Sources of Vitamin D
Vitamin D is metabolized from dietary sources and from ultraviolet B (UVB) sunlight. However, the majority of women in their childbearing years who reside in the United States have vitamin D insufficiency and/or deficiency that results from lower amounts of UVB exposure because of lifestyle preferences, work schedules, and fear of skin damage and cancer.[8,9] Protective clothing and sunscreen are often used as barriers to UVB exposure, which prevent the skin's ability to manufacture adequate levels of vitamin D. Darker skin pigmentation also limits the skin's ability to manufacture vitamin D from UVB exposure. Therefore, dietary sources of vitamin D are essential in attaining adequate levels of vitamin D to meet daily requirements.
Only a few foods contain vitamin D naturally; these include oily fish (salmon and mackerel), cod liver oil, irradiated mushrooms, and egg yolk.[10,11,12] Foods fortified with vitamin D may include milk, orange juice, yogurt, cheese, cereal and breads, although the amounts of vitamin D vary, and several servings need to be consumed to meet the minimum daily requirement of vitamin D. Dietary supplements can either contain vitamin D2 or vitamin D3. Vitamin D3 is thought to have greater efficacy in elevating serum 25-hydroxyvitamin D (25[OH]D) levels compared to vitamin D2.
The dietary intake of vitamin D that is required to obtain optimal levels of serum vitamin D to maintain many body functions is debated by leading researchers.[1,14,15,16,17] Currently, the Institute of Medicine has established the adequate intakes (AI) of vitamin D at 200 IU/day for adults up to 50 years of age, 400 IU/day for adults aged 51 to 70 years, and 600 IU/day for adults over 71 years of age. A recent risk assessment of vitamin D revealed that these AIs are too low to maintain optimal vitamin D status and concluded that the safe upper limit of daily vitamin D intake should be 10,000 IU/day.
J Midwifery Womens Health. 2008;53(5):440-446. © 2008 Elsevier Science, Inc.
Cite this: Vitamin D and Mood Disorders Among Women: An Integrative Review - Medscape - Sep 01, 2008.