Ever heard of prebiotics?
Maybe not but no doubt you’ve heard of probitoics and their role in digestive health. The WHO defines probiotics as “live microorganisms which when administered in adequate amounts confer a health benefit on the host” (1).
Prebiotics you say? YES.
They are moving into the mainstream now like probiotics did 10 to 15 years ago but what are they? What do they do for us? What are the health benefits of prebiotics and how do you include more of them in your diet?
Prebiotics are a type of fiber that support the growth of beneficial bacteria (a.k.a. “microbiota”) in your digestive tract, most importantly the colon or large bowel.
Prebiotics act as ‘food’ for the countless microorganisms that reside in our gut. When the bacteria have enough food, they reproduce, ensuring you have a diverse and plentiful amount of those beneficial bugs.
The health benefits of prebiotics
Your colon is the ideal environment for these beneficial bacteria to grow and thrive.
The colon is home to close to 100 trillion microorganisms but like anything, if we don’t take care of our gut and specifically feed the little guys their preferred diet, they’ll respond in kind to that neglect.
Starving beneficial bacteria of their favourite food – prebiotics – decreases their nubers as would any species of plant or animal in the face of famine.
When there’s little food to go around, the harmful bacteria take advantage and start to take a foothold, leading to dysbiosis [bacterial imblance] and causing a bunch of problems.
Sadly, the risk of developing dysbiosis not only increases as we age but also when we consume diets low in fiber [think not enough plant foods] and specifically sources of prebiotic-rich foods.
Other factors that can use bacteria imbalance include repeated use of antibiotics, medications such as acid reducers, excess sugar and a lack of sleep and increased stress (2. 3, 4).
By increasing the number of healthy bacteria in your gut, prebiotics help them to work better to our benefit. A robust and diverse microbiota population helps to produce essential nutrients for the cells of your colon.
Gut bacteria also promote the production of something called short chain fatty acids (SCFAs too. Like all fatty acids, they serve as a fuel source.
SCFAs provide energy for the digestive tract and the rest of the body when they are absorbed into the blood; making their way to our various tissues and organs. SCFAs also improve metabolic health (5).
Fortunately, it is easy to keep your gut microbiome happy and to fix dysbiosis – simply eat more prebiotic-rich foods!
The 9 best prebiotic-rich foods you should eat
Chicory root
Ground chicory root powder was popular in the 70s as a coffee substitute back in the days when we thought coffee was the devil in liquid form; it is not.
Chicory root is a great source of prebiotics boasting a 47% inulin content. Inulin is a type of prebiotic fiber that is added to some prebiotic supplements and powders.
As a food ingredient, chicory root has been shown to improve gut bacterial numbers, improve digestion, and as a result, normalize bowel movements (6).
Dandelion greens
Until recently, anyone who admitted to eating dandelion or those who picked it in the ‘wild’ were seen as odd; eating ‘weeds’ seemed, well, unseemly BUT thank God, cooler heads prevailed.
Cooked or as part of a salad mix, dandelion leaves are also a good source of inulin and studies have shown dandelion to ease constipation and improve the profile of gut bacteria (7).
Garlic
Long been seen as a healthy food, not the least of which for its anti-microbial, antiseptic properties, garlic is rich in both inulin and another prebiotic called fructooligosaccharides (FOS).
Garlic is a potent simulator of the genus of bacteria called Bifidobacteria; having more bifido in your digestive tract is a very good thing.
Garlic, for those without any gut issues like IBS, offers a double whammy to any unwanted bacteria that are thinking of setting up shop; garlic increases the number of bifidobacteria while at the same time, prevents disease-promoting bacteria from growing by using a kind of antiseptic chemical warfare (8).
Bananas
Like other prebiotic-rich foods, bananas have inulin but they also have another prebiotic darling du jour: resistant starch. Starch is the storage form of glucose (a carbohydrate) found grains and grain products, potatoes etc.
It might surprise people to know that not all of the starch that they eat is digested; some of it (close to 10%) passes through your digestive tract untouched, ultimately ending up in the large colon (e.g. ‘resistant’ to digestion).
Resistant starch has prebiotic effects; increasing the good bacteria and offering all the same benefits as inulin and FOS (9, 10).
FUN FACT: all prebiotics are fiber but not all fibers are prebiotics. Dietary fiber is a broad term to describe those types of dietary carbohydrate that our digestive tract cannot breakdown. Fiber is resistant to the effects of stomach acid and the other carbohydrate digestive enzymes.
Jerusalem artichoke
Probably the darling of the prebiotic universe. Jerusalem artichokes were one of the first foods talked about when the prebiotic conversation started a few decades ago.
They contain a lot of inulin; 76% of the 2 grams of fiber in 100 g of Jerusalem artichokes is inulin – impressive to say the least and like other inulin-rich foods, boost the ‘friendly’ bacteria in our colon (11).
Barley
Not as well known for it’s prebiotic prowess, barley is best promoted for it’s cholesterol and blood sugar balancing attributes because barley, like other soluble fibers, become viscous and slow the digestion of food.
Barley contains beta-glucan which helps with gut and metabolic health but beta-glucan is another type of prebiotic fiber which promotes the growth of friendly bacteria in the digestive tract (12, 13). Gooooo barley!
Flaxseed (ground)
Yes they must be ground to get the health benefits. Another great source of prebiotics. Flax seeds have a nice profile of fibers too. Flax has the soluble type as mucilage gums and insoluble fiber from cellulose and lignins. Lignins are responsible for flax seed’s super star, anti-cancer properties.
Ground flax seeds are a great way to manage bowel movements, treatment constipation and boost gut bacterial numbers (14, 15). A couple of tablespoons of ground flax per day will do wonders for your digestive health and bowel habits.
Wheat bran
Bran is the outer layer of whole grain kernel and its name just reflects the grain it came form, e.g. wheat bran, oat bran, barley bran etc. Wheat bran is an excellent source of prebiotics.
It also contains a special type of fiber made of arabinoxylan oligosaccharides (AXOS) (you’re testing your pronunciation skills with this post!) which represents about 64–69% of wheat bran’s fiber content.
AXOS fiber from wheat bran has also been shown to boost healthy Bifidobacteria in the gut (16, 17). Bran cereals, muffins and breads do more for the bowel than just promoting regularity.
Apples
An apple a day keeps the doctor away and this common fruit is a stable fruit in North America. Apples haven’t been given the attention they deserve specifically when it comes to bowel health. It’s not just goji berries, or blueberries or kale when it comes to ‘superfoods’.
Apples are an inexpensive fruit with amazing ingredients like phenols; potent health promoting antioxidants.
Apples also contain prebiotic fiber such as pectin which accounts for about 50% of the total fiber content in apples. Pectin does double duty when it comes to gut health; it increase SCFAs (specifically butyrate) and increases the good bacteria thereby keeping the other, least desirable bacteria, in line (18, 19).
What could be easier than adding 1 apple a day to your daily fare?
Doug Cook RDN is a Toronto based integrative and functional nutritionist and dietitian with a focus on digestive, gut, and mental health. Follow me on Facebook, Instagram and Twitter.