This year’s cold and flu season has proven to be one of the most severe and widespread in a decade—and it hasn’t yet peaked. Short of isolating yourself and your family for the next several weeks, what can you do to prevent illness or, at least minimize the symptoms and discomfort?

Doctors recommend an annual flu shot at least two weeks before the season begins, as well as frequent hand-washing, getting adequate sleep and moderate exercise.

Another important step you can take is right in your kitchen—strengthening your natural immune system with a diet dense in protein, vitamins, minerals and other nutrients found in whole, unprocessed foods.

Flu Fighting Nutrition

A strong immune system is your best defense against disease, but most people pay little attention until they see their coworkers coughing and sneezing and, generally, contaminating every surface around them.

Whether at work, or school, we’re all at risk of being exposed to bacteria and viruses, which can then be brought into the home environment. Younger children, in particular, are more likely to be around people who are sick at school.

“Children’s immune systems are immature and it’s normal for them to have multiple viruses or infections each year; their immune systems are building memory,” says MemorialCare Medical Group Pediatrician Silvia Martinez- Wikefeldt, MD. “Unfortunately, the children bring it home to their parents, whose immune systems may be weakened by poor diet, lack of sleep, lack of exercise, or stress, and the parents take it to their workplace.”

While we tend to pay more attention to our health during cold and flu season, maintaining a healthy immune system should be a priority all year—like maintaining weight, muscle mass, or even our teeth—but if that hasn’t been the case, right now is a good time to start! Here’s a look at some immunity-building nutrients and the foods that provide them.

Vitamin A
Function: Helps maintain the mucosal lining of the respiratory and gastrointestinal tracts to protect against infection. Also strengthens the adaptive immune system to help fight invasive viruses and bacteria.

Food Sources: Orange foods, such as sweet potatoes, carrots and apricots; dark leafy greens, like spinach and kale; eggs; and bell peppers.

Vitamin B6
Function: Supports numerous biochemical reactions that help your body fight infection.

Food Sources: Meat, such as grass-fed beef, turkey or chicken breast; fish, such as salmon and tuna; pistachios, sunflower or sesame seeds; pinto or garbanzo beans; avocados; grains, such as amaranth.

Vitamin C
Function: Has a wide-ranging impact on the immune system, including the activity of T-lymphocytes, which recruit and coordinate the body’s disease-fighting cells, and phagocytes, which engulf and destroy foreign invaders.

Food Sources: Citrus fruits, such as oranges, grapefruits and tangerines; strawberries and papaya; vegetables, such as spinach, kale, Brussel sprouts and broccoli.

Vitamin D
Function: Regulates both the innate and adaptive immune systems to quickly identify and destroy pathogens that enter the body.

Food Sources: Fatty fish, such as salmon, herrings and sardines; shellfish, such as oysters and shrimp; egg yolks; mushrooms; fortified milk, juice or cereal. Your body also synthesizes Vitamin D when exposed to sunlight.

What to eat: shellfish, such as cooked oysters, crab and lobster; meats, especially grass-fed beef and lamb; toasted wheat germ; spinach; cashews; pumpkin, squash and sesame seeds; dark chocolate.

Function: Develops and activates T-lymphocytes. When taken at the first sign of illness, zinc prevents cold viruses from binding and replicating in the mucous membranes of the nose.

What to eat: yogurt with live and active cultures; kefir; milk with probiotics, such as buttermilk or sweet acidophilus; cultured vegetables, such as unpasteurized sauerkraut and kimchi; miso; kombucha; soft cheeses, such as those made from goat’s or sheep’s milk; sourdough bread; sour pickles or olives cured in brine, not vinegar.

Function: Healthy human intestines support some 10-trillion microorganisms which not only break down particles of food, but also dangerous bacteria, viruses, germs and fungi. Keeping a healthy bacteria balance in your gut prevents pathogens from entering the bloodstream.

Raw Garlic contains alliin, which converts to allicin when the clove is crushed or chewed. Allicin increases the cold- and flu-fighting response of certain white blood cells.

Onions contain a variety of nutrients that boost your immune system, plus a powerful antioxidant called quercetin which has antiviral and histamine-regulating properties.

Ginger has powerful anti-bacterial, anti-viral and anti-inflammatory compounds that target stuffy noses and keep rhinoviruses from binding to cells in the mucus membranes.

Turmeric contains curcumin, a compound widely known for its anti-inflammatory properties, but research has also shown that it has the ability to support and modulate the immune system.

What to eat: meats and fish; low-fat dairy products, such as yogurt, milk and cottage cheese; plant-based combinations, such as beans and brown rice; soy products; nuts and nut butters.

Function: The protein you consume is broken down into smaller pieces, known as amino acids. These pieces are then reassembled into proteins your body needs to function, including antibodies and complement proteins that support your immune system cells.

Drinking eight to ten glasses of water every day is one of the most effective ways to flush toxins from your body and support the health of your immune system.

“Water plays a critical role in the production of blood and lymph which work together to carry nutrients and pathogen-fighting cells from your thymus and bone marrow to every cell in your body,” says Dr. Martinez-Wikefeldt. “Without water, the body’s defenses can’t be mobilized and toxins can’t be removed.”

Water is also critical to maintaining colon health, the most important pathway for the elimination of toxins and waste. If toxins are allowed to accumulate in the colon, healthy bacteria will die off and unhealthy microorganisms will grow. In fact, studies have shown that 80 to 90 percent of all diseases are directly or indirectly related to gut health.

The best part of how nutrition can boost your immune system, is that we have complete control over what we put in our bodies and the bodies of our kids. It’s important to talk to your doctor before flu season, so you can learn about preventive measures and ways to maintain a powerful immune system.