You have likely heard of probiotic foods and supplements. Maybe you’ve taken a high dose probiotic supplement after being on antibiotics, or maybe you include yogurt, sauerkraut or kombucha in your diet, because you have heard about the health benefits of these foods. The beneficial microbes in these foods and supplements support the health of your digestive system, and have effects on every aspect of your biology.
But what about pre and post biotics, and do you need them?
PREBIOTICS
Prebiotics are food for the microbes in your gut. Every bite of food that you eat feeds both you and your microbes. First you digest your food, and then any undigested substances make their way to the large intestine where they feed your beneficial microbes. Fibre is a good example. You can’t digest it, but your microbes can. Good food sources of prebiotic fibre include onions, garlic, leeks, asparagus, dandelion greens (spring is a great time to collect them), sun chokes (Jerusalem Artichokes), and apples.
Fresh asparagus is so tasty, and your microbes think so too.
Resistant starch is another form of prebiotic. As the name suggests, it is “resistant” to digestion, so similarly to fibre, it makes it’s way to the large intestine undigested, where it feeds your beneficial microbes. Green bananas, plantains, cassava, cold potatoes, and cold rice are good sources.
Most supplemental probiotics contain some form of prebiotic as well. Fructooligosaccharides (FOS) are commonly used, and are well researched for their ability to increase beneficial bifidobacteria (1).
In addition to supplements, research also supports the addition of oligosaccharides in infant formula for pre-term babies (2). Luckily human breastmilk contains both pre and probiotics, still making it the best food for infants. Nature knows what it’s doing!
What if prebiotic food and supplements make you feel worse? If bacteria are overgrown in the small intestines, in a condition known as SIBO (small intestinal bacterial overgrowth), then prebiotic foods or supplements can make symptoms of bloating, cramping and abdominal pain worse. If you find yourself feeling worse after consuming any of the foods listed above, or after taking a probiotic supplement that contains prebiotics, then you should discuss the possibility of SIBO with your naturopathic or functional doctor.
DO YOU NEED THEM?
You bet you do! The health of your beneficial microbes (and conversely YOU) is dependent on them. The old adage, “an apple a day keeps the doctor away” is true. It’s a good source of prebiotics! Flavour your meals with onions and garlic, and make sure to eat a large variety of vegetables, and fruit. These foods are not only high in prebiotic fibre, but also contain polyphenols, which benefit your microbes too.
For resistant starch I love frying up plantains, or using them to make a wrap. Cold potato salad and sushi are also great ways to get resistant starch. Resistant starch preferentially feeds microbes that make butyrate. Butyrate is a postbiotic, providing me with the perfect segue to discuss postbiotics.
POSTBIOTICS
Postbiotics are byproducts from the feeding of probiotics on prebiotics. Postbiotics are sometimes also called metabolites (or collectively called the metabolome). I like to compare postbiotics to poop. When you eat food, you digest, absorb and metabolize it, and then the waste product is poop. Microbes metabolize the food you eat (prebiotics) and also have waste products, but unlike your poop which is excreted, those metabolites or postbiotics have a variety of functions in your body. These metabolites act as messenger molecules that communicate information to your body, thereby impacting your health. Some postbiotics benefit you, while others can be harmful.
Some of the better known postbiotics include
B and K vitamines (3)
Short chain fatty acids: butyrate, acetate, propionate (4)(5)(6)
Muramyl dipeptide (7)
Indole (8)
Lipopolysaccharides (9) - this one has been studied for a long time, and its inflammatory role in many health conditions is recognized. Do an online search to see if it’s involved in your health conditions!
DO YOU NEED THEM?
B vitamins and vitamin K2 are common supplements, and have a wide variety of uses. B vitamins are important to regulate your stress response, for hormonal health, and for brain health. These key nutrients are involved as cofactors to support many of your body’s chemical reactions. K2 is often added to Vitamin D supplements and bone formulations, as it plays a role in bone metabolism. It is also important for heart health and as a blood clotting factor. Your practitioner might recommend supplementing with these.
Good food sources of both B and K vitamins include meat, liver, eggs, avocado, and dark leafy greens, so make sure to get a variety of these daily. If you want your microbes to be able to make these nutrients, then pre and probiotics foods are important to eat too.
Another well researched postbiotic is butyrate, especially in the areas of inflammatory bowel disease, and brain health. Research supports the use of butyrate with Crohn’s and colitis (10)(11). It is a fuel source to the cells of the small and large intestine. In the area of brain health, butyrate reduces neuroinflammation (12). Research correlates inflammation with all brain conditions.
Plantain wraps are a great source of resistant starch, and they make great tacos and sandwiches. Eating them will help your microbes make butyrate.
If you have Crohn’s, colitis, or any brain condition, then discuss supplemental butyrate with your practitioner. Butter and ghee contain butyrate, so make sure to add this to your diet. Make sure to consume those food sources of resistant starch, so that your microbes can make butyrate too.
According to the website Postbiotica.com, postbiotics can be used to treat inflammatory conditions such as allergy, dermatitis, and conjunctivitis. Diabetes can also be supported by postbiotics (7), but the problem is that while the research supports its uses, these postbiotics simply aren’t available commercially.
HOW TO GET THE MOST FROM PRE, PRO & POSTBIOTICS
We still have a long way to go before we have a good understanding of all the postbiotics, and whether or not they have therapeutic applications. One of the complex aspects of postbiotics is cross-feeding, where some of the metabolites produced are food for other microbes (13). Mimicking that complexity of the entire metabolome in supplements will be challenging if not impossible. Your best bet is still a diet rich in fibre, resistant starch, and prebiotic foods. That way you are adding a variety of pre and probiotics, which will in turn produce postbiotics.
Additionally you may want to add a good quality probiotic supplement that contains prebiotics. I always encourage people who supplement with probiotics to rotate through various brands, unless they have been advised on specific strains. Rotating provides exposure to greater diversity, since each supplement will have a unique formula of microbial strains.
So fill your shopping cart with a variety of colourful vegetables, and add some plantains, cassava flour or potatoes (for potato salad) too. What is your favourite food that makes your microbes happy too?
Happy, Healthy Eating (and Feeding your microbes)!
Tracey