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Immune-Boosting Superfoods For Cold And Flu Season

The Huffington Post     First Posted: 01/04/2012 8:13 am   Updated: 01/04/2012 2:52 pm

First that nasty cold knocked out the IT department, then your desk-mate started sniffling. At this time of year, there seems to be a perpetual virus going around the office. One way to help? Load up on superfoods that give your immune system a fighting chance, but don't wait until you're already feeling under the weather. Studies show that infection-fighting nutrients like zinc, selenium and beta-glucans work better before symptoms start, so load up on healthful foods now to keep your body's defense system strong throughout the season.

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  • Garlic

    Garlic's history as an infection fighter runs long (it was used as an antibiotic during both World Wars) thanks to the sulfur-containing compounds in each clove, <a href="http://apps.who.int/medicinedocs/en/d/Js2200e/4.html">including powerful allicin, ajoene and thiosulfinates</a>. The anitmicrobial effects of the garlic compound allicin are well-documented, including in <a href="http://www.allimax.us/Cutler.pdf">a 2004 study</a> in the <em>British Journal of Biomedical Science</em>, where researchers found the sulfinate effective against powerful, antibiotic resistant bacterial infections from Methicillin-resistant Staphylococcus aureus (MRSA). The medical literature consistently shows that <a href=http://www.ncbi.nlm.nih.gov/pubmed/10594976>allicin is also active</a> against drug-resistant E.coli infections, fungal infections (particularly oral and vaginal yeast infections), and parasites, including Giardia -- a common cause of traveler's diarrhea. Allicin also has antiviral properties. It's important to note that these findings have been on the cellular level in a lab setting, rather than observed from human diets. But at least one clinical trial found that dietary garlic was <a href=http://www.ncbi.nlm.nih.gov/pubmed/11697022>useful in preventing colds</a>. Allicin is only released when garlic cells are damaged (cutting, crushing, chewing) and is heat sensitive. Try adding some minced, raw garlic to a salad dressing.

  • Wheat Germ

    Wheat germ is one of the richest vegetarian sources of zinc -- an important mineral that is involved in nearly every aspect of immune system regulation. Zinc aids in the <a href="http://www.ncbi.nlm.nih.gov/pubmed/19519463" target="_hplink">development of T-lymphocytes</a>, a group of white blood cells that are central to fighting off infection. It also helps maintain healthy skin and mucus membranes -- the body's first barriers to infection. Wheat germ has 17 milligrams of zinc per 100 gram serving, more than the government's recommended daily allowance, <a href="http://ods.od.nih.gov/factsheets/Zinc-QuickFacts/" target="_hplink">which is 11 mg for men and eight for women</a>. Animal protein is the best, most bioavailable form of zinc -- particularly oysters, lobster, beef and pork shoulder. But not only are these sources also high in cholesterol and saturated fat, they are not an option for vegetarians, vegans and those who keep religious diets, like kosher and halal traditions. <a href="http://ods.od.nih.gov/factsheets/Zinc-QuickFacts/" target="_hplink"> According to the National Institutes of Health (NIH)'s Office of Dietary Supplements</a>, the reason grain-derived zinc is less available to humans than meat sources is because grains also contain phytates, a compound that binds to zinc and inhibits its absorption by the body. Soaking or sprouting the wheat germ before eating it will help to break down the phytates, improving zinc absorption.

  • Brazil Nuts

    Brazil nuts are the richest source of selenium, a nutrient that helps to form selenoproteins -- <a href="http://ods.od.nih.gov/factsheets/selenium">a powerful antioxidant that helps prevent cellular damage from free radicals</a>. That means selenium may help prevent chronic diseases like some cancers and heart disease, but selenoproteins also play a role in protecting the immune system by helping to form infection-fighting T-cells. One study in mice showed that the compound also <a href="http://www.ncbi.nlm.nih.gov/pubmed/21493887">helps regulate intestinal flora</a> -- helping gut bacteria to defeat invading pathogens. But Brazil nuts are <em>so</em> high in selenium that a single nut has nearly twice the recommended daily dose, as determined by the Institute of Medicine. While adults require 55 microgams per day, a Brazil nut has 95 mcgs -- and a single ounce has 544 mcgs. Too much selenium can be bad for your health, so it's better to consider the nuts an occasional dietary source rather than a daily one.

  • Mushroom Barley Soup

    Mushrooms and barley are both high in beta-glucan, a type of carbohydrate that's found on the cell walls of fungi, yeast, bacteria, algae, lichens, and plants. <a href="http://www.ncbi.nlm.nih.gov/pubmed/17161824">Researchers say that beta-glucan can stimulate the immune system</a> by mimicking an invading pathogen, which in turn improves the function of two types of immune defense cells: natural killer cells and macrophages, a type of white blood cell found in human tissue. And veterinary studies, <a href="http://www.ncbi.nlm.nih.gov/pubmed/15030604">including a 2004 experiment involving five-day-old piglets that had been exposed to swine influenza virus (SIV)</a>, have found that a daily dose of 50 mg of beta-glucan protected the treated piglets from the virus, compared to a control group that received placebo. While those studies used a beta-glucan extract rather than dietary beta-glucan, food sources of the compound -- particularly those found in mushrooms -- have been used to boost immune response by practitioners of folk and Eastern medicine for centuries.

  • Raw Kale Salad

    Raw kale is one of the best sources of vitamin C and has the added benefit of being low in sugar and high in fiber -- an overall healthy choice. Why raw? Vitamin C is <a href="http://www.nap.edu/openbook.php?record_id=9810&page=95">very sensitive to heat</a>, breaking down the nutrient and making it less effective. Stick to thinly cut ribbons of the veggie, which packs a bigger punch than salad greens. Each 100 gram serving of raw kale includes about 120 mg of vitamin C, well over the recommended dietary amounts for men (90 mg) and women (75 mg). Vitamin C, also known as ascorbic acid, is an antioxidant <a href="http://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional">that helps prevent cell damage caused by free radicals</a>. It is a very commonly used immune-boosting nutrient, though there is little clinical research that can explain how vitamin C helps boost immunity. But while studies prove that vitamin C won't help curtail a cold that's already in progress, observational data shows that people who have a vitamin C-rich diet tend to have shorter, more mild colds.

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