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Can food prevent the common cold?

School Of Nutrition Posted Mar 17, 2014 Future Fit Training


The common cold fills doctors' surgeries and increases sick-leave work and school. So can nutrition prevent you from falling ill in the first place?

Can food prevent the common cold?

Symptoms also vary from person to person and from cold to cold. Since the common cold is usually caused by one of the respiratory viruses, antibiotics are useless.

Can vitamin C stop a cold?

Vitamin C has been the subject of much controversy since the 1970s when Nobel laureate Linus Pauling’s research suggested that vitamin C could prevent and alleviate the common cold.

A recent review of trials testing 2g or more of vitamin C found that regular ingestion of vitamin C had no effect on the incidence of the common cold in the ordinary population. However, regular supplementation does appear to have a consistent, although modest, effect in reducing the duration of common cold symptoms. On the other hand, in people exposed to short periods of extreme physical stress (such as marathon runners and skiers), vitamin C did halve the common cold risk.[1]

Unless you are an athlete, you should be able to get all the vitamin C you need by eating a varied and balanced diet. So, instead of supplementing on a day-to-day basis, make sure to include lots of vitamin C-rich foods such as oranges, kiwis, strawberries, blackcurrants, red peppers and broccoli.

Can Beta-glucans boost your immune system?

Beta-glucan is a soluble fibre derived from the cell walls of algae, bacteria, fungi, yeasts, and plants. As well as being able to lower bad LDL cholesterol and regulate blood sugar levels, beta-glucans have the ability to boost immunity [2]. However, not all beta-glucans are effective at improving immune response. According to Dr Clemens [3], an expert in functional foods at the University of Southern California, beta-glucans from mushrooms and yeast have been shown to enhance the activity of macrophages, a type of white blood cells, which are critical in warding off infection. In a recent study, supplementation with beta-glucan from yeast reduced the number of  common cold infections by 25%.[4] Beta-glucans found in oats and barley, however, do not appear to be effective.

So to boost your immune system this winter remember to toss extra mushrooms in your pasta sauce, soups, stir-fries, casseroles or pizza. Alternatively, if you do not like mushrooms, you could try taking a beta-glucan supplement made from brewer’s yeast.

Will Zinc blast a cold?

Zinc, an essential mineral found in meat and seafood, has a strong track record of fighting the common cold. A comprehensive review of the research concluded that supplementation with zinc was associated with a significant reduction in the duration but not the severity of common cold symptoms. [5]

However, as zinc supplements carry a risk of side effects such as nausea and headaches, a better bet may be to get zinc straight from your diet. Oysters contain more of the nutrient per serving than any other food – but uncooked shellfish could contain harmful bacteria that could make you sick in other ways so you might not want to eat them raw. Other rich sources of zinc include beef, lamb, wheatgerm, pumpkin seeds, dark chocolate and cashew nuts.

Can the beneficial bacteria in probiotics fight the common cold?

Eating probiotic foods, such as yogurt and kefir, is a good way to replenish beneficial strains of bacteria, which promote digestive health and help prevent stomach ailments. The benefits of good bacteria may go beyond our gut and some strains - like Lactobacillus casei and Lactobacillus reuteri - have been shown to boost your immune system also.

The evidence for a beneficial effect of probiotics on preventing the common cold is weak but promising. A 2011 review of the research found that consuming probiotics - whether in food or supplement form - lowers the risk of developing upper respiratory tract infections.[6] Furthermore, results from a review published in 2013 implied that probiotics have a modest effect in the reduction of the common cold.[7]

Will drinking tea stop you from catching the flu?

A steaming hot cup of tea can help soothe a sore throat, but its benefits may run even deeper. All tea - black, green or white - contains a group of antioxidants known as catechins, which may have flu-fighting properties. In a 2011 japanese study, people who took catechin capsules for five months had 75% lower odds of catching the flu than people taking a placebo. [8]

Another reason to put the kettle on? Research suggests that, as well as boosting overall immunity, catechins may help protect against heart disease [9] and cancer [10].

Conclusion

While eating foods rich in anti-oxidants, vitamins and minerals will probably not stop you from catching a cold altogether, they will certainly ensure that your immune system is in good condition and ready to fight infection if it occurs. The duration and severity of symptoms will be lessened as a result. Other things that you can do to build up your immune system are getting adequate sleep, taking regular exercise and controlling your stress levels.

Written by Victoria Trowse

Written by Victoria Trowse

REFERENCES

1. Hemilä H and Chalker E. (2013). Vitamin C for preventing and treating the common cold (Review). The Cochrane Collaboration, Cochrane Library 2013, Issue 1. http://www.thecochranelibrary.com

2. Volman JJ, Ramakers JD and Plat J. (2008). Dietary modulation of immune function by beta-glucans. Physiol Behav 94: 276–284.

3. Roger Clemens, Dr PH, spokesman and incoming president, Institute of Food Technologists; member, 2010 Dietary Guidelines advisory committee; professor, University of Southern California; associate director, regulatory science, and adjunct professor, pharmacology and pharmaceutical science, the University of Southern California, spokesman, American Society for Nutrition.

4. Auinger A , Riede L, Bothe G, Busch R and Gruenwald J. (2013). Yeast (1,3)-(1,6)-beta-glucan helps to maintain the body’s defence against pathogens: a double-blind, randomized, placebo-controlled, multicentric study in healthy subjects. Eur J Nutr. 52(8): 1913-8.

5. Singh M and Das RR. (2011). Zinc for the common cold. Cochrane Database Syst Rev. Issue 2. Published Online: 18 JUN 2013.

6. Hao Q, Lu Z, Dong BR, Huang CQ and Wu T. (2011).  Probiotics for preventing acute upper respiratory tract infections. Cochrane Acute Respiratory Infections Group. Published Online: 7 SEP 2011.

7. Kang E-J, Kim SY, Hwang I-H and Ji Y-J. (2013). The Effect of Probiotics on Prevention of Common Cold: A Meta-Analysis of Randomized Controlled Trial Studies. Korean J Fam Med. 34(1): 2–10.

8. Matsumoto K, Yamada H, Takuma N, Niino H and  Sagesaka YM. (2011). Effects of Green Tea Catechins and Theanine on Preventing Influenza Infection among Healthcare Workers: A Randomized Controlled Trial. BMC Complementary and Alternative Medicine 11: 15.

9. Huxley, RR and Neil, HA (2003). The relation between dietary flavonol intake and coronary heart disease mortality: a meta-analysis of prospective cohort studies. Eur J Clin Nutr, 57: 904-8.

10. McKay DL and Blumberg JB (2002). The Role of Tea in Human Health: An Update. JACN 21: 1-13.

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