What Is The Deal With Fiber? Is It Really A Must?

My Journey with Fiber and Gut Health

After having my son, I began struggling with persistent gut issues—bloating, discomfort, and constipation. It wasn’t fun. A well-meaning friend suggested fiber as the solution, assuring me it would fix everything. I eagerly took the recommended supplement, expecting immediate relief. Instead, my stomach looked like it had inflated and my gut issues only worsened. My friend advised that I might just need more fiber, but I was already so uncomfortable I couldn’t imagine taking another dose. At that time, a couple decades ago, I didn’t know much about gut health or why my body was reacting so poorly to fiber. I read so many articles about how good it was for me so I was frustrated and wanted to figure this out.

Eventually, I took a step back to address my gut health more holistically. I developed a healthier eating plan, checked my food sensitivities, added probiotics, and started a gut reconditioning program. Gradually, over 12 months my gut health improved. Now, I not only tolerate fiber—I love it! I’ve experienced firsthand how incredible it feels when your gut is balanced, you aren’t bloated, and fiber works with your body, not against it.

Why Fiber is So Important

Fiber is a powerhouse for health, affecting nearly every part of the body. Here’s why it’s worth including in your diet:

1. Weight Loss & Appetite Control: Fiber helps you feel fuller for longer, especially soluble fiber, which absorbs water and forms a gel-like substance that slows digestion. This can curb hunger and help with calorie control, making it a fantastic tool for anyone aiming to manage their weight.
2. Blood Sugar Regulation: By slowing the absorption of sugar, fiber supports better blood glucose control, helping to prevent spikes and crashes. This is crucial for those with or at risk of diabetes, as fiber can enhance insulin sensitivity over time.
3. Gut Health and Disease Prevention: Fiber provides fuel for the beneficial bacteria in your gut, producing short-chain fatty acids that reduce inflammation and support the gut lining. Additionally, fiber bulks up stool, promoting regular bowel movements and reducing the risk of conditions like constipation, diverticulitis, and even colon cancer.
4. Skin Health: Fiber’s support for gut health also benefits skin by reducing systemic inflammation, which may help reduce skin issues like acne, redness, and irritation.
5. Mood Regulation: The gut-brain connection is real, and fiber plays a vital role in maintaining it. By feeding good bacteria, fiber supports the production of neurotransmitters like serotonin, which is linked to mood stabilization and may help with symptoms of anxiety and depression.
6. Pain Relief: Some studies show that having a diet rich in fiber may help decrease painful joints.

Why Does Fiber Make My Gut Worse?

The human digestive system isn’t built to break down fiber directly. Instead, fiber passes undigested into the colon, where it becomes a key food source for the gut microbiome. If your gut flora is balanced, these microbes thrive on fiber, supporting a healthy gut environment and overall well-being.

However, if your gut is predominantly populated with “bad” bacteria, yeast, fungi, or adhesions exist resulting after some abdominal surgeries, limiting the transport of fecal matter,  fiber can exacerbate symptoms. This is because fiber acts as a general growth factor for intestinal bacteria—it doesn’t discriminate between beneficial and harmful species. When “bad” microbes dominate, they too can feed on fiber, proliferating and potentially worsening health issues. And if surgeries to the abdominal area left you with scarring and disruptions to the fascia surrounding the bowel, the fiber can create a backup, if you will, and contribute to constipation and or diarrhea. 

Can Too Much Fiber Cause Constipation or Diarrhea?

While fiber is highly beneficial, too much of it—or adding it too quickly—can backfire, literally. Consuming an excessive amount of fiber, especially without enough water, can actually cause constipation and gas. Fiber needs water to move smoothly through the digestive tract, so an imbalance can lead to stool that’s too bulky or hard.

In addition, consuming a lot of fiber too quickly or in the form of high-FODMAP foods (fermentable fibers) may result in diarrhea and bloating. This is common for those whose gut bacteria are unprepared to break down large amounts of fiber. So it’s recommend to limit these types of foods until you can get on a program to address the bowel issues.

Here are examples of high-FODMAP foods across different categories:

1. Fruits

• Apples
• Pears
• Mangoes
• Cherries
• Watermelon
• Blackberries
• Plums
• Nectarines

2. Vegetables

• Onions
• Garlic
• Cauliflower
• Broccoli
• Asparagus
• Artichokes
• Brussels sprouts
• Mushrooms

3. Grains & Cereals

• Wheat-based products (such as bread, pasta, and cereals)
• Rye
• Barley

4. Dairy Products (high in lactose)

• Milk
• Soft cheeses (like ricotta and cottage cheese)
• Yogurt (especially those with added sweeteners)
• Ice cream

5. Legumes & Pulses

• Lentils
• Chickpeas
• Black beans
• Kidney beans

6. Sweeteners & Processed Foods

• High-fructose corn syrup
• Honey
• Agave syrup
• Sorbitol, mannitol, and xylitol (often in sugar-free gum and candies)

7. Nuts and Seeds

• Cashews
• Pistachios

For people sensitive to FODMAPs, reducing or avoiding these foods can help alleviate symptoms while you work on creating a healthy balance of good microbes in your gut.  Many low-FODMAP alternatives, like bananas, carrots, and rice, offer nutritional options that are typically gentler on the digestive system. Keep in mind the trap many fall into when eating a low FODMAP diet is the diversity of foods in their diet becomes very limited. This also negatively impacts gut bacteria so a vicious cycle ensues. It seems like there are less and less foods you can tolerate.

In addition, if you have had abdominal surgery and are concerned about adhesions, my patients have found our visceral manipulation/massage to be a huge benefit to release the constraints put on the bowel by those adhesions. Too much fiber when adhesions are present can cause IBS symptoms, i.e. constipation, diarrhea, and bloating.

For Those Who Can’t Tolerate Fiber Easily

If you’re like I was and find fiber challenging to tolerate, you’re not alone. Fiber intolerance often comes from an imbalanced gut microbiome, which may struggle to process fiber effectively. Here are ways to gently introduce fiber:

1. Consider food sensitivity testing (preferably not IgG as these have been shown not to be as accurate for food sensitivities).  We use the ALCAT and have had great success helping patients find foods that they aren’t reacting to and expanding instead of shrinking their food choices, as well as eliminating the those foods that do create discomfort.
2. Start Slowly: Ease into fiber gradually, especially if you’ve been consuming a low-fiber diet. A sudden increase can shock your digestive system, causing discomfort. Some of my patients have to add just a sliver of the food or supplement over a long period until they are able to tolerate more. In addition try adding a very small serving of fiber-rich foods per day and see how your body responds.
3. Pick Easily Digestible Fibers: Start with soluble fibers, such as oats, chia seeds, and peeled fruits, which are usually gentler on the digestive tract than insoluble fibers found in whole grains and some vegetables. If you do the food sensitivity testing this can help you choose easily digestive fibers and low FODMAP fiber sources.
4. Focus on Low-FODMAP Fiber Sources: Some people react to FODMAPs—fermentable fibers that can cause bloating and discomfort. Low-FODMAP fiber options like kiwis, carrots, and zucchini provide fiber without overwhelming your system.
5. Use Prebiotics and Probiotics: Prebiotics (fiber that feeds good gut bacteria) and probiotics (beneficial bacteria found in fermented foods) can strengthen your gut over time. Foods like yogurt, kefir, asparagus, and bananas are excellent places to start. But if they are not tolerated well, then consider seeing us for a consultation to help determine where to start.
6. Seek Guidance if Needed. Testing for specific gut imbalances can reveal personalized dietary strategies to ease fiber into your routine. There are other sources of these symptoms as well, such as SIBO (small intestinal bacterial overgrowth), or IMO (Intestinal Methanogen Overgrowth), so seek help if you are having issues with fiber rich foods, probiotics or if your gut just doesn’t feel right.

The Bottom Line

Fiber is essential for overall health, playing a key role in weight management, blood sugar control, gut health, skin, and even mood. However, for those with gut sensitivities, fiber intake must be handled with care. A balanced, gradual approach can help make fiber your ally rather than a source of discomfort. By strengthening your gut health, you can reap fiber’s full benefits. GIve us a call at 414-299-8121 for help if you need it. Fiber is such an important aspect of a healthy eating plan that it’s essential to find the type that is right for you and ease it into your eating plan.

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This post is for educational purposes only and never constitutes medical device. Always seek out your medical provider to assess and discuss your options.

References: https://nutritionsource.hsph.harvard.edu/carbohydrates/fiber/

Lyon, M. R., & Kacinik, V. (2012). Is There a Place for Dietary Fiber Supplements in Weight Management?. Current obesity reports, 1(2), 59–67. https://doi.org/10.1007/s13679-012-0016-9

Zeng, H., Lazarova, D. L., & Bordonaro, M. (2014). Mechanisms linking dietary fiber, gut microbiota and colon cancer prevention. World journal of gastrointestinal oncology, 6(2), 41–51. https://doi.org/10.4251/wjgo.v6.i2.41

Dai, Z., Lu, N., Niu, J., Felson, D. T., & Zhang, Y. (2017). Dietary Fiber Intake in Relation to Knee Pain Trajectory. Arthritis care & research, 69(9), 1331–1339. https://doi.org/10.1002/acr.23158

Sharma, N., Chaudhary, S. M., Khungar, N., Aulakh, S. K., Idris, H., Singh, A., & Sharma, K. (2024). Dietary Influences on Skin Health in Common Dermatological Disorders. Cureus, 16(2), e55282. https://doi.org/10.7759/cureus.55282

Hajara Aslam, Mojtaba Lotfaliany, Daniel So, Kirsten Berding, Michael Berk, Tetyana Rocks, Meghan Hockey, Felice N Jacka, Wolfgang Marx, John F Cryan, Heidi M Staudacher, Fiber intake and fiber intervention in depression and anxiety: a systematic review and meta-analysis of observational studies and randomized controlled trials, Nutrition Reviews, 2023;, nuad143, https://doi.org/10.1093/nutrit/nuad143