SUN EXPOSURE - JULY 2013 - VOLUME 5 ISSUE 4
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For years now, we’ve been told to stay out of the sun, and if that’s not possible, to wear a sunscreen with a suitably high SPF, or a hat and long sleeves etc. Well, now there’s good evidence that some sun is actually good for us. The key, of course, is moderation. The benefits are very impressive. Have a safe and happy summer! |
While there’s no denying that too much sun can be unhealthy, overall, excessive UVR (ultra-violet radiation) exposure accounts for only 0.1% of the total global burden of disease in disability-adjusted life years (DALYs) according to the 2006 World Health Organization (WHO) report, The Global Burden of Disease Due to Ultraviolet Radiation. DALYs measure how much a person’s expectancy of healthy life is reduced by premature death or disability caused by disease. Many diseases linked to excessive UVR exposure tend to be relatively harmless (with the obvious exception of malignant melanoma) and occur in older age groups, due to the long lag time between UVB exposure (and its accumulation) and the occurrence of disease. Therefore the burden of disease is fairly low in spite of high prevalence of some conditions. In contrast, the WHO report noted that a much larger annual disease burden of 3.3 billion DALYs worldwide may result from very low levels of UVR exposure. Those of us who live at higher latitudes (usually interpreted as farther north, but also true for far south) know that we see the sun a lot more in the summer than the winter. We’re also aware that the sun is not nearly as high in the sky in the winter. This means the sun’s rays are passing through a thicker layer of the earth’s atmosphere, which filters out many of the sun’s rays. Therefore, we can’t get the UV exposure in winter that we can in summer – or the health benefits. Living at higher latitudes is associated with higher risk of dying from Hodgkin’s lymphoma as well as breast, ovarian, colon, pancreatic, prostate and other cancers. Low sun exposure (or low levels of vitamin D) or residence at higher latitudes has been associated with increased risk of multiple sclerosis. Also, UV exposure can suppress the clinical symptoms of multiple sclerosis independently of vitamin D synthesis. There is a similar latitudinal gradient for type 1 diabetes. There is also a connection with metabolic syndrome and type 2 diabetes, as well as heart disease. However, not all of this may be attributable to low levels of vitamin D – see the next section. In summary, much more ill health can be attributed to too little sun exposure than too much. |
A recent study has shown that sun exposure protects against heart disease, and this protective effect is not due to higher vitamin D levels. Scientists at the University of Edinburgh have gone as far as to say that the heart-health benefits of sun exposure may outweigh the risk of developing skin cancer. In this landmark study, Richard Weller and colleagues found that when sun touches our skin, a compound called nitric oxide (NO) that helps lower blood pressure, is released into our blood vessels. Dr. Weller, a senior lecturer in dermatology, says that the effect is such that overall, sun exposure could improve health and even prolong life, because the benefits of reducing blood pressure, which cuts the risk of heart attacks and strokes, far outweigh the risk of getting skin cancer. The researchers noted that rates of high blood pressure and cardiovascular disease rise in winter and are tied to geographic latitude; i.e. they are higher farther north than closer to the equator. They also point out that in northern Europe, for every death from skin cancer, about 100 people die of stroke and heart disease linked to high blood pressure. This is the first study to show that NO is produced as a result of sun exposure from nitrates and nitrites which are stored just underneath the skin. This is a big plus in addition to the long-known benefits of vitamin D from sun exposure. Dr. Weller points out that the benefits of sun exposure are even greater in older people (“older” not precisely defined, since he was talking about people his mother-in-law’s age, who, he claims, he only knows is older than his wife!). I highly recommend watching Dr. Weller’s TED talk (see third reference for link). It’s only 13 minutes, a small investment of your time, and he’s very entertaining as well as informative. Also, you might want to review the benefits of NO that we discussed in the February 2013 newsletter (available at www.ramilas.com). |
The sun is best known for its ability to boost your body’s vitamin D supply. Vitamin D can be synthesized in the skin as a result of exposure to UVB radiation. The initial photosynthesis produces vitamin D3, most of which undergoes additional transformations starting with the production of 25-hydroxyvitamin D (25[OH]D), the major form of vitamin D circulating in the blood stream and the form that is routinely measured to determine a person’s vitamin D status. Although some of this conversion can take place in certain types of skin cells, most of the conversion takes place in the liver. Another set of transformations occurs in the kidney and other tissues, forming 1,25(OH)D. This form of the vitamin is actually a hormone, chemically similar to the steroid hormones. 1,25(OH)D accumulates in cell nuclei of the intestine, where it enhances calcium and phosphorus absorption, controlling the flow of calcium into and out of bones to regulate bone-calcium metabolism. Michael Holick, a medical professor and director of the Bone Health Care Clinic at Boston University Medical Center, says, “The primary physiologic function of vitamins D is to maintain serum calcium and phosphorous levels within the normal physiologic range to support most metabolic functions, neuromuscular transmission, and bone mineralization.” |
Note that the UVA light that we’re exposed to indoors actually breaks down vitamin D3 formed by UVB (sun) exposure. This has led to the finding that safe sun exposure can actually protect you from melanoma (the dangerous form of skin cancer). In a study, indoor workers were found to have increased rates of melanoma because they were only exposed to UVA light, which is associated with skin damage and skin cancer. These workers were found to get 3 to 9 times less sun exposure than outdoor workers and had correspondingly lower levels of vitamin D. Most melanomas occur on the least sun-exposed areas of the body, and occupational exposure to sunlight actually reduced melanoma risk in a study reported in the June 2003 Journal of Investigative Dermatology. Moreover, although excessive sun exposure is an established risk factor for melanoma, continued high sun exposure was linked with increased survival rates in patients with early-stage melanoma in a study reported in 2005 in the Journal of the National Cancer Institute. |
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There is no single recommendation for how much sun is the ideal amount, partly because the answer depends on your skin colour. Fair skinned people need less sun than those who are darker because darker skins do not absorb the UVB rays as readily. It also depends on how deficient your levels of vitamin D are – the lower they are, the more sun you need to bring them back to a good level. Many experts are recommending a middle-ground approach that focuses on modest sun exposures. The American Academy of Dermatology and most dermatologists (in the US) suggest sun protection in combination with vitamin D supplementation as a means of minimizing the risk of both skin cancer and internal cancers. Brief, repeated exposures are more efficient at producing vitamin D. Longer sun exposures cause further sun damage to skin and increase the risk of photo-aging and skin cancer, but do not increase vitamin D production, according to one expert. So what does all that mean? Well, there are many different estimates of ideal amounts of sun exposure out there, but one that is in line with most others suggests that 12-15 minutes per day in sunlight could confer significant health benefits together with 2000 IU of vitamin D3. Without sun exposure, 4000 IU of vitamin D3 is recommended (as well as Arginine Plus Mixed Berry for NO, of course). Some sunlight enters the skin even through high SPF sunscreen, so people can maximize their dermal vitamin D production by spending additional time outdoors while wearing protection. It is always important to avoid burning! |
Vitamin D3 1000IU /store/#!/~/product/id=6402671 Arginine Plus Mixed Berry /store/#!/~/product/id=8132592 For additional information, please email ramila@ramilas.com; or call Ramilas Healing Arts Clinic at 613.829.0427 for an appointment. Please continue letting friends and family know about this newsletter. Also on our website, please see back issues of this newsletter, additional information about products, order products, and see information about our Clinic. |
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The suggestions and recommendations in this newsletter are not intended to be prescriptive or diagnostic. The information is accurate and up to date to our knowledge, but we are not responsible for any errors in our sources of information. |
These newsletters will help you make better choices for better health. The choices that you make today can either have a positive or negative impact on your overall health. Begin by choosing better. It is a step toward longevity. Sincerely, Ramila Padiachy |
