Yogurt, a dairy product cultured with bacteria, provides beneficial effects within the human body. These bacteria normally live within the digestive tract, but are sometimes depleted by disease or the use of certain medications such as antibiotics. Consuming yogurt with live bacterial cultures can replace these lost bacteria and introduce new colonies of beneficial microorganisms into the body. Collectively, these bacteria are called probiotics.
One of the most common forms of bacteria in yogurt are strains of Lactobacillus. The strain Lactobacillus bulgaricus is commonly added to milk along with the bacteria Streptococcus thermophilus during the production of yogurt. Other strains of lactobacillus that may be added to yogurt include Lactobacillus acidophilus, Lactobacillus caseii and Lactobacillus reutri. Bifidum bacteria, such as Bifidobacterium animalis and Bifidobacterium lactis, are also a popular addition to yogurt.
While probiotic bacteria are also available in supplement form, consuming these beneficial bacteria in whole foods such as yogurt may boost their beneficial effects, explains Penn State University. The bacteria may also make other nutrients in yogurt, such as calcium, more easily utilized by the body. Yogurt containing probiotic bacteria is available as a creamy semi-solid or as a thick drinkable liquid.
Probiotic bacteria in yogurt can colonize the gut, crowding out any unfriendly bacteria that may try to invade and allowing other healthy gut bacteria to flourish. Lactobacillus acidophilus in particular promotes the growth of friendly bacteria in the gut. Children who are taking antibiotics or infected with rotavirus may be protected from diarrhea if they consume yogurt containing probiotic lactobacillus. Yogurt containing the strains Lactobaciullus acidophilus and Bifidobacterium lactis shows a protective effect against stomach ulcers. Probiotic bacteria, including Bifidobacterium animalis, also help speed the passage of food through the digestive tract, lessening the incidence of constipation.
The bacterial cultures in yogurt may produce compounds that stimulate the immune system. According to World's Healthiest Foods, Lactobacillus casei can fight off a pneumonia infection. The bacteria's protective effects may also protect women from yeast infections. Lactobacillus strains may also have a positive effect on arthritis, helping to ease inflammation. Probiotic yogurt may also help lower LDL cholesterol and improve bad breath. Live active cultures of Lactobacillus also produce lactase, an enzyme that destroys lactose, making yogurt tolerable even by lactose-intolerant individuals who cannot drink milk.
Since specific bacterial strains confer different health effects, the precise content of a given brand of yogurt matters. Some packaged yogurt has been found to not contain the specific strains claimed in the packaging. Yogurt confers the most benefit when it contains at least 100 million active live cultures per gram. When choosing yogurt for health, avoid versions with added sugars and opt for plain yogurt that is made from reduced fat or skim milk.