With every change of season our immune system takes a beating, especially between fall and winter. Our body comes under stress when the microbe populations fluctuate, favored by the changes in atmospheric conditions. Only the most robust immune systems can withstand the onslaught of new types of microbes.
Many ancient cultures had special brews of immunity-boosting  herbs and foods that were ritually taken at the turn of seasons or at the beginning of winter and summer solstices. Ancient wisdom may be lost to us forever, but we can still take advantage of nutritious foods that contain active compounds designed to build up the body’s defenses.
Edible seeds in the process of germination are excellent sources of many bioactive compounds that increase immunity. B-group vitamins and Vitamin C are among them. Food grains like quinoa, oats, brown rice and barley, different kinds of beans and lentils, as well as oilseeds like sunflower and linseed are almost as popular in sprout form. On germination, their complex carbohydrates, proteins and fats turn into simpler sugars, amino acids, and fatty acids, making them easily digestible and absorbable by the body. The greatest advantage of sprouts is that you can easily make a fresh batch on your kitchen counter, and enjoy all the health benefits without worrying about nutrient loss in storage.
2. Fermented foods
Fermentation  of food is caused by the growth of bacteria and fungi. Man learned to take advantage of certain microbial actions by introducing their cultures into food items like milk and dough. Yeasts are used to ferment dough and in the making of wine.
Lactobacillus bacteria turn milk into yogurt. These organisms partially digest the food, and make many essential nutrients like vitamins available to the body. Moreover, live cultures keep the intestinal flora healthy. Since a large portion of our immune system is regulated by our intestinal health, it is wise to consider keeping as many healthy bacteria thriving as possible.
Other traditional fermented foods includes natto, tempeh and miso made from soy beans, and pickled cabbage commonly called sauerkraut. Kefir is a fermented milk drink that has demonstrated capability to prevent the growth of E. coli.
3. Brewer’s yeast
Made from the single-celled fungus Saccharomyces cerevisiae used in the making of beer, brewer’s yeast  tablets have been used as a health-giving food supplement for a long time. It is a rich source of most of the B-complex vitamins like thiamine, riboflavin, niacin, pantothenic acid, pyridoxine, folic acid and biotin. It contains minerals like selenium and chromium too. The high vitamin content, blood-sugar and cholesterol lowering chromium, as well as the immunity-enhancing selenium, may be responsible for the super food status of brewer’s yeast.
Edible mushrooms are another group of nutritious fungi favored for their immunity-enhancing properties. Regular consumption of either shittake  or maitake mushrooms may keep you in the pink of health, in spite of all the germs that are doing their rounds. Their typical action is by increasing the white blood cell count; fortifying the body’s main defense against invading microbes.
5. Spices and condiments
Spices can perk up not only your food and senses but also your immune system. Cloves and cinnamon top the list in ORAC values, closely followed by oregano and turmeric.  ORAC stands for Oxygen Radical Absorbance Capacity, an indication of their antioxidant power. Some of the other high ORAC spices include cumin, parsley, basil, ginger, garlic, pepper and turmeric. Garlic is effective against bacterial, viral and fungal infections. It is actually the spices in the chicken soup that work the magic.
Turmeric is a highly potent condiment; its active ingredient curcumin has anti-cancer and anti-inflammatory properties. Researchers at the Anderson Cancer Center in Houston attribute the protective effect of turmeric to the immune-modulating action of curcumin. Having curries more often may help you stay healthy all through the flu season.
6. Unrefined oils
Fresh oils have immunity boosting fatty acids; examples are lauric acid found in coconut oil and oleic acid in olive oil. Lauric acid and its derivative monolaurin can protect you from invading microorganisms by damaging their lipid coats. Sesame oil has anti-bacterial and anti-oxidant properties. To get maximum benefit, oils should be cold-pressed, organic and free of additives.
7. Green tea
Green tea has several times the anti-oxidant power of the usual tea brewed from fermented tea leaves. Japanese organic matcha tea, made of whole powdered tea leaves, is the best form of green tea.
Healthful herbal tea blends can be made from different kinds of medicinal herbs as well. The islanders of Ikaria , known for their longevity, reportedly drink a lot of herbal teas throughout the day. Licorice tea and Tulsi tea are very popular as immunity boosters. Catechins are the potent antioxidants found in the teas.
8. Raw milk and eggs
Milk and eggs in their raw state are storehouses of immunity-boosting substances. A raw egg beaten into a glassful of raw milk can be termed as the ultimate health tonic. In Southern parts of India, donkey’s milk is traditionally given to infants to increase their immunity to common childhood diseases. Until the 19th century, donkeys were reportedly very common in the French cities so that young children could have fresh milk straight from them.
Much like the vitamins in fresh fruits and vegetables are lost in cooking and storage, the active ingredients in milk and eggs undergo irreversible changes during heating that render them ineffective. But consuming milk that’s not boiled or pasteurized carries the risks associated with all foods of animal origin. Salmonella scare has made people wary of using raw eggs in even mayonnaise. Locally produced fresh eggs from free-range hens and fresh milk from grass-fed cows may be safer options.
Vitamins are indispensable for the metabolic functioning of our body. Water soluble vitamins C and B-complex can be obtained from fresh fruits and vegetables. They are better eaten raw, as the vitamins are lost in cooking. Since any excess is excreted in the urine, we need to replenish them constantly. Fat soluble Vitamins A, D and E are abundant in foods of animal origin and in oil seeds and are stored in the body. A continuous supply of Vitamin C and a good amount of Vitamin E can significantly improve immune status.
Our body needs certain minerals like calcium and potassium in large quantities. But there are others it needs in much smaller quantities; they are often overlooked. Our immune system in particular needs zinc to function properly. Even mild deficiency of this mineral can weaken the T-cells that guard us from infections and even cancerous growths. Severe deficiency may cause complete T-cell dysfunction. Zinc also aids the absorption of selenium, another mineral necessary for immune function.
Minerals can be taken in supplement form, but they do not benefit the body in the same way as those obtained from fresh food. In foods, they are in forms that are easily absorbed. Oysters are the richest source of zinc; most other seafood, meat, and dairy products, have respectable amounts. Shiitake mushrooms , spinach and pumpkin seeds are excellent sources of plant-based zinc.
11. Colorful vegetables and fruits
Fruits and vegetables are loaded with vitamins and minerals, the more colorful  the more potent these compounds are. Chalk full of phytonutrients, antioxidants, oils, fibers and acids in fruits and vegetables give them their color and flavor. The body uses these bioactive compounds to combat inflammation and infections, support detoxification and immune cell function. Eating a variety of fresh or frozen organic fruits and vegetables daily is recommended for optimal immune  function.
In addition to eating immune boosting foods, managing stress, sleeping well and getting ample exercise will all work towards making your body strong and armed for whatever foreign invaders cross its path.