How Some Foods Can Compromise Your Immunity

Poor eating habits can be harmful to your immune system.

A healthy diet plays an important role in the proper functioning of our immune system, says Maggie Michalczyk, a registered dietitian based in Chicago. “Having a well-balanced diet made up of nutrient-dense food helps to ensure that our immune system can function properly and protect our body from foreign invaders,” she says, like bacteria, fungi or viruses.

It’s important to understand that foods cannot by themselves boost your immune system. However, a well-rounded diet can help prevent nutrient deficiencies that can hinder immune function, which in turn helps to ensure our immune system functions smoothly. “Vitamins and minerals are needed for the growth and function of immune cells, further underscoring the importance of a healthy diet that supplies our bodies with a variety of nutrients,” Michalczyk says.

On the other hand, some some foods and beverages can be harmful to your immune system.

Here are eight foods and beverages that can compromise your immunity:

Alcoholic beverages

Alcohol compromises the immune system by reducing the cells that fight infection, says Shelly Wegman, a registered dietitian with UNC REX Nutrition Services in Raleigh, North Carolina. Consuming alcoholic beverages increases your susceptibility to pneumonia, sepsis and poor wound healing. It also triggers inflammation that can damage the lungs, which the coronavirus attacks.

For optimal health, you shouldn’t drink alcohol, or at least consume it in moderation.

If you do drink alcoholic beverages, whether you’re a man or a woman, you should limit yourself to these amounts on a daily basis:

— Beer, no more than 12 ounces.

— Wine, 5 ounces.

— Liquor or spirits, 1.5 ounces.

“Replacing alcohol with fruit- and herb-infused water such as watermelon and mint, an herbal tea like ginger tea or a low-sugar kombucha would benefit your immune system,” Wegman says. “Some herbs are high in anti-inflammatory phytochemicals, and kombucha and green tea are fermented foods that promote good gut health.”

Caffeine before bedtime

Consuming caffeine isn’t necessarily bad for your immune system, Michalczyk says. “However, if it hinders your sleep, that’s when it becomes a problem for your immunity,” she says. “This is because adequate sleep is crucial for proper immune function. Enough sleep ensures that your hormones are functioning properly and that there is less inflammation in the body, bettering your immune function.”

— Caffeinated tea.

— Chocolate.

— Certain protein bars.

Even before bedtime, it’s important to consume caffeine in moderation, says Lisa Jones, a registered dietitian based in Philadelphia. She notes that the Food and Drug Administration recommends that healthy adults consume about 400 milligrams or less of caffeine a day. As points of reference, an 8-ounce cup of coffee contains about 80 to 100 milligrams of caffeine, and a 12-ounce soft drink has about 30 to 40 milligrams.

It’s a good idea to consume caffeinated foods or beverages at least three hours before bedtime, to allow for proper digestion. Research suggests that rich dark chocolate that has at least 50% to 70% cacao content, for example, has an anti-inflammatory benefit — Jones says she eats a small square of dark chocolate after dinner, allowing enough time to digest before bedtime.

Foods with added sugar

Research published in 2018 in the journal Experimental Cell Research suggests that consuming a diet high in added sugar can be harmful to the immune system.

Coffee isn’t the only thing you shouldn’t consume before bed. You should also refrain from consuming these caffeine-laden items before bedtime:

There are a wide variety of foods high in added sugar, including:

— Cakes.

— Candy.

— Canned fruits in sugary syrup.

— Cookies.

— Dried fruits.

— Fruit juices.

— Fruit pies.

Added sugar comes in a variety of forms, including dextrose, honey, sucrose and table sugar. Some foods that may seem to be healthy actually have significant amounts of added sugar.

For example, while seemingly healthy, dried or canned fruits often contain added sugar, says Dr. Raphael Kellman, founder of the Kellman Wellness Center in New York City.

Everyone has a microbiome, which is a collection of more than 100 trillion microbes that live in and on our body. The majority of these microbes are in our large intestine. Canned and dried fruits feed glucose and fructose to the unhealthy bacteria in your microbiome, and also promote a craving for sweets by feeding yeast and other sugar-loving microbes, Kellman says. Giving in to those cravings by consuming foods with added sugar can affect your immune system.

Dairy products

While consuming dairy products can be beneficial for some people, for others it can lead to inflammation, a leaky gut, food intolerance and reactions that can negatively affect the immune system, Kellman says.

Many people benefit from cutting down on their dairy intake or abstaining entirely.

Dairy products include:

Cow’s milk.

— Ice cream.

— Butter.

— Cheese.

— Yogurt.

Fast food

Burgers, burritos and fries from fast-food joints are tasty — but they provide high amounts of calories, fat and sodium. These food items do little or nothing to boost your immune system because they’re low in nutrients like vitamins and minerals, Michalczyk says.

On the other hand, foods rich in antioxidants, like fresh fruits and vegetables, contain plenty of nutrients like vitamin C to help support your immune system. High fast-food consumption means you’re less likely to be eating balanced meals with fruits and vegetables as much as you should.

Food additives, preservatives and colorings

Research published in 2021 in the International Journal of Environmental Research and Public Health suggests that a food additive used to preserve the shelf life of some processed snack treats may compromise the immune system.

These products are highly processed and associated with inflammation, and they can lead to imbalance in your bacterial communities, Kellman says. That in turn can affect your immune system.

Processed foods

Some processed foods claim to be “natural,” but contain significant amounts of sugar, refined carbs and additives and preservatives that are associated with inflammation. Higher levels of inflammation can weaken your immune system, Michalczyk says.

Research published in the American Journal of Lifestyle Medicine in 2018 found that processed foods are high in sugar, fat and salt, which creates a taste that makes people crave more of these kinds of foods.

Consuming these types of foods, however, can lead to weight gain, which is associated with increased risks for:


Cardiovascular disease.


Consuming too much sugar and salt is also associated with an increased risk of stroke.

Foods high in salt

If you want to keep your immune system healthy, you’re better off not reaching for the salt shaker, research suggests.

A study published in the journal Science Translational Medicine in 2020 suggests that individuals who consume a diet high in salt might be making themselves more vulnerable to bacterial infections. The study, conducted by researchers from the University of Bonn in Germany, noted that the typical Western diet is high in salt.

The American Heart Association recommends that adult consume no more than 2,300 milligrams of sodium — the amount in one teaspoon — a day.

To recap, here are eight foods and beverages that can compromise your immunity:

— Alcoholic beverages.

— Caffeine before bedtime.

— Foods with added sugar.

— Dairy products.

— Fast food.

— Food additives, preservatives and colorings.

— Processed foods.

— Foods high in salt.

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How Some Foods Can Compromise Your Immunity originally appeared on

Update 04/28/22: This story was published at an earlier date and has been updated with new information.

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