Another Vitamin Bites the Dust
As a Los Angeles ENT and sinus surgeon, I get a lot of questions about vitamin supplements. Maybe it goes with the territory: LA is an urbane, educated and affluent city, and Angelenos (like most people) just want to know the best way to stay healthy.
I have covered Vitamin C in this space before, but until now I have largely ignored the growing trend toward taking Vitamin D supplements. A few years ago, media stories began to suggest that these supplements might have a host of benefits, from protection against cancer to curing the common cold.
We can now scratch that second one off the list definitively. A recent controlled study divided a few hundred people into two groups: one was given Vitamin D for 18 months, the other got a placebo. The findings on URTIs (upper respiratory tract infections) were fairly grim:
Half the participants were administered large monthly oral doses of Vitamin D3 (the form of Vitamin D that the body produces when exposed to sunlight); the other half were administered placebo drugs resembling the vitamin supplements. Over the year-and-a-half study period, which encompassed two mild flu seasons, 593 people receiving Vitamin D3 and 611 receiving placebo contracted URTIs; the study authors say that difference isn’t statistically significant. There were no significant differences between the two groups in the severity or duration of illness or the number of workdays missed due to URTIs.
Should this surprise us? Anyone paying close attention to health science in the past decade may have noticed the increasing number of vitamin studies that disprove the purported benefits of these pills. The reason is simple: if you’re healthy, you probably don’t need to be taking anything other than what you eat. (Fish oil included.)
The larger reason that the media gets these stories wrong can be found here: noncontrolled studies tend to give skewed results because the kind of people who take vitamins also happen to take better care of themselves in general. So results that seem to indicate that vitamins are correlated with better health may not mean much at all.
My advice for avoiding the common cold? Get sleep, stay hydrated, and eat a good diet. And leave the pills at the pharmacy.