Busting the 7 most common health myths

5. The pill makes you fat
For years, we have blamed the birth control pill for our extra curves, but it seems we have been fooling ourselves all along. International public-health research organization Family Health International (FHI) recently reviewed 44 trials to see whether hormonal contraceptives like birth control pills pile on the pounds. While some subjects did put on weight, FHI concluded that the pill was not the culprit. "Women tend to gain weight over time," says FHI researcher Laureen Lopez. "But as far as we were able to tell, there is no evidence of a causal relationship between birth control pills and weight gain."

6. Stress causes infertility
"Stress doesn't cause infertility," says Dr. Carol Redmond of the LifeQuest Centre for Reproductive Medicine in Toronto, "but infertility sure can cause stress. What bothers me most when people say 'Just relax -- it will happen' is that it blames the victim and implies the sort of control over our fertility that we don't have." A new study from Sweden suggests that there is no link between anxiety and successful in vitro fertilization (IVF). "During IVF, patients often express worries that their own stress may have a negative influence," says Dr. Lisbeth Anderheim of Sahlgrenska University Hospital in Gothenburg, Sweden. "The fact that our study does not indicate any relationship is reassuring." And what about that other fertility myth, "Once you adopt, you'll get pregnant"? Around five percent of women who adopt later become pregnant -- the same percentage as infertile couples who don't adopt or have treatment and then get pregnant.

7. Melatonin cures jet lag
Weary travellers and shift workers will try anything to get some shut-eye, and many swear by synthetic melatonin. Marketed as a diet supplement, melatonin pills mimic the sleep-inducing hormone that our pituitary gland secretes at night. But a new study from the University of Alberta in Edmonton found no evidence to suggest that melatonin is effective at treating jet lag, shift-work disorder or secondary sleep disorders that stem from medical or psychiatric issues. It may not work, but is it harmful? "The study found evidence to suggest that melatonin is safe for short-term use," says Nina Buscemi, a research associate in the department of pediatrics at the University of Alberta, "but more research is needed to determine its long-term safety." Still unavailable in Canada, melatonin pills are sold in health food stores across the United States.