• Kefir (a cultured drink that is similar to yogurt)
• Acidophilus milk
• Sour cream
• Aged cheeses (Gouda, Swiss, etc.)
• Cottage cheese that contains active cultures
• Miso (a fermented soybean paste)
• Tempeh (a fermented soybean product)
Other foods that may contain added probiotics are certain varieties of cereal, juice, frozen yogurt, and even candy. According to the Web site www.usprobiotics.org, foods that have added probiotics usually contain Lactobacillus or Bifidobacterium bacteria, or Streptococcus thermophilus. One way to tell if a food contains probiotics is to look for the phrase “live and active cultures” on the package. Some foods may contain more than one type of probiotic. For example, yogurt in the United States must be made with two types of bacteria, Lactobacillus bulgaricus and Streptococcus thermophilus. Stonyfield Farm yogurt contains four other strains, as well: L. acidophilus, Bifidus, L. casei, and L. rhamnosus. Some varieties of yogurt may be heat-treated, which prolongs their shelf life but can kill off their probiotics. These varieties will not carry a “live and active cultures” seal.
One side benefit of eating foods that contain probiotics is that many of them have a low glycemic index, thanks to the acid-producing bacteria they contain. This means you’re less likely to experience a spike in your blood glucose level after eating these foods compared with others with a similar carbohydrate content.
Probiotics are also available as capsules, tablets, powders, and liquids. Like other dietary supplements, probiotics are not regulated by the US Food and Drug Administration (FDA). If you’re considering taking a probiotic supplement, talk with your health-care provider first. Probiotics may not be safe for people with certain medical conditions. Here are a few tips for choosing and using probiotic supplements:
• Don’t stop using prescribed medicines — unless your doctor tells you to stop — just because you’re taking a probiotic.
• Choose a supplement manufactured by a reputable company.
• Choose a supplement that is uncentrifuged, which is a process that can destroy living cells. Look for the word “uncentrifuged” on the supplement, or contact the company directly to inquire about processing methods.
• There is likely benefit from choosing a supplement with multiple types or strains of bacteria. Ideally, the types of bacteria and amounts per dose should match what was used in research studies of the supplement. A product’s Web site will often provide information on these details.
• Capsules are the best form of probiotic supplements because of the protection they offer against heat and moisture.
• Always check the expiration date before buying — and before using — a supplement.
• Some supplements may require refrigeration; read the label to see if this is the case.
• A probiotic supplement should contain at least 1 billion live cells per gram and may contain upwards of 10 billion, although more is not necessarily better. The upper limit should be based on doses used in clinical research.
Another option when choosing a supplement is to look for the number of CFUs (colony-forming units) on the label. This number is another way to indicate the amount of live microbes in the product. In general, a dose of about 20 billion CFUs is suggested.
• If you have any side effects from a probiotic supplement, stop taking it and contact your doctor.
The use of probiotic supplements in the United States is still relatively new, and there’s a lot we don’t know about their long-term effects. As is the case with many dietary supplements, their safety hasn’t been thoroughly studied. And it’s particularly unclear how safe they are for children, the elderly, pregnant women, and people with compromised immune systems. Foods that contain probiotics are more clearly safe than supplements, given that they have been safely consumed for thousands of years. However, people with severely compromised immune systems—such as those with HIV or AIDS, or who are undergoing chemotherapy or radiation—should consult their health-care team before consuming any food or product containing probiotics. Probiotics may also be inappropriate for people with organ failure or who are in the ICU. In one clinical trial, 24 people with severe pancreatitis died after being giving probiotics.