Yogurt, long known as an excellent source of protein, has recently been touted as a "functional food," or a food that has benefits beyond its normal nutritional value. The additional value of yogurt comes from the live cultures, also called probiotics, used to turn milk into yogurt, and other beneficial bacteria added during processing. Naturally occurring probiotics help keep the gut healthy by crowding out harmful bacteria that can cause diarrhea, gas, constipation or bloating. Probiotics may also inactivate potentially harmful substances with cancer-causing potential such as nitrites.
Lactobacillus Bulgaricus
Lactobacillus bulgaricus is one of two types of bacteria that must be used as a starter culture for a product to be called yogurt, the National Yogurt Association states. Products that contain at least 100 million cultures per gram at the time of manufacture can label their products with the "live and active culture seal." Lactobacteria help break down lactose found in milk products. They may benefit people with lactose intolerance who develop stomach problems when they consume lactose, a sugar found in milk and milk products. Lactobacteria also produce B-complex vitamins and vitamin K. Lactobacillus bulgaricus may have anti-tumor properties, as noted by an animal study reported in December 1999 in "Cancer Letters." However, the application for humans is not established. Lactobacillus is easily destroyed in the stomach by stomach acid and may not have the ability to colonize the intestinal tract. This strain of bacteria does not normally live in the gut.
Streptococcus Thermophilus
The second bacteria required as a starter culture in yogurt, Streptococcus thermophilus, one of the smallest types of lactic acid bacteria, also benefits people with lactose intolerance and may have other intestinal benefits. This bacterium has important commercial properties in that it produces products with consistent flavor and texture, the European Bioinformatics Institute states. Like Lactobacillus bulgaricus, Streptococcus thermophilus breaks down in the stomach when exposed to acid as well and also may not be able to colonize the intestinal tract.
Bifidus Regularis
Dannon yogurt adds the bacterium, Bifidus regularis, which is not found in other yogurts, as a way to increase bacteria survival as yogurt passes through the highly acidic stomach into the intestines. Consumer Reports verified the claim, stating that 3 million of the original 3 billion Bifidus regularis bacteria made it through the acidic stomach and into the intestines. Dannon claims this increases their yogurt's ability to prevent intestinal disorders.
References
- European Bioinformatics Institute: Streptococcus Thermophilus
- PubMed: Inhibitory Effects of Freeze-Dried Milk Fermented by Selected Lactobacillus Bulgaricus Strains on Carcinogenesis; R. Balansky; December 1999
- Columbia University's Health Q&A Internet Service: Will Probiotic-Enriched Yogurt Enhance Digestion?
- Ask Dr. Sears:Yogurt
- Denver Post: Consumer Reports Analyzes Probiotics
- Nutrition Review: Lactobacillus GG
