What Is Probiotic Food?

Unlike antibiotics, which kill harmful bacteria in the body, probiotics add helpful bacterial cultures, almost always to the digestive tract. The intestines are naturally teeming with bacteria that help process food and eliminate waste, but these processes are not always as efficient as they could be. Poor nutrition, imbalanced hydration, illness, and other environmental factors can also lead to a number of digestive troubles. Not all medical professionals agree that probiotics can cure problems like diarrhea, persistent constipation, or irritable bowel syndrome, but there is wide consensus that they can at least help in most cases.

Food manufacturers in many countries artificially introduce probiotics into milk, yogurt, and some cheeses as a way of making them more digestible. Raw cow and goat milk contains some of these bacteria, but not always very much. Human breast milk, on the other hand, typically has very high levels of probiotic cultures, which many experts believe helps infants’ digestive tracts mature.

Researchers began experimenting with the addition of Lactobacillus acidophilus bacteria to commercial milk in the early 1900s in both Europe and North America after medical professionals began noticing an increase in patients with lactose intolerance and other digestive troubles thought to be caused by dairy products. Adding the cultures can make milk more easily digestible without altering its taste or nutritional composition, so people still get the benefits, like calcium and protein, without as much stomach upset. Modern day manufacturers do not usually fortify milk with cultures automatically, though probiotic milk — usually called acidophilus milk — is available in many markets, often as an alternative for those with lactose intolerance.

Helpful bacteria additions are standard in most yogurt products, however. Any yogurt that says “live and active cultures” on its labeling contains probiotics. These cultures are usually added to help the yogurt thicken during processing, and the digestive benefits are often something of an added bonus for the consumer. Some yogurt manufacturers add more cultures than are strictly needed in order to boost the probiotic effect of the final product; many of these are sold with promises of improved regularity or marketed as a digestive “wonder food,” though the accuracy of these claims is somewhat controversial.

L. acidophilus is only one of many bacteria that can help regulate digestion. Other bacterial strains in the Lactobacilli genus, as well as some Bifidobacterium species, grow in fermented foods. These bacteria generally occur naturally, though some food manufacturers will take steps to encourage their presence. Miso, sauerkraut, and the fermented soy product sold in many places as tempeh are a few common examples of foods high in these cultures.

Pickled vegetables may also be good sources of probiotics. Homemade pickles typically have higher concentrations of helpful bacteria than mass-produced or commercially prepared products, as many of the preservatives common in store-bought foods restrict bacterial growth. Much depends on the process and the vegetable at issue, however.

Algae are not the only probiotic foods with a limited shelf life. Like most living things, bacteria only thrive in certain conditions, and they will die at some point. As a result, many of these foods have very strict expiration dates. Individuals who eat out of date products will not necessarily be harmed by them, but they may not produce any benefit, either. Most active cultures will stay alive under refrigeration, pressure, or liquid suspension for anywhere from a week to 10 days once they have been exposed to oxygen. Heating, freezing, and aggressive agitation can cause the bacteria to die more quickly.