The gastrointestinal tract is a complex ecosystem and microorganisms are essential. Experts have estimated that the human body contains more bacterial cells than human cells, so it’s no wonder that intestinal flora can have important impacts on health. The balance of microorganisms in the gastrointestinal tract can be influenced by age, diet, antibiotic use and stress. When the delicate balance is disturbed, disease and dysfunction often follow. Fortunately, as recent research studies show, supplementing healthy flora can reestablish microbial balance and improve many health conditions.
Probiotics are beneficial live microorganisms naturally present in the human gastrointestinal tract. They can be taken as a dietary supplement in capsule, tablet or powder form, but certain foods, such as yogurt, kefir and miso contain these organisms as well.
Probiotics generally come from two groups of bacteria, Lactobacillus and Bifidobacterium, and one species of yeast, Saccharomyces boulardii. Each bacterial group has several species, such as Lactobacillus acidophilus and Bifidobacterium bifidis, and within each species exist several strains. Probiotics are generally safe and well tolerated. Side effects are rare and usually limited to mild digestive disturbances such as gas and bloating.
Probiotics prevent pathogenic microbes such as parasites, fungi, yeasts and bacteria from attaching to the wall of the intestines. They also produce bacteriocins, proteins that are lethal to disease-causing bacteria. Probiotics also that maintain a pH that is unfavorable for many pathogenic microorganisms by secreting compounds such as lactic acid, acetic acid and hydrogen peroxide.
Not only are probiotics useful for preventing and treating gastrointestinal infections, but they are also effective against diarrhea and other infections. Probiotics can improve symptoms of antibiotic-induced diarrhea, radiotherapy-induced diarrhea, irritable bowel syndrome, sinus infections, urinary tract infections, bacterial vaginosis and yeast infections in women. Continued use of probiotics can also prevent recurrences.
Anti-allergy and Anti-inflammatory Effects
Researchers in Finland have demonstrated the benefit of probiotic supplementation in the prevention and treatment of allergic inflammation. In a double-blind, randomized, placebo-controlled study, twenty-seven breast-fed infants diagnosed with atopic eczema were weaned to whey formulas with or without probiotics, specifically Bidifobacterium lactis or Lactobacillus rhamnosus GG. The infants who were given either strain of probiotics experienced great improvements in their skin conditions compared to the placebo group. Another study followed more than one hundred four year old children and concluded that those given Lactobacillus rhamnosus GG during the first two years of life had the lowest rates of eczema.
The use of probiotics in other inflammatory conditions, such as Crohn’s disease and ulcerative colitis, is under investigation. A small study in Italy followed twenty-four patients with Crohn’s disease and found that after four weeks of supplementation with Saccharomyces boulardii, seventeen of them went into remission. Overall, studies have had mixed results, but the research continues.
Immune System Support
Supplementation with probiotics has been associated with increased immunity and resistance to cancer and infection. Studies on animals and humans have demonstrated that lactic acid bacteria like Lactobacillus acidophilus and Bifidobacterium lactis can increase levels of white blood cells and immune factors – such as antibodies, cytokines and interferon – that modulate the immune system. Additionally, Bifidobacterium lactis has also been shown to enhance activity of natural killer cells.
Clinical trials have tested the effectiveness of probiotics on certain immune-related diseases, such as cancer. A double-blind, randomized, placebo-controlled study in Ireland followed eighty patients for twelve weeks. Some had been diagnosed with colon cancer and others had undergone surgery for removal of intestinal polyps. Those who had been given probiotic strains Lactobacillus rhamnosus GG and Bifidobacterium lactis reduced their risk of development and recurrence of colorectal cancer.
Benefits for Babies
Probiotics have benefits for babies too. Supplementation can reduce risk of diarrhea in infants, especially rotavirus gastroenteritis. Lactobacillus rhamnosus GG has been shown to decrease incidence of cavities in children. Preliminary trials also suggest that supplementation with Lactobacillus rhamnosus GG may reduce frequency of respiratory tract infections as well as related antibiotic treatments and absences from school. Additionally, there is evidence that preterm infants and babies with low birth weight may benefit from supplementation with Saccharomyces boulardii. This yeast inhibits colonization by pathogenic Candida species and promotes a balance of stool flora similar to that of breast-fed babies.
Your doctor can recommend the best strains of microorganisms for you, as well as an appropriate dosage. Some probiotic supplements also contain prebiotics, which are complex sugars such as inulin, lactulose or fructo-oligosaccharides (FOS) that stimulate growth of beneficial bacteria. In some individuals, FOS can cause gas and bloating. Alternatively, prebiotics can also be supplied by the diet. Food sources include garlic, onions and fermented foods such as miso, tempeh, kefir and kombucha.
Choose carefully when selecting probiotic supplements. Unless otherwise indicated, most probiotics need to be refrigerated to maintain viable and stable live cultures. Buy products that have been kept cool and store them in the fridge when you get home. The label should list the ingredients and each serving should contain at least one billion colony-forming units (CFU). A lot or batch number should also be listed, along with the name and address of the manufacturer.
To ensure that products have been tested by an independent lab, look for seals from independent organizations like the United States Pharmacopeia, the National Nutritional Foods Association, Consumer Lab or National Sanitation Foundation (NSF) International. Certification guarantees that supplements contain what they are labeled to contain. However, it doesn’t ensure that manufacturers started with the highest quality raw ingredients or tested them in clinical trials.