Experts weigh-in on what to add and subtract to your diet for a healthy immune system.

Most of us can say that we at least try to eat a healthy diet full of fruits, vegetables, whole grains, and all of the other recommended superfoods that aid in warding off illness. While this should always be a top priority, there's no time like the present to ensure your immune system is in fighting condition and to know what not to eat or drink when you're sick—especially when the novel coronavirus (COVID-19) is spreading like wildfire across the globe.

woman squeezing lemon into soup bowl
Credit: Handemandaci / Getty images

"If there has been one consistent message regarding COVID-19 it is that those with weaker immune systems are at far greater risk of contracting the most severe symptomatic consequences," says Maria Sorbara Mora, R.D., founder of Integrated Eating. "While our nutritional status may not dissuade this foreign and novel invader from entering our body, how healthy we are can mean less severe symptoms and a better prognosis for recovery." Whether or not you're sick, proper nutrition is essential for keeping your body healthy both in the short and long-term. "When we eat a nutrient-rich diet, we give our body the tools it needs to support a healthy response to inflammation, which includes keeping us protected from antigens like bacteria and viruses," says Maggie Luther, N.D., medical director and formulator for Care/of.

If you do fall ill, what you eat becomes even more pivotal—as well as what you don't eat. Abstaining from certain foods and beverages can lift an extra burden from your body, which is already weak, Dr. Luther notes. Here's a guide for what foods and drinks you should avoid when you're sick.

Soda and Juice

Due to their high sugar content, drinks like soda and processed juice should be avoided whenever possible, but especially when you're sick. "Sugar suppresses the innate immune responses, leaving your body wide open to infection and open to the worsening of symptoms for hours after consuming these types of drinks," says Olivia Rose, N.D., a naturopathic doctor in Toronto, Canada. "Sugar is fuel for bacteria and viruses, causing increased replication, which can make you feel worse."

Instead, experts suggest sticking to water as opposed to sugar-laden drinks. "When you are dehydrated it is a stressor to the body and your immune system cannot function," notes Adam Splaver, M.D., clinical cardiologist and co-founder of NanoHealth Associates in Hollywood, Florida. "Hydration helps you flush out toxins through elimination and sweat."

Fried and Greasy Foods

When you're sick and camped out at home, you might be tempted to eat foods that make you feel good in the moment, like greasy takeout. But fried foods are devoid of many of the key nutrients needed for immune system activation, according to Dr. Rose. "Fried foods may also be laden with MSG which can decrease the function of your spleen and thymus gland cells—two key organs responsible for the production of immune cells that help fight infection," she says. Instead of eating something fried, opt for protein. Whether you get it from meat or a plant-based source, it's an essential nutrient our bodies use to build immune cells, according to Dr. Luther. Additionally, nuts, seeds, and foods like quinoa, squash, carrots, and beets are great foods to keep in the pantry and fridge. "They're packed with nutrients, and complex carbohydrates tend to keep us feeling full, which can help limit the urge to snack on junk food."


Most people love to start their day with a cup of joe, but coffee contains caffeine, which is a stimulant that can increase your stress hormones and disrupt your sleep. "Poor sleep weakens your immune system," notes Dr. Rose. "And, of course, add in a few spoons of sugar and that can have an even worse effect on your immune system's ability to fight infection." Instead of your typical coffee, make an antioxidant-rich tea. It can give you a caffeine boost while arming your body with powerful antioxidants that can fight off certain viruses. It also has anti-inflammatory effects keeping your health at its peak, so that you lower your chances of getting sick in the first place, notes Mora.


"It is not so much that gluten-containing foods are 'bad,' but because they are carriers for pollutants, toxins, and pesticides they may produce more inflammation in the body," says Mora. "Those with immune suppressed or immune compromised systems should be careful to put anything into their system that increases the inflammatory response." She recommends opting for naturally gluten-free carbohydrates, such as rice and potatoes and veering away from wheat products when you are under the weather or have allergy symptoms.


Many people enjoy a glass of wine or a beer at the end of the day to help themselves relax, but this can be self-sabotaging when you're already feeling run down. "Alcohol is dehydrating, can cause GI distress, and promotes inflammation which might aggravate your symptoms," says Samantha Cassetty R.D., chief nutrition officer for OMG! Nutrition. "Plus, if you're taking a fever-reducer with acetaminophen, the combination can lead to severe liver damage." If you're sick of plain old water and are looking for a hydrating flavorful option, coconut water is a good choice. "Fever can lead to fluid and electrolyte loss and coconut water is a natural electrolyte replenishment beverage," says Cassetty. "And sometimes when you're sick, it's easier to sip on a flavored drink like this."

Comments (1)

Martha Stewart Member
May 29, 2020
This ND is not offering particularly sound advice. Her assertion that sugar feeds bacteria and cancer omits the startling fact that glucose is required for every cell of the human body. White sugar isn't the best form of glucose for health, but when you are sick, it can certainly can fuel your cells if you're having trouble eating. It does not suppress the immune system in the short term. This myth should not be perpetuated by so-called "experts" on nutrition. I much more value what the dietician said. Stick with those for nutrition information, please. That is all they learn about and do, and they are the experts!