Natural light stimulates vitamin D production
The term „vitamin“ is not correct: Vitamins – by definition – cannot be synthesized by our body. But we can make all the vitamin D we need by ourselves with sufficient sun exposure. Due to this, D is not a vitamin but a hormone produced by our skin.
Vitamin D is very important in calcium regulation and bone health, but it is also a hormone of reproduction and fertility, of growth and development, of immune and stress response, of the digestive system, of endocrine regulation, and of central nervous functions. Having low levels of vitamin D is associated with impairs in bone mineralization leading to osteoporosis, depression, myasthenia (muscle weakness), aching knees, backache, headache, sleeping disorders, skin problems, and increased susceptibility to bacterial infection. The more overall stress you have (and e.g. lack of sleep) the more vitamin D you need for compensation.
Sun exposure is linked to lower rates of 15 different cancers and improved cancer survival (such as colorectal cancer, breast cancer, ovarian cancer, lymphoma, etc.). High levels of vitamin D are associated with lower mortality of patients with colorectal cancer – nearly 47% (!) reduction in mortality compared to patients with low concentrations. The higher the vitamin D levels are, the lower the death rate was. All related to the sun.
Benefits beyond vitamin D production
Sunlight may have benefits beyond vitamin D production – there is even some evidence that it can maximize the effects of eating green leafy vegetables. While being exposed 30 minutes to sunlight, you get a significant drop in blood pressure levels and an improvement in artery function.
Morning sunlight exposure can help you with seasonal winter depression. Underexposure of sunlight a day can affect our melatonin levels. If we do not get enough sunlight, our body produces too much melatonin. Sunlight and even daylight block its production: Melatonin is a hormone produced by our brain when it is dark. In winter, due to the lack of day- and sunlight our melatonin levels are too high. It is normally predominant at night and involved in the regulation of the circadian rhythm. Having too much of it is associated with tiredness, insufficient melatonin is linked to difficulties in falling asleep.
The problem is: Not only are the days shorter in winter, in many places, there are also fewer sunny days in winter. The level of outdoor physical activity is lower than in summer as well because many people avoid going outside when it is cold. Plus, people having a nine to five job leave their home „at night“ and come home „at night“ in Winter, while working the whole day under artificial light. Scientists say that 10 to 20 minutes of sunlight a day is enough – depending on how much you are wrapped in clothes: The sunlight – or daylight if it’s cloudy – has to touch your skin to be able to stimulate vitamin D production. If you are covered completely and just your face is exposed, you need to spend more time outdoors or use a daylight lamp. Daylight lamps simulate the sun’s natural rays which artificial light does not do. Or travel in winter! 😉
Too much sunlight isn’t good either
Negative effects of sun exposure may be a higher risk for cataract extraction – this can be minimized by wearing a brimmed hat and sunglasses. Sunlight also ages your skin – 90% of visible skin aging is said to come from sunlight: wrinkles, thickening, and others. Furthermore, skin cancer/melanoma is caused by excess used sunbeds and sunshine. There even is evidence that sunlight activates the same reward pathway and releases endorphins such as drugs do as well. You can get addicted to sunlight. The problem is, that in sunbeds we mostly get UVA radiation but UVB radiation causes vitamin D production. UV (ultraviolet) radiation is a proven carcinogen that is the cause of more than 50% of all human malignancies.
To conclude: The fear of skin cancer can not be neglected. However, there is little evidence that normal exposure to sunlight will considerably increase the risk of skin cancer. Chronic exposure to sunlight causing sunburns are most responsible for the high incidence of skin cancer.
What about you? Do you feel like a newborn when the first shafts of sunlight make their way through the wintry grey? Do you feel sad and listless in winter? Tell me! 🙂
Here are the sources used for this blogpost
Fell, G. L./Robinson, K. C./Mao, J./Woolf, C. J./Fisher, D. E. 2014: Skin β-Endorphin Mediates Addiction to UV Light, in: Cell, Vol. 157, 2014, pp. 1527-1534.
Keum, N./Giovannucci, E. 2014: Vitamin D supplements and cancer incidence and mortality: a meta-analysis, in: British Journal of Cancer, Vol. 111, 2014, pp. 976-980.
http://www.nature.com/bjc/journal/v111/n5/full/bjc2014294a.html
Maalmi, H./Ordóñez-Mena, J. M./Schöttker, B./Brenner, H. 2014: Serum 25-hydroxyvitamin D levels and survival in colorectal and breast cancer patients: Systematic review and mata-analysis of prospective cohort studies, in: European Journal of Cancer, Vol. 50, 2014, pp. 1510-1521.
Mohr, S. B./Gorham, E. D./Kim, J./Hofflich, H./Cuomo, R. E./Garland, C. F. 2015: Could vitamin D sufficiency improve the survival of colorectal cancer patients?, in: Journal of Steroid Biochemistry & Molecular Biology, Vol. 148, pp. 239-244.
Smolensky, M. H./Sackett-Lundeen, L. L./Portaluppi, F. 2015: Nocturnal light pollution and underexposure to daytime sunlight: Complementary mechanisms of circadian disruption and related diseases, in: Chronobiology International, Vol. 32, 2015, No. 8, pp. 1029-1048.
Stumpf, W. E. 2012: Vitamin D and the scientific calcium dogma: understanding the ‚Panacea‘ of the sun, in: European Journal of Clinical Nutrition, Vol. 66, 2012, pp. 1080-1081.
Wacker, M./Holick, M. F. 2013: Sunlight and Vitamin D – A global perspective for health, in: Dermato-Endocrinology, Vol. 5, 2013, No. 1, pp. 51-108.
Webb, P. M./de Fazio, A./Protani, M. M./Ibiebele, T. I./Nagle, C. M./Brand, A. H./Blomfield, P. I./Grant, P./Perrin, L. C./Neale, R. E. 2015: Circulating 25-hydroxyvitamin D levels and survival in women with ovarian cancer, in. American Journal of Clinical Nutrition, Vol. 102, 2015, pp. 109-114.
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