Vitamin D is a fat soluble vitamin that is found in foods and is manufactured by the body when the skin is exposed to the ultraviolet rays of the sun. There are several different forms of the vitamin in the body that have different activities. The major function of the vitamin is to maintain normal blood levels of calcium and phosphorus and is used in the production of different hormones and enzymes.
Causes of Deficiency
Deficiency of vitamin D is more likely in older adults who do not have exposure to sunlight for more than 20 minutes each day. In fact, the Harvard School of Public Health estimates that more than 1 billion people worldwide have inadequate levels of vitamin D in their blood stream. Living in the northern hemisphere or being of African American descent or darker skin will also place you at greater risk of developing a vitamin D deficiency.
How it Works
Vitamin D levels that are within a normal range can significantly reduce your mortality rate from all known causes of disease and illness. This is because it is used in the body for multiple purposes, such as repair and maintenance of hormones, and serves to regulate genetic function in the body. There is compelling evidence that vitamin D is one key factor in the ability of the body to properly express gene function. For instance, vitamin D is used to access DNA that enables the response to estrogen in a woman's ductile cells, producing milk for breast feeding. Scientists have found that it is important in 3,000 genes of the 30,000 total genes identified in the body, according to Dr. Joseph Mercola.
Symptoms
Symptoms of vitamin D deficiency include some common cancers, type 1 diabetes, cardiovascular disease and osteoporosis, according to an article in the "American Journal of Clinical Nutrition" in 2004. Each of these diseases contributes to a significant lack of energy and fatigue.
Seasonal affective disorder is another condition that increases fatigue, decreases energy levels and increases your desire for sweets and starchy foods. This condition is triggered by a lack of sunshine during the winter months. MayoClinic.com reports one study that found using vitamin D supplementation was better than light therapy in the treatment. Although further research is needed to confirm these results, it is believed that vitamin D does play a role in the fatigue and lack of energy that results from SAD.
Treatment
The simplest treatment is to increase your exposure to sunlight to 20 minutes or more each day without sunscreen protection. However, if you live in the northern hemisphere or have dark skin you may not absorb enough ultraviolet rays in the winter months to manufacturer adequate amounts of vitamin D. In fact, the Institute of Medicine has recommended tripling the daily dose of vitamin D in all children and adults in the U.S. and Canada to 600 International Units per day. The upper limit of vitamin D considered to be safe was also increased to 4,000 IU per day. However, these doses may not supply enough vitamin D to prevent chronic disease and improve bone health, according to the Harvard School of Public Health.
References
- Harvard School of Public Health: Vitamin D and Health
- Dr Mercola: The Vitamin D Solution
- American Journal of Clinical Nutrition: Vitamin D: Importance in the Prevention of Cancers, Type 1 Diabetes, Heart Disease and Osteoporosis
- MedlinePlus: Seasonal Affective Disorder
- Mayo Clinic: Vitamin D
- Institute of Medicine of the National Academies: Dietary Reference Intakes for Calcium and Vitamin D
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