As we shared in the first post in this two-part series, many people are confused about the differences between prebiotics and probiotics. A lot of us think they mean the same thing. That can make it hard to know potential benefits they offer, which one is in the foods or supplements you’re taking, or what questions to ask your healthcare team. The first post in this series reviewed prebiotics – with an “E” – what they are, how they may be helpful, and why they’re included in some nutritional products. Today – you guessed it – we’ll review the same information for probiotics – with an “O”!
Probiotics, sometimes referred to informally as “good bugs,” are living microbes that are in some way good for us, or good for a specific condition. We naturally have lots and lots of microbes living in and on our bodies. In fact, if you count all of them, the number of human cells in our body is far outnumbered by the number of microbes!
When you look at the microbes in our guts, you can classify them as ones that are neutral, ones that are beneficial, or ones that may be harmful (in certain conditions). Probiotics are ones that are beneficial in some way.
Consuming a probiotic puts some of a good microbe directly into your digestive tract. This can have general benefits, like crowding out potentially harmful microbes. Or it can have specific benefits. For example, some probiotics may be helpful for people with diarrhea related to antibiotics, and others can help people with specific digestive disorders. It’s important to know that not all probiotics are the same.
Probiotics are available as supplements, such as in sachets, tablets or capsule form. Probiotics can also be present in certain foods, such as yogurts or other beverages. Probiotics are also added to some nutritional formulas. Of note, probiotics can be sensitive to heat, so read directions. Don’t cook foods that contain probiotics, and you may not be able to add them to anything warmer than body temperature without affecting their benefits.
While everyday foods – in particular yogurt and fermented foods – contain microbes, probiotics are specific microbes that are added to foods or formula. More on that below!
How do you define probiotics?
Here is a list of characteristics that have been used to define what makes a microbe a probiotic:
- a live microorganism (meaning that it’s a bacteria, yeast, fungus, or alga that is still alive or dormant)
- that, when administered in adequate amounts (meaning you have to take enough of it)
- confers a health benefit on the host (that’s us!)
So, in essence, a probiotic is a living microbe that we take as a supplement or add to food or nutritional formula for the benefits it offers. The benefits are specific to each probiotic, because every microbe is unique. I like to compare them to plants and animals: some live on land, in the air, or in water. Some plants make energy from the sun, some animals eat plants, and some animals eat animals. Taken together, plants and animals form a giant community with lots of different roles. The microbes in our gut have a similar community with different niches and roles.
That introduces another concept that’s crucial to probiotics. First, it’s important to know that most probiotics are bacteria, though probiotic yeasts are also common. But bacteria come in a HUGE variety of shapes, sizes, and they’re able to do many different things. Because of that, a probiotic is a specific strain of a bacterium.
So what are some examples, and how do you know what strain you have? Well all strains start with a genus name, which is broad. Examples include Lactobacillus, and Bifidobacterium. Next is the species name which comes after the genus name. Examples are L. rhamnosus, L. reuteri, B. breve, and B. lactis. (Since we already named the genus, we can abbreviate it to the capital letter!)
But those names only tell you the species. With bacteria, the strain is even more specific than the species, and different strains within the same species can be very different. Unless you know the strain, you don’t really know what probiotic you’re taking. Names that include strains are L. rhamnosus GG, L. reuteri DSM 17938, B. breve M-16V, and B. lactis Bb-12. (Notice how the genus and species are in italics, but the strain is not. Funny science!) These are just a handful of examples.
Of note, while all yogurt is made using bacteria, not all yogurt contains probiotics. Even buying yogurt that says “live active cultures” doesn’t necessarily mean it contains probiotics. The bacteria used to make yogurt can be considered “beneficial bacteria,” but they haven’t all been shown to have specific benefits, so are not probiotics. Some yogurts, though, do have an added probiotic strain that has demonstrated benefits.
Why would clinicians recommend prebiotics? How can they be helpful?
While all probiotics have some benefit, the benefits are not all the same. Various probiotics have been shown to have a variety of health benefits. Probiotics may help to bring the community of microbes in the gut into balance. They can also influence digestion or other aspects of health. Here are some conditions in which research has found evidence that certain, specific probiotics may be helpful:
- Helping manage infectious diarrhea
- Lessening risk of antibiotic-associated diarrhea
- Lessening risk of daycare-associated diarrhea
- Lessening risk of nosocomial diarrhea (related to infections picked up in a hospital)
- Helping manage inflammatory bowel disease (Crohn’s disease, Ulcerative colitis)
- Helping manage atopic dermatitis associated with food allergy
- Lessening risk of necrotizing enterocolitis
- Helping manage irritable bowel syndrome
Again, there are specific strains that have been studied for these conditions. A healthcare provider can provide more information about which specific strains have been studied in a condition, and how strong the evidence is of benefit for that specific strain.
People may take probiotics that were recommended by a doctor or dietitian due to specific benefits. The best thing to do if you have questions about the possible benefits of probiotics is to talk to your healthcare team. They can help you to understand the possible benefits of adding a specific probiotic to your diet, and may be able to help you choose the best source or type.
Why are probiotics in some nutritional formulas?
For breastfed infants, breast milk naturally contains beneficial bacteria. These bacteria come from the mom and can help to provide a community of microbes for the infant. Sometimes the community of microbes in an infant’s gut can get out of balance – more of some and less of others than is typical. The addition of probiotics to an infant formula can help to correct that imbalance. (Prebiotics can also help impact the balance.) The probiotics added to various infant formulas in the US include:
B. breve M-16V
B. lactis Bb-12
B. longum BB536
L. reuteri DSM 17938
L. rhamnosus GG
L. rhamnosus HN0001
In the Neocate family of products, Neocate Syneo Infant is supplemented with the probiotic B. breve M-16V. It also contains the prebiotics scFOS and lcFOS. The combination of probiotics and prebiotics is known as a synbiotic.
We hope that these two posts helped clear up any confusion! What questions do you have about probiotics?
Rob McCandlish is a registered dietitian nutritionist (RDN) who joined the Nutricia team in 2010. Rob has years of experience at Nutricia following food allergy research, working with Neocate products, talking with Neocate families and learning about the science behind Neocate and food allergies. Rob has two nephews who both used Neocate for their cow milk allergies!