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Are Probiotic Supplements Right for You?

By Stephen Ornes

About 40 trillion bacteria call the human body home, and the vast majority live in the large intestine. Some are good, some are bad, and some are both. Maintaining a population of helpful bacteria—the kind that ward off disease—is critical to good health, says Sarah Rafat, a senior clinical dietitian at the University of Texas M. D. Anderson Cancer Center in Houston. 

Rafat has seen an increase in patients asking about probiotic supplements—pills that contain live, “helpful” bacteria like Lactobacillus and Bifidobacteria that help break down food in the gut. 

“Probiotics in general are good, yes, but in the cancer patient population, it depends on the patient,” says Rafat. Treatments like antibiotics, which wipe out good and bad bacteria indiscriminately, can decimate the microbial population of a person’s intestines. 

“Having a compromised immune system or being neutropenic can put one at risk of getting an infection,” says Lisa Lillie, a registered dietitian at Vanderbilt-Ingram Cancer Center in Nashville. A person with neutropenia has an abnormally low level of white blood cells called neutrophils that fight infection.

A cancer patient may want to use probiotic supplements in an attempt to re-establish good bacteria, although clinical studies haven’t demonstrated a benefit in using these products. A 2013 study published in Science suggested a large population of good strains of bacteria increases the effectiveness of chemotherapy—but the study was done on mice, not humans, and didn’t look specifically at supplements. Other studies have associated serious side effects (including pneumonia and endocarditis) with probiotic supplement use in immunosuppressed patients—though the researchers weren’t looking specifically at cancer patients. 

Until better evidence becomes available, Rafat and her colleagues recommend that patients wait until treatment is completed before considering probiotic supplements and then discuss them with their health care providers. 

“We don’t say don’t ever take it. We tell the patients to hold on until you’re done with treatment,” she says. 

In addition, she says, not all supplements contain what their labels advertise; some include ingredients not listed on the label. Supplements do not require approval by the U.S. Food and Drug Administration, and the agency warns consumers to be aware of the risks. Rafat recommends that patients consult with a nutrition expert to ensure the product they are looking at is safe and of good quality. 

Lillie agrees. “There are many different probiotics, so discuss which strains and species would be appropriate to take based on the patient’s condition, a trusted manufacturer and suggested dose,” she says. 

Both experts note that probiotics occur naturally in foods like yogurt and sauerkraut and in high-fiber foods like leafy green vegetables. The best strategy for incorporating probiotics into a diet is to increase consumption of these foods, says Rafat, rather than taking a pill.


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