Ask Mayo Clinic: Jury still out on benefits of fermented foods

DEAR MAYO CLINIC: Are there any special health benefits to fermented foods?

The jury's still out. In recent years, claims of possible health benefits of fermented dairy or plant foods, such as yogurt, kefir, aged cheese, tempeh, miso, sauerkraut and many others, have gained the spotlight.

The digestive tract is loaded with beneficial bacteria. Likewise, live, active bacteria make fermented foods possible. These bacteria, known as probiotics, are where the potential health benefits in fermented food may be.

While it sounds promising, the evidence is more suggestive than proved. Some evidence supports select probiotic use for certain bowel disorders. Research is ongoing to understand how probiotics may influence other areas of health, including obesity and regulation of the immune system.

To gain benefits, it's generally thought that a daily probiotic dose of around 10 billion colony-forming units (CFU) of certain bacteria strains is needed. However, fermented foods are all over the map in terms of the dose and type of beneficial bacteria. Some fermented foods contain supplemental probiotics to achieve a consistently high dose. Others might contain only moderate or low levels of live cultures — or no live cultures at all.


Fermented foods can be a part of a healthy diet and may provide health benefits that other foods can't. But, it's hard to say exactly what you're getting from a fermented food in terms of bacterial type or dose. Therefore, it's difficult to know what you can expect in terms of probiotic benefits. In addition, a fermented product with live active cultures also may contain high levels of saturated fat, salt or added sugars. (adapted from Mayo Clinic Health Letter) — John K. DiBaise, M.D., Gastroenterology and Hepatology, Mayo Clinic, Scottsdale, Ariz.

READERS: You try to eat plenty of fresh produce, but worry about your risk of ingesting pesticides. Most nonorganic crops — and even some organically grown crops — come in contact with pesticides and may contain traces of pesticidal residue on the surface of, or inside, the plant. The U.S. Environmental Protection Agency monitors domestic and imported foods to ensure that pesticide residues are below certain levels. However, you can take extra steps to minimize pesticide exposure further by:

Cleaning produce

Rinsing produce with running water for 15 to 30 seconds, while gently rotating the produce removes most surface pesticide residue. Scrubbing with a brush also may aid in the removal of pesticides and other substances.

Peeling produce

It makes sense to peel an outer layer from foods such as lettuce or onions. For foods such as apples and potatoes, peeling removes pesticide residues, but also the nutrients in the peel. Rinse before peeling, so that the knife doesn't transfer substances to the peeled produce.

Buying organically grown produce

Not every piece of produce labeled organic is 100 percent pesticide-free, and not everything that's conventionally grown has pesticides. Still, for the most part, consuming organic produce significantly reduces your exposure to pesticide residues, compared to consuming conventionally farmed produce. (adapted from Mayo Clinic Health Letter)

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