Vitamin D

The major functions of vitamin D are to increase the efficiency of intestinal calcium absorption and to mobilize calcium stores from bone in order to maintain the serum calcium and phosphorus concentrations within the normal physiological range.

Deficiencies: In humans, deficiency symptoms include rickets in children, osteomalacia in adults, muscle weakness, bony deformities, neuromuscular irritability causing muscle spasms of the larynx (laryngospasm) and hands (carpopedal spasm), generalized convulsions and tetany.

Food sources: Very few foods are naturally rich in vitamin D, and most vitamin D intake is in the form of fortified products including milk, soy milk and cereal grains.

Sunlight: Sun exposure is perhaps the most important source of vitamin D because UV rays from the sun naturally trigger vitamin D synthesis in skin. Ten to fifteen minutes of sun exposure at least two times per week to the face, arms, hands, or back is usually sufficient to provide adequate vitamin D. Keep in mind that sunscreens with a sun protection factor (SPF) of 8 or greater will block the UV rays that produce vitamin D (please use common sense to avoid overexposure and sunburn). Also, season, geographic latitude, time of day, cloud cover, smog, and sunscreen affect UV ray exposure and vitamin D synthesis. It is very important for individuals with limited sun exposure to include good sources of vitamin D in their diet.

2000-Calorie Diet Recommendations

Shown below are the reference numbers used to compute the Daily Value percentages that appear on the Nutrition Facts labels on foods sold in the U.S. These numbers are meant to approximate the nutrients needed for the average person consuming 2000 calories per day.

Click any of the vitamin or nutrient names below to learn more about the importance of each element, and to see detailed dietary allowances for specific population groups.

***Daily Value recommendations are based on a 2000-calorie diet. Recommendations for individuals will vary depending on gender, age, weight, and other factors.