beta-carotene, alpha-carotene, crytoxanthin, zeaxanthin, and lutein. Erythema was induced by a blue-light solar simulator, and thereafter serum beta-carotene and alpha-tocopherol concentrations and skin carotenoid levels were assessed. These concentrations increased with supplementation, and erythema on dorsal skin (back) was significantly diminished after week 8. Importantly, erythema suppression was greater with the combination of carotenoids and vitamin E than with carotenoids alone. Carotenoids and vitamin E are synergistic.
In a study conduced at the University of Arizona, the protective effects of oral alpha- and beta-carotene supplementation on UVA- and UVB-induced erythema in humans was measured.26 Altogether 22 subjects (11 men and 11 women) were supplemented with natural carotenoids for 24 weeks. Each day for the first 8 weeks, subjects were given 30 mg of natural carotenoids containing 29.4 mg of beta-carotene, 0.36 mg of alpha-carotene, and traces of crytoxanthin, zeaxanthin, and lutein in vegetable oil.
Importantly, erythema suppression
was greater with the combination of
carotenoids and vitamin E than with
carotenoids alone. Carotenoids and
vitamin E are synergistic.
The carotenoid dose was progressively raised by 30-mg increments, every 8 weeks, from 30 mg to 90 mg at end of trial. Skin exposed to increasing doses of UV light was examined to determine the MED, which was obtained by visual inspection 24 hours after irradiation. Serum levels of alpha- and beta-carotene serum were taken for a lipid peroxidation analysis. The MED of solar simulator radiation increased significantly and after 24 weeks serum beta-carotene levels were increased nearly 8-fold. Alpha-carotene serum levels rose by 5 times. Serum lipid peroxidation was significantly inhibited in a dose-dependent manner during natural carotenoid supplementation. The present data suggest that supplementation with natural carotenoids may partially protect human skin from UVA- and UVB-induced erythema.
One study reported an 83.2% lower sunburn cell count in subjects receiving an oral lycopene supplement.27 Another study found a 40% reduction in erythema in subjects consuming 16 mg/day of lycopene (from 40 g or 3 tbsp tomato paste) in combination with olive oil (10 g or 2 tsp).28
In another study, scientists investigated the photoprotective effects of synthetic lycopene in comparison with a tomato extract (Lyc-o-Mato) and a drink containing solubilized Lyc-o-Mato (Lyc-o-Guard-Drink).29 Volunteers ingested similar amounts of lycopene (about 10 mg/day). After 12 weeks of supplementation, significant increases in lycopene serum levels and total skin carotenoids were observed in all groups. Significant increases in the serum levels of phytofluene and phytoene occurred in the Lyc-o-Mato and the Lyc-o-Guard-Drink group. At weeks 0, 4, and 12 an erythema was induced with a solar light simulator. The protective effect was more pronounced in the Lyc-o-Mato (38%) and Lyc-o-Guard-Drink (48%) groups. In the two latter groups, phytofluene and phytoene may have contributed to protection. Both of these carotenoids exhibit absorption maxima at wavelengths of UV light. Absorption of UV light protects skin from photodamage and might explain the differences observed between groups.
Supplements and Sunscreens Are Complementary
Presupplementation with moderate dosages of beta-carotene (30 mg/d) before and during sunlight exposure provides protection against sunburn, possibly because of the increased absorption capacity of the skin or because beta-carotene concentrations in the skin do not decrease below levels considered to be critical. A study with 20 healthy women given 30 mg of beta-carotene/day for 12 weeks had two interesting findings.30Not only did carotene supplementation reduce erythema, when combined with sunscreen the combination of systemic and topical photoprotection offers a synergistic effect. In other words, moderate doses of beta-carotene before and during natural sunlight exposure, combined with topical sunscreens, are more effective than sunscreen lotion alone.
Vitamin D Without Depending on the Sun
Avoiding the sun is one way to be sure that you don’t damage your skin, but there is a consequence of not getting any sun, and it is severe. For a growing number of reasons,vitamin D is of great importance for health (see “Vitamin D Could Anti-Age You” in the January 2008 issue), yet for many people, sun exposure is the route they choose to most significantly increase vitamin D production in their skin. But that production comes at a high price. In a paper about the relationship of vitamin D and cancer risk, the authors state that to prevent cancer, it may be advisable for all adults to maintain a circulating 25-hydroxyvitamin D level of at least 55 nanograms per milliliter (a nanogram is one-billionth of a gram) throughout life.31 However, according to their analysis, this is attainable with a daily intake of several thousand IU of vitamin D3, a recommended dose not only for people in northern latitudes during winter months, when sun exposure is minimal, but also for those who live in areas with high sun exposure, such as Arizona. According to a study that investigated vitamin D concentrations in southern Arizona, a region with high chronic sun exposure, residents were commonly found to be deficient in vitamin D, particularly among blacks and Hispanics.32
According to a study that investigated
vitamin D concentrations in
southern Arizona, a region with
high chronic sun exposure, residents
were commonly found to be deficient
in vitamin D, particularly among
blacks and Hispanics.
Selenium and Copper Help Reduce Sunburn
The trace element selenium along with the mineral copper and a vitamin complex (with vitamins E and A) were studied for their ability to prevent sunburn cell formation in human skin exposed to ultraviolet radiation.33 Following three weeks of supplementation with 200 mcg of selenium, 2.7 mg of vitamin A, and 14 mg of vitamin E, protection (versus placebo) against ultraviolet-induced cell damage was found in the suberythemal area of the skin. This was attributed to the antioxidant properties of the compounds which also were found to offer an additional reduction in the number of sunburn cells.
Folate, Vitamin B6, DNA, and Vitilago
DNA damage as a result of UV exposure plays an important role in the progression of cutaneous aging, to which folate has been linked to the process of DNA protection and repair. However, observations have suggested that UV radiation may cause folate deficiency. But when folate is taken orally as a supplement, levels are maintained. Folate also has been shown to be beneficial for vitilago, a chronic disorder that causes depigmentation in patches of skin.
Delayed-hypersensitivity skin test
responses were significantly increased
at 12 months in the group taking
ascorbate, beta-carotene, folate,
vitamin B6, and alpha-tocopherol.
A placebo-controlled double-blind trial of the effects of daily micronutrient supplements on circulating vitamin and trace metal concentrations and delayed-hypersensitivity skin test responses was conducted.34 Micronutrients, including ascorbate, beta-carotene, folate, vitamin B6, and alpha-tocopherol, were given to 56 subjects (59–85 years old) who were randomly assigned to placebo or micronutrient groups. At 6 and 12 months, there were increases in the mean serum concentrations of ascorbate, beta-carotene, folate, vitamin B6, and alpha-tocopherol, and concentrations were low in the placebo group. Delayed-hypersensitivity skin test responses were significantly increased at 12 months in the micronutrient group, but not the placebo group. This demonstrates that daily supplementation with micronutrients can prevent low concentrations of some micronutrients and thus improve delayed-hypersensitivity skin test responses in healthy, independently living older adults.
Polypodium leucotomos is an epiphytic fern (a plant that grows upon another plant) native to tropical and subtropical regions of the Americas. Decoctions of P. leucotomos have been used as panaceas in Central American folk medicine. Recently, interest has been growing in the scientific evaluation of the mechanisms underlying its use.
In a recent study, with healthy volunteers, at two times the MED average “common deletion” values in a non-P. leucotomos-treated group increased by 217% over baseline, while values in a P. leucotomos-treated decreased by 84%.35 Common deletion causes mitochondrial DNA damage. According to the researcher’s interaction analysis, P. leucotomos’ effect exhibited a trend towards preventing the increase of common deletion levels as the UVA dose increased.
demonstrated a significant protective
effect of skin in idiopathic (cause
In another study, P. leucotomos (PL) administration was shown to be an effective and safe method leading to a significant protection of skin in idiopathic photodermatoses.36Also, an immunohistochemical study revealed photoprotection of Langherhans cells by oral as well as topical PL.37 The observed photoprotective activities of oral or topical PL reveal a new avenue in examining the potentially useful field of systemic photoprotection. This suggests that PL can be used as adjunct treatment and can make photochemotherapy and phototherapy safer when the control of cutaneous phototoxicity to PUVA or UVB is a limiting factor in such phototherapies.
Green and Black Teas
Regular intake of the catechin EGCG, found in green tea, strengthens the skin’s tolerance by increasing MED and thus prevents UV-induced disturbance of epidermal barrier function and skin damage. These results suggest that EGCG is a potent candidate for systemic photoprotection.38 Participants treated with a combination regimen of topical and oral green tea showed histologic improvement in elastic tissue content.39 Green tea polyphenols have been postulated to protect human skin from the cutaneous signs of photoaging, but clinically significant changes could not be detected. Longer supplementation may be required for clinically observable results.
Mechanistic studies support the potential nutritional value of green tea in skin photoprotection. In another study, researchers show that green tea polyphenols are effective via oral administration in drinking water.40 Hence, green tea polyphenols, in combination with sunscreens, may provide an effective strategy for reducing the risk of skin cancers. In addition, the data presented in this study indicate that UVB-induced DNA damage and inflammatory responses are causally related to an increased risk of photocarcinogenesis.
Green tea polyphenols, in
combination with sunscreens,
may provide an effective strategy for
reducing the risk of skin cancers.
Regular intake of EGCG strengthens the skin’s tolerance by increasing MED and thus prevents UV-induced disturbance of epidermal barrier function and skin damage.41These results suggest that EGCG is a potent candidate for systemic photoprotection. Similarly, oral and topical administration of standardized black tea extract and its two major polyphenolic sub-fractions protect against UVB-induced erythema in mice.42
A population-based case-control study was used to evaluate the relationships between citrus peel and black tea intake and squamous cell carcinoma of the skin.43Researchers assessed the independent and interactive effects of citrus peel and black tea in the development of squamous cell carcinoma. The odds ratios associated with citrus peel use were significantly lower, and subjects who reported consumption of both hot black tea and citrus peel had a significant marked decrease risk of skin squamous cell carcinoma. Both citrus peel use and black tea, especially served hot, have independent protective effects for squamous cell carcinoma of the skin.
Pine Bark Extract
In a study using pine bark extract, the average melasma (a tan or dark skin discoloration) area of the patients decreased by by about 26 mm and the average pigmentary intensity decreased by 0.47 units.44 Pine bark extract was shown to be therapeutically effective and safe in patients suffering from melasma.
Tyrosine for Tanning
When skin was exposed to UVA light, the administration of phenylalanine was found to be effective in vitiligo.45 Phenylalanine is an amino acid which constitutes part of the daily dietary protein, and when orally administered in a dose of 50 mg/kg body weight, results in an elevated plasma level. Since peak concentrations of phenylalanine in the blood are reached between 30 and 45 minutes after ingestion, UVA exposure was administered at this time. After 4 months (over which 32 treatments were given) repigmentation occurred in the skin area of subcutaneous fat (adipose tissue). While vitiligo patients can tolerate more sun than those without it, no sunburn resulted as a result of the phenylalanine-UVA therapy. Normal skin also tans very well. Phenylalanine is converted to the non-essential amino acid tyrosine.
Taking L-tyrosine as a supplement can
help the body to produce melanin,
which helps tanning and is likely to
reduce the risk of sunburn.
Some 50 years ago, an American doctor named John Myers developed a natural way to lengthen the time an individual can spend in sunlight without getting burnt.46 In the sunlight, skin cells produce more of a substance known as melanin. Melanin is made from an amino acid known as tyrosine. Taking tyrosine as a supplement can therefore help the body to produce melanin, which helps tanning and is likely to reduce the risk of sunburn. The conversion of tyrosine into melanin is helped by certain nutrients, notably vitamin C, vitamin B6 and copper. Taking these nutrients is likely to help improve your tolerance of the sun and reduce the risk of sunburn.
Returning to the “Ocean” of Sun
Just when you thought it was not safe to step outside, there is more than hope. With the kind of added nutritional protection you can employ, it is now possible to enjoy the outdoors again. Don’t forget to use a good sunscreen. Even though sunshine is good, too much is not!
- Howard W. Rogers, MD, PhD, Martin A. Weinstock, MD, PhD, et al. Incidence Estimate of Nonmelanoma Skin Cancer in the United States, 2006. Archives of Dermatology 2010.
- American Cancer Society. Cancer Facts & Figures 2009. Atlanta: American Cancer Society; 2009.
- Robinson JK. Sun Exposure, Sun Protection, and Vitamin D. JAMA 2005; 94:1541-43.
- Skin Care Foundation. Skin Cancer Facts Page. http://www.skincancer.org/Skin-Cancer-Facts. Updated April 1, 2010. Accessed April 22, 2010.
- American Academy of Dermatology. Squamous Cell Carcinoma Page. http://www.aad.org/public/publications/pamphlets/sun_squamous.html. Updated April 15, 2008. Accessed April 22, 2010.
- National Cancer Institute. Sun Protection. Cancer Trends Progress Report – 2009/2010 Update April 15, 2010. Accessed April 22, 2010.
- Bickers DR, Lim HW, Margolis D et al. The burden of skin diseases: 2004. J Am Acad Dermatol 2006; 55: 490-500.
- Armstrong BK, Kricker A, How much melanoma is caused by sun exposure? Melanoma Research 1993: 3:395-401.
- Taylor CR, Stern RS, Leyden JJ, Gilchrest BA. Photoaging/Photodamage and Photoprotection J Am Acad Dermatol 1990 Jan;22(1):1-15.
- Godar DE, Urbach F, Gasparro FP, van der Leun JC. UV Doses of Young Adults. Photochem Photobiol 2003;77(4):453-7.
- Pleasance ED, Cheetham RK, Stephens PJ, et al. A comprehensive catalogue of somatic mutations from a human cancer genome. Nature 2010 Jan 14;463(7278):191-6.
- National Cancer Institute. SEER Cancer Statistics Review, 1975-2004 Page.http://seer.cancer.gov/csr/1975_2004/. Accessed April 22, 2010.
- American Cancer Society. Cancer Facts & Figures 2009. Atlanta: American Cancer Society; 2009.
- American Cancer Society. How Many People Get Melanoma Skin Cancer? May 13, 2008. Updated March 29, 2010. Accessed April 22, 2010.
- National Center for Chronic Disease Prevention and Health Promotion. The Burden of Skin Cancer. May 13, 2008. Updated March 29, 2010. Accessed April 22, 2010. Updated October 28, 2008. Accessed April 22, 2010.
- Huang CL, Halpern AC. Management of the patient with melanoma. In: Rigel DS, Friedman RJ, Dzubow LM, Reintgen DS, Bystryn J-C, Marks R, eds. Cancer of the Skin. New York, NY: Elsevier Saunders; 2005:265-75.
- National Cancer Institute. Cancer Epidemiology in Older Adolescents & Young Adults. SEER AYA Monograph 2007:53-63
- Lew RA, Sober AJ, Cook N, Marvell R, Fitzpatrick TB. Sun exposure habits in patients with cutaneous melanoma: a case study. J Dermatol Surg Oncol1983;12:981-6.
- Pfahlberg A, Kolmel KF, Gefeller O. Timing of excessive ultraviolet radiation and melanoma: epidemiology does not support the existence of a critical period of high susceptibility to solar ultraviolet radiation-induced melanoma. Brit J Dermatol March 2001;144;3:471.
- Boelsma E, Hendriks HF, Roza L. Nutritional skin care: health effects of micro-nutrients and fatty acids. Am J Clin Nutr 2001 May;73(5):853-64. Review.
- Shapira N. Nutritional approach to sun protection: a suggested complement to external strategies. Nutr Rev 2010 Feb;68(2):75-86.
- Mireles-Rocha H, Galindo I, Huerta M, Trujillo-Hernández B, Elizalde A, Cortés-Franco R. UVB photoprotection with antioxidants: effects of oral therapy with d-alpha-tocopherol and ascorbic acid on the minimal erythema dose. Acta Derm Venereol 2002;82(1):21-4.
- Fuchs J, Kern H. Modulation of UV-light-induced skin inflammation by D-alpha-tocopherol and L-ascorbic acid: a clinical study using solar simulated radiation. Free Radic Biol Med 1998 Dec;25(9):1006-12.
- Eberlein-König B, Placzek M, Przybilla B. Protective effect against sunburn of combined systemic ascorbic acid (vitamin C) and d-alpha-tocopherol (vitamin E). J Am Acad Dermatol 1998 Jan;38(1):45-8.
- Stahl W, Heinrich U, Jungmann H, Sies H, Tronnier H. Carotenoids and carotenoids plus vitamin E protect against ultraviolet lightinduced erythema in humans. Am J Clin Nutr 2000;71:795–8.
- Lee J, Jiang SG, Levine N,Watson RR. Carotenoid supplementation reduces erythema in human skin after simulated solar radiation exposure. Proc Soc Exp Biol Med 2000;223:170–4.
- Draelos ZD, Djerassi D, Nir Z. The Cutaneous Benefits of an Oral Antioxidant Dietary Supplement. Rostock, Germany: Dermatology Consulting Services; 2008. Report No.: DCS-55-07.
- Stahl W, Heinrich U, Wiseman S, Eichler O, Sies H, Tronnier H. Dietary tomato paste protects against ultraviolet lightinduced erythema in humans. J Nutr2001;131:1449–51.
- Aust O, Stahl W, Sies H, Tronnier H, Heinrich U. Supplementation with tomato-based products increases lycopene, phytofluene, and phytoene levels in human serum and protects against UV-light-induced erythema. Int J Vitam Nutr Res2005 Jan;75(1):54-60.
- Gollnick HPM, Hopfenmuller W, Hemmes C, et al. Systemic beta-carotene plus topical UV-sunscreen are an optimal protection against harmful effects of natural UV-sunlight: results of the Berlin-Eilath study. Eur J Dermatol 1996;6:200–5.
- Garland CF, Grant WB, Mohr SB, Gorham ED, Garland FC. What is the dose-response relationship between vitamin D and cancer risk? Nutr Rev2007;65(8):S91-5.
- Jacobs ET, Alberts DS, Foote JA, Green SB, Hollis BW, Yu Z, Martínez ME. Vitamin D insufficiency in southern Arizona. Am J Clin Nutr 2008 Mar;87(3):608-13.
- La Ruche G, Cesarini JP. Protective effects of oral selenium plus copper associated with vitamin complex on sunburn cell formation in human skin. Photodermatol Photoimmunol Photomed 1991;8:232–5.
- Bogden JD, Bendich A, Kemp FW, et al. Daily micronutrient supplements enhance delayed-hypersensitivity skin test responses in older people. Am J Clin Nutr 1994;60:437–74.
- Villa A, Viera MH, Amini S, Huo R, Perez O, Ruiz P, Amador A, Elgart G, Berman B. Decrease of ultraviolet A light-induced “common deletion” in healthy volunteers after oral Polypodium leucotomos extract supplement in a randomized clinical trial. J Am Acad Dermatol 2010 Mar;62(3):511-3
- Caccialanza M, Percivalle S, Piccinno R, Brambilla R. Photoprotective activity of oral polypodium leucotomos extract in 25 patients with idiopathic photodermatoses. Photodermatol Photoimmunol Photomed 2007 Feb;23(1):46-7.
- González S, Pathak MA, Cuevas J, Villarrubia VG, Fitzpatrick TB. Topical or oral administration with an extract of Polypodium leucotomos prevents acute sunburn and psoralen-induced phototoxic reactions as well as depletion of Langerhans cells in human skin. Photodermatol Photoimmunol Photomed 1997 Feb-Apr;13(1-2):50-60.
- Jeon HY, Kim JK, Kim WG, Lee SJ. Effects of oral epigallocatechin gallate supplementation on the minimal erythema dose and UV-induced skin damage. Skin Pharmacol Physiol 2009;22(3):137-41.
- Chiu AE, Chan JL, Kern DG, Kohler S, Rehmus WE, Kimball AB. Double-blinded, placebo-controlled trial of green tea extracts in the clinical and histologic appearance of photoaging skin. Dermatol Surg 2005 Jul;31(7 Pt 2):855-60; discussion 860.
- Bouzari N, Romagosa Y, Kirsner RS. Green tea prevents skin cancer by two mechanisms. J Invest Dermatol 2009 May;129(5):1054.
- Jeon HY, Kim JK, Kim WG, Lee SJ. Effects of oral epigallocatechin gallate supplementation on the minimal erythema dose and UV-induced skin damage. Skin Pharmacol Physiol 2009;22(3):137-41.
- Bickers DR, Athar M. Novel approaches to chemoprevention of skin cancer. J Dermatol 2000 Nov;27(11):691-5.
- Hakim IA, Harris RB. Joint effects of citrus peel use and black tea intake on the risk of squamous cell carcinoma of the skin. BMC Dermatol 2001;1:3.
- Ni Z, Mu Y, Gulati O. Treatment of melasma with Pycnogenol. Phytother Res2002 Sep;16(6):567-71.
- Cormane RH, Siddiqui AH, Westerhof W, Schutgens RB. Phenylalanine and UVA light for the treatment of vitiligo. Arch Dermatol Res 1985;277(2):126-30.
- Wright JV. Nutrition & Healing, June 2002.