What Happens to Your Body When You Take a Fiber Supplement

Trendy new supplements with big price tags are all over social media, but don’t forget the humble fiber supplement. Almost all Americans are falling short: about 93% fail to eat the recommended amount of fiber (28 grams on a 2,000-calorie diet).

There are many health benefits to eating more fiber, such as better gut health and a lower risk of high cholesterol, heart disease, obesity and type 2 diabetes. If you are one of many Americans who struggle with constipation or diarrhea, incorporating more fiber in your diet may also help reduce your symptoms. 

Fiber supplements include inulin, psyllium (like Metamucil) and methylcellulose (like Citrucel). These differ from food sources of fiber, as they don’t offer the vitamins, minerals and other nutrients of things like fruits, vegetables, whole grains and beans. A food-first approach to getting in all your fiber is ideal, but eating plenty of fiber-rich foods doesn’t always happen every day. If you’re wondering if a fiber supplement is right for you, keep reading to find out more about fiber supplements and what happens to your body when you start taking them regularly.

Health Benefits of Taking a Fiber Supplement

You might be most familiar with dietary fiber (i.e., fiber in fruits, vegetables, whole grains), which is the indigestible carbohydrate naturally contained in plants. Functional fibers, like those in supplements, are isolated or synthetic indigestible carbohydrates which have been shown to provide specific health benefits. But can these fiber supplements still improve your health? Let’s explore what may happen when you start taking them.

You Might See Your Cholesterol Levels Improve

If you struggle with high cholesterol, adding some soluble fiber to your diet may help keep your levels in check. “Fiber works like a sponge, absorbing harmful LDL cholesterol and preventing its entry into the bloodstream, thus reducing the risk of high cholesterol levels” explains Claire Rifkin, M.S., RDN, a New York City-based dietitian and founder of the telehealth private practice Claire Rifkin Nutrition.

Two soluble fibers that have been well-researched and approved to claim that they lower cholesterol levels are psyllium and beta-glucan. A meta-analysis of 61 randomized controlled trials of more than 4,000 people concluded that psyllium decreased total and “bad” LDL cholesterol levels and systolic blood pressure (the top number on a blood pressure reading), as well as improved measures of blood sugar.

Beta-glucan (which is also found in foods like oats and barley) can also be taken via a supplement for cholesterol. Research has found that taking at least 3 grams of beta-glucan daily could significantly reduce both total and LDL cholesterol in people with mildly elevated cholesterol levels.

You Might Have an Easier Time with Weight Management

Ever notice that higher-fiber foods tend to fill you up? “Fiber is like a volume knob that turns up the feeling of fullness as we eat,” says Rifkin. “It helps slow the digestion process, which helps you feel satiated,” she adds. The satiating effects of fiber may also make it easier to stick with a reduced-calorie diet. One study noted that simply increasing your fiber servings could aid in weight loss. From baseline to end of study, the group who lost weight added 2.8 servings of high-fiber foods over their baseline number; the weight neutral group—meaning they didn't lose weight—added 1.93 servings each day. This means that adding one more fiber-rich food, such as a fruit, vegetable, nut, bean, or whole grain could be the push your body needs to lose weight.

However, it is important to note that a fiber supplement alone probably won’t have a significant impact on your body weight. A better strategy for losing weight is making healthy diet changes like incorporating more fiber-rich foods into your diet.

You Could Experience Digestive Benefits

No matter your digestive woes, fiber can likely help. “It is generally believed that fibers like psyllium or cellulose can help with constipation, while soluble fibers such as guar and acacia fiber may help make stool firmer for those dealing with diarrhea,” says Alyssa Simpson, RDN, an integrative and functional nutritional therapist and owner of Nutrition Resolution in Phoenix. In addition, some fiber supplements can act like prebiotics, or food for the good bacteria in your gut. The bacteria ferments those fibers, creating short-chain fatty acids and bringing water into the intestines to soften stools.

You May Better Your Blood Sugar Control

If better blood sugar control is your goal, choosing a supplement containing soluble fiber is a smart option. Soluble fiber helps lower blood sugar by forming a thick gel in the digestive tract so less glucose can be absorbed. That thick gel also slows digestion, preventing spikes in blood sugar.

Research has found that taking 5 grams of beta-glucan daily for 12 weeks could improve hemoglobin A1C (a measure of blood sugar) by 0.68% in individuals with type 2 diabetes. That’s considered a significant change: A 1% decrease in A1C corresponds to about a 30 mg/dL decrease in one’s blood glucose level. Depending on your starting A1C, that can be enough to move you out of the diabetes range.

You May Improve Your Heart Health

We already discussed how fiber can help lower cholesterol, manage weight and improve blood sugar control, all factors that can keep your heart healthy. Soluble fiber may be good for your blood pressure, too. Research has found that 20 grams of soluble fiber per day could lower systolic blood pressure by up to 1.79 mm Hg, which may be impactful enough to help manage hypertension and help reduce the risk of cardiovascular disease, the authors note.

Types of Fiber Supplements

With so many options available, shopping for the right fiber supplement can be overwhelming. 

For starters, not all fiber offers the same health benefits. Although we normally analyze fiber in terms of soluble vs. insoluble fiber, when talking about fiber supplements, it’s helpful to break it down even further.

Insoluble Fiber 

Insoluble fiber particles do not dissolve in water, and they pass through the gastrointestinal tract largely intact, which bulks up stools. Insoluble fibers are most helpful for constipation and include wheat bran, resistant starch and cellulose (Citrucel). 

Soluble Fiber 

These fiber particles dissolve in water to form a gel. Soluble fiber can help lower cholesterol, improve blood sugar and slow down digestion. Examples include beta-glucan, guar gum, pectins, psyllium (Metamucil) and wheat dextrin (Benefiber). 

Fermentable Fiber 

Most fibers will favorably improve the health of your gut microbiome. However, soluble fibers are those that are the most fermentable, and certain types mainly function as a prebiotic. This can create gas, so certain fermentable fibers may cause uncomfortable cramping and bloating. Ask your doctor to help you choose the right fiber supplement for you, especially if you have a condition like IBS (irritable bowel syndrome). Examples include beta-glucan, guar gum, pectins, inulin, polydextrose, fructo-oligosaccharides (FOS), resistant starch and wheat bran. 

How to Choose and Use Fiber Supplements

Figuring out which fiber supplement is the best fit for you is going to depend on why you need fiber in the first place. Once you know what type of fiber you want to take (soluble, insoluble, fermentable), you’ll need to figure out how you’d like to take it. Fiber supplements come in a variety of different forms, including powder, capsules, gummies and food-based products like cookies or crackers. 

Powders can be easily added to a variety of beverages and may be appealing to those who don’t like taking capsules. If you are deciding between a capsule and a powder fiber supplement, double-check the dosage, as you may have to take a high number of capsules (some as high as 15 per day!).

Keep in mind that some powders, gummies or food-based products may also contain added sugars, so you may want to choose a sugar-free option instead. For those with gluten sensitivity, be sure to double-check the labels on fiber supplements, as some contain gluten or are processed in a facility that produces products with gluten.

How Much Fiber Supplements Should You Take?

Fiber needs vary based on your age, dietary pattern and medical conditions. Working with a health care professional or dietitian can help you better understand how to manage your symptoms with the correct supplement. 

Although there is no tolerable upper limit set for fiber, there’s no significant health advantage to consuming more than the recommended 25 daily grams for women and 38 grams for men. The standard recommended dose for most fiber supplements provides between 10 and 18 grams of fiber. Take into account your dietary sources of fiber and add supplemental fiber until you’ve reached the recommended total daily fiber intake. 

When you find a fiber supplement that can address your needs, Rifkin recommends “starting with a lower dose and gradually increasing, which can help your body adjust smoothly, reducing the likelihood of digestive discomfort.” Drink lots of fluids when taking a fiber supplement to reduce the likelihood of side effects. Most fiber supplements recommend consuming at least 8 ounces of water with the supplement.

When starting a fiber supplement, keep in mind some of the potential side effects of fiber supplements, including: 

• Abdominal pain and cramps
• Diarrhea
• Gas and bloating
• Loose stools
• More frequent bowel movements
• Nausea and vomiting
• Stomach pain
  

The Bottom Line

When it comes to fiber, we always recommend taking a food-first approach. But we also know that eating a nutrient-dense, high-fiber diet isn’t going to happen every day. If you’re struggling to hit the mark for fiber in your diet regularly, adding a fiber supplement to your wellness routine may be beneficial. Fiber supplements can also be helpful for addressing certain digestive issues, like constipation, and they have been shown to improve cholesterol, lower blood sugar and possibly support weight loss. With so many different fiber supplements available, we recommend consulting with a health care professional or dietitian to help you find the right fiber supplement to address your specific needs.