During Cold & Flu Season, Protect Yourself by Eating Right

September 29, 2016 by Joel Fuhrman, MD

Health Concerns: Cold and Flu, Immune Function

Colds and flus are a large burden on our society. Between treatments, illness-compromised productivity, and lost workdays, it is estimated that the common cold alone costs the U.S. $40 billion each year.1

We all know the basics for reducing exposure—wash your hands, avoid touching your face, and avoid being exposed to people who are already ill.  As for the influenza vaccine it is important to know that it is not very effective.

An independent analysis of flu vaccine studies by Cochrane -- a non-profit, non-government organization that organizes medical research information-- found that under typical conditions, for every 71 adults  vaccinated only one person would avoid influenza, or another way of saying it, you would have to be vaccinated every year for 71 years to save yourself one flu episode. For every 29 adults vaccinated, one would avoid a flu-like illness according to the Cochrane analysis. The study showed that the flu vaccine did NOT significantly affect the number of people hospitalized or working days lost, and did not prevent flu–associated complications or those rare flu–associated deaths in healthy adults.2

Staying safe from flu virus and colds

Those of us who eat healthfully need not worry about the dangers of the flu. Excellent nutrition can reduce our vulnerability to infection and reduce the length and severity of illness if we do become infected. Many micronutrients are required to support proper function of the immune system, and phytochemicals from colorful produce have additional anti-microbial and immune-boosting effects.

Make sure your diet includes the following immune boosting superfoods.


Mushrooms have a unique ability to activate the body’s natural immune defenses. Reishi and shiitake mushrooms enhance activity of natural killer (NK) cells, which attack cancerous and virus-infected cells.3,4 Shiitake mushrooms protect against influenza infection in animal studies.5-7

Fortunately, it is not only exotic mushrooms that benefit the immune system. Eating white button mushrooms daily was found to enhance immune defenses in mucosal linings such as those in the mouth and respiratory tract.8  Dendritic cells are another type of immune cell that protects the respiratory tract, and their activity is also enhanced by white button mushroom phytochemicals.9

Mushrooms should only be eaten cooked: several raw culinary mushrooms contain a potentially harmful compound called agaritine, and cooking mushrooms significantly reduces the agaritine content.10,11

Because various mushrooms have differing and profound immune system and anti-cancer benefits, I even recommend taking a mixed mushroom supplement containing 10 well-documented protective species. 

Cruciferous vegetables

The cruciferous family of vegetables includes kale, collards, mustard greens, arugula, watercress, broccoli, broccoli rabe, cabbage, cauliflower, kohlrabi, and more. The bitter, spicy or pungent flavors of these vegetables are provided by glucosinolates, which are converted into potent anti-cancer compounds, called isothiocyanates (ITCs), upon chopping or chewing.

In addition to their anti-cancer effects, ITCs also support the immune system and have antimicrobial properties.

To maximize ITCs, chop cruciferous vegetables finely, eat them raw and chew them well; the enzyme that converts glucosinolates to ITCs (called myrosinase) is activated by disrupting the plant cells and deactivated by heat. However, you can still get ITCs from your cooked cruciferous vegetables: chop them finely before you begin to cook and add some raw cruciferous to the meal.

For instance, if you are eating cooked broccoli, add some shredded cabbage to your salad, which will provide some myrosinase to produce more ITC from the already cooked broccoli. Gut bacteria have the myrosinase enzyme, so a small amount of ITCs from cooked cruciferous vegetables will be produced in the digestive tract as well.

Cruciferous vegetable phytochemicals may enhance interferon activity, which is an important component of the body’s antiviral response.12,13


Berries are powerful anti-cancer foods that also offer protection against viruses. Antioxidants called flavonoids, which are abundant in berries, have antiviral activity.14 In fact, if you do get the flu, taking anthocyanin-rich elderberry juice may even shorten the duration of your symptoms.15-17

Berries and grapes are also rich in resveratrol, another antioxidant phytochemical with strong antiviral effects—resveratrol has been shown to block the replication of influenza and other respiratory viruses.18-20

Plus, strawberries are high in vitamin C, which protects immune cells from oxidative damage.21

The benefits of berries go far beyond cold and flu protection. Flavonoid antioxidants like those in berries are not just antioxidants—they have many beneficial effects inside cells: flavonoids activate the body’s natural detoxification enzymes, block the growth of cancer cells, decrease inflammation, and support proper blood pressure regulation.22

Berries (and pomegranates) are also extremely rich in another antioxidant called ellagic acid, a compound known to block cancer cell and tumor growth.23-25

Onions & Garlic

There is no convincing evidence for using garlic supplements for symptoms of the common cold.26 However, eating garlic and onions daily has clear benefits when it comes to cancer prevention, and may help to increase functionality of the cells in our immune system..27,28  Plus, several phytochemicals in garlic have virus-killing activity against common respiratory viruses.29

Like cruciferous vegetables, the active compounds in onions and garlic are produced when the plant cells are disrupted, so It’s best to chop them before eating raw and before they are heated when cooking.

Helpful supplements

Vitamin D and zinc are important players in immune function, so maintaining adequate stores of these micronutrients will also help to protect against colds and flus. Children given vitamin D supplements throughout the winter reduced the occurrence of flu compared to a placebo group, and taking supplemental zinc regularly was found to slightly reduce the number of colds caught by children.16,30 Since vitamin D is not readily available in the food supply, and zinc is not highly absorbed from plant foods, well-designed supplements are a good choice. Please see my Vitamin Advisor for more information. (link to VA)

Treating cold and flu symptoms

Common cold remedies are ineffective, and some may even prolong the illness. For example, mega doses of vitamin C do not prevent colds or reduce symptoms, and fever-reducing medications actually hinder the body’s attack on the infection. (In my book Super Immunity, I evaluate a number of common cold and flu remedies.)

Don’t be alarmed if your cold symptoms last longer than you expect. On average, patients report that their common cold symptoms last one and a half to two weeks. In children, earaches tend to last anywhere from less than one day to 9 days, sore throat 2 to 7 days, cough up to 25 days, and the common cold 7 to 15 days.31

In time, the body will clear the virus on its own. Remember, over-the-counter medications merely mask symptoms, and may even impair healing. However, if you experience a sudden worsening of symptoms, especially including labored breathing, or a fever above 103 degrees for three days, then it is time to call the doctor.

Of course, as your diet improves, you will be less likely to become ill, and if you do, you will recover more quickly. This year, to protect yourself against cold and flu, get enough sleep, avoid putting your hands near your nose or mouth, and eat healthfully. A nutrient-rich diet provides your body with a spectrum of immunity-boosting phytochemicals that also protect against heart disease, diabetes and cancer.

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Joel Fuhrman, M.D. is a board-certified family physician, seven-time New York Times bestselling author and internationally recognized expert on nutrition and natural healing, who specializes in preventing and reversing disease through nutritional methods. Dr. Fuhrman coined the term “Nutritarian” to describe his longevity-promoting, nutrient dense, plant-rich eating style.
For over 30 years, Dr. Fuhrman has shown that it is possible to achieve sustainable weight loss and reverse heart disease, diabetes and many other illnesses using smart nutrition. In his medical practice, and through his books and PBS television specials, he continues to bring this life-saving message to hundreds of thousands of people around the world.