Your money might be better spent on something else.

During the winter months, you've likely seen ads for products that claim to give your immune system a boost to help you ward off colds and the flu. But can something in a bottle, whether a vitamin formulation or probiotic, really rev up your immune system to help you stay healthy?

"Unfortunately, the reality is that those kinds of products aren't really offering you any benefit," says Michael Starnbach, a professor of microbiology at Harvard Medical School. "There's no evidence that they help in fighting disease."

To understand why, you need to know a little about how the immune system works. The very idea of boosting the immune system is flawed.

"The immune system is very finely tuned," says Starnbach. There is a balance between an immune system that is effective at limiting the ability of bacteria, viruses, and parasites to cause infection, and a hyperactive immune system that can cause such problems as allergies, diabetes, and other types of autoinflammatory and autoimmune disorders.

"If there were a wholesale boost to the immune system, it could trigger autoimmunity and other problems," he says.

What's in the bottle

Products that claim to boost or "support" the immune system typically fall into a couple of categories: vitamin formulations and probiotics.

There is some truth to the idea that vitamins can help immunity. Vitamins can help ward off disease and other health problems, but only in people who are severely malnourished, something that's not true of the average American adult, says Starnbach. So, vitamin formulations will do little to help you stay healthy if you are healthy already.

When it comes to probiotics, there is also some truth to the idea that the bacteria and organisms living in your gut may play a role in your health.

"There is a lot of research going on as to how these friendly organisms that live in us, and on us, contribute to immune function, and how they disrupt immune function," says Starnbach. Someday, scientists may very well be able to tell us how to prevent disease by modifying these various species inside our bodies, which make up what is called the microbiome.

"I think we will become much more aware in the next 10 years of the ways in which specific microbes are involved in certain diseases," he says. But today, there isn't enough understanding of the complex interplay between the body and the microbiome to effectively use probiotics to improve health. "We don't have any evidence yet as to how we might be able to use dietary supplements to correct problems," he says.

That may change, but in the meantime, be skeptical of claims to the contrary.

Strategies to stay healthy

So, if you can't help your immune system by taking an over-the-counter potion or pill, what can you do to cut down on illness this winter? Differences between people who rarely get sick and those who are sick all the time may have more to do with habits than immune function, says Starnbach. Here are some tips that might help.

Clean your hands. While some germs are airborne, more often than not, illness occurs after you touch a contaminated surface, says Starnbach. Most often germs move from your hands into your eyes, nose, or mouth, so also make an effort not to touch your face.

Keep your body in top shape. Maintaining a healthy and balanced diet, exercising regularly, and getting enough sleep can help keep your body and your immune system working well.

Manage stress. Research has shown that high stress levels may impair the immune system. So whenever possible, try to be aware of your stress levels and work to lower them when they get too high.

Get vaccinated. Getting vaccinated against the flu and other diseases stimulates the immune system to protect against illness. Vaccines teach the immune system to recognize specific pathogens and prepare them to mount a defense if they are encountered.

The bottom line is that aside from vaccines, there's really nothing you can take to improve your immune system, so it's probably best to avoid pills and potions that make those types of claims.

"While these things may not cause harm, you will probably enjoy your money more if you are using it for something else," says Starnbach.

Image: Courtney Hale/Getty Images

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