If you’re looking for ways to prevent  colds and flu, your first step should be to plan your meals to include foods that are powerful immune system boosters.
Citrus fruits: Vitamin C is thought to increase the production of white blood cells. These are key to fighting infections. Because your body doesn’t produce or store them, you need daily vitamin C for continued health. Almost all citrus fruits are high in vitamin C. Try to add a squeeze of this vitamin to any meal.
Red bell peppers: Red bell peppers contain twice as much vitamin C as citrus. They’re also a rich source of beta carotene. Besides boosting your immune system, vitamin C may help maintain healthy skin.
Broccoli: Broccoli is supercharged with vitamins and minerals. Packed with vitamins A, C, and E, as well as many other antioxidants and fibre, broccoli is one of the healthiest vegetables you can put on your table. The key to keeping its power intact is to cook it as little as possible — or better yet, not at all.
Garlic: Garlic’s immune-boosting properties seem to come from a heavy concentration of sulphur-containing compounds, such as allicin.
Ginger: Ginger may help decrease inflammation, which can help reduce a sore throat and other inflammatory illnesses.
Spinach: Spinach is rich in vitamin C. It’s also packed with numerous antioxidants and beta carotene, which may increase the infection-fighting ability of our immune systems. Similar to broccoli, spinach is healthiest when it’s cooked as little as possible so that it retains its nutrients. However, light cooking enhances its vitamin A and allows other nutrients to be released from oxalic acid.
Yogurt: Look for yogurts that have “live and active cultures” printed on the label, like Greek yogurt. These cultures may stimulate your immune system to help fight diseases. Try to get plain yogurts you can sweeten with healthy fruits and a drizzle of honey instead. Yogurt can also be a great source of vitamin D. Vitamin D regulates the immune system and is thought to boost our body’s natural defences against disease.
Almonds: Vitamin E is key to a healthy immune system. It’s a fat-soluble vitamin, meaning it requires the presence of fat to be absorbed properly. Nuts, such as almonds, are packed with the vitamin and also have healthy fats. A half-cup serving, which is about 46 whole, shelled almonds, provides nearly 100 percent of the recommended daily amount of vitamin E.
Tumeric:  This spice has been used for years as an anti-inflammatory in treating both osteoarthritis and rheumatoid arthritis.
Green tea: It really excels is in its levels of Epigallocatechin Gallate, or EGCG, another powerful antioxidant. EGCG has been shown to enhance immune function.
Kiwi: Naturally full of a ton of essential nutrients, including folate, potassium, vitamin K, and vitamin C. Vitamin C boosts white blood cells to fight infection, while kiwi’s other nutrients keep the rest of your body functioning properly.
Poultry: Chicken soup helps improve symptoms of a cold and also helps protect you from getting sick in the first place. Poultry, such as chicken and turkey, is high in vitamin B-6. About 3 ounces of light turkey or chicken meat contains 40 to 50 percent of your daily recommended amount of B-6. Vitamin B-6 is an important player in many of the chemical reactions that happen in the body. It’s also vital to the formation of new and healthy red blood cells. Stock or broth made by boiling chicken bones contains gelatin, chondroitin, and other nutrients helpful for gut healing and immunity.
Sunflower seeds: Sunflower seeds are full of nutrients, including phosphorus, magnesium, and vitamin B-6. They’re also incredibly high in vitamin E, a powerful antioxidant. Vitamin E is important in regulating and maintaining immune system function. Other foods with high amounts of vitamin E include avocados and dark leafy greens.