Vitamin D: The Hot New Vitamin
Are you getting enough?
by Elizabeth Somer, MA, RD
The Tolerable Upper Limit (UL) for vitamin D should be raised five-fold, according to a report from the Council for Responsible Nutrition (the professional branch of the supplement industry), as well as researchers from Mount Sinai Hospital in Toronto and Creighton University in Omaha. These reviewers pooled data from 21 clinical trials that used doses far above the current UL of 50 micrograms (2,000IU), and recommend the UL should be raised to 250 micrograms (10,000IU). They conclude that:
"The lack of adverse effects in clinical trials that used intakes up to 1,250 micrograms vitamin D per day and the lack of adverse effects at lower doses inspires a high level of confidence in the data from the strongly designed clinical trails that used 250 micrograms vitamin D per day."
This proposed UL is not meant to suggest that higher levels might be unsafe, nor does it present a recommended intake. In fact, some past studies have suggested intakes for vitamin D far higher than this proposed UL. The new recommendations are meant to provide guidelines for a daily intake that is nontoxic and that has ample evidence to support its safety. Many experts have called for revisions in the current vitamin D recommendations, set back in 1997 and considered outdated and too restrictive; however, this is the first published review that provides a quantitative basis and recommendation for a new UL.
Why Now?
Vitamin D is the "hot" new vitamin. Until recently, its only substantiated role was in boosting calcium intake and deposition into bone, thus reducing the risk for bone disorders including osteoporosis, osteomalacia, and rickets. Now research is showing this vitamin also aids in the prevention and/or treatment of muscle weakness, gum disease, diabetes, insulin resistance, arthritis, multiple sclerosis, hypertension, and certain cancers, including colon, breast, pancreas, and prostate cancers. Vitamin D supplements also reduce the incidence of falls by up to 60% in seniors, while a deficiency can mimic symptoms of fibromyalgia. In all cases, researchers conclude that much higher amounts than the current RDAs are needed to see benefits.
Example #1: Vitamin D and Diabetes
Vitamin D helps the pancreas release insulin. People with low blood levels of vitamin D produce less insulin and their bodies' cells are less sensitive to the hormone, allowing blood sugar levels to rise. It's double trouble for anyone at risk for diabetes, affecting both the release and effectiveness of this hormone. In people with pre-diabetes, a deficiency of this vitamin could tip the balance. Research on the NOD mouse, which is used to study diabetes, who are given vitamin D cut their risk for diabetes by 80%. A study in Finland found that children who take at least 2,000IU of vitamin D a day during the early years have an 80% lower risk of developing diabetes than those who do not supplement with vitamin D
