43 Prebiotic foods to improve Gut Health: A nutritionist’s guide

When it comes to gut health, probiotics often get all the attention, but did you know that prebiotics are just as essential? In this blog, I'll go into detail about what prebiotics are, including types like FOS (fructooligosaccharides), GOS (galacto-oligosaccharides), resistant starch, pectin, inulin, and psyllium husk. We’ll also explore ‘prebiotic-like polyphenols,’ their benefits, potential side effects, and practical ways to include them in your diet. And of course, I’ll share my take on whether prebiotic supplements are worth the hype.

So, what exactly are prebiotics ? (not to be confused with probiotics). They are specific types of food, typically high in fiber, that act as fuel for the good bacteria in your gut, feeding beneficial microbes like Bifidobacteria and Lactobacillus. Some also serve as a source of soluble fiber, which can help regulate blood sugar, lower cholesterol, and support regular bowel movements ¹.

1.FOS (Fructooligosaccharides)

FOS supplementation promoted beneficial bacteria like Bifidobacterium and Lactobacillus, along with butyrate-producing microbes such as Faecalibacterium and Ruminococcus, which are linked to anti-inflammatory effects and overall gut health ².

Sources include: garlic, onions, bananas, leeks, Jerusalem artichokes, and asparagus.

2. Galacto-oligosaccharides (GOS)

GOS are commonly found in a variety of foods, particularly in dairy products containing lactose and some legumes. These are especially beneficial for supporting Bifidobacterium and Lactobacilli species ³ ⁴.

Sources include: lentils, chickpeas, kidney beans, and black beans

3. Resistant Starch (RS)

Resistant Starch (RS) is a type of starch that isn’t fully digested in the stomach or small intestine. Instead, it reaches the colon, where it is fermented by gut bacteria, producing beneficial compounds called short-chain fatty acids (SCFAs), such as butyrate ⁵.

Sources include:

• Cooled, cooked rice (brown rice is slightly better, but the difference is negligible)

• Cooked and cooled pasta (whole-grain pasta offers slightly more nutrients)

• Cooked and cooled potatoes

• Oats, barley, quinoa, millet

• Green bananas, pinto beans, soybeans, garden peas

4. Pectin

Pectin stands out as a slow-fermenting, gentle prebiotic with specific benefits for gut health, such as feeding beneficial bacteria and promoting the production of short-chain fatty acids (SCFAs) like butyrate, which reduces inflammation and strengthens the gut barrier ⁶.

Here’s a cool fact about pectin: Pectin is not just great for gut health: it’s also what makes your favorite jams and jellies gel! This natural fiber found in some fruits acts as a thickener when combined with sugar and heat, giving jams their smooth, spreadable texture ⁷.

The best way to release pectin is by heating high-pectin fruits or their parts (like skins, cores, or peels) with water and sometimes acid, like lemon. Simmer gently and avoid boiling. My favorite and easiest way to enjoy pectin is by adding it to my oats or yogurt: simply stir the warm, softened fruit directly into your cooked oats.

Sources include: citrus fruits (peels), Granny Smith apples, pears, quince, raspberries, blackberries, plums, peaches, guava, carrots, sugar beets, carrots and peas.

5. Inulin

Inulin is a soluble dietary fiber that resists digestion, ferments slowly, and supports gut health by strengthening the intestinal barrier and promoting beneficial bacteria. However, excessive intake (over 40 g/day) may cause bloating and can exacerbate conditions like inflammatory bowel disease (IBD) ⁸.

Sources include: chicory root, dandelion greens, Jerusalem artichoke, garlic, onions, leeks, asparagus, barley, and rice.

6. Psyllium husk 

Oh look, finally something I actually use! Yes, I add psyllium husk to my smoothies. So, what is psyllium husk? It’s a type of soluble fiber derived from the seeds of the Plantago ovata plant. It supports gut health by promoting regular bowel movements, relieving constipation, and nourishing healthy gut bacteria with its prebiotic effects ⁹. You can easily incorporate psyllium husk into your diet by adding it to smoothies, oatmeal, cookies, pancakes, or waffles for a fiber boost.

Found in: Health food stores, online or pharmacies.

7. Polyphenols with prebiotic effects

Polyphenols are natural compounds found in plant-based foods and drinks like fruits, vegetables, tea and coffee. They help improve your health by supporting good gut bacteria, acting as antioxidants, and supporting cardiovascular health ¹⁰. There are countless polyphenols, but I’ll focus on the ones that offer the most benefits for gut health, like flavanols and anthocyanins.

Flavanols Sources include: Cocoa (dark chocolate, 70% or higher cocoa content), green tea, apples, and berries.

Anthocyanins Sources include: Blueberries, blackberries, raspberries, cherries, and red cabbage.

Possible side effects of prebiotics

Prebiotics can sometimes cause side effects because they are fermented in the colon. This may lead to gas, bloating, abdominal pain, and, in some cases, diarrhea ¹¹. My advice is to be mindful when introducing these foods into your diet and to pay attention to the quantities you consume. I remember the first time I ate Jerusalem artichokes (probably too many) and experienced horrible abdominal pain. To avoid this, start with small amounts and gradually increase as your body adjusts.

! It is also important to note that FOS (fructooligosaccharides) and GOS (galactooligosaccharides) are considered high in FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols). These prebiotic fibers are fermentable carbohydrates that can cause symptoms like bloating, gas, and discomfort in people with sensitivities, such as those with irritable bowel syndrome (IBS).

Are prebiotic supplements worth the hype?

As a nutritionist, I always lean towards a food-first approach, so my answer is no. If you already have a healthy and diverse diet, food sources are the best way to go. Many supplements are not well-regulated, could be contaminated, and often lack solid scientific backing.

That said, I do make an exception for psyllium husk and inulin. It is incredibly easy to add to your diet and offers massive benefits for gut health. If you are traveling, going through a busy period, or unable to stick to your usual healthy routine, adding 3-5 g of inulin or psyllium husk can help maintain bowel regularity and support gut health. There is no need to splurge on anything fancy. A basic psyllium husk or inulin from a reliable store like Holland & Barrett will do the job perfectly.

How to include prebiotics in your diet?

Incorporating prebiotics into your meals is easier than you might think, and you’re probably already doing some of these. Here are a few simple ideas:

• Add to smoothies: Blend prebiotic-rich fruits like bananas, apples, or berries into your morning smoothie.

• Upgrade your salads: Toss resistant starches like cooked and cooled potatoes, rice, or pasta into your salad for a prebiotic boost.

• Include whole grains and legumes: Add beans, barley, quinoa, or lentils to your salads for a fiber-packed meal.

• Cook with flavorful veggies: Use garlic, onions, and leeks in soups, stir-fries, or roasted veggie dishes to enhance flavor and gut health.

• Hearty stews: Make a stew with prebiotic-packed ingredients like beans, lentils, and root vegetables.

• Snack or breakfast bowls: Top your yogurt or oatmeal with berries, ground flaxseeds, or green bananas for a satisfying and gut-friendly start to the day.

Final thoughts on prebiotics 

Prebiotics are very beneficial for your gut health, feeding the good bacteria and keeping your digestive system running smoothly. The best part? You do not need anything fancy or expensive; simple foods like fruits, veggies, whole grains, and legumes are better than any supplement. Sure, supplements like psyllium husk or inulin can be useful when life gets busy, but nothing can replace the benefits of whole foods, as they also provide extra vitamins and minerals your body needs along with prebiotics.

P.S. Looking for a sustainable approach to weight management, gut health, and overall wellness? As a registered nutritionist (ANutr) with a BSc in Human Nutrition, I’m here to help!

I look forward to helping you thrive!

Mia

Bonus: Here is a compiled list of the 43 foods mentioned.

Fruits

• Granny Smith apples

• Apples

• Bananas

• Green bananas

• Citrus fruits

• Guava

• Peaches

• Pears

• Quince

• Raspberries

• Blackberries

• Blueberries

• Cherries

• Plums

Vegetables

• Jerusalem artichokes

• Asparagus

• Carrots

• Red cabbage

• Leeks

• Onions

• Garden peas

• Dandelion greens

• Chicory root

• Sugar beets

Legumes

• Lentils

• Chickpeas

• Kidney beans

• Black beans

• Pinto beans

• Soybeans

Grains and Starches

• Barley

• Oats

• Quinoa

• Millet

• Brown rice

• Cooked and cooled rice

• Cooked and cooled potatoes

• Cooked and cooled pasta

• Whole-grain pasta

Other

• Dark chocolate (70% or higher cocoa content)

• Green tea

• Psyllium husk

Curious to learn more ? These articles cover related topics to keep you informed:

References (to geek out further):

1.Bevilacqua, Antonio, et al. “An Update on Prebiotics and on Their Health Effects.” Foods, vol. 13, no. 3, 1 Jan. 2024, p. 446, www.mdpi.com/2304-8158/13/3/446, https://doi.org/10.3390/foods13030446.

2.Tandon, Disha, et al. “A Prospective Randomized, Double-Blind, Placebo-Controlled, Dose-Response Relationship Study to Investigate Efficacy of F Ructo- O Ligo S Accharides (FOS) on Human Gut Microflora.” Scientific Reports, vol. 9, no. 1, 2 Apr. 2019, p. 5473, www.nature.com/articles/s41598-019-41837-3#Abs1, https://doi.org/10.1038/s41598-019-41837-3.

3.Mei, Zhaojun, et al. “Biological Activity of Galacto-Oligosaccharides: A Review.” Frontiers in Microbiology, vol. 13, 6 Sept. 2022, https://doi.org/10.3389/fmicb.2022.993052.

4.Looijesteijn, Ellen, et al. “A Double-Blind Intervention Trial in Healthy Women Demonstrates the Beneficial Impact on Bifidobacterium with Low Dosages of Prebiotic Galacto-Oligosaccharides.” Frontiers in Nutrition, vol. 11, 19 Aug. 2024, https://doi.org/10.3389/fnut.2024.1440319.

5.DeMartino, Peter, and Darrell W Cockburn. “Resistant Starch: Impact on the Gut Microbiome and Health.” Current Opinion in Biotechnology, vol. 61, Feb. 2020, pp. 66–71, https://doi.org/10.1016/j.copbio.2019.10.008.

6.Pascale, Nélida, et al. “The Potential of Pectins to Modulate the Human Gut Microbiota Evaluated by in Vitro Fermentation: A Systematic Review.” Nutrients, vol. 14, no. 17, 2 Sept. 2022, p. 3629, https://doi.org/10.3390/nu14173629.

7.Wikiera, Agnieszka, et al. “Health-Promoting Properties of Pectin.” Postępy Higieny I Medycyny Doświadczalnej, vol. 68, 2 Jan. 2014, pp. 590–596, https://doi.org/10.5604/17322693.1102342.

8.Sheng, Wei, et al. “Immunomodulatory Effects of Inulin and Its Intestinal Metabolites.” Frontiers in Immunology, vol. 14, 2023, p. 1224092, pubmed.ncbi.nlm.nih.gov/37638034/, https://doi.org/10.3389/fimmu.2023.1224092.

9.van der Schoot, Alice, et al. “The Effect of Fiber Supplementation on Chronic Constipation in Adults: An Updated Systematic Review and Meta-Analysis of Randomized Controlled Trials.” The American Journal of Clinical Nutrition, vol. 116, no. 4, 11 July 2022, https://doi.org/10.1093/ajcn/nqac184.

10.Grosso, Giuseppe, et al. “The Effect of Dietary Polyphenols on Vascular Health and Hypertension: Current Evidence and Mechanisms of Action.” Nutrients, vol. 14, no. 3, 27 Jan. 2022, p. 545, https://doi.org/10.3390/nu14030545.

11.Marteau, Philippe, and Philippe Seksik. “Tolerance of Probiotics and Prebiotics.” Journal of Clinical Gastroenterology, vol. 38, no. Supplement 2, July 2004, pp. S67–S69, https://doi.org/10.1097/01.mcg.0000128929.37156.a7.