There are few times of the year when we're busier and in greater need of good health than the holidays. Unfortunately, there are also few times when it is harder to stay healthy. Flu season, which typically starts in November and peaks in January\/February, strikes up to 20 percent of Americans. Here are five immunity boosters that can help you function at your best this holiday season: #1 Eat a Nutritious Diet Like any other machine, the human body requires the proper fuel to function. Some studies have found that deficiencies in protein and various micronutrients, such as zinc, selenium, iron, copper, folic acid, and vitamins A, B6, C, and E, have altered immune responses in animals. A diet rich in fruits, vegetables, whole grains and lean protein (including nuts, beans, fish and lean cuts of meat) can help ensure that you get adequate amounts of each of these disease-fighters. While any type of fruit or vegetable can be health-promoting, those with vitamin A (sweet potatoes, carrots and dark leafy greens), vitamin C (citrus fruits, bell peppers and broccoli) and vitamin E (nuts, seeds and turnip greens) are particularly helpful in preventing illness. #2 Embrace a Healthy Lifestyle A healthy lifestyle is the best armor against colds and flus. This means avoiding smoking cigarettes and use of other drugs, drinking alcohol moderately, and washing your hands regularly. It also means exercising for 20 to 30 minutes a day, most days of the week. Physical activity promotes good circulation, allowing cells to move through the body freely, which improves immune function. Keep your routine regular and moderate as high-intensity activity may actually increase your risk of illness. #3 Keep Stress in Check Stress hormones impact many aspects of the immune response. In research published in Biological Psychiatry, people exposed to chronic stress (caregivers of family members with cancer) experienced changes in their white blood cells that left them with an increased risk of illness. Find healthy ways to cope with stress, such as practicing yoga, listening to music or taking a walk. You'll not only feel better but you'll likely stay healthier through the holiday season #4 Get Plenty of Sleep It's tempting to cut out an hour or two of sleep to find the time for last-minute holiday preparations, but losing sleep is not worth the sacrifice you make in terms of health. Animal studies show that sleep deprivation results in a suppressed immune system. Most people need seven to nine hours of sleep per night, and the holidays are no exception. #5 Supplement Your Diet Not everyone can get all of the necessary vitamins and nutrients from diet alone. For maximum immune protection, consider supplementing with the following: \tGinseng \tRhodiola Rosea \tGarlic \tProbiotics ("good bacteria") \tGlutamine These supplements have minimal side effects and have some evidence supporting their role in immune function. Also consider getting your vitamin D levels checked. In studies, low levels of vitamin D have been linked to an increase in seasonal cold and flu, and many people are deficient. To keep up with the holiday parties, gift-buying and family get-togethers that contribute to the joy of the season, you need to feel your best. While there are no guarantees that you'll manage to elude the dreaded cold or flu this season, by building up your immune system you can give yourself a fighting chance.