Vitamin D is a group of fat-soluble prohormones, the two major forms of which are Vitamin D2 (or ergocalciferol) and Vitamin D3 (or cholecalciferol), that is naturally present in very few foods, added to others, and available as a dietary supplement. It is also produced endogenously when ultraviolet rays from sunlight strike the skin and trigger Vitamin D synthesis. Vitamin D obtained from sun exposure, food, and supplements is biologically inert and must undergo two hydroxylations in the body for activation. The first occurs in the liver and converts Vitamin D to 25-hydroxyVitamin D, also known as calcidiol. The second occurs primarily in the kidney and forms the physiologically active 1,25-dihydroxyVitamin D, also known as calcitriol.
Calcitriol plays an important role in the maintenance of several organ systems. However, its major role is to increase the flow of calcium into the bloodstream, by promoting absorption of calcium and phosphorus from food in the intestines. Vitamin D is essential for promoting calcium absorption in the gut and maintaining adequate serum calcium and phosphate concentrations to enable normal mineralization of bone and prevent hypocalcemic tetany(a muscle spasm caused by reduction in the concentration of calcium circulating in the blood). It is also needed for bone growth and bone remodeling by osteoblasts and osteoclasts. Without sufficient Vitamin D, bones can become thin, brittle, or misshapen. Vitamin D sufficiency prevents rickets in children and osteomalacia in adults. Together with calcium, Vitamin D also helps protect older adults from osteoporosis.
Vitamin D has other roles in human health, including modulation of neuromuscular and immune function and reduction of inflammation. Many genes encoding proteins that regulate cell proliferation, differentiation, and apoptosis are modulated in part by Vitamin D.
Vitamin D is found in the following foods:
Fortified milk (all milk in the U.S. is fortified with Vitamin D),
Vitamin D deficiency can lead to osteoporosis in adults or rickets in children.
Too much Vitamin D can make the intestines absorb too much calcium. This may cause high levels of calcium in the blood. High blood calcium can lead to calcium deposits in soft tissues such as the heart and lungs. This can reduce their ability to function.
Kidney stones, vomiting, and muscle weakness may also occur if you have too much Vitamin D.
Vitamin D is also known as the "Sunshine Vitamin" because the body manufactures the Vitamin after being exposed to sunshine. Ten to 15 minutes of sunshine 3 times weekly is enough to produce the body's requirement of Vitamin D. However, many people living in sunny climates still do not make enough Vitamin D and need more from their diet or supplementation.
The Food and Nutrition Board at the Institute of Medicine recommends the following dietary intake for Vitamin D as cholecalciferol. (One microgram of cholecalciferol is the same as 40 IU of Vitamin D.)
0 - 6 months: 5 micrograms per day (mcg/day)
7 - 12 months: 5 mcg/day
1 - 13 years: 5 mcg/day
Adolescents and Adults
Males and Females age 14 to 50: 5 mcg/day
Males and Females age 51 to 70: 10 mcg/day
Males and Females age over 70: 15 mcg/day
Specific recommendations for each Vitamin depend on age, gender, and other factors (such as pregnancy). In general, those over age 50 need higher amounts of Vitamin D than younger persons. Most people should be able to get all the Vitamin D they need from their diet and by getting a little sun. Ask your health care provider which amount is best for you.
Resounding evidence proving the effectiveness of Vitamin D in slowing the onset of breast, colon, and other cancers is convincing a growing body of doctors and physicians to utilize the sunshine Vitamin in their arsenal of cancer treatment weapons. In the last several years, numerous epidemiological studies have illustrated the correlation between Vitamin D deficiency and serious disease, including cancer. Researchers are now focusing attention on elevated levels of "therapeutic" Vitamin D, far above the government's daily recommended amounts, for use in disease treatment and prevention.
Although the link between low Vitamin D status and chronic disease has been well known for some time, a new study has shed further light on the role of Vitamin D in cases of hypertension and congestive heart failure.
Researchers from the Medical College of Wisconsin analysed genetic data from 617 individuals stored at the Marshfield Clinical Personalized Medicine project, a DNA databank. They separated the group equally into a healthy control group, those with high blood pressure and those with high blood pressure and congestive heart failure, and it became clear that there was a striking correlation between those who suffered from both ailments and a deviation in the CYP27B1 gene, which reduces the rate that the body converts stored Vitamin D into its active form.
Many in the medical profession are beginning to recognize that people who take cholesterol-lowering statin drugs are becoming Vitamin D-deficient. Cholesterol is required by the body to synthesize Vitamin D and statin drugs are are responsible for eliminating it, leading many to speculate that statin drug users do not have enough cholesterol to process Vitamin D.
Contrary to popular belief, cholesterol actually plays an important role in maintaining health. It regulates proper hormonal levels and is the precursor substance for the production of Vitamin D. Cholesterol also works to digest and absorb fats, nutrients, and Vitamins.
When converting sunlight into Vitamin D, cholesterol in the skin acts as the catalyst for this important process. Vitamin D is crucial for mineral metabolization and is said to target over 2000 human genes. Deficiency is linked to over 17 varieties of cancer as well as heart disease, autoimmune diseases, muscle and bone problems, and other serious diseases.
In the study (January 2013), researchers found a clear connection between Vitamin D deficiency and muscle pain. Over 64 percent of patients with muscle pain who were taking statin drugs were also deficient in Vitamin D. Those with muscle pain in general were found to be deficient in Vitamin D.
When study participants who reported muscle pain were given 50,000 IU of Vitamin D a week for 12 weeks, more than 92 percent of them were completely relieved of all muscle pain. The prescribed supplementation also raised blood levels of Vitamin D to normal levels.
It is also known that statin drugs are responsible for depleting CoQ10 (known as the Energy Enzyme, CoEnzyme Q10 has been promoted as a supplement for supporting cardiovascular health and increasing energy as well as a potent antioxidant) levels, a vital substance that metabolizes energy in the body. Both CoQ10 and Vitamin D supplementation are recommended for anyone who takes statin drugs. A minimum of 2,000 IU of Vitamin D and between 100 and 200 mg of CoQ10 daily are appropriate doses.
While vitamin D’s role in bone health is clearly established, the debate continues about whether higher doses might prevent, treat, or delay a wide variety of conditions. On one side are some experts who point to the massive body of research, much of it promising, and advocate higher intakes and blood levels of vitamin D. On the other side are researchers who fear that the vitamin D bandwagon has gotten far ahead of the science and who worry that it may crash—as did the bandwagon for antioxidant supplements when long-awaited clinical trials failed to find benefit and sometimes even suggested harm.
Studies have shown that taking CoQ10 by itself helps to maintain proper cholesterol levels without the need for statin drugs. While keeping bad cholesterol (LDL) levels low is beneficial, it is important to keep good cholesterol (HDL) levels high. CoQ10 works well at maintaining healthy levels of both. Some other alternatives to keeping cholesterol levels in check include supplementation with niacin and policosanol. In conjunction with a healthy diet low in refined sugars and bad fats, these natural alternatives are both safe and effective. Exercise and a diet rich in omega-3 fatty acids are also good suggestions.
Scientists at the University of Copenhagen have discovered (March 2013) that Vitamin D is crucial to activating our immune defences and that without sufficient intake of the Vitamin, the killer cells of the immune system – T cells – will not be able to react to and fight off serious infections in the body. One thing is clear: Blood levels of vitamin D are a good barometer of overall health. But whether high levels are the cause or result of good health will remain an open question until the results of several large important clinical trials come out in a few years.
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A new study (October 2016) by the University of Southhampton states: Vitamin D supplements are less effective at raising vitamin D levels in pregnant women if they deliver their babies in the winter, have low levels of vitamin D early in pregnancy or gain more weight during pregnancy, a new Southampton study has shown. The University of Southampton researchers suggest that supplement levels should be tailored according to individual risk factors.
Vitamin D is a hormone that helps the body absorb calcium. It plays a crucial role in bone and muscle health. The skin naturally produces vitamin D after exposure to sunlight but people also obtain smaller amounts of the vitamin through foods, such as milk fortified with vitamin D.
Evidence suggests vitamin D deficiency during pregnancy can harm maternal health, fetal development and the child's long-term skeletal health.
Professor Nicholas Harvey, of the Medical Research Council Lifecourse Epidemiology Unit, University of Southampton, who led the study with Dr Rebecca Moon, Clinical Research Fellow, comments: "It is important for pregnant women to have sufficient levels of vitamin D for the health of their baby. Our study findings suggest that in order to optimise vitamin D concentrations through pregnancy, the supplemental dose given may need to be tailored to a woman's individual circumstances, such as the anticipated season of delivery."
The Maternal Vitamin D Osteoporosis Study (MAVIDOS), is a multi-centre, double-blind, randomised, placebo-controlled trial of vitamin D supplementation in pregnancy. More than 800 pregnant women were recruited and randomised to take either 1000 units (25 micrograms) of vitamin D every day or a matched placebo capsule from 14 week's gestation until delivery of the baby.
Analysis showed that participants who received the vitamin D supplement achieved different levels of vitamin D in the blood, even though they received the same dose. Researchers found women who delivered in the summer, who gained less weight during pregnancy and who had higher vitamin D levels early in pregnancy tended to have higher levels of vitamin D in the blood than their counterparts. Women who consistently took the supplement also had higher levels of vitamin D than participants who did not.
"Our findings of varied responses to vitamin D supplementation according to individual attributes can be used to tailor approaches to antenatal care," said Professor Cyrus Cooper, Director, and Professor of Rheumatology at the MRC Lifecourse Epidemiology Unit, University of Southampton. "This work forms part of a larger programme of research at the MRC Lifecourse Epidemiology Unit, University of Southampton, addressing the early life determinants of bone development, and will inform novel strategies aimed at improving bone health across future generations."