Now is the time to take preventative action and “power up” for the cold days ahead. Prevention is better than the cure — how many times have we heard that? We hear it, but do we heed it?

Take preventative action against colds, flu and many other illnesses (such as seasonal affective disorder), that prevail in the winter time by paying special attention to your nutrition. Don’t throw all your healthy eating habits out the window just because it’s cold outside and you are feeling down. Did you know that the average adult catches between two and four colds per year, and children get up to 10 colds a year? That’s a lot of tissues and time off work. The human body has many internal and external barriers that it uses to defend itself against infection. Instead of defending your body with hand sanitizer, try tweaking your diet to include some of nature’s own immune-boosting super-foods:

1) Your skin is an external defense barrier against bacteria and toxins, so ensure that you are promoting its natural barrier functions by eating Vitamin C – eat plenty of fruits and vegetables. Crank up your immunity with plenty of cruciferous vegetables — examples include broccoli, bok choy, brussel sprouts and kale — which increase your body’s ability to fight infection and have the added bonus of being potent sources of Vitamins C and E and promote healthy skin. Root vegetables, such as the sweet potato, are packed full of beta-carotene, a precursor to Vitamin A and loaded with Vitamin C, and are perfect paired with carrots in a warming soup. Vegetable soups are an excellent way of staying warm, promoting healthy skin and boosting your immunity.

2) Gut flora that reside in your digestive system help to protect the body against infection by creating a natural barrier against harmful toxins, bacteria and antigens. These bacteria also aid in food digestion, nutrient and vitamin absorption. Imbalances in gut flora often occur after an illness, stress or after taking a course of antibiotics. You should know that good bacteria in your gut thrive on a generous supply of fiber contained in vegetables, legumes, nuts and seeds. Yogurts populated with probiotics (live active bacterial cultures) are a good way to boost immunity, but buyers beware: certain brands of yogurt may contain live cultures but are often loaded with sugar which can compromise your immunity. Stick to the low-fat plain varieties and sweeten them naturally with fruit.

3) Other power foods that boost immunity include garlic (which contains allicin, a natural antibacterial and anti-fungal), and mushrooms, especially shitake and mitake, which boost white blood cell production. Foods like garlic and green tea also contain polyphenols which foster friendly microbes in the gut.

During the winter months, diminished sunshine levels lead to a decline in serotonin (a “feel good” chemical released by the brain) which in turn is linked to symptoms of depression, anxiety, fatigue and insomnia. There are plenty of mood elevating, serotonin-enhancing antidepressants available by prescription; but for a lighter case of the blues, there are several quick nutritional fixes that can be used to boost serotonin levels naturally. Reduced serotonin levels may explain why we crave our comfort foods and are tempted to stay huddled indoors by the fire with our TV remote close at hand.

1) Instead of reaching for a calorie-laden Danish and hot chocolate, try a bowl of oatmeal with fruit and a cup of tea for breakfast.

2) Opt for breads made with whole grains, like spelt, which are good sources of both tryptophan (a precursor to serotonin) and zinc.

3) By choosing healthy carbohydrates like whole grains, winter squash and pumpkin, you will boost serotonin levels and pack a nutrient dense punch of vitamins without consuming high calories.

4) Low levels of the mineral zinc have been associated with an increase in depression and lowered immunity, so oyster enthusiasts can rejoice — they’re packed full of zinc! Not too keen on eating them raw? Then bake them, shell and all.

Our bodies make serotonin from a precursor amino acid called tryptophan — tryptophan is not synthesized by our bodies so we must eat foods rich in the amino acid: sources include eggs, cottage cheese (low-fat varieties are recommended), turkey, poultry, sesame and sunflower seeds, walnuts, banana and oats. You also need to combine these with foods rich in vitamin B, (folate) such as brown rice, corn, green leafy vegetables, beans, lentils, broccoli and spinach. Turkey and chicken are excellent sources of tryptophan so combine these foods with a small amount of complex carbohydrates that help in processing tryptophan. In fact, people often feel relaxed and sleepy after eating Thanksgiving dinner and this may be attributed to the fact that turkey contains tryptophan in high concentrations.

Avoid over-stimulating your body with caffeine, alcohol and sugar. Although these substances give you a quick lift, they blunt hormonal processes like serotonin production in the long run so limit caffeine to one a day but avoid the sugar rush altogether!

Warming drinks like black or green tea contain polyphenols that boost immunity (that goes for the caffeine-free varieties as well). Flavor tea with herbs like mint or chamomile, which are calming. In addition, drink lots of water even though you may not feel the urge to do so in winter. We often confuse hunger with thirst so it’s a good idea to drink a glass of water before reaching for a snack; but more importantly, keeping well hydrated will help keep those germs at bay!

On sunny days, even if it’s cold, make it a priority to bundle up and get outdoors for a brisk walk — not only will you feel good but will boost both your serotonin and Vitamin D levels. Lastly, let’s not forget the most powerful mood enhancer of all — spending time with a loved one!

So this winter stay healthy, boost your immunity, keep warm and eat yourself to a happier mood!

Rosemary Barclay holds a bachelor’s degree and a PhD in biochemistry and is a board-certified nutritionist and esthetician. She is a member of the American College of Nutrition. For more information, visit www.bonnesantellc.com.