Too Much Vitamin D?

Between the sunlight and vegetable sources, how do we know when we have had too much vitamin D?

 

Calcium Supplement tablets

Supplement tablets

“I am going outside to get some vitamin D.” As the quest for a darker tan has become less popular through a greater understanding of skin cancer, other sunlight-linked health aspects have risen in importance. Vitamin D is one of the most important nutrients human body needs to absorb minerals into bone. As the body can naturally create its own vitamin D through exposure to sunlight, should individuals still intake dietary vitamin D at the same rate? Fortunately, the body has a mechanism to make sure that you do not have too much vitamin D. Vitamin D is fat-soluble, which means it can be stored in multiple types of tissue within the body and used when needed. This is why in colder climates; individuals can still have higher levels of vitamin D even if not exposed to regular sunlight. Before understanding how much is too much vitamin D, two questions must be asked.

1. What is the minimum needed for proper functioning of the body?

2. How much is too much?

Recently, researchers wanted to see differences in blood function between adolescents who took a regular supplement dose versus an “overdose.” Adolescents 11 to 19 who already had high levels of vitamin D were selected. Subjects were divided into two groups, one group taking 200 international units (IU)/day of vitamin D for 11 weeks, the other taking 1000 IU/day for the same period of time. The food and drug administration recommends 600 IU per day by contrast. After the 11 weeks was finished the blood levels of the two different groups did not have a statistically significant difference (Putnam et al. 2013).

Another study sought to document the limit of toxicity for vitamin D in the body. This was literally too much vitamin D, as the objective. The subjects were individually identified and documented from many locations based on illness and vitamin D being the root cause. Taking 50,000 IU a day of vitamin D for several months seemed to be toxicity limit (Lowe, 2011). The individuals that were identified for this upper limit were done so as a diagnosis of vitamin D toxicity is a buildup of calcium in the blood (hypercalcemia). This is observed via symptoms of poor appetite, frequent urination, nausea and vomiting, weakness, and kidney problems also may occur. Typically this should not be a concern for very many people as an individual would need to consume unreasonable amounts of foods and supplements rich in vitamin D to get to this upper limit.

 

References:

Putman, M. Pitts, S. Milliren, C. Feldman, H. Reinold, K. and Gordon, C. (2013). A Randomized Clinical Trial of Vitamin D Supplementation in Healthy Adolescents,” Journal of Adolescent Health. 52(5): 592-598

Lowe H. (2011). Vitamin D toxicity due to a commonly available ‘over the counter’ remedy from the Dominican Republic. Journal of Clinical Endocrinology and Metabolism. 96:291.

 

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