DR. ISLAM: Fiber’s role in gut health explained by a GI doctor

By Dr. Rafiul Sameer Islam

There are almost unlimited recommendations for foods and supplements that can improve your health. With this in mind, we’re going to focus on one of the most important things you can do to boost your gut health — eat enough fiber.

If you’re experiencing digestive problems, it may be because your diet lacks this essential carbohydrate.

In this article, we’ll help you understand what fiber is, how much you need, and how consuming enough fiber can benefit your gut health.

What Is Dietary Fiber?

Dietary fiber is a type of non-digestible carbohydrate that naturally occurs in plants. Your body is unable to absorb or break down fiber, so it ends up passing through the digestive system relatively intact.

There are two types of fiber that are equally valuable for your gut health.

1. Soluble fiber. This type of fiber dissolves in water and forms a gel-like substance that slows down the digestive process. Most soluble fibers are readily fermented by bacteria in the gut.

2. Insoluble fiber. This type of fiber keeps its original form and acts as roughage. Instead of slowing digestion down, insoluble fiber speeds it up. Some insoluble fibers undergo fermentation in the gut, whereas others are solely responsible for bulking up the stool.

Fiber – Daily Recommendations

To keep your digestive system running smoothly, you should consume a certain amount of dietary fiber each day. Your daily recommended fiber intake depends on your age and gender.

Men who are 50 years of age or younger should consume at least 38 grams of fiber daily. Men who are older than 50 years should consume at least 30 grams of fiber per day.

Women who are 50 years old or younger should consume at least 25 grams of fiber daily. Women who are older than 50 years should consume at least 21 grams of fiber per day.

Alarmingly, 95% of Americans consume less than their daily recommended fiber intake. This may be due to a poor understanding of high-fiber foods. Or the growing popularity of gluten-free and grain-free diets.

Best Fiber Sources

Naturally, since fiber comes from plants, the best fiber sources are plant-based foods. High-fiber foods fall into the following categories:

  • Whole grains
  • Fruits
  • Vegetables
  • Legumes
  • Nuts and seeds

Besides fiber, these foods are also packed with vitamins and minerals and don’t contain unhealthy additives.

High-fiber foods are generally good for your health. But you should limit your intake of processed foods that claim they are high in fiber. These foods are often filled with refined carbohydrates, added sugar, fat, and salt.

Fiber Supplements

Getting fiber from whole foods is best. But we know that it’s not always doable to meet your daily recommended intake with food alone. In this case, we recommended taking a fiber supplement to fill in the gaps.

A fiber supplement is just that — it’s not meant to replace your intake of high-fiber foods.

If your digestive system feels sluggish, taking a fiber supplement can give it the kick-start it needs. Just remember to start slowly. Adding too much fiber at once can unintentionally cause bloating, gas, and cramping.

You should take a fiber supplement with a large glass of water to help keep you hydrated and improve overall digestion. As always, it’s a good idea to talk with your doctor before taking any supplements. In some cases, fiber supplements can affect the absorption of other medications.

The Role of Fiber in Digestion

Fiber plays a vital role in the digestive process. Fiber increases stool size and normalizes bowel movements, which can prevent constipation and diarrhea. Some fibers, known as prebiotics, feed the healthy bacteria in the gut.

Because digestive enzymes don’t break down fiber, the added volume in the stomach makes you feel full and can control hunger cravings.

Consuming adequate dietary fiber can keep blood sugar levels balanced and lower LDL or “bad” cholesterol. The gel-like substance of soluble fiber traps sugar molecules, which prevents blood sugar spikes after eating. Soluble fiber also binds to cholesterol molecules and excretes them from the body.

Fiber can also be beneficial for many digestive conditions. High-fiber foods can reduce heartburn in people with GERD by decreasing the time food particles reside in the stomach. This narrows the window that the stomach contents can flow backward into the esophagus.

Small, hard stools increase pressure within the colon and can lead to the development of diverticulitis. Fiber softens stools, which can reduce pressure in the colon and lower your risk of medical complications. In people with IBS with constipation, eating fiber can increase the frequency of bowel movements and ease uncomfortable symptoms.

If you’ve been diagnosed with a digestive condition, you should always consult your doctor before making any dietary changes.

Colon Cancer Prevention

Many studies show that consuming enough dietary fiber can reduce the risk of colorectal cancer. This occurs through the beneficial effects of fiber on the stool and gut microbiome.

Dietary fiber produces larger stools that move through the digestive tract more quickly. This limits the time your colon cells are exposed to fecal carcinogens. Basically, fiber flushes cancer-causing substances out of your system.

When healthy bacteria in the gut ferment prebiotic fibers, it produces good by-products known as short-chain fatty acids.

Short-chain fatty acids such as acetate, butyrate, and propionate lower the risk of colorectal cancer by:

  • Improving the health of colon cells
  • Protecting and maintaining the integrity of the mucus lining in the colon
  • Reducing inflammation in the colon
  • Preventing the growth and spread of colon cancer cells
  • Programming colon cancer cell death

Fiber Recommendations

Consuming enough fiber is essential for optimal digestive health. We encourage everyone to prioritize dietary fiber intake to reduce the risk of conditions such as hemorrhoids and colon cancer.

Choosing a variety of foods with 3 or more grams of fiber per serving can make it easier to meet your daily fiber needs. You can research the plant-based food groups mentioned above to find high-fiber foods that appeal to you. Understanding what foods are good sources of fiber can help you make healthier choices whether you’re eating at home or dining out.

Depending on your situation, fiber supplements may be right for you. Make sure to consult your doctor before starting a new supplement to avoid any potential medication interactions.

If you’re concerned about dietary or digestive issues, contact your healthcare provider!

Sameer Islam, MD is a board-certified Gastroenterologist and Hepatologist practicing at Lubbock Gastroenterology (www.lubbockgastro.com). For an appointment feel free to contact his office at (806)-696-4440. You can get more information from his webpage (www.sameerislam.com) where you can also subscribe to his monthly newsletter. He also has a weekly Facebook Live show on Tuesday, 8:00 PM CST.