Recent research indicates that dosages up to 5,000 IU may provide significant health benefits, and that safe upper limits could be as high as 10,000 IU.The findings are very exciting.
Vitamin D3, also known as cholecalciferol, is a form of vitamin D that the body manufactures when skin is exposed to UV radiation from the sun. It's converted from food sources and sunlight into its active form, calcitriol, by the liver and kidneys.
Vitamin D is necessary for the maintenance of healthy calcium and phosphorous levels in the body. Calcium, the main structural element in bones and teeth, can only be absorbed by the body when vitamin D is present. Vitamin D is therefore essential for building and maintaining healthy bones and teeth. It's also believed to contribute to increased muscle strength, which may help improve balance and reduce the risk of falls among the elderly.
Vitamin D also plays a part in regulating cellular growth and keeping the nervous and immune system functioning properly. A review article in the September 2006 issue of Progress Biophysics Molecular Biology indicated that vitamin D can also help maintain healthy blood pressure, blood sugar and overall cellular healthı.
It's estimated that a significant percentage of adults suffer from vitamin D deficiency. Vitamin D deficiency is associated with a variety of health complications, including rickets (in which bones are unable to properly calcify, or harden) in children, poor prostate health in men and poor bone health in older adults.
The elderly, alcoholics and strict vegetarians (vegans) are particularly at risk for deficiency and should consider regular supplementation. Individuals with darker skin pigments may also be at increased risk, as darker skin contains higher levels of melanin, which may inhibit the skin's ability to produce vitamin D from sunlight. Also, people with intestinal malabsorption, hyperthyroidism, liver or kidney disease, or pancreatic conditions may be at risk.
Vitamin D deficiencies are common among those with overactive parathyroid glands. This gland is responsible for maintaining calcium levels, which is vital for proper functioning of the muscular and nervous systems. One study found that insufficient levels of immune cells were produced in the thymus glands of laboratory animals with vitamin D deficiencies. However, a normal eight-week vitamin D intake led to healthy levels.
Recent studies suggest that the current RDA/DV of vitamin D (200 IU for individuals under age 50,400 IU for those between the ages of 50 and 70, and 600 IU for those over the age of 70) may not be adequate. In fact, optimal levels are between 2,000 and 10,000 IU per day.
