Hippocrates, the father of modern medicine, is credited with saying: “Let food be thy medicine and medicine be thy food.” That advice, which dates to 400 B.C., still prevails today.

It’s particularly relevant when you’re feeling under the weather. In fact, eating the right foods – and avoiding the wrong ones – can help boost your immune system to fight infections, including cold and flu viruses, experts say.

“What you put in your mouth can have an enormous influence on the digestive tract and the balance of healthy gut flora which has been scientifically proven to affect all kinds of conditions from mental health to immune response,” says Sophie Manolas, clinical nutritionist and author of “The Essential Edible Pharmacy.”

She tells Newsmax Health good nutrition is the “cornerstone of good health,” adding: “When you are ill using medicinal foods which have been proven to be effective for millennia should always be the starting point to recovery.”

With that in mind, here are some suggestions for using food as medicine when you’re feeling sick:

Your flu remedy: Coconut oil. No one want to be felled by the flu so stopping it in its tracks is essential, says Manolas. “Since the flu is caused by a virus, taking coconut oil, an incredible heat stable antiviral can help you recover.” Simply stir a teaspoon of coconut oil into a cup of herbal tea.

Best stress aid: Parsnips. “Parsnips are the new carrot,” says the Australian expert. “The complex carbohydrate aids in serotonin production which helps you reach a state of calm more quickly.” The mineral rich veggie also supports healthy bones, blood cells and clear skin.

Common cold fighter: Zinc. Ramp up your intake of foods rich in zinc such as pumpkin seeds, pecans, almonds, beans, and lentils, says Dr. Jennifer Stagg N.D., author of “Unzip Your Genes: 5 Choices to Reveal a Radically Radiant You.”

She tells Newsmax Health: “Zinc has been shown to reduce the duration of a cold and one of my favorite remedies.” If you are dealing with a nagging cough, use honey which is a natural and effective cough suppressant, Adding essential oils like thyme—which has antiviral activity--to traditional steam inhalation can help ease congestion and a stuffy nose.

Ideal multivitamin: Greens and fruits. Stagg says that optimal levels of vitamins and minerals are important but don’t overlook the pigments and small chemicals or micronutrients found in plants, called phytonutrients. These compounds affect how your DNA is expressed and have a significant impact on your health. “My top choices are broccoli, leafy greens, green tea, apples, and raspberries. Red wine is another good choice,” says Stagg

Headache remedy: Water. The simplest and most effective remedy for tension headaches is water. Staying hydrated is an important foundation in preventing headaches, too, but even at the first sign of a headache coming on, drink a large glass of water. Manolas suggests adding a slice of lemon to the water for extra healing power.

Eating magnesium rich foods like nuts, especially almonds, cashews and Brazil nuts can offer relief as well. The anti-inflammatory effect of turmeric can be of great benefit when dealing with headaches, says Stagg, who often prescribes this potent herb as a safe alternative taking pain relievers.

Your emergen-C replacement: Red pepper. “In my opinion, red peppers are one of the finest raw foods to eat,” says Manolas. “Snacking on red peppers boosts your immunity by giving it a mega dose of vitamin C as well as carotenoids, fiber and vitamin E. Fill your fridge with extra peppers during the cold and flu season to ward off unwanted illnesses.

Nausea relief: Ginger. If you have an upset tummy during the stressful holiday season, ginger may be your go -to rescue remedy. This powerful spice has been proven to be effective against morning sickness and sea sickness. It contains a powerful compound called gingerol which helps quell bloating and indigestion as well. It also keeps bacterial infections at bay.

Add grated ginger to stir fries and salad dressing or puree it into smoothies or juices.