Dear Dietician: Probiotics show promise beyond digestive health

Leanne McCrate

Dear Dietitian,

My friend is always on the latest health kick, so now she takes probiotics every day and swears she feels so much better. She keeps bugging me to take them too, but I priced them at the drugstore, and they are expensive. Are they worth it?


Dear Sharon,

In recent years, probiotics have been a popular health trend, with sales reaching $47 billion in 2020 and projected to grow to $76 billion by 2026. In order to be labeled as probiotic, a product must contain “live microorganisms that, when administered in adequate amounts, provide a health benefit to the host.”

Leanne McCrate, RDN, LD, CNSC

First, let’s discuss the difference between probiotics and prebiotics. Prebiotics are specialized plant fibers that act as “fertilizers” in your gut, thereby increasing the number of good bacteria in your intestines. Conversely, probiotics actually contain live organisms, usually certain strains of good bacteria, that add to the number of healthy bacteria in the gut. Both prebiotics and probiotics are found in food and can also be purchased in capsule form.

Most research performed on probiotics has been in the area of bowel disorders. In a 2017 review of 17 studies involving more than 3,500 participants, probiotics were beneficial in reducing antibiotic-associated diarrhea in young and middle-aged adults, but not in people 65 years of age and older. The lack of benefit for elderly adults may be due to the low numbers of study participants in this age group (1).

Probiotics were also effective in reducing diarrhea caused by Clostridium Difficile (C. diff). C. diff is a bacterium that is always present in the large intestines of humans, but it may cause diarrhea when the healthy gut flora is diminished. This type of diarrhea may occur when the immune system is suppressed.

Those who suffer from Irritable Bowel Syndrome (IBS) have found relief in probiotics. IBS is a condition fraught with abdominal pain, diarrhea, constipation, or alternating constipation and diarrhea.

In recent years, probiotics have been studied in other areas of health. A review of 12 studies with 3,720 people showed that those taking probiotics might have fewer and shorter respiratory infections. However, the result is uncertain because the quality of some of the studies was poor (1).

Acne is a condition many of us have suffered during adolescence and early adulthood. Some evidence has shown a favorable influence of probiotics on acne. However, the research on using probiotics for acne treatment is relatively new.

When purchasing a probiotic, look for one with the USP emblem on the label. The United States Pharmacopeia (USP) is a non-profit organization that tests supplements for quality. Probiotics vary in cost from $15 to $50 for a quantity of thirty.

Consult your doctor before starting a probiotic regimen. He will advise you on the best product for you, as well as the proper dosage. Also, probiotics are not without side effects, as they have actually caused harm in people whose immune systems are compromised.

Until next time, be healthy!

Dear Dietitian

Leanne McCrate, RDN, LD, aka Dear Dietitian, is an award-winning dietitian based in Missouri. Her mission is to educate consumers on sound, scientifically-based nutrition. Do you have a nutrition question? Email her today at Dear Dietitian does not endorse any products, health programs, or diet plans.


  1. “Probiotics: What You Need to Know” (Aug 2019). National Center for Complementary and Integrative Health.