Taking vitamin D supplements does not ward off the common cold, according to a new study that contradicts some previous research suggesting it might have a protective effect.
The study, conducted in 2010 and 2011 by researchers at the University of Otago in New Zealand and Harvard Medical School, included 322 healthy adults in Christchurch, N.Z. Half of the adults were randomly assigned to receive an initial pill containing 200,000 international units (IU) of vitamin D, followed by another pill one month later and then half the dose monthly for 18 months. The other half was given the same schedule of placebos.
Vitamin D supplements did not reduce the number of colds, nor the length or severity of the cold compared with placebo, the study found. Those who took vitamin D and got a cold also took, on average, the same number of days off of work as those who took a placebo.
Most multivitamins include vitamin D in strengths from 50 IU to 1,000 IU. The 200,000 IU of vitamin D used in this study is equivalent to 5,000 micrograms.
Previous studies suggest that vitamin D supplements may help prevent certain conditions besides the common cold such as heart disease and osteoporosis. Supplements are especially beneficial for adults with a vitamin D deficiency, the researchers said.
BOTTOM LINE: Vitamin D did not prevent the common cold or reduce its severity.
CAUTIONS: The study doesn’t rule out a benefit from vitamin D supplements in other populations or with other doses.
WHERE TO FIND IT: Journal of the American Medical Association, Oct. 2
Genes may influence desire to be thin
Genetics, not just environmental triggers, may be linked to why some young women are more likely to desire being thin, according to a study led by Michigan State University researchers.
They interviewed nearly 350 female twins ages 12 to 22 about their ideal level of thinness, based on how much the participants wanted to look like people in films, TV shows, and magazines. The researchers compared identical twins, who share 100 percent of their genes, to fraternal twins, who share only half of their genes.
The identical twins were more likely to report admiring similar thinness types than the fraternal twins. Analysis by the researchers suggested that the twins’ genes accounted for 43 percent of the similarity of their views on the ideal level of thinness.
Generally, women who have a stronger desire to look like the media images are at a higher risk for eating disorders, according to the authors.
BOTTOM LINE: Genetics may be associated with some women’s desire to be thin.
CAUTIONS: The study did not show a causal link between genes and the desire to be thin or the development of eating disorders. The study also did not determine the specific genes that may be involved.
WHERE TO FIND IT: International Journal of Eating Disorders, Oct. 3