Dietary antioxidants as a complementary defense against melanoma and skin cancer

Nutritional Approach to Sun Protection by Niva Shapria

This article titled "Nutritional approach to sun protection: A suggested complement to external strategies' by Niva Shapria, is an extensive review of recent research evidence on the efficacy of a simple, natural, dietary model in protecting against harmful UVR exposure and related skin cancers. Through this article, the author clearly points out that a dietary or internal method of sun protection is a very effective complementary approach to preventing skin cancer due to solar radiation for the more susceptible light skinned population living in very sunny regions.

At the outset the author highlights that there is a growing incidence of melanoma around the globe with a significant number of new cases diagnosed among U.S. women. Projections indicate that the rates of melanoma will literally double over the next 2 decades with the increase in UVR exposure due to global warming as well as the increased sun exposure due to vitamin D awareness. It is also now observed that the use of sunscreen encourages extended exposure to the harmful UVR, and this, paradoxically, contributes to the increasing rates of melanoma. With a growing body of recent research providing evidence for the positive sun protective effects of diet that includes carotenoids, flavanoids, vitamins, n-3 polyunsaturated fatty acids, n-9 monounsaturated fatty acids, 'low pro-inflammatory n-6 polyunsaturated fatty acids', etc., a diet based approach against solar oxidative damage is clearly indicated. Through this article the author emphasizes that such a dietary approach coupled with the external protective methods may offer the ideal defense against melanoma and other skin cancers.

Main Facts

The author provides a brief background of UV rays and how they are harmful to the human body. The author then discusses the natural defense mechanisms available against UVR exposure. In particular, she discusses the anitioxidative pathways. Enzymes such as superoxide dismutase, catalase, glutathione Peroxidase, other nutrients with anti-oxidant properties such as carotenoids that are readily derivable from vegetables such as carrots, potatoes, spinach, etc., and other vitamins and peptides such as ascorbic acid, vitamin E and glutathione are the main antioxidants that the body utilizes to counteract oxidative stress. Hence the increasing consumption of dietary antioxidants is a good way to reduce the damaging effects of UVR exposure. This is verified by studies that show that dietary antioxidants are evenly distributed across the outer skin layer offering an internal protective effect against sun damage. Studies have also shown that naturally occurring antioxidants such as selenium is important for the body to maintain its anti-oxidative enzyme system. So there is strong evidence to suggest that a diet containing high levels of antioxidants would greatly reduce the disruptive effects of UVR by boosting the natural protective defense of the body.

The author also discusses the protective effects of the various antioxidants such as carotenoids, flavanoids, vitamins, minerals and fatty acids by discussing empirical research evidence for each of these. For instance, the author cites research from Wertz et.al (2005) which concluded that carotenoids act by quickly consuming the destructive superoxide free radical (o2 -1). Other studies conducted by the author (Shapira & Kulklinski) also indicate the protective effects of beta carotene in combination with other antioxidants such as vitamin C and E. In controlling the increase in plasma malonyldialdehyde (MDA) (a reactive mutagen and known marker of preoxidative damage) formation after prolonged sun exposure in the dietary supplement group, while the control group who were not given the dietary antioxidant supplement showed a drastic (50%) increase in plasma MDA. Evidence from Astner et.al (2007) and Lee et.al (2004) for the beneficial effects of dietary Lutein in slowing down photocarcinogeneis adds more support to dietary model of photoprotection. The article also includes evidence from Draelos et.al (2008) and Stahl et.al (2001) that corroborate the positive protective effects of another dietary antioxidant, Lycopene.

The author then describes the efficacy of dietary flavanoids in the control of skin cancer due to UV radiation. Particularly, the author stresses the anticarcinogenic effects of consuming green tea, black tea, caffeine, citrus juice, etc. For instance, the author cites evidence from Rees et.al (2007) to demonstrate an inverse effect between tea consumption and skin cancer while Hakim et.al (2001) showed that regular consumption of black tea in combination with citrus peel led to a drastic reduction in squamous cell carcinoma (SCC) incidence. Similarly, the author also uses research evidence to discuss the protective effects of Vitamin C and Vitamin E When supplemented with Folate, Vitamin C is also shown to downplay the photosensitizing effect of riboflavin. The article highlights how both these vitamins in combination with beta carotene provide a synergistic effect that helps prevent lipid peroxidation and photosensitization of DNA. [Niva Shapria, (2010)]

Implications

This important insight about Mediterranean diet and its efficacy is particularly significant for people living in very sunny climates and with lighter skin color as they happen to be the population most affected by UVR related skin cancer. As the author indicates, the most dry and sunny countries like Australia and Israel happen to have the highest incidence rates for melanoma. Therefore, the target population would be the people living in these extremely sunny regions and with a lighter skin tone. From the nursing perspective, this article is highly educative and has practical implications. Community nurses caring for people affected by melanoma or other skin related symptoms can help create more awareness about the protective effects of Mediterranean diet to the patients and their family members who may also be at risk for sun induced skin cancer. This article offers conclusive evidence for the positive impact of a diet rich in antioxidants.

Also, it is to be noted that the risk for melanoma is greater particularly during the early years of life and hence children who are exposed to UVR for prolonged periods are at an increased risk for developing skin cancers. Early exposure (before 20 years) and the onset of melanocytic nevi also creates an increased risk for melanoma much later in life due to cumulative effect. Therefore people who are born and raised in these hot regions and with early history of melanocytic nevi, have a heightened risk for melanoma during their later adult stage. This has been confirmed by the prevailing high incidence and mortality rates for melanoma observed among the native populations in Australia and Israel (which have extremely hot climate). The incidence rates are much less for populations of people who immigrated to these regions after 20 years of age. So the results of this extensive review by the author are particularly significant for young children from these extremely hot places. This article would provide professional dermatology nurses the awareness to identify such high risk population and advise them suitably regarding the efficacy of Mediterranean dietary choice

From a community nursing perspective the information derived from this article is ideal for educating young children. In this case, the target audience, 6th grade elementary school children, would be vastly benefited from the nursing initiative. Nurses can emphasize the age associated high risk for skin cancers among this population. While stressing on the need for effective protective measures such as avoiding peak sun hours, using sunscreens, appropriate clothing, etc., nurses can use the latest research information provided in this article to encourage healthy eating habits among the kids as a natural protective method against UV damage. Sixth graders are in the phase of rapid physical growth and it is a very apt time to condition their eating behaviors.

In the classrooms nurses can recommend Mediterranean diet for kids and encourage the consumption of flavanoids, carotenoids and vitamins that could be entirely derived from natural food sources. To press home these points nurses can work closely with school program coordinators to create fun oriented as well as informative programs. To ensure that these health messages are strongly impressioned in the young minds, it should be repeatedly disseminated. More importantly, school nurses should appreciate the developmental characteristics of the particular age group. Educational program content should be planned to include teaching sessions, didactic presentations, quiz programs that would interest the 6th graders. Nurses can also encourage children to routinely screen themselves for any skin lesions or unusual redness, lumps or new moles to aid in early diagnosis of serious skin problems. Thus these educational nursing programs are very useful not only for creating awareness and promoting healthy living but also to facilitate early diagnosis of pre-existing problems.

The crux of this research, as the author reiterates, is that solid research evidence proves that even for people in these highly sunny regions, the incidence and mortality rates for melanoma and other skin cancers drastically reduce when a Mediterranean diet is followed. This gives new hope for the target population as just by switching over to a simple, natural and a more healthy life style, they could achieve natural protection against the harmful UVR exposure. Given the plethora of evidence that the author shares with the readers in this article, there is little doubt that a diet-based model of photoprotection should be more seriously followed up as a complement to the external protective methods.