Determination of Optimum Vitamin D Nutrition in Young Women

Project: Research project

Project Details



Vitamin D is an unique nutrient in that its requirement can be met by both endogenous production from sun and from diet, which makes it difficult to determine the actual requirements as for other nutrients. The current recommended dietary reference intake (DRI) for vitamin D is 200 IU for adults between 25-50 years, 400 IU for adults between 51-70 years and 600 IU for adults >70 years of age. In the view of many scientists in the field of vitamin D, the current DRI of vitamin D is too low. This is mainly because of the increase in prevalence of vitamin D deficiency observed in the population is based on measured serum 25OHD levels. It is now recognized that serum 25OHD is an indicator of vitamin D status. There is growing consensus that serum 25OHD concentrations of at least 30-32 ng/ml are needed to reduce serum parathyroid hormone (PTH) and reduce bone loss. Also, research over the last two decades has provided additional evidence that higher vitamin D levels (25OHD> 30ng/ml) are necessary for optimum overall health and to prevent disease. There is no clear view of the amount of vitamin D intake required to maintain the optimum level of serum 25OHD levels in the population of all ages, and there are no systematic dose response studies of vitamin D in women of all ages. A few studies carried out with different sexes and age groups have suggested that an untreated subject with a serum 25OHD concentration of 20 ng/ml would need a daily dose of ~1700 IU/d of vitamin D3 to reach a serum 25OHD of 32 ng/ml in Caucasians, while in African Americans the vitamin D3 requirement would be higher - 1860-2480 IU/d.

The current proposal aims at studying the dose response effect of vitamin D3 400 IU, 800 IU, 1600 IU, and 2400 IU on serum 25OHD and serum PTH in young women with vitamin D insufficiency (serum 25OHD

Determination of vitamin D intake to maintain optimum vitamin D status is of high importance as vitamin deficiency/hypovitaminosis D is implicated in a variety of health conditions and because of the high prevalence of hypovitaminosis D in the population throughout the world. The proposed study will be the first systematic study to examine the effect of graded doses of vitamin D supplementation with the aim of determining the vitamin D intake required to maintain optimum vitamin D status (25OHD) and optimum serum PTH in a defined population of young women. The results of this study will help in determining optimum vitamin D intake in select population of young women. We expect that the results from this proposal will also provide important information to help design future larger clinical trials, which will study the effects of adequate vitamin D in groups that are susceptible to fractures, osteoporosis, and other disease such as colon cancer, prostate cancer, and infectious diseases such as tuberculosis.

Effective start/end date1/1/0612/31/06


  • U.S. Department of Defense: $889,506.00


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