Vitamin D Toxicity And Pregnancy

Vitamin D is actually a group of five similar substances that are all hormone-like in action. The D2 and D3 forms are the most biologically active. The D3 form can be taken as a supplement, but it is also produced by your skin in large quantities in response to certain frequencies of sunlight and exhibits extremely low toxicity despite being stored within your body. The D2 form is less studied and may be more toxic, especially in its synthetic supplemental form. Although very rare, maternal overdose of synthetic vitamin D during pregnancy can lead to altered mental and physical development in infants.

Vitamin D Functions and Recommendations

Vitamin D is essential for a healthy musculoskeletal system, which is clearly demonstrated by bone deformity in children and adults who are deficient, but it also plays important roles in modulating cell growth, enhancing immunity, reducing inflammation and regulating mood. In many ways, the five forms of vitamin D are better thought of as hormones. The National Institutes of Health recommends 600 IU of vitamin D per day for pregnant women to prevent any deficiency complications, with the upper limit set at 4,000 IU daily.

Vitamin D Toxicity

Vitamin D toxicity can become a serious health issue because it causes too much calcium to be released into your blood, which leads to bone pain, muscle weakness, headache, reduced appetite, nausea and vomiting. If you are pregnant, too much vitamin D affects bone development and neurological function within your developing baby. However, according to an article published in a 2006 edition of the "Canadian Medical Association Journal," vitamin D toxicity is very rare and has been greatly exaggerated by inappropriate animal studies. The authors go on to say that vitamin D deficiency for pregnant women is much more of a concern than toxicity and dosages have exceeded 10,000 IU daily for many months in various studies of non-pregnant volunteers with no adverse reactions of any kind. Since vitamin requirements are generally higher during pregnancy, 10,000 IU of supplemental vitamin D3 per day appears safe while pregnant.

Vitamin D Production

According to "Nutritional Sciences," your body has the capacity to make tens of thousands of IU of vitamin D3 hourly when exposed to midday summer sunshine, which suggests higher requirements for your body. Indeed, sunshine is the best source of vitamin D because it is not found in abundance in most foods. Avoidance of sunshine is the leading cause of vitamin D deficiency in the United States and is estimated to affect at least 70 percent of the population, as cited in "Nutrition and Public Health" (Reference 4). As such, if you are pregnant, vitamin D deficiency should be more of a concern than toxicity. Natural sources of vitamin D include fatty fish, beef and pig liver, egg yolks, shrimp and fortified dairy products and orange juice.

Supplementing with Vitamin D

Vitamins D2 and D3 are the primary forms used for supplements and are often available as liquids. Supplemental D3 has shown no toxicity from long-term use of 10,000 IU daily and short-term use of 40,000 IU daily, although the D2 form has not been tested above 10,000 IU per day, as cited in "Vitamins: Fundamental Aspects in Nutrition and Health." Further, supplemental D3 is considered superior to D2 because it is absorbed better and has a variety of hormonal advantages. The problem is that vitamin D is still poorly understood and its requirements during pregnancy have only been guessed and are not based upon scientific evidence. If you are unable to get adequate sunshine during your pregnancy, then supplementing with D3 seems to be the best bet, although at doses less than 10,000 IU daily. Consult with your doctor before embarking on any supplemental regiment.