Bifidobacteria is a bacterial genus. Bacteria in this genus can be found as part of the normal gut flora, the bacteria which live in the intestinal tract and assist with digestion. These “good bacteria,” as they are sometimes known, have a symbiotic relationship with the body, taking advantage of nutrients the body can't use and breaking down digested foods so that the body can access useful nutrients. Historically, bifidobacteria were known as Lactobacillus bifidus, but eventually researchers realized that they should be placed in their own genus.
These bacteria are gram positive, rod shaped, and non-motile. They attach to the lining of the intestines, producing acetic and lactic acids as digestive byproducts. These acids help to maintain a desirable pH level in the digestive tract, contributing to digestion and also discouraging the growth of many harmful bacteria which cannot thrive in high acid environments.
Babies have the highest concentrations of bifidobacteria, with levels declining in the body over time. These bacteria can be found in many cultured dairy products, along with other beneficial bacteria, and people are sometimes encouraged to eat products like yogurt with live active cultures to boost their digestive tracts. People who have taken a lot of antibiotics or experienced significant disruption to their normal gut flora can sometimes benefit from complementing their diet with so-called probiotic bacteria which will help re-establish a normal balance of bacteria in the gut.
In addition to being found in many foods, bifidobacteria can also be accessed through supplements which are marketed to people with digestive problems such as irritable bowel disease. These supplements are designed to maintain the population of beneficial bacteria in the gut, and they are sometimes recommended to older individuals who may have unbalanced gut flora. However, people should be aware that the balance of the bacteria in the gut is complex, and that most supplements will not instantly restore the gut flora to normal.
Studies do suggest that bifidobacteria supplements can improve digestion. The bacteria also appear to be linked with a decrease in cancer risk, and a decrease in the severity of allergies, although these links have not been positively proved. People who are interested in the idea of using probiotic bacteria to support general intestinal health and to address specific medical issues should talk with a doctor to determine whether or not supplements would be appropriate, and how the supplements should be taken to promote absorption by the body.