Vitamin D is actually a collection of five fat-soluble molecules known as secosteroids. Of these, vitamins D2 and D3 are the most essential to human physiology. Vitamin D2, or ergocalciferol, is obtained from food sources and via supplementation. Vitamin D3, or cholecalciferol, is produced within the skin in response to the ultraviolet rays from the sun. Vitamin D deficiency causes characteristic side effects.
Considerations
The National Institutes of Health recommends 200 IU of vitamin D per day for adults up to the age of 50, which is an amount meant to avoid acute deficiency. For comparison, fully exposed light-colored skin synthesizes about 10,000 IU of vitamin D3 in 20 minutes when exposed to midday summer sunshine. The body cannot overdose on vitamin D3, but can show signs of hypervitaminosis at single dosages above 10,000 IU of vitamin D2.
Causes
Vitamin D, in all its forms, is not especially prevalent in natural food sources, although some products, such as milk, orange juice and breakfast cereals that are sold in the United States are fortified with vitamin D. Poor nutrition is certainly a contributing cause of vitamin D deficiency in geographical locations that do not get much sun exposure, but in areas where there is ample sunshine, lack of sun exposure is the most dominant cause. Indoor sedentary lifestyles, fear of skin cancer and use of sun screens are preventing people from getting their daily dose for free.
Early Side Effects
According to the National Institutes of Health, serum concentration of calcidiol is the best indication of vitamin D status, and levels below 37.5 nanomoles per liter are considered inadequate. The initial signs of vitamin D deficiency may take months to develop, but included excessive sweating, anxiety, fatigue and muscle cramping.
Bone Malformations
It is well-known that vitamin D deficiency causes rickets in children and osteomalacia in adults, which are both painful bone malformation diseases. Less well known is that vitamin D deficiency also contributes to osteopenia, osteoporosis and muscle weakness, which all increase the risks of bone fractures, especially in the elderly.
Musculoskeletal Effects
Other musculoskeletal conditions, such as muscle wasting and pain, have been linked to vitamin D deficiency in multiple studies. A study of Egyptian women published in a 2007 edition of the journal "Clinical Rheumatology" found that chronic low back pain of more than three months duration was linked to significantly lower levels of vitamin D.
Depressed Mood
Depression, reduced cognition and psychiatric disorders have all been linked to vitamin D deficiency, especially in the elderly. A 2006 study of elderly people, half of which displayed mild dementia, concluded that vitamin D deficiency was associated with depressed mood and cognitive impairment.
Other Side Effects
Researchers have linked other disease conditions to vitamin D deficiency. "Professional Guide to Diseases" notes that vitamin D deficiency can reduce immune system function, cause hypertension and fibromyalgia, and contribute to type 2 diabetes, multiple sclerosis, inflammatory arthritis and macular degeneration.
References
- National Institutes of Health, Office of Dietary Supplements: Vitamin D Fact Sheet
- "The Vitamins, Third Edition"; Gerald F. Combs; 2007
- "Professional Guide to Diseases, Eighth Edition"; Springhouse; 2005
- "Clinical Rheumatology"; Hypovitaminosis D in female patients with chronic low back pain; A. Lotfi et al; March 2007
- "American Journal of Geriatric Psychiatry"; Vitamin D deficiency is associated with low mood and worse cognitive performance in older adults; C.H. Wilkins et al; December 2006
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