Vitamin supplementation has long been a popular way of ensuring that people receive the sufficient amount of vitamins. However as it pertains to Vitamin D, there is some amount of controversy as it pertains to Vitamin D supplementation (25-hydroxy) concentration and safety. The literature review will discuss the need for vitamin D supplementation and the findings of various studies and Vitamin D trials.
An article entitled "Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety" the daily allowance of vitamin D is 200 IU. The medical community has established that this amount will prevent the softening of the bones known as osteomalacia. However, there is also a consensus that more vitamin D is need to avoid other conditions such as hyperparathyroidism and osteoporosis.
In fact an article found in the Archives of Gerontology and Geriatrics confirms that the proper amount of vitamin D can reduce the chances of the development of hyperparathyroidism. The article reports the result of 52 clinical trials involving the evaluation of vitamin d supplementation in order to evaluate the experimental evidence and the effects of age and chronic immobility on responses of parathyroid hormone (PTH). The meta-analysis trials found that "responses of PTH to vitamin D supplementation are not only determined by the baseline PTH levels and changes in vitamin D status, but also by age and mobility of the patients...PTH decreases quite linearly during vitamin D supplementation at any given 25-OHD level (Bjorkman et al.)." The meta-analysis also found that longitudinal vitamin D supplementation studies involving participants from a larger age range are needed to verify the aforementioned effects (Bjorkman et al.).
In addition to the aforementioned advantages associated with consuming the proper amount of Vitamin D, there are also other health benefits. These benefits include the prevention of multiple sclerosis, high blood pressure and certain types of cancers. The article also points out that total body exposure to the sun will provide the body with 10,000 IU of Vitamin D The problem is that most people do not get an adequate amount of sun exposure because of the fear of being exposed to too much ultraviolet sunlight, which can cause skin cancer. Most people wear sun screen and cover a large percentage of their bodies when they go out into the sun. The author asserts that Our evolution has effectively designed us to live in the presence of far more vitamin D (calciferol) than what most of us get now, yet there is no consensus about what vitamin D intakes are optimal or safe. Unlike anything else used in the fortification of foods, the purpose of vitamin D is to correct for what is an environmental deficit (less ultraviolet exposure) and not to correct for lack due to classical nutritional reasons. With a few exceptions reviewed by Takeuchi et al. (2), there is little or no vitamin D in the kind of foods that humans normally eat. Therefore, conclusions about the efficacy and safety of vitamin D must be in the context of the role of environmental factors. (Vieth)
Additional literature reiterates the need for the proper amount of vitamin d intake. For instance, an article found in The Journal of Nutrition asserts that vitamin D deficiency is an issue that affects people throughout the world (Calvo et al., 2005). The article also asserts that the reemergence of rickets is of particular concern to the medical community (Holick). Rickets is a disorder that is linked directly to low circulating 25-hydroxyvitmain D (Calvo et al., 2005). According to Hollick, in the past treatment for rickets was sun exposure. Today such treatments are more difficult because of the threat of skin cancer and as such supplementary vitamin D is necessary.
The lack of consensus on this issue has led to many different studies designed to investigate the proper amount of vitamin D supplementation required. An article found in the journal Clinical Therapeutics reports on a study of the clinical and laboratory safety involving a one year treatment of Vitamin D and Calciumto a group of participants. These participants were all women 65 and older. All participants were also ambulatory -- that is, all participants were able to walk. All participants also had a Vitamin D deficiency.
The results of this particular study found that participants tolerated the intake of vitamin D and Calcium very well. The study found that there were no significant effects on the clearance of creatinine. The study did find that women taking the combination pill had higher levels of serum uric acid that the women who took the placebo (Brazier et al.).
An article published in the Journal of the American Dietetic Association reports on a study conducted by the Women's health Initiative. This study was a randomized trial of calcium and vitamin D supplementation. The results of the trial found that there was a reduction in bone less for those treated with the aforementioned combination but not for those that received the placebo. The article also reports that a follow-up study was conducted to determine whether or not the treatment had an impact upon the self reporting of physical functioning and objective ways to measure physical functioning. The study found that Neither intention to treat nor high adherence analyses produced substantial effects of calcium/vitamin D compared to placebo on physical functioning or performance. The interaction analyses also did not result in differences because of calcium/vitamin D. As the first l long-term randomized trial to examine the effectiveness of calcium and vitamin D in protecting against decline of physical functioning in older women, the results did not support benefit (Brunner)."
Other studies (Weisman & Shwartz) have found that the vitamin D calcium combination increased the likelihood of kidney stone development in women. Weisman and Shwartz also point out that women are most likely to be adversely effected by vitamin D supplements that have too low or too high a dose.
Vitamin D supplementation also has implications for newborns. Alouf, MD and Meg Grigalonis, explain that "Vitamin D is essential for bone formation and calcium and phosphorous homeostasis. It stimulates intestinal absorption of calcium and phosphorous, renal reabsorption of filtered calcium, and mobilization of calcium and phosphorous from bone (Alouf)."
The article further explains that pregnant women with vitamin D deficiencies often experience poor weight gain, fractured bones and prolonged labor. Additionally the children they give birth quite often experience poor bone development.
In addition to vitamin D in utero, newborns also need to receive the proper amounts of vitamin D when they are breast fed.
According to an article found in the Archives of Disease in Childhood, the medical community has long debated whether or not the amount of Vitamin D in breast milk was sufficient enough to keep newborns from acquiring rickets (Ala-Houhala, et al.). The article explains that research suggests the need for vitamin D supplementation for infants that are breastfed. This supplementation is especially vital during the winter months when infants do not have as much exposure to the sun (Ala-Houhala, et al.).
In addition to the impact of vitamin D deficiency in infants, research also suggest that such a deficiency can contribute to the development of type 2 diabetes. According to an article entitled "The Role of Vitamin D and Calcium in type 2 diabetes. A systematic Review and Meta-Analysis" the prevalence of diabetes has increased drastically in recent years. Although obesity is one of the primary reasons for the increase in occurrences of diabetes, some researchers also believe that the increase is related to vitamin D deficiency (Pittas et al.). The article reports that it has been established that vitamin D deficiency is correlated with the development of type 1 diabetes and it recent years it has also been correlated to the development of type 2 diabetes (Pittas et al.).