Vitamin D is essential to absorb calcium, modulate cell growth, maintain the balance between calcium and phosphate, enable bone mineralization and prevent hypocalcemic tetany, which is a metabolic disorder that causes muscles to strongly and involuntarily contract as a result of a calcium deficiency. The skin naturally produces a variant called cholecalciferol, or vitamin D3, when exposed to ultraviolet rays, while plants produce ergocalciferol, or vitamin D2. Vitamin D also naturally occurs in eggs, fish and fortified foods like milk. Given that it's an essential vitamin, a deficiency in vitamin D can cause health complications.
Risks
An estimated 1 billion people, or almost 15 percent of the world population, suffers from a vitamin D deficiency, according to Michael Holick in an article published in the "New England Journal of Medicine." Holick defines a vitamin D deficiency as a blood concentration of less than 20 nanograms per milliliter. The best way to obtain vitamin D is through sun exposure; Holick reports that deficiencies are common among those with limited sunlight exposure due to climate or dress, despite supplementation or diets that include vitamin D. Pregnant or lactating women and the elderly are at the greatest risk for a vitamin D deficiency. The most serious complication associated with a vitamin D deficiency is hypocalcemia, or a calcium deficiency. The body absorbs up to 15 percent of the calcium consumed in the absence of sufficient vitamin D. Sustained hypocalcemia from a vitamin D deficiency can eventually become osteomalacia or osteoporosis.
Symptoms
Although the outcome of a vitamin D deficiency is potentially serious, there are few to no symptoms prior to these serious complications. Although bone pain, muscle weakness, and similar symptoms may evidence a vitamin D deficiency, these issues manifest only when a vitamin D deficiency is in its advanced stages. In addition to osteomalacia and osteoporosis, the disorder most frequently associated with the deficiency is rickets, or "soft bones," characterized by deformities like bowed legs or posture malformations.
Infertility
There is no conclusive evidence that a vitamin D deficiency results in infertility for either sex. However, in a study by Halloran and DeLuca from the "Journal of Nutrition," clinical tests revealed that vitamin D deficiencies reduced rat fertility by 45 percent, although the deficiency did not diminish it altogether. Litter size also reduced and neonatal growth and development was hindered. Despite growth underdevelopment, though, the rats survived and remained relatively healthy. Vitamin D-deficient mothers produced milk that was similarly deficient of calcium with an overabundance of phosphate.
Bottom Line
Although a vitamin D deficiency can be potentially serious, it is treatable through supplementation and may exhibit no symptoms until the condition worsens. Moreover, vitamin D will not cause infertility. Instead, it affects several bodily systems, since it also causes secondary complications like calcium deficiencies and phosphates excesses, including the reproductive system, without completely disabling them. In fact, it is common for mothers to give birth to vitamin D-deficient children while having the same deficiency.
References
- "The Journal of Nutrition"; Effect of Vitamin D Deficiency on Fertility and Reproductive Capacity in the Female Rat; B. P. Halloran and H. F. DeLuca; August 1980
- MayoClinic.com; Vitamin D; April 2011
- Office of Dietary Supplements: Vitamin D
- "New England Journal of Medicine"; Vitamin D Deficiency; Michael F. Holick, M.D., Ph.D.; June 2007
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