Viral Upper Respiratory Infections (Colds and Influenza) and Acidophilus and Other Probiotics

Probiotics are healthy organisms (bacteria and yeasts) that colonize the digestive tract. They are commonly referred to as "friendly bacteria." Not only can probiotics help prevent intestinal infections, they also appear to help prevent colds. Research suggests that supplementing with probiotics might also increase the effectiveness of the flu vaccine.

Probiotics are believed to help prevent infections through various mechanisms, including supporting the immune system.

Read more details about Acidophilus and Other Probiotics.

A 7-month, double-blind, placebo-controlled study of 571 children in day care centers in Finland found that use of milk fortified with the probiotic bacteria Lactobacillus GG modestly reduced the number and severity of respiratory infections.⁷³ In another controlled trial, probiotics (Lactobacillus rhamnosus GG and Bifidobacterium lactis Bb-12) given daily to infants in their formula significantly reduced the risk of acute otitis media and recurrent respiratory infections during the first year of life, compared to placebo.¹⁷⁰

Benefits were also seen in three other large studies, in which probiotics alone or combined with multivitamins and minerals helped prevent colds and/or reduce their duration and severity in adults.^153-155

Another controlled trial involving 20 healthy elite distance runners found that Lactobacillus fermentum given over a 4-month period during winter training was significantly more effective at reducing the number and severity of respiratory symptoms than a placebo.¹⁶⁶

In addition, a small double-blind study found evidence that use of the probiotic bacteria Lactobacillus fermentum improved the effectiveness of the influenza vaccine.¹⁵⁸ The probiotic supplement was taken in two doses: one, two weeks before the vaccine, and the other, two weeks after.

Probiotic supplements are widely available in powder, liquid, capsule, or tablet form. Because probiotics are not drugs, but rather living organisms that you are trying to transplant to your digestive tract, it is necessary to take them regularly. Each time you do, you reinforce the beneficial bacterial colonies in your body, which may gradually push out harmful bacteria and yeasts growing there.

The downside of using a living organism is that probiotics may die on the shelf. Look for products that guarantee living organisms at the time of purchase, not just at the time of manufacture. Another approach is to eat acidophilus-rich foods such as yogurt and kefir, in which the bacteria are most likely still alive.

In addition to increasing your intake of probiotics, you can take fructo-oligosaccharides (FOS) supplements that can promote thriving colonies of helpful bacteria in the digestive tract. (Fructo-oligosaccharides are carbohydrates found in fruit. Fructo means "fruit," and an oligosaccharide is a type of carbohydrate.) Taking FOS is like putting manure in a garden; it is thought to foster a healthy environment for the bacteria you want to have inside you. The typical daily dose of fructo-oligosaccharides is between 2 g and 8 g. Note: FOS can also nourish "bad bacteria," so it is probably best to re-balance your intestinal flora with "good bacteria" before introducing FOS.

In the case of Lactobacillus fermentum improving the effectiveness of the influenza vaccine,¹⁵⁸ the probiotic supplement is taken in two doses: one, two weeks before the vaccine, and the other, two weeks after.

A number of health practitioners, including physicians, naturopathic doctors and nutritionists, might be knowledgeable about using probiotics.

Safety Issues

Probiotics may occasionally cause a temporary increase in digestive gas. But, beyond that, they do not present any known risks for most people. In one trial of 140 healthy infants, formula supplemented with long-chain polyunsaturated fatty acids and probiotics appeared as safe as standard formula, and did not have any effect on infant growth by the end of the 7-month trial. ¹ However, individuals who are immunosuppressed could conceivably be at risk for developing a dangerous infection with the probiotic organism itself; at least one person taking immunosuppressive medications has died in this manner. ² In a detailed review of four studies, researchers concluded that the use probiotics did not benefit patients with severe acute pancreatitis. ³ Furthermore, according to one study, the use of probiotics led to an increased risk of mortality in patients with severe acute pancreatitis, and should, therefore, be avoided under these circumstances. ⁴

A Note About Prebiotics (FOS and others)

Some probiotic supplements also contain prebiotics like FOS to "feed" the good bacteria. FOS appear to be generally safe. However, they can cause bloating, flatulence, and intestinal discomfort, especially when taken at doses of 15 g or higher daily. People with lactose intolerance may particularly suffer from these side effects.

Interactions You Should Know About

• If you are taking antibiotics : It may be beneficial to take probiotic supplements at the same time, and to continue them for a couple of weeks after you have finished the course of drug treatment. This will help restore the balance of natural bacteria in your digestive tract.

1. Gibson RA, Barclay D, Marshall H, Moulin J, Maire JC, Makrides M. Safety of supplementing infant formula with long-chain polyunsaturated fatty acids and Bifidobacterium lactis in term infants: a randomised controlled trial. Br J Nutr. 101(11):1706-13.
2. MacGregor G, Smith AJ, Thakker B, Kinsella J. Yoghurt biotherapy: contraindicated in immunosuppressed patients? Postgrad Med J. 78(920):366-7.
3. Sun S, Yang K, He X, Tian J, Ma B, Jiang L. Probiotics in patients with severe acute pancreatitis: a meta-analysis. Langenbecks Arch Surg. 394(1):171-7.
4. Besselink MG, van Santvoort HC, Buskens E, Boermeester MA, van Goor H, Timmerman HM, Nieuwenhuijs VB, Bollen TL, van Ramshorst B, Witteman BJ, Rosman C, Ploeg RJ, Brink MA, Schaapherder AF, Dejong CH, Wahab PJ, van Laarhoven CJ, van der Harst E, van Eijck CH, Cuesta MA, Akkermans LM, Gooszen HG, Dutch Acute Pancreatitis Study Group. Probiotic prophylaxis in predicted severe acute pancreatitis: a randomised, double-blind, placebo-controlled trial. Lancet. 371(9613):651-9.

73. Hatakka K, Savilahti E, Ponka A, et al. Effect of long term consumption of probiotic milk on infections in children attending day care centres: double blind, randomised trial. BMJ. 2001;322:1-5.
153. Tubelius P, Stan V, Zachrisson A, et al. Increasing work-place healthiness with the probiotic Lactobacillus reuteri: A randomised, double-blind placebo-controlled study. Environ Health. 2005 Nov 7. [Epub ahead of print]
154. de Vrese M, Winkler P, Rautenberg P, et al. Effect of Lactobacillus gasseri PA 16/8, Bifidobacterium longum SP 07/3, B. bifidum MF 20/5 on common cold episodes: A double blind, randomized, controlled trial. Clin Nutr. 2005;24:481-491.
155. Winkler P, de Vrese M, Laue Ch, et al. Effect of a dietary supplement containing probiotic bacteria plus vitamins and minerals on common cold infections and cellular immune parameters. Int J Clin Pharmacol Ther. 2005;43:318-326.
158. Olivares M, Diaz-Ropero MP, Sierra S, et al. Oral intake of Lactobacillus fermentum CECT5716 enhances the effects of influenza vaccination. Nutrition. 2007;23:254-260.
166. Cox AJ, Pyne DB, Saunders PU, et al. Oral administration of the probiotic Lactobacillus fermentum VRI-003 and mucosal immunity in endurance athletes. Br J Sports Med. 2008 Feb 13.
170. Rautava S, Salminen S, Isolauri E. Specific probiotics in reducing the risk of acute infections in infancy—a randomised, double-blind, placebo-controlled study. Br J Nutr. 2008 Nov 6.