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    Increase Vitamin D Minimum Daily Requirements Says Research

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    Vitamin D is essential for in overall health of several body organs, says UC Riverside biochemist Anthony Norman, an international expert on vitamin D, who advocates increasing the adult daily intake of the vitamin to a minimum of 2000 iu for disease prevention.

    In a paper published in the American Journal of Clinical Nutrition, Norman identifies vitamin D’s potential for contributions to good health in the adaptive and innate immune systems, the secretion and regulation of insulin by the pancreas, the heart and blood pressure regulation, muscle strength and brain activity. In addition, access to adequate amounts of vitamin D is believed to be beneficial towards reducing the risk of cancer.

    “It is becoming increasingly clear to researchers in the field that vitamin D is strongly linked to several diseases,” said Norman, who has worked on vitamin D for more than 45 years. “Its biological sphere of influence is much broader than we originally thought. The nutritional guidelines for vitamin D intake must be carefully reevaluated to determine the adequate intake, balancing sunlight exposure with dietary intake, to achieve good health by involving all 36 target organs.”


    The recommended daily intake of vitamin D is 200 international units (IU) for people up to 50 years old. The recommended daily intake of vitamin D is 400 IU for people 51 to 70 years old and 600 IU for people over 70 years old. Norman’s recommendation for all adults is to have an average daily intake of at least 2000 IU.

    Vitamin D is synthesized in the body in a series of steps. First, sunlight’s ultraviolet rays act on a precursor compound in skin. When skin is exposed to sunlight, a sterol present in dermal tissue is converted to vitamin D, which, in turn, is metabolized in the liver and kidneys to form a hormone. It was Norman’s laboratory that discovered, in 1967, that vitamin D is converted into a steroid hormone by the body.

    “To optimize good health you must have enough vitamin D,” he said. “Vitamin D deficiency is also especially of concern in third world countries that have poor nutritional practices and religious customs that require the body to be covered from head to toe. Ideally, to achieve the widest frequency of good health by population, we need to have 90 percent of the people with adequate amounts of vitamin D.”


    “There needs to be a sea change by various governmental agencies in terms of the advice they present to citizens about how much vitamin D should be taken,” Norman said. “The tendencies of people to live in cities where tall buildings block adequate sunlight from reaching the ground, to spend most of their time indoors, to use synthetic sunscreens that block ultraviolet rays, and to live in geographical regions of the world that do not receive adequate sunlight all contribute to the inability of the skin to bio-synthesize sufficient amounts of vitamin D.”


    While deficiency of vitamin D impacts health negatively, ingestion of extremely high doses of vitamin D can cause hypercalcemia, a condition in which the blood’s calcium level is above normal. The highest daily ‘safe’ dose of vitamin D is 10,000 IU.


    American Journal of Clinical Nutrition
    Eureka Alert

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