Probiotics are supplements that contain strains of normal bowel flora. The large intestine normally contains several pounds of bacteria, and the presence of appropriate bacterial populations is considered essential for digestive and immune health. Beneficial intestinal bacteria help limit the growth of harmful organisms, support the intestinal lining, participate in toxin metabolism, and produce certain vitamins. Learn more about a healthy microbiome. Probiotics have been studied for digestive health, immune balance, and even microbial ecosystems outside the gut.

Research published in the Allergy (2006; 61(4):431–437) examined the effects of probiotic and prebiotic supplementation in children with atopic dermatitis. Prebiotics are substances that help nourish beneficial intestinal bacteria. This double-blind, placebo-controlled study included 39 children over the age of two with atopic dermatitis. Participants received either a combination of probiotics and prebiotics or a placebo for three months. Disease severity was assessed using the Scoring Atopic Dermatitis (SCORAD) index, with all participants having a minimum baseline score of 15.

After three months, the group receiving supplementation experienced a reduction in mean SCORAD score from 39.1 to 20.7, indicating a significant improvement in disease severity. These findings suggest that probiotic and prebiotic supplementation may help improve symptoms of atopic dermatitis in children.

Probiotic supplementation has also been studied for its effects on immune function and childhood infections. A randomized, double-blind, placebo-controlled study evaluated the impact of a specific probiotic formulation on common infectious illnesses in school-aged children during winter months. The study included 135 children between the ages of three and seven. Over a three-month period, 73 children received placebo and 63 received a probiotic supplement containing Lactobacillus helveticus R0052, Bifidobacterium infantis R0033, Bifidobacterium bifidum R0071, and fructooligosaccharide. Click here for more about probiotics and the immune system.

In the probiotic group, 51.6% of children experienced at least one illness during the study period, compared with 67.1% in the placebo group. School absenteeism was also reduced: 42.5% of children in the control group missed at least one day of school, compared with 25.8% in the probiotic group. These findings suggest that probiotic supplementation may reduce the risk and impact of common childhood infections.

Research published in the Vaccine (Volume 24, Issues 44–46, November 10, 2006, Pages 6670–6674) examined probiotic supplementation and upper respiratory tract infections in adults. In this double-blind, placebo-controlled study conducted over two winter/spring seasons, 479 healthy adults received either a vitamin/mineral supplement containing probiotics (lactobacilli and bifidobacteria) or a vitamin/mineral supplement alone. While probiotic supplementation did not reduce the number of respiratory infections, it shortened the duration of illness by nearly two days and reduced symptom severity. Supplementation was also associated with increases in certain immune cell populations, including cytotoxic T cells, T suppressor cells, and T helper cells.

Probiotics have also been evaluated in surgical settings. Researchers in China published a study in Zhonghua Wei Chang Wai Ke Za Zhi (January 2010; 13(1):40–43) examining probiotic supplementation in patients undergoing surgery for colorectal cancer. Sixty patients were randomly assigned to receive either a bifidobacterium-containing probiotic or placebo. Patients receiving probiotics experienced fewer postoperative infections and demonstrated improvements in immune markers.

In the supplemented group, blood levels of immunoglobulins IgG, IgM, IgA, and interleukin-6 (IL-6) were lower, suggesting reduced systemic immune activation. In contrast, IgA levels in stool samples were higher, indicating enhanced localized immune activity at the intestinal level. C-reactive protein (CRP) levels were also lower in the probiotic group, reflecting reduced inflammation. These findings suggest that probiotic supplementation may be beneficial for patients undergoing colorectal cancer surgery. Also, the reduction in inflammatory markers make them useful for people with IBD.

While they can play a key role in gut health, taking probiotics is just the beginning. Click to learn what everyone taking probiotics needs to know. 

Educational note:
This article is for informational purposes only and is not intended as medical advice.