You might have noticed “contains live cultures” on the labels of most yogurt in the supermarket. Those live bacterial cultures are what make yogurt one of the most accessible probiotic foods. Although probiotic foods have existed for centuries, recent research on the benefits of probiotics has caused a surge in popularity.

But what are probiotics, and what do they do for your health? Read on to learn how some everyday foods may be working a lot harder than you might think to keep you feeling great.

Probiotic literally means “for life.” The name refers to beneficial bacteria, yeasts, and other microorganisms that offer health benefits.

In foods, probiotic refers to good bacteria that is added to or occurs in fermented items. Examples include yogurt, buttermilk, some soft cheeses, miso, sauerkraut, and other pickled vegetables.

Most probiotics contain bacteria from the lactobacillus and/or bifidobacterium families. While these strains have different properties, there is some evidence that they can help with a number of health issues.

Learn about the probiotic Lactobacillus acidophilus »

Probiotics aren’t necessary for a healthy diet, but they work with and support the existing beneficial bacteria in the gastrointestinal tract, which helps keep your body running.

It’s no surprise that probiotics like yogurt can help ease digestive woes, and the benefits don’t stop there. Research suggests that a balanced gastrointestinal flora supports immune function throughout the entire body as well.

So probiotics can help keep you feeling good if your flora is already balanced, and can help get you back on track if you’re feeling a little out of whack. In fact, some doctors recommend you take probiotics after a course of antibiotics to help boost good bacteria and restore this balance.

Although further research is needed, a 2008 finding suggests that probiotics may even help with:

  • diarrhea (including “traveler’s diarrhea”)
  • lactose intolerance
  • inflammatory bowel diseases (such as IBS)
  • atopic eczema in infants

Some research shows that probiotics can also treat vaginal infections, such as yeast infections and urinary tract infections. They can also prevent tooth decay, help with colds and flus, and even prevent certain cancers.

However, research on probiotics is complicated by the fact that each probiotic bacterial strain is unique. This means that the benefits of each may also be unique.

The known side effects of most probiotics (for example, gas) are minimal. However, this requires more study, and the long-term effects of sustained probiotic use have not been thoroughly investigated.

You should consult with your doctor before you use probiotics if you are seriously ill, an older adult, or if you have a compromised immune system.

Yogurt is a versatile and easily accessible probiotic food. Try a plain, low-fat Greek yogurt for a low-sugar protein boost. You can add yogurt to your breakfast routine, mix it with fresh fruit for a sweet dessert, or whip into smoothies and dips.

Look for yogurts that say “probiotic” or “contains live cultures.” Many commercial yogurts are pasteurized past the point of probiotic benefit.

Other good dairy sources of probiotics include:

  • soft cheeses
  • buttermilk
  • kefir,
  • probiotic-labeled cottage cheese

Just remember that cooking a probiotic food will kill the bacteria. If dairy doesn’t work for you, try:

  • tempeh
  • miso
  • sauerkraut
  • kimchi
  • other pickled vegetables

Probiotics gradually affect your gut flora, so it may take weeks to notice any effects, especially if you’re not treating a specific condition.

Probiotics are also available in supplement form, which have more concentrated doses of particular strains. You should talk to your doctor about desired effects before you add supplements to your diet.