DEAR DOCTOR K:
My mom always told me to take vitamin C and not to drink milk when I had a cold. Is this true or just an old wives’ tale?
The idea that vitamin C supplements might prevent the common cold, or shorten the duration and reduce its symptoms, was popularized by the biochemist Linus Pauling. Pauling was indisputably a genius, a Nobel Prize winner who was one of the most distinguished scientists of the 20th century. When Pauling talked, people listened.
In fact, people not only listened; they put the scientist’s ideas to a scientific test. Randomized controlled trials involving thousands of people were conducted. My interpretation of the results of those studies is that they showed no evidence that vitamin C supplements reduced the duration or severity of the common cold. There was weak evidence that they might reduce the risk of catching it.
Still, studies like these can tell us only about the results in the “average” person. It may be that there really are some people who do benefit from vitamin C supplements; the problem is that we currently have no way of identifying these people. Some of my patients insist that vitamin C helps them to deal with the common cold, and they could be right.
What about drinking milk? There is a rather widespread belief that dairy products trigger mucous production during a cold and can slow recovery or even cause another cold. You hear it a lot, but it’s just not true.
The argument was that milk increased the amount and thickness of phlegm that is produced during a cold. Phlegm is the thick, mucous-containing fluid responsible for congestion and post-nasal drip.
But a remarkable set of studies published in 1990 found no clear connection between milk consumption and cold symptoms.
In one study, researchers exposed study subjects to a cold virus. They kept track of the dairy products the subjects ate and their symptoms over 10 days. Secretions from the nose were collected, the collection jars promptly sealed to avoid evaporation and then weighed.
The verdict? The amount of nasal secretions and symptoms of congestion had no relationship with milk or dairy intake. Later studies agreed.
Researchers involved in these studies concluded that the combination of saliva and a high-fat beverage (such as milk) may mimic mucous. This could lead to the false assumption that drinking milk during a cold is bad.
The bottom line: There’s good evidence that the intake of milk or dairy products does not delay recovery from a cold or make symptoms worse.
If you have a cold or are recovering from one, it’s OK to drink milk. But if it gives you the sensation that you have more phlegm or that your congestion is worse, you’re probably responding to the fat in the milk — not the milk itself. In that case, switch to skim milk, tea or other low-fat fluids.