Sunday, 2 December 2012

Vitamin D, a brief description of a long term killer

Vitamin D is a group of fat-soluble secosteroids responsible for intestinal absorption of calcium and phosphate. In humans, vitamin D is unique because it can be ingested as cholecalciferol (vitamin D3) or ergocalciferol (vitamin D2) and because the body can also synthesize it (from cholesterol) when sun exposure is adequate (hence its nickname, the "sunshine vitamin").
Although vitamin D is commonly called a vitamin, it is not actually an essential dietary vitamin in the strict sense, as it can be synthesized in adequate amounts by all mammals exposed to sunlight. An organic chemical compound (or related set of compounds) is only scientifically called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from their diet. However, as with other compounds commonly called vitamins, vitamin D was discovered in an effort to find the dietary substance that was lacking in a disease, namely, rickets, the childhood form of osteomalacia. Additionally, like other compounds called vitamins, in the developed world vitamin D is added to staple foods, such as milk, to avoid disease due to deficiency.

Vitamin D travels top the liver, where it picks up extra oxygen and hydrogen molecules to become 25-hydroxyvitamin D, or 25(OH)D. This is the chemical that doctors should measure to diagnose vitamin D deficiencies. But although 25(OH)D is used for diagnosis, it can’t function until it travels to the kidney. There it acquires a final pair of oxygen and hydrogen molecules to become 1,25 dihydroxyvitamin D; scientists know this active form of the vitamin as 1,25(OH)2D, or calcitriol, or vitamin D.
Calcitriol circulates as a hormone in the blood, regulating the concentration of calcium and phosphate in the bloodstream and promoting the healthy growth and remodeling of bone. Calcidiol is also converted to calcitriol outside of the kidneys for other purposes, such as the proliferation, differentiation and apoptosis of cells; calcitriol also affects neuromuscular function and inflammation.
Beyond its use to prevent osteomalacia or rickets, the evidence for other health effects of vitamin D supplementation in the general population is inconsistent. The best evidence of benefit is for bone health and a decrease in mortality in elderly women
Limited exposure to sunlight can have a negative effect to the production of Vitamin D . Except during the short summer months, people who live at latitudes above 37 degrees north or below 37 degrees south of the equator don’t get enough UVB energy from the sun to make all the vitamin D they need. The same is true for people who spend most of their time indoors and for those of us who avoid sunshine and use sunscreens to protect our skin from the harmful effects of ultraviolet radiation (see "Suncreens"). It’s an example of an unforeseen consequence of wise behavior, but you can enjoy sun protection and strong bones, too, by taking vitamin supplements.
Low blood levels of vitamin D are associated with increased mortality, and giving supplementary vitamin D3 to elderly women in institutional care seems to decrease the risk of death. Vitamin D2, alfacalcidol, and calcitriol do not appear to be effective. However, both an excess and a deficiency in vitamin D appear to cause abnormal functioning and premature aging. The relationship between serum calcidiol level and all-cause mortality is U-shaped, Harm from vitamin D appears to occur at a lower vitamin D level in the black population than in the white population.

Vitamin D deficiency causes osteomalacia (called rickets when it occurs in children). Beyond that, low serum vitamin D levels have been associated with falls, and low bone mineral density.
Evidence for health effects from vitamin D supplementation for cardiovascular health is poor. Moderate to high doses may reduce cardiovascular disease risk but are of questionable clinical significance. Also Low levels of vitamin D are associated with multiple sclerosis. Supplementation with vitamin D may have a protective effect but there are uncertainties and unanswered questions. Low vitamin D levels are associated with some cancers and with worse outcomes in other cancers, but taking supplements does not appear to help people with prostate cancer. Currently evidence is insufficient to support supplementation in those with cancer. Results for a protective or harmful effect of vitamin D supplementation in other types of cancer are inconclusive.
When researchers looked at 25 hydroxyvitamin D [25(OH)D] levels in 492 men age 40 to 79 who lived in Chicago, Illinois, they found that 93% of African-American men and 69.7% of European-American men were vitamin D-deficient, with 25(OH)D levels of less than 30 ng/mL. (According to the National Oceanic and Atmospheric Administration, Chicago gets 54% sunshine, compared with Yuma, Arizona, which gets 90%.). Vitamin D levels were low in not only African-American men but those with lower incomes and people with higher body mass indexes. Although low sunlight exposure is a known factor in lower levels of vitamin D, researchers found that African-American men also had lower levels of vitamin D in sunnier seasons as well.

Higher vitamin D dietary intake is associated with a lower risk of developing Alzheimer’s disease, according to research conducted by a team led by Cedric Annweiler, MD, PhD, at the Angers University Hospital in France. Similarly, investigators led by Yelena Slinin, MD, MS, at the VA Medical Center in Minneapolis found that low vitamin D levels among older women are associated with higher odds of global cognitive impairment and a higher risk of global cognitive decline.
Short term Vitamin D deficiency can manifest as weak muscles or flu like symptoms while long term effects could ultimately bring immune-mediated diseases, Cardiovascular disease, diabetes, Schizophrenia and Depression. Considering a daily mid-day sun exposure of 15 minuets for light color skin while dark color skin takes and hour. Modern living has drastically reduced our natural sun light intake, which may have a slow long term effect. Although still early to conclusively prove modern living might be making you sick, it is worth noting that the majority of dark skin people suffer cardiovascular disease and have symptoms similar to the deficiencies of vitamin D. Its is unlikely that modern living will stop knowing that we need to change our lives for longer exposure. Hopefully being made aware that sunlight is important every day might just save your life, some time later in life...

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