Do certain foods or nutrients boost the immune system? It’s a recurring theme on the internet: Lists of immune-boosting foods and recipes for tonics, teas, soups, and other concoctions that will allegedly strengthen your resistance to disease are always popular during cold and flu season and never more so than today.

It is true that various nutrients are essential to proper immune function. If you are malnourished, your ability to resist infection will almost certainly be impaired. Eating a healthy and balanced diet can help ensure that you are getting all the protein, vitamins, and minerals you need for your immune system—and all your other biological systems—to function properly.

Doubling or tripling up on the recommended amount of foods or nutrients doesn’t necessarily make your immune system function more properly.

But doubling or tripling up on the recommended amount of foods or nutrients doesn’t necessarily make your immune system function more properly. In fact, overloading the body with too much vitamin A or zinc (two of the most touted immune-boosting nutrients) can actually impair your immune response.

RELATED: Can You Get Too Many Vitamins?

Turning up the volume

When we think of boosting our immune system, we might think of turning a knob to turn up the volume, the way we would on a radio. And, just like Spinal Tap, looking for that extra edge, we’re looking for a special immune system amplifier that gives us the option of turning up the volume to 11.

But in reality, the immune system doesn't just have a single volume knob. Picture instead a sound mixing board with dozens of sliders that each modulate different aspects of the sound across lots of different channels. When you’re operating a mixing board, you don’t get the best sound by moving all the sliders to the maximum. Instead, you’re trying to find just the right balance of all the different frequencies and channels. And the optimal balance is constantly shifting, depending on the type of music, which instruments are being featured, the venue, the size of the crowd, and all kinds of other variables.

And so it is with the human immune system; it’s not a single biological function. It’s a vast array of cellular and chemical responses that take place in tissues and organs throughout the body, in response to a wide array of threats. Turning up the volume on every channel at once won’t make any one channel more effective. It might even diminish the effectiveness of the overall response.

Inflammation, for example, is one of the body’s immune responses. In the right place, at the right time, inflammation is a good thing. Too much inflammation at the wrong time becomes a problem.

Allergies and auto-immune disorders are both examples of conditions where one channel of the immune response is turned up too high. The solution in these cases is not to “boost the immune response” but to lower the volume on certain channels.

How does nutrition impact immunity?

So, what does it really mean when someone says that a food or nutrient has been proven to boost the immune system? It might be based on a study that found that one of the nutrients or compounds in that food activated one type of immune cell or chemical against a specific pathogen in a petri dish.

Will it work the same way in your body, where dozens of different nutrients are fueling dozens of different immune responses against dozens of different targets, all at the same time?

When you think about it, indiscriminate or imbalanced boosting of certain parts of the immune system could easily do more harm than good.

And how does whatever they tested in that petri dish correspond to the specific type of immune response you’re trying to boost--or the pathogen you’re worried about? A nutrient that might activate a T-cell’s assault on a cancer cell might not do anything to boost a B-cell’s ability to form an antibody to a virus or a vaccine.

When you think about it, indiscriminate or imbalanced boosting of certain parts of the immune system could easily do more harm than good. So, it’s probably a pretty good thing that what we eat doesn’t have an as direct or dramatic effect on our immune function as we like to think.

It may also come as a bit of relief to know that sugar does not cripple the immune system—or at least not in the way that most of us have been led to believe.

RELATED: Does Sugar Really Suppress the Immune System?

What’s the harm in eating healthy foods?

Okay, so maybe those green smoothies and garlic juice shots aren’t actually doing that much to protect you from whatever is going around. But if it’s motivating you to eat your vegetables, then what’s the harm? If you’re eating less refined sugar in an effort to avoid suppressing your immune system, maybe some good could come of that, too. Fair enough.

Exercise, time in nature, and random acts of kindness can make you stronger, happier, healthier, and more resilient. So be sure to keep those on the menu, as well.

But if it’s creating a false sense of security that causes you to disregard other more effective precautions--such as proper handwashing, staying away from sick people, and so on—then your green smoothie could actually be making you less safe. Or, if you are spending hundreds of dollars on immune-boosting supplements, that money could potentially be put to better use.

Even if we can’t just "turn up the volume" on our immune systems by eating certain foods, a good diet can definitely keep you healthier than a poor one. That means:

lots of fruits and vegetables

adequate protein

healthy sources of fats such as fish, nuts, olive, and avocadoes

legumes, whole grains, and other sources of fiber to nurture your microbiome

not too much sugar or alcohol.

(If you’d like a fun way to assess and track how you’re doing, check out my free Nutrition GPA app.)

Finally, although good nutrition is important for proper immune function, there are other factors that also come into play. Chronic stress can increase the body’s susceptibility to infection. (And, by the way, lack of sleep is experienced by your body as stress!) Exercise, time in nature, and random acts of kindness can make you stronger, happier, healthier, and more resilient. So be sure to keep those on the menu, as well.