Probiotics for Immunity
By Jennifer Morganti, ND, Director of Education for NEEDS
One of my top picks for vitamin must-haves is probiotics, those beneficial bacteria that naturally reside in the intestinal tract, but are often insufficient. Probiotics are an obvious choice for treating digestive disorders. However, a lesser-known, but equally important benefit is that they support the intestinal tract's own immune system, called gut associated lymphoid tissue or GALT. An even more compelling reason to choose probiotics as a must-have is the ample clinical research to support their efficacy.
In one of the many existing clinical trials, researchers looked at the immune activity of probiotics by monitoring their effects in a small group of healthy, elderly volunteers over the course of 12 weeks. Half the group drank plain milk and the other half drank milk supplemented with Bifidobacterium lactis twice a day. They were tested for specific immune parameters, including interferon production (known to have antiviral activity) and phagocyte activity (immune cells that digest foreign microbes). It was found that drinking the probiotic-fortified milk significantly increased the immune parameters within six weeks as compared to drinking the plain milk.1
Another small study compared the immune effects of Lactobacillus acidophilus versus Bifidobacterium bifidum in healthy adults and found that both strains significantly enhanced phagocyte activity in just three weeks. 2
Taking a different approach, one study examined the effects of Lactobacillus casei in smokers, a population known to have suppressed immune systems, looking specifically at natural killer cell activity (direct-killing immune cells). Half the group drank milk fortified with the probiotic and half drank the placebo milk. All the smokers were found to have suppressed immune responses before starting the supplementation, but in the group supplementing with L. casei, there was significant improvement in the natural killer cell activity as compared to the group taking the placebo. 3
How Do They Work?
Probiotics reside all the way from the mouth down to the intestines, but the majority of the beneficial bacteria are concentrated in the large intestines. They help line the intestinal wall and prevent microbes from being absorbed systemically, thus improving intestinal permeability (aka leaky gut). Probiotics stimulate the different parts of the immune system, but most importantly, they have the dual ability to act as a modulator by boosting immune cells that are sluggish or calming an overactive immune system. 4
Probiotics may not be an obvious choice for immune support, but when added to your supplement regime, you'll find it can make a big difference in your overall wellbeing.
1) European Journal of Clinical Nutrition (2000) 54, 263–267
2) Journal of Dairy Science Vol. 78, No. 3. 1995
3) Preventive Medicine 40 (2005) 589–594
4) Am J Clin Nutr 2001;73(suppl):444S–50S.