Rev up your body’s defenses with these everyday strategies.

1. Mind the Fat

High-fat diets can make your immune system “less functional and more sluggish,” says Simin Nikbin Meydani, Ph.D., the associate director of the Jean Mayer USDA Human Nutrition Research Center on Aging, at Tufts University, in Boston. In fact, a Tufts study compared the effects on immune function of a typical Western diet (containing 38 percent fat) to those of a cholesterol-lowering diet (28 percent fat) and discovered that the lower-fat diet enhanced the functioning of T lymphocytes (or T cells), which help ward off infections. Aim to get 25 to 30 percent of your total daily calories from fat, with most of those coming from monounsaturated fats (found in olive oil, avocados, and peanut butter) and polyunsaturated fats (think sunflower and corn oils, salmon, and walnuts). Limit saturated fats (such as those in whole milk, butter, and high-fat meats) and trans fats (which are listed on labels as partially hydrogenated oils).

2. Eat Plenty of Protein

The amino acids in protein are the building blocks of the cells in your immune system, and they help create protective white blood cells and antibodies. “These cells then block invading pathogens,” says Meydani. Women should consume approximately 50 grams of protein a day (about 60 to 75 grams a day during pregnancy) or get at least 10 to 15 percent of their daily calories from protein. Choose lean protein, such as fish, skinless poultry, eggs, beans, low-fat cuts of beef, or soy products.

3. Stay in Motion

According to several studies, moderate exercise (walking briskly, cycling, or swimming for 45 minutes, five times a week) has been shown to enhance your body’s defenses and even cut down sick days by up to 50 percent. Aerobic exercise enhances blood flow, and “the circulatory system is the route of transport for those cells that fight off infection,” says David Katz, an internist and the director of the Yale University Prevention Research Center, in Derby, Connecticut. But don’t assume that more exercise makes for superhuman bug resistance. Studies have revealed that prolonged, vigorous exercise (like running a marathon) can compromise immunity after the workout.

4. Fit Into Your Skinny Jeans

In a study conducted at Tufts University, researchers put slightly overweight adults with elevated cholesterol levels on a low-fat diet. After 12 weeks, the subjects had lost weight and lowered their cholesterol. More surprising, their T-cell function had noticeably improved. “And we’re not talking about drastic weight loss,” says Meydani. “Losing even a few pounds can yield an improvement in how well your immune cells function.” To drop a pound a week, each day aim to trim 250 calories from your diet and burn 250 calories through exercise.

5. Show Off Your Musical Talents

Research conducted at Johann Wolfgang Goethe University, in Frankfurt, indicates that singing helps improve both a person’s mood and the levels of antibodies that protect from invading germs. If you really want to ward off those pesky germs, you may want to arm yourself with a bottle of Hand Sanitizer so you can give your hands a clean between coming into contact with surfaces. Also, a study at Willamette University, in Salem, Oregon, found that when people played percussion instruments, like the drums, and sang along, they showed greater concentrations of these antibodies than did those who simply listened to music. This is an example of how something that is enjoyable is also good for you, says Carl Charnetski, Ph.D., a professor of psychology at Wilkes University, in Wilkes-Barre, Pennsylvania.

6. Pet Something Fluffy

Strange but true: A study conducted at Wilkes University found that stroking a dog for 18 minutes led to a significant spike in secretory immunoglobulin A (IgA), which helps protect the body against germs trying to enter it. Again, chalk this up to the power of pleasure, says Charnetski, which triggers the release of chemicals in the brain that enhance immune function. That’s why it pays to pet your dog or cat (or your neighbor’s) as often as possible. If you’re not an animal lover, don’t worry. A study conducted at the University of Zurich revealed that touching a loved one in an affectionate way?rubbing each other’s shoulders or neck, say?has a similar effect. A simple act like that can help lower levels of the stress hormone cortisol, which can hamper white blood cell function.

7. Get Three Colours in Every Meal

Fruits and vegetables in reds, oranges, yellows, and greens, are especially rich in carotenoids, which help immune cells surround and kill off a virus. If you struggle to eat enough fruits and vegetables, has options in order to obtain the vitamins they provide. Fruits and vegetables also contain antioxidants and vitamins A and C, which strengthen cells and help them defend against invading bacteria, says Charles Stephensen, Ph.D., a research scientist with the U.S. Department of Agriculture’s Western Human Nutrition Research Center, at the University of California, Davis. In addition to fruit and veg, adding certain extracts containing antioxidants will help boost your immune system further. Using things like a black elderberry supplement (elderberry is known for its immunity-boosting properties) will help give you that extra boost by just adding a few drops to some water; it’s much easier than fitting your fruit and veg into your schedule! Aim for five to nine servings of produce a day, which is easier to do than you may think: Have at least one serving at each meal and two as snacks and?bingo?you’ve already reached five.

8. Eat Good Bacteria

Studies on specific probiotic products have shown that their ‘good bacteria’ can help prevent or reduce the duration of some gastrointestinal, urogenital, and respiratory illnesses,” says Gregor Reid, Ph.D., a scientist at the Lawson Health Research Institute, in London, Canada. Probiotic foods or supplements can be found in foods that are easy to incorporate into your daily diet. Look for probiotic yogurts (such as Dannon Activia and DanActive), tempeh, fortified cheeses, and kefir drinks. Be sure to choose probiotic foods or supplements that contain proven strains, such as Lactobacillus rhamnosus GR-1 or GG, L. casei Immunitas, and Bifidobacterium animalis DN 114 001; don’t rely just on the words PROBIOTIC or ACIDOPHILUS on the label.

9. Make Late Nights an Exception

Set aside ample time to get the restorative shut-eye that your body needs (most experts advise seven to nine hours a night). In a study conducted at the Mount Sinai School of Medicine, in New York City, women who were well rested had more active killer cells (white blood cells that attack germs) than did women who felt tired. To make sure you nod off quickly, keep your room cool, quiet, and dark. Try to avoid caffeine, alcohol, and strenuous exercise at least three hours before bedtime.

10. Resolve to Really Relax

Carve out time for whatever helps you unwind?be it yoga, painting, or crossword puzzles?on a regular basis, and ideally every day. “That chronic, teeth-grinding kind of stress suppresses circulation of your immune cells, inhibits your body’s responses to invaders, and elevates levels of cortisol,” says Bruce McEwen, Ph.D., the director of the Harold and Margaret Milliken Hatch Laboratory of Neuroendocrinology, at Rockefeller University, in New York City.