his is the time of year when we're all more susceptible to getting colds, flus and other yucky illnesses. Catching a cold or flu in the winter time is more likely, since we're spending more time indoors where we are more exposed to other people's germs. The holidays can increase our stress levels and interfere with our sleep, which leaves us more vulnerable to illnesses, too. With all of these changes and stresses, our immune systems and our eating habits can suffer. Maintaining your healthful diet, exercising regularly, and getting enough sleep throughout the year help to keep your health on track, but there are a few specific nutrients and practices that you can target to help give your immune system the extra boost it needs to combat those winter stressors.

Antioxidants, specifically vitamins A, C and E, are a key line of defense against immune system invaders. Found mainly in orange, green and red fruits and vegetables, as well as nuts and plant oils, these vitamins keep our skin and mucous membranes healthy so they can block any germs that try to enter our bodies. They also help repair cells inside the body. Top food sources include carrots and orange-fleshed sweet potatoes for vitamin A and beta-carotene; red bell peppers, broccoli, oranges and kiwi for vitamin C; and nuts, sunflower seeds, avocado and olive oil for vitamin E.

Zinc, iron, and selenium are all immune-boosting minerals found in common in eggs, whole grains, chicken, turkey, beef, fish and seafood. They work together to help produce white blood cells and other immune-protecting cells. Our bodies only need small amounts of these nutrients (that's why they're called trace minerals), so don't think that increasing your portion sizes of these foods will give you extra protection. Just be sure that you eat a good variety of these foods and choose the leanest cuts of red meat and poultry.

Allyl sulfides may have antibacterial, antiviral, and antifungal powers that help tone up the immune system-great for fighting colds and infections! This phytonutrient is found in garlic and onions and has many cardiovascular benefits, too. For the best and most pleasant results, chop up a clove of fresh garlic and swallow the pieces as you would a pill-without chewing-once a day (not if you take blood thinners, though).

Beta glucans are a type of soluble fiber that enhance the immune system. Mushrooms, like shiitake, oyster, enoki, portobello and maitake, are usually touted for their immune-boosting powers, and these large sugar molecules are the reason. They can help increase the number and activity of immune cells and defend against bacteria and viruses that enter the system. Whole grains, mainly oats and barley, also contain beta glucans.

Probiotics are the live and active cultures found in yogurt and other fermented dairy products, like Dannon DanActive Immunity. There is some evidence that cultures help to strengthen the body's defenses. Cultures such as lactobacillus acidophilus are "good" bacteria that live in the intestine and may protect against diarrhea, as well as boost the immune system.

Washing your hands frequently is perhaps the most important thing you can do to prevent illness. Use soap and water and rub your hands together vigorously for 20 seconds to kill all the bacteria that can cause colds, flus or even give you diarrhea. Be mindful of what you touch and try to avoid touching your face, especially your mouth, nose and eyes, as much as possible, since they are common points of entry for infections.

Exercise, especially yoga, can help to boost the immune system. Both have stress-reduction benefits, which can help free up our immune systems to make more powerful disease-fighting cells. Yoga seems to be especially helpful for those prone to respiratory problems, like colds, asthma, allergies and chest infections. If you're in the throes of an illness, however, try to stay out of the gym or yoga studio, since its bad karma to spread your germs and you may run your immune system down even more.

Adequate sleep goes a long way towards helping your body repair itself and boost the number of killer cells your immune system makes to fight off illness. Most of us need seven to nine hours a night.

As I said before, eating well is just one important component of a healthy lifestyle. The best cold and flu protection is integral; try to get regular aerobic exercise, drink plenty of water, get adequate sleep each night, consider getting a flu shot and remember to laugh as often as possible. Laughter seems to help boost our immune systems, too! Of course there are not guarantees in life, but all that should add up to a healthy winter season.