Sunny treatment for diseases: updates on vitamin D deficiency and sufficiency
Sunshine is the major source of vitamin D, an essential vitamin synthesized by skin exposure to sunlight. So how can vitamin D deficiency be a global problem? Below is a review of recent research on the benefits of vitamin D and possible causes of its deficiency.
Vitamin D and Alzheimer’s disease [1]
A small retrospective study (n= 32) found strong links between low serum levels of vitamin D and low performance in cognitive tests in patients with Alzheimer’s disease. Supplementation with vitamin D improved test outcomes. The results suggest that optimal vitamin D levels are important in cognitive function in older adults.
Vitamin D and myopia [2]
Vitamin D deficiency is linked to myopia in the Asia-Pacific region. Results show that 90% of conscription-aged Singaporean males are myopic. This is a dramatic increase compared to the incidence of 20 to 30% about 40 years ago. In Australia on the other hand, the incidence went from 15% to 20-25% within the same time period.
Ethnicity may play a role because of the “genetic susceptibility to environmental risk factors associated with intensive education and urbanisation” among East Asians. However, myopia seems equally prevalent across all ethnic groups (including Malay and Chinese) in Singapore.
Furthermore, the prevalence of myopia was found to be 10 times more among Chinese-Singaporean children than Chinese children based in Sydney. The difference lies in the number of hours of exposure to the sun. The Australian children stayed outdoors 4 times longer than their Singaporean counterparts. Researchers hypothesize that exposure to sunlight encourages the release of dopamine, which in turn inhibit excessive eye growth that leads to myopia. In many Asian countries, sun exposure is actually avoided due to a cultural preference for lighter skin.
Vitamin D and multiple sclerosis [3]
Multiple sclerosis is strongly linked to genetics. However, there are strong geographical patterns in the incidence of multiple sclerosis that cannot be fully explained by genetics alone. It has been observed, for example, that multiple sclerosis is less prevalent in the tropics and subtropics than in higher latitudes. Environmental factors are involved in the epidemiology of this disease and one of these is vitamin D.
Vitamin D3and osteoporosis [4]
Vitamin D plays a major role in the prevention and management of osteoporosis. Vitamin D deficiency has been linked to osteopenia, osteoporosis and osteomalacia. Cholecalciferol or vitamin D3 enhances the absorption of calcium and phosphorous in the intestine.
Vitamin D and pregnancy [5]
Vitamin D during pregnancy can lead to craniotabes or softening of the skulls in newborn infants. This deficiency may persist one month after delivery especially among breastfed babies. This probably the reason behind prescription of vitamin D supplement to breastfed infants in many countries.
Vitamin D synthesis in the skin is influenced by “season, latitude, skin pigmentation, sunscreen use, clothing and aging” [4] as well as lifestyle and cultural preferences [2]. To prevent deficiency, appropriate exposure to sun should be encouraged. A daily supplement of 800 to 1000 IU of vitamin D3 may also help.
Sources:
- Przybelski RJ, Binkleya NC. Is vitamin D important for preserving cognition? A positive correlation of serum 25-hydroxyvitamin D concentration with cognitive function. Arch Biochem Biophys. 2007; 460(2):202-205
- Nowak R. Lifestyle causes myopia, not genes. New Scientist 2004.
- Ascherio A, Munger K. Epidemiology of Multiple Sclerosis: From Risk Factors to Prevention. Seminars in Neurology 2008; 28: 017-028.
- Holick MF. Optimal vitamin D status for the prevention and treatment of osteoporosis. Drugs and Aging, 2007; 24(12): 1017-29.
- Yorifuji J et al. Craniotabes in normal newborns; the earliest sign of subclinical vitamin D deficiency. Journal of Clinical Endocrinology & Metabolism February 12, 2008.
4 Comments
- Vitamin A Iu replied:
Vitamin A Iu
I think it really depends.
May 13th, 2008 at 6:26 pm. Permalink.
- Vitamin D Supplement For Infants replied:
Vitamin D Supplement For Infants
you are exactly right and there is nothing wrong with it.
May 14th, 2008 at 2:20 pm. Permalink.
- Nutritional Supplements Vitamin World Cholesterol replied:
Nutritional Supplements Vitamin World Cholesterol
I didn’t agree with you first, but last paragraph makes sense for me
May 21st, 2008 at 9:29 pm. Permalink.
- Is there a link between peripheral arterial disease and vitamin D? | Battling Heart and Stroke replied:
[…] Vitamin D is also known as the sunshine vitamin. It is synthesized by our body when our skin is exposed to the sun. It is therefore surprising that vitamin D deficiency is becoming a global problem and has been linked to many diseases including Alzheimer’s disease, multiple sclerosis, and osteoporosis. […]
June 12th, 2008 at 11:28 pm. Permalink.