We might instinctively want to squash spiders or insects that crawl around our homes because we see armies of ants or spiders with spindly, sprinter-fast legs scurrying across the floor and think invasion, not how these bugs support our environment. Whether creepy crawlies make you squeamish or not, none of us can thrive without bugs. 

Take your gut, for instance. It’s home to trillions of microbes that form an ecosystem involved in survival-dependent functions like warding off infection, digesting food and dispelling waste, controlling your metabolism, and more. When the amount of good bacteria in your gut is off, you may get sick, run into tummy troubles, and even gain weight. 

We’re each born with unique, diverse microbiomes, but did you know that your diet can dramatically impact your gut health? To do so, consume a plant-rich whole foods diet for optimal wellness—particularly one that’s rich in probiotic and prebiotic foods. Read on to find out more about how prebiotic fiber naturally occurring in foods can improve your gut health. 

How Prebiotics Impact Your Gut Health

Prebiotics are non-digestible food ingredients that stimulate the growth and activity of good gut bacteria. Bacteria in your intestines play a vital role in maintaining immune and metabolic homeostasis and protecting you against germs. 

The most well-studied prebiotics include:

• Fructo-oligosaccharide (FOS): oligosaccharides that occur naturally in plants 
• Inulin: a type of FOS 
• Resistant starches
• Galacto-oligosaccharide: soluble fiber that occurs naturally in human milk; can be produced from lactose as well.
• Beta-glucan: soluble fiber that occurs naturally in oats, barley, and mushrooms.

Your microbiome ferments and produces short-chain fatty acids (SCFAs), such as acetate, propionate, and butyrate, from non-digestible carbohydrates (aka prebiotics). These SCFAs help keep you regular, may reduce the risk of cancer, and provide fuel for colon cells. They also provide make up the mucus barrier that prevents pro-inflammatory bacteria from penetrating the gut wall¹. 

Acetate is produced by bacteria metabolizing fat in your intestines and may play a direct role in appetite regulation². One scientific review suggests that acetate stimulates the release of satiety hormones³ and could help regulate inflammation. Fermented foods and drinks deliver SCFAs to the blood; vinegar and kombucha⁴provide more than 1,000mg of acetate per serving. 

A disruption in the balance of your microbiota can make you feel gassy, crampy, bloated, constipated, or like you have to run to the toilet. This condition, clinically known as dysbiosis, is associated with some inflammatory diseases and infections⁵.

Research on the impact inulin may have on glucose metabolism in overweight or obese people, those with abnormally high cholesterol or fats in their blood, and type 2 diabetics showed that inulin can reduce LDL cholesterol⁶ across these groups. Only type 2 diabetics saw improved HDL levels and better glucose control. 

A study of people with prediabetes showed that the group who supplemented with inulin for 18 weeks lost weight, had less stored fat in the liver, and ate less⁷. While this study proves promising, more human trials need to be conducted to observe the long-term benefits of weight loss. 

One study showed increased fat oxidation and energy expenditure⁸ as well as decreased lipolysis in overweight men given colonic infusions of a mixture of SCFAs. Now, SCFA enemas sound as fun as falling into a snake pit, and we don’t recommend them. 

Another less, uh, invasive way to get SCFAs: consume foods or drinks with inulin, a prebiotic that’s readily fermented and produces SCFAs that have been shown to help with obesity⁹, insulin sensitivity, and appetite regulation. The ideal amount of inulin intake is still being studied, and the effects of different amounts on humans in studies published since 2018 remain inconsistent. 

<p class="pro-tip">Read more about probiotics and blood sugar</p>‍

Prebiotics vs. Probiotics

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It’s easy to confuse prebiotics with probiotics—the more buzzy bacteria and yeasts that may confer health benefits when consumed. Prebiotics are components of food that you don’t digest that can encourage the growth and activity of beneficial bacteria. Probiotics are live microorganisms that you can ingest. 

Potential probiotic positives include: 

• keeping your body’s community of healthy microorganisms in check and able to bounce back after being disturbed (by a round of antibiotics, for example) 
• influencing your body’s immune response. 
  

If you’re a sharp food label reader, you may have seen the most common probiotic bacteria groups, Lactobacillus and Bifidobacterium, printed on a bottle of kefir or probiotic yogurt. 

The best way to influence your microbiota makeup to reap the most benefits? Your diet¹⁰. 

Fermented foods contain naturally occurring probiotics; good sources include kombucha, kimchi, some yogurt and cheeses, kefir, sauerkraut, miso, tempeh, pickled vegetables, and sourdough bread. Pick plain varieties of yogurt or kefir and eat them with fresh fruit or a sprinkle of allulose if you want a sweeter taste. 

Incorporate foods that contain prebiotics—ideally from whole food sources if possible. Prebiotic supplements can suffice, but you’ll get extra phytonutrients from real foods. 

<p class="pro-tip"><strong>Learn more about </strong> <a href="./blog/probiotics-metabolic-health">how probiotics and prebiotics can affect metabolic health</a>.</p>

Best Natural Sources of Prebiotics 

Prebiotic foods stimulate healthy gut bacteria. Here's a list that tells you foods to eat for better gut health and overall health.

Best Prebiotic Vegetables

• Chicory root: A good source of inulin, roasted and ground chicory root can be added to many packaged foods to boost the dietary fiber content. Steep the grounds in hot water, strain, and serve with frothed oat or whole milk for an alternative to a coffee latte. 
  

• Green leafy veggies, especially raw dandelion greens: Assertively bitter and peppery, raw dandelion greens taste like arugula on steroids. Finely chop these greens and combine with raw pecans, fresh blueberries and blackberries, diced shallots, a dusting of goat cheese, and a citrus or raspberry vinaigrette. The tart and sweet fruit, slight sharpness from the shallot, mellow nuttiness from the pecans, mellow and creamy tang from the goat cheese, and bright acidic dressing compliment and help shade the aggressive greens.
  

• Garlic: Sharp, pungent, yet sweet and mellow when roasted, raw garlic adds an in-your-face bite to any dip, dressing, or dish. Dried garlic contains higher amounts of inulin and oligofructose than raw, so stock some in your spice pantry and use liberally in sauces, stews, soups, and as a sprinkle on steamed, roasted, or grilled veggies. Garlic can also help lower blood sugar.
  

• Jerusalem artichoke: These knobby, brown-skinned, white-fleshed vegetables look like ginger but belong to the sunflower family. Nutty, slightly sweet with a flavor similar to chestnuts when eaten raw, Jerusalem artichokes adapt a potato-like texture when cooked with a faint flavor or the grassy and briny flavor of the green-leaf artichokes that are more common. 
  

• Onions: Unmistakably punchy when eaten raw, onions chill out and can transform into caramelized sweetness if cooked low and slow enough. Similar to garlic, dried onion contains higher amounts of inulin and oligofructose than raw so stash some dried onion with your spices and use them often. Dried onion rehydrates when added to sauces or water-containing veggies so the stew you sprinkled them in won’t taste like Funyuns.
  

• Leeks: The most dulcet of the amaryllis family, leeks are a cousin to onions and garlic with a taste similar to scallions. Chop off the dark green tops, remove the root end, then soak the white and light green parts of the leek in a large bowl of water to remove any grit tucked in between the sheaths (leeks grow in sandy soil). Enjoy raw in salads, sauces, or dips, or add to a big sheet pan of vegetables for roasting.
• Jicama: High in inulin and potassium, jicama is a Mexican turnip. It’s not sharp and peppery like other turnips but rather has a neutral flavor with a crisp bite similar to an Asian pear or apple. Shred into coleslaw, dice in salads, bake as fries, or add to stir-fries as a replacement for water chestnuts. 
  

• Artichoke: Found on antipasto platters, brined in jars, grilled or steamed fresh and dipped in aioli, artichoke tastes like a more vegetal version of hearts of palm. Pluck the pine cone-like leaves from the exterior, remove the choke, and poach or steam the heart.
  

• Asparagus: These spring green spears can dress up a meal when wrapped elegantly with prosciutto and drizzled with balsamic reduction. They can go with the no-cook flow and be shaved with a vegetable peeler along with parmesan cheese, radicchio, and endive leaves to make a classy, casual salad. Roast them, grill them, poach or pan sear these bucolic vegetables, or steam them and serve with hollandaise sauce for dipping. 

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Best Prebiotic Fruit

• Bananas: Easy to pop into smoothies, add to oatmeal, or to sweeten and add moisture to quick bread recipes, bananas offer bunches vitamins and minerals, like potassium and vitamin B6. Underripe green bananas, a great source of resistant starch, have the most prebiotic effect. Yellow bananas with black spots on the skin contain the highest amount of sugar, so they may spike your glucose if you eat them alone or combine them with other sugary fruits or foods. 
  

Best Prebiotic Dairy

• ‍Human milk contains oligosaccharides that contribute to infants’ development of intestinal flora¹¹. ‍
• Fermented dairy products, including kefir, yogurt, and buttermilk, can also be considered prebiotic.

Best Prebiotic Nuts & Legumes‍

All Nuts

We’re nuts about nuts at Signos—we recommend that our members snack on a portion of nuts if feeling rumbly in the tummy. We’ve found that doing so typically means we don’t eat as much as we otherwise might at the meal following the nutty snack. Almonds, walnuts, pistachios, and hazelnuts have a moderate impact on gut microbiota diversity¹², said one review of several studies. They also have anti-inflammatory characteristics. Walnut fermentation results in increased SCFA concentrations (fatty acids that help protect against infection, if you recall from above) and reduced proinflammatory acids in the gut¹³. Almonds and almond skins may improve the health-benefiting factors¹⁴ and inhibit the harmful ones in the gut, one study summarized.

<p class="pro-tip">Read more about the best nuts for blood sugar</p>

Peanuts

Don’t pick out and discard this legume from your low-sugar trail mix. The loveable legume from your childhood is good for more than the smashed white bread peanut butter and jelly sandwiches you toted to school. Similar to pistachios, peanuts appear to have a stimulatory effect on lactobacillus growth¹⁵ and their polyphenol content is likely why peanuts have superpower prebiotic potential.

<p class="pro-tip"><strong>Learn more about </strong> <a href="./blog/metabolic-health-nut-butters">how nut butters can support metabolic health</a>.</p>

Chickpeas, lentils, beans, peas

Packed with pectin, polysaccharides, and fiber, legumes such as green peas, kidney beans, and red lentils typically induce a low-glycemic response. Homemade hummus and buttered peas are beloved ways to enjoy these prebiotics, but more imaginative meal prep ideas can include lentil-and-mushroom ragu, bean-rific veggie burgers, tuna and white bean-topped sweet potato toast, and chickpea cookie dough dip. 

Best Prebiotic Grains 

Bran, wheat, barley, oats, and rye contain some inulin. Yes, those bland brown cereal flakes dotted with raisins you might recall your mom trying to get you to eat for breakfast as a kid contain bran, but you can make more tasty breakfast bites by baking bran, wheat, rye, or barley flour into muffins, protein balls, or breakfast cookies (sweetened with dates or allulose).

Food manufacturers also add inulin and FOS—mostly from chicory root—to packaged goods such as granola, protein, or cereal bars. Longer-chain inulin adds a creamy appeal and can be added to products to reduce the fat content. Fructo-oligosaccharide tastes a bit sweet and is often added to foods to reduce the amount of added sugar or artificial sweeteners. 

Tips for Adding More Prebiotics to Your Diet

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Ease into eating more prebiotic foods, powders, or supplements. The high fiber content can make you gassy, bloated, and a bit too regular if you increase your intake too quickly. 

While the high fiber content and other noted pluses make eating prebiotics beneficial, some of the foods on the list could spike your glucose. Everyone’s blood sugar response to foods differs and is contextual—for example, did you eat a ripe banana in your oatmeal and then saw a post-breakfast glucose spike in Signos? 

If you notice a rise in your glucose after eating some of the prebiotic foods on this list, try: 

• eating smaller portions of the food 
• combining the prebiotic food with protein or healthy fats 
• eating that prebiotic food earlier in the day to give yourself a chance to move and burn that extra glucose
• consuming that prebiotic food 45 minutes before or 20–30 minutes after exercising.
  

If you’re a Signos member, try these tips for potentially “spikey” foods such as beans, dairy, or bananas. Try one approach each day with the same food that spiked your glucose and see which one(s) net the most improved glucose response.

<p class="pro-tip">Curious about Signos? See plans and pricing.</p>

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