The new issue of the Mayo Clinic Health Letter says that while vitamin D is known to offer many benefits, there is no consensus on what level of the nutrient is optimal for good health.
The report points out that recent findings suggest that vitamin D offers many benefits, especially for older adults, such as improved balance, reduction in the risk of bone fractures, and better thinking skills such as planning, organizing and abstract thinking.
It further states that low levels of vitamin D are associated with diabetes, cardiovascular disease, multiple sclerosis and other autoimmune disorders, infections such as tuberculosis, and periodontal disease.
Low vitamin D levels may also lead to certain cancers, including colon, breast and prostate cancers.
Vitamin D is the only vitamin that the body can manufacture itself, and sunshine is the only requirement for the purpose.
About 10 to 15 minutes of exposure two to three times a week during non-peak sun hours is considered adequate, but the sunshine approach doesn't work for everyone.
With age, the body is less efficient at processing vitamin D. ther barriers are darker skin and living in northern climates. The use of sunscreen, recommended to prevent skin cancer, also reduces absorption of ultraviolet B rays.
Even though vitamins can be obtained from food sources, choices are limited for vitamin D.
Rich sources are fatty fish, fish-liver oils, liver and egg yolks. Milk fortified with vitamin D is another option.
With limited food choices, consumers may opt to rely on vitamin D supplements.
The current daily recommended dose of vitamin D for adults is 50, and older is 400 to 600 international units (IU).
However, many researchers believe that a higher amount is warranted because of the many health benefits.
The National Osteoporosis Foundation recommends a daily intake of 800 to 1,000 IU per day for adults over age 50, and the upper daily limit considered safe for use is 2,000 IU per day.
However, there is debate about this level, with some scientists suggesting that very large doses of vitamin D taken over time can cause ill effects, including nausea, vomiting, poor appetite, constipation, weakness and weight loss.