Probiotics: What Do These Bacteria Do?

by Nusheen Orandi

When I’m shopping in the dairy aisle of the grocery store, I stand in front of the yogurt section for a while. When did it get so huge? Greek, Icelandic, Kefir, whole milk, low-fat, non-fat, goat’s milk, and coconut milk are all options. What’s making yogurt so popular? Well, its probiotic nature is one of its claims to fame.

What does probiotic mean?

“Probiotic” describes anything that stimulates the growth of microorganisms in large enough numbers to enhance health. With food, this involves bacteria and yeast that ferment products we love, like beer, yogurt, and cheese. With health, the primary interest lies with gut microflora. Gut microflora affects health and digestion in a number of ways including food intolerances, food allergies, and other forms of gastrointestinal discomfort. This not only sparks nutrition research interests but food industry interests as well, who try to market the “functional foods” that could enhance health.

What makes yogurt so special?

The making of yogurt involves probiotic bacteria. Starter cultures begin the process of fermenting hot pasteurized milk to make yogurt. These starter cultures are bacteria not found in the intestinal tract that include Streptococcus thermophilus and L. delbrueckii ssp. Bulgaricus. However, other bacteria used in yogurt-making are found in the intestinal tract, such as members of the Lactobacillus and Bifidobacterium species. Because these bacteria are also found in the intestinal tract, they are known as “dietary adjuncts.” The bacteria in yogurt produce lactic acid, which reacts with milk protein to give it the creamy texture and tart taste. These bacteria’s ability to be produced in high amounts, withstand long shelf life, and benefit human health give yogurt’s its probiotic reputation.

What are the health benefits of probiotics?

Should we eat another bowl of yogurt or a second pint of Guinness? Microbiology experts think so. Scientific evidence points to many health benefits including anti-microbial activity, anti-diarrheal function, enhanced immune function, and improved lactose intolerance and gastrointestinal function.

Anti-microbial activity

Probiotic bacteria produce organic acids that suppress the multiplication of pathogenic bacteria like E.coli and salmonella, which can make us sick. The increased acidity of the intestinal tract enables this function.

Lactose Intolerance

People who experience discomfort from dairy products due to lactose intolerance can sometimes tolerate yogurt due to the probiotic bacteria. People with lactose intolerance lack sufficient amounts of the enzyme lactase in their intestine. Without enough lactase, people inadequately digest the milk sugar. The probiotic bacteria in yogurt contain an enzyme called b-D-galactosidase that partially digests the lactose in yogurt, making it easier for lactose intolerant people to eat yogurt comfortably.  Research also suggests that probiotic bacteria can enhance lactase activity.

Anti-diarrheal Function

Pathogenic bacteria and antibiotic use can cause diarrhea. Probiotic bacteria compete with diarrhea- causing pathogenic bacteria on epithelial cells in your intestine, which reduces the likelihood of diarrhea. Probiotic bacteria especially help people required to take a lot of antibiotics. The antibiotics reduce the amount of “good” microorganisms in your intestine, which can causes diarrhea symptoms. Probiotics help re-colonize the intestine with these “good” bacteria to improve intestinal movement. Hospitalized people who take a variety of medications may benefit from certain probiotic bacteria.

If probiotic bacteria are so good, should we add more to foods?

Because of the noted benefits of probiotic bacteria, debate surrounds the idea of adding more probiotic bacteria in addition to the ones found in traditionally made yogurt and other fermented products. One example is Activia brand yogurt. Probiotic bacteria are available in powders, capsules, and tablets. However the type, amount, and ratio of added probiotic bacteria remain unclear. Clinical trials raised discussion about whether probiotic bacteria given to infants could decrease food allergies later in life. However, further studies provided inconclusive evidence.

Probiotic bacteria not only help make the food we love, but help our bodies know what to do with it! Although those with dietary restrictions or illness may benefit from added probiotic bacteria, the probiotic bacteria found in our foods may be enough to give the rest of us the potential benefits. It just gives us another reason to maintain a well-balanced diet.

Nusheen Orandi is a first-year student from California in the Nutrition Communication program and likes to spend her time tea-shop hunting, tensely watching the Tottenham Hotspurs, and cooking and eating with friends and family.

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