Nothing helps keep a body healthier than a strong immune system.  In healthy people, this happens naturally through adequate nutrition and moderate exercise.  However, different ingredients have different effects on immune systems, and some foods are known to be bigger immune system boosters than others.  Here's a list of foods containing high levels of nutrients that are especially known or their illness-fighting properties.  

Almonds

A half-cup serving size of almonds is not only high in protein, but contains all of your daily recommended Vitamin E, which is known to help boost the immune system.  Almonds also contain other important nutrients like niacin and riboflavin..

Oranges

Oranges are high in Vitamin C, which increases the production of infection-fighting white blood cells and antibodies, among other things.  Clinical studies have shown that people whose diets are higher in vitamin C have lower rates of colon, prostate, and breast cancer.

Blueberry

Blueberries are one of those “Super foods,” very high in disease-fighting antioxidants.  Blueberries are best eaten fresh, but they are also good dried, or blended into a cool purple smoothie.  

Seeds, Grains and Vegetable Oils

These food are high in Vitamin E, which is an important antioxidant, and enhances the production of B-cells, the immune cells that produce antibodies that destroy bacteria. Vitamin E is also popular for its anti aging properties.  In a study done at the Harvard School of Public Health, Vitamin E was shown to reduce the risk of heart attacks by fifty percent.

Garlic

When it comes to health benefits, garlic is another “Super food.”  An allium vegetable in the onion family, the nutritional benefits of garlic include immune system boosting and (some say) protection against certain forms of cancer.  

Green Tea

Clinical studies have shown that green tea (like most teas, only more so) is chock full of antioxidants that work at destroying potential cancer cells.  

Mushrooms

Mushrooms contain selenium and important antioxidants. Laboratory studies suggest that mushrooms also have antiviral, antibacterial, and anti-tumor effects.

Sweet Potato

Yams are loaded with beta-carotene, which helps eliminate cancer-causing free radicals. Sweet potatoes also contain a healthy dose of Vitamin A, which is believed to have some anti aging characteristics.

Oysters

Oysters are very high in Zinc, which has been shown to boost the immune system.  Zinc increases the production of white blood cells that fight infection, and is also known to slow the growth of cancer.  Six medium oysters contain three times the daily requirement for Zinc.  Still, many people buy Zinc-fortified cereals or Zinc supplements, because not everyone eats oysters all that often.   

Lobster, Shrimp and Red Snapper

These delicious foods contain high doses of selenium, a mineral that increases natural cancer-fighting cells. Selenium is also found in whole grains, brown rice, egg yolks, cottage cheese, sunflower seeds, garlic, Brazil nuts, and lamb.

Salmon, tuna and Mackerel

The oils derived from these types of fish are high in Omega-3 fatty acids.  People who ingest high levels of this nutrient seem to experience fewer and milder upper respiratory infections.  

Basically, a common sense diet of tasty, nutritious foods in moderate portions is a safe way to ensure getting all the vitamins your body needs.  But eating more of the foods mentioned above can lead to less frequent illnesses, and less severe symptoms when illnesses do occur.