Thursday Aug 7, 2014 (foodconsumer.org) -- Some individuals and organizations promote use of tanning beds for the serum vitamin D maintenance while high exposure to ultraviolet B rays emitted from tanning beds is known to increase risk of skin cancer.

A case report recently published in Annals of Internal Medicine suggests that excessive use of tanning beds can cause another health problem - hypervitaminosis D - too much vitamin D in the blood.

Hypervitaminosis D, which can be caused by taking high doses of vitamin D supplements, is known to be associated with a number of medical conditions including hypercalcemia, hypercalciuria, hyperphosphatemia, and low levels of parathyroid hormone.

According to the report authored by Priyamvada Singh, MD and Nitin Trivedi, MD from Saint Vincent Hospital in Worcester, Massachusetts, a 26-year-old asymptomatic white woman was found during an annual routine health examination in July 2012 to have 339 nmol/L of serum 25-(OH)D. The normal reference ranges between 75 and 185 nmol/L.

Six months later when she visited the authors' clinic, her blood sample was tested again only to show that she still maintained the serum 25-(OH)D at 299 nmol/L.

The patient reported no excessive intake of milk or over-the-counter vitamin D supplements or other medications.  She did not get exposed to the sun often.  She did report that she had been using a tanning bed three or more times per week for at least six months.

She had polycystic ovarian disease and followed a low fat low carb diet and modified lifestyle to lose weight while levels of calcium, phosphorus, 1,25-dihydroxyvitamin D and parathyroid hormone were found normal.

Doctors advised her to discontinue using tanning beds as they suspected that use of tanning beds was the cause for hypervitaminosis D, and one month later, vitamin D in her blood sample was measured again and found to drop to 182 nmol/L.

Vitamin D deficiency is known to be associated with more than 100 medical conditions including depression, Alzheimer's disease, infections, diabetes mellitus, heart disease, metabolic syndrome, and cancer among many others.

Sun exposure is the major source of vitamin D.  It should be noted that vitamin D is fairly safe and intake of up to 10,000 IU vitamin D per day is considered tolerable.  Exposure of the bare face and hands to the sun for 15 to 20 minutes at the hottest hours of the day in the summer can get a person 10,000 IU.  To prevent medical conditions, some vitamin D researchers consider about 5000 IU of vitamin D3 necessary for adults. (David Liu, PHD)