“To keep the body in good health is a duty… Otherwise we shall not be able to keep our mind strong and clear.”
(Buddha)
Last week, Dr. Tom told us about probiotics, the good bacteria that live in our intestines and help keep us healthy in numerous ways. He recommended adding probiotic foods like sauerkraut, yogurt and kefir to your diet and suggested taking a probiotic supplement. Building upon Dr. Tom’s wise counsel to ensure you have a well-populated gut, I suggest that you also add prebiotics to your healthy eating plan.
You see, bacteria are living creatures… teeny tiny, invisible to the human eye living creatures, but living all the same. As such, they need to be fed or else they will starve to death! And what’s the point of us consuming them just to kill them off once they’ve made their home in our guts?
Prebiotics are carbohydrates that are not digestible by humans, but are digestible by bacteria. In other words, these carbohydrates travel through our digestive system intact until they reach the good bacteria living in our large intestine and serve as good gut bug food. The best part is that in the process of consuming (aka, fermenting) these carbohydrates to keep themselves alive, the good bacteria like lactobacilli and bifidobacteria give off substances like butyrate and vitamin K2 which we can absorb and use[1]. If that’s not a win-win, I don’t know what is!
So, what can you do to feed those good bacteria? You can eat lots of unprocessed plant foods because prebiotics are primarily fermentable fibers and are found in lots of vegetables, fruits, legumes, nuts and seeds. (Keep reading for more details about which ones are the best sources.)
By the way, some fermentable fibers are not considered prebiotics because they do not feed the good bacteria living in the gut, which is one of the criterion of being classified as a prebiotic. Also, you may have heard of soluble and insoluble fiber. Prebiotics tend to be insoluble fiber, but some soluble fibers are also fermentable… in case you were curious.
If you weren’t curious, don’t worry! There’s really no reason for you to remember all of that. Rather, focus your efforts on consuming a variety of the foods listed below to be sure you are ingesting at least most of the five different types of prebiotics: fructans, galactans, beta-glucans, pectins and guar gum.
1. Fructans
Fructans are carbohydrate chains primarily made of the sugar fructose. Depending on how the fructose molecules within the chain are hooked together, if the last molecule in the chain is fructose or glucose, and how many fructoses there are in the chain, determines if the fructan is an inulin, oligofructose or fructooligosaccharide (FOS). Inulin and FOS are sometimes added to foods and supplements to increase their fiber content, and consuming these can help feed the good bacteria. However, you can also get them from food, as fructans are abundant in plant foods.
The biggest source of fructans for many people is wheat and products made from it like bread. Although all wheat products contain at least some fructans, whole wheat products contain much more than processed products (like white bread). Also, with all the problems that wheat can cause, from wheat allergy to gluten sensitivity to processed wheat products being devoid of other nutrients, consuming large amounts of wheat isn’t the best way to get your regular dose of fructans. Rather, consider other dietary sources like onions, leeks, garlic, Jerusalem artichokes, asparagus, corn, beets, Brussels sprouts, broccoli, savoy cabbage, radicchio, fennel, chicory, peas, cashews, pistachios, nectarines, peaches and watermelon. If you aren’t sensitive to gluten, you can also get your fructans from rye and barley.
2. Galactans
Galactans are made of chains of the sugar galactose, and as the human body cannot break the connection between two galactose molecules, these galactans end up in our gut, creating a delicious feast for our bacteria[2]. Natural sources of galactans include all legumes like lentils, garbanzo beans (chickpeas), kidney beans, soybeans and black-eyed peas. Some vegetables also contain galactans, including Jerusalem artichokes, onions and peas.
3. Beta-glucans
Beta-glucans contain glucose molecules linked together in such a way that humans can’t break the links in order to absorb them, and off they go to the gut too. The primary sources of beta-glucans are oats and barley, while rye, wheat, baker’s yeast and some mushrooms provide some of this valuable fiber. If you have a gluten sensitivity, be sure to look for certified gluten-free oats and avoid rye, barley and wheat.
(As a side note and bonus for us, eating beta-glucans helps stabilize blood sugar and lower cholesterol levels in the blood. If you’ve ever wondered why CheeriosTM help reduce cholesterol, it’s because they are made from whole grain oats which are full of beta-glucans!)
4. Pectins
If you’ve made jelly or jam, then you will be familiar with pectins, as these are the carbohydrates in fruit that cause thickening after the fruit has been cooked. As may seem like an obvious follow on from this, fruits are the greatest source of pectin, with many of them containing 5 – 30% pectin by volume[3].
The best sources include apples, apricots, cherries, quince, plums, gooseberries, oranges and other citrus fruits. To a lesser extent, other fruits like bananas and strawberries, some vegetables (like carrots, beets and cabbage) and legumes also contain pectin. So you have plenty of choice!
5. Guar gum
Guar gum is derived from guar beans, which are commonly found in India and Pakistan where the whole bean is included in vegetable dishes. Outside of this region, guar gum tends to be added to foods as a thickening agent[4]. (You may have seen it added to products like canned coconut milk.)
You shouldn’t necessarily seek out foods that include guar gum in order to help feed your good bacteria, and I’m including it here because it is a prebiotic. The problem is that studies have shown that too much guar gum from packaged foods can cause digestive upset for some people. This is no doubt due to the guar gum making its way to the good gut bugs where they chow down on it and produce lots of gas in the process!
By the way, other carbohydrates are fermentable, but aren’t necessarily considered prebiotics as they aren’t consumed with the intention of feeding the bacteria living in the large intestine. A great example is lactose. Anyone who is lactose intolerant is all too familiar with this concept as lactose is readily fermentable by good gut bugs, once it gets through the small intestine of those who lack the enzymes to digest it. In this way, it acts as a prebiotic, but isn’t classified as one, since a person is either able to digest it themselves and use the nutrients or generally avoids it so that they don’t have tummy trouble.
As a final note: although consuming plenty of prebiotics is necessary for gut health, I definitely recommend avoiding prebiotic foods that upset your intestinal tract, like guar gum and lactose mentioned above or any other food to which you have a sensitivity or intolerance. (For the record, this could be absolutely any food because we are all unique, so keep an eye out for how different foods make you feel!)
Even if you have one or more foods that give you digestive trouble, you don’t have to worry. By consuming plenty of vegetables, fruits and legumes, you can ensure that you keep your good gut bugs well-fed… and alive! In turn, they will help keep you happy and healthy.
[1]Linus Pauliing Institute.Fiber
[2]Scarlata K. The FODMAPs Approach — Minimize Consumption of Fermentable Carbs to Manage Functional Gut Disorder Symptoms.
[3]Srivastava P, Malviya R. Sources of pectin, extraction and its applications in pharmaceutical industry − An overview.
[4]Kresser C. Harmful or Harmless: Guar Gum, Locust Bean Gum, and More.
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