What are probiotics? Your questions answered
Probiotics are the rage these days as a result of their health halo and the growing range of products, including foods and dietary supplements, containing these so-called “friendly bacteria.” While dairy foods, such as yogurt, are the major dietary source of probiotics, they recently have been added to a plethora of nondairy food products such as cereals, snacks, juices, pizza dough, and water. Although many people are familiar with the word “probiotics,” questions about them abound. Below are answers to five common questions about probiotics.
What are probiotics?
The term “probiotic” comes from the Greek language meaning “for life.” Although many definitions of probiotics have been suggested over the years, the most common one accepted by the scientific community is “live microorganisms (typically bacteria) that, when administered in adequate amounts, confer a health benefit on the host.” For a microorganism to achieve probiotic status, it must be alive when consumed; its health benefit must be demonstrated by properly controlled studies; and it must be given at levels shown to confer a benefit. Some common health-promoting probiotics include specific strains of Bifidobacteria, Streptococci, and Lactobacilli. Many of the microorganisms in probiotics are just like those naturally found in our bodies.
What are the health benefits of probiotics?
Probiotics are associated with a number of health benefits. In general, the best documented health benefits are their ability to prevent or treat digestive disorders, including diarrheal illnesses such as antibiotic-associated diarrhea, travelers’ diarrhea, and that associated with irritable bowel syndrome; boost the immune system; and improve the digestion of lactose (the natural sugar in cow’s milk). Emerging evidence also suggests a potential role for probiotics in preventing or treating allergies, some cancers, and gastric ulcers; lowering blood cholesterol levels and high blood pressure; and reducing the risk of obesity and metabolic syndrome.
It’s important to appreciate that not all probiotics are the same and the purported health benefits associated with any one probiotic depend on its genus (e.g., Lactobacillus), species (e.g., rhamnosus), and strain (e.g., GG), as well as the amount, potency, and mode of delivery. While numerous claims about probiotics are being made, in many cases the science needs to catch up with these claims. Further research, especially controlled studies in humans, is needed to determine which probiotics at what dosages are associated with specific health benefits. Also, probiotics’ health effects can vary among individuals.
Why are dairy foods a preferred “probiotic delivery vehicle”?
Probiotic bacteria have long been associated with dairy foods. There are several reasons why dairy foods such as yogurt and kefir (a fermented dairy drink) may be a desirable vehicle to deliver probiotics.
- Dairy foods can protect probiotics from stomach acid and pancreatic secretions, thereby increasing the likelihood the probiotics will survive as they travel through the human digestive tract.
- Dairy products are refrigerated, which helps promote the stability of probiotics.
- The healthful properties of probiotic bacteria blend well with those of nutrient-rich cow’s milk.
Are fermented dairy foods the same as probiotic dairy foods?
Not all fermented dairy foods are considered probiotics, although both are made with microorganisms. Only probiotic dairy foods have enough live microorganisms to deliver a proven health benefit.
Yogurt is the best known probiotic food. To be called “yogurt,” at least two active cultures, Lactobacillus bulgaricus and Streptococcus thermophilus, must be present. In addition, other probiotics such as Lactobacillus acidophilus and Bifidobacteria are commonly added to confer unique characteristics. Consuming yogurt with “live and active cultures” allows many lactose maldigesters to comfortably include dairy products and their accompanying nutrients in their diet. While some brands of yogurt contain the “live and active culture” seal on the package, use of the seal is voluntary and it may not appear on other brands even if the product contains adequate amounts of live cultures.
To learn whether a food is a probiotic, refer to product labels and web sites. These may provide information about the types of probiotic microbes present, their levels in the food through the end of its shelf life, whether health benefits have been demonstrated in human studies, and whether claims are validated. As more and more foods are being marketed as containing probiotics, confirming whether these products contain viable microorganisms and confer health benefits is an ongoing area of research.
Fermented dairy foods, like cheese and kefir, may contain probiotics, but are not considered probiotic foods because they do not meet the current definition. Although some research links kefir with potential health benefits, including gut health, further study, especially in humans, is needed to verify these findings. It cannot be assumed that the health benefits suggested by current research apply to the kefir purchased at grocery stores or made at home.
Consuming a nutrient-rich probiotic dairy food such as yogurt with live, active cultures and fermented dairy foods such as kefir and cheese can help meet current daily dietary recommendations for dairy as part of a healthy dietary pattern to maintain health and help reduce the risk of chronic disease.
Where can I get more information about probiotics?
To learn more about probiotics, numerous resources are available. Here are a few: