INDUSTRY INSIDER | NUTRITION | and high blood pressure, and found
that sunlight could play a role in protecting our heart. A PubMed database search yielded 63
observational studies of low vitamin D status in relation to cancer risk, including 30 of colon, 13 of breast, 26 of prostate, and seven of ovarian cancer, and a number of studies that assessed the association between the vitamin D receptor genotype with cancer risk.
New thinking on UV rays and vitamin D This is where the controversy begins. conventional wisdom on UV exposure is being challenged in light of its contribution to vitamin D production. Scientists across a range of specialties
argue that small and controlled amounts of UV rays on unprotected skin for a very short time might be beneficial for both our general health and specifically, to make our skin stronger. And they hope that in the near future weÕll be able to control our sun exposure better, allowing just the right dose of UV light to come through. Professor Newton-Bishop, Professor of
Dermatology at Leeds University, conducted a study published in 2010 that showed how the relationship between sun exposure and risk is complex. For
example, some studies have suggested that occupational sun exposure, like that which gardeners face, might actually be protective against melanoma. Continuous sun exposure (not associated with severe sunburn) can induce photoadaptation (i.e. increased melanisation and epidermal thickening) ® a possible reason why sun exposure might actually protect against skin cancer. Dr Frank R. de Gruijl, Associate Professor in Skin Research at the Leiden University Medical Center, says that if we completely shy away from the sun, the risks of sun allergy ® known as polymorphic light eruption in medical terms ® will increase; one out of three women with skin type I are reported as having a mild form of sun allergy, experiencing a rash several hours after sun exposure. Indeed, we might be losing our own
natural defence against sunlight. Melanin protects us from the sun by increasing our level of pigments, and the outer layer of our skin gets thicker when exposed to light. These natural processes could happen in the spring to prepare our skin for summer. In other words, in some cases sunlight in the right dose seems have a preventive effect for future photodamage, helping the skin protect itself from sun radiation. When you expose your skin to sunlight
with UVB, two things happen simultaneously: on the one hand, you get skin damage, and on the other, you make vitamin D. Dr Mason found that when you make vitamin D in the skin, it is converted to other vitamin D compounds, which might play a role in protecting skin from sun damage. She believes that the damage from sunlight is less than what would occur if you didn't make vitamin D, and the sun damage would be worse if vitamin D and its metabolites, including those from over-irradiation products, were not formed in the skin. Endocrinologist and Professor of
Medicine and Dermatology Veterans Affairs Medical Center and University of California, San Francisco, Dr Daniel D. Bikle, has also found that vitamin D is photoprotective. It has been proven in mice that vitamin D receptors (VDR), which are available in many cells in the body, such as keratinocytes, can protect against skin cancer. However, it is yet to been proven in humans. VDR in combination with
1,25-dihydroxyvitamin D (calcitriol) enhances the differentiation of keratinocytes and inhibits proliferation. On a daily basis, UVB causes mutation in the DNA. This is actually a very common and natural process, and the epidermis knows how to repair these mutations,
Scientists across a
range of specialties argue that small and controlled amounts of UV rays on an unprotected skin for a
very short time might be beneficial for both our general health and
specifically, to make our skin stronger
20
❚
March 2013 |
prime-journal.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140