Fiber 101: Gut Health, Weight Management, Cholesterol, and More

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The importance of fiber in a balanced diet can’t be overstated. It serves critical roles from aiding digestion to keeping cholesterol levels in check. While whole foods are the best source, fiber supplements offer a practical solution for those who find it challenging to meet their daily fiber requirements through food alone. Population research suggests that most people only get about half the fiber they need *.

What Is Fiber?

Fibers are chains of glucose units that cannot be broken down by the enzymes in the human digestive system. While most other carbohydrates break down into sugars and are absorbed into the bloodstream, fiber passes largely intact through your digestive system. There are two main categories of fiber: soluble and insoluble, each with its own specific uses and benefits for health. [PMC3705355]

Soluble Fibers: Soluble fiber is the type that dissolves in water, forming a gel-like substance. This characteristic makes it particularly beneficial for heart health. When you consume soluble fiber, it binds with cholesterol particles and helps flush them out of your body, thus lowering overall cholesterol levels. This type of fiber also helps regulate blood sugar by slowing down sugar absorption, making it useful for people with diabetes or those looking to maintain steady energy levels.

Common sources of soluble fiber include oats, legumes, fruits like apples and oranges, and certain vegetables like carrots. Beta-glucan, pectin, guar gum, acacia gum, alginate, inulin, xanthan gum, locust bean gum, psyllium, mucilage, polydextrose, agar-agar, and carrageenan are some commonly recognized types of soluble fiber.

Insoluble Fibers: In contrast, insoluble fiber does not dissolve in water and remains relatively unchanged as it moves through your digestive tract. This type of fiber is best known for its ability to combat constipation by adding bulk to stool and helping it move more quickly through the intestines. It also helps you feel full for longer, aiding in weight management.

What Are the Benefits of Fiber?

One, among many of the health benefits associated with a plant-based diet are thought to be related to its higher fiber content. Here are some of the benefits specific to fiber intake:

  • Improves Digestive Health: Both soluble and insoluble fiber help regulate bowel movements, reducing constipation and diarrhea. Multiple studies have demonstrated the positive impact of both soluble and insoluble fiber on digestive health.
    • Constipation: Insoluble fiber is generally more effective for relieving constipation than soluble fiber. Insoluble fiber adds bulk to the stool and helps it move more quickly through the intestines. On the other hand, soluble fiber can absorb water and form a gel-like substance, which can slow down bowel movements. Therefore, for constipation relief, foods rich in insoluble fiber like whole grains, vegetables, and fruits are often recommended. [PMC9535527]
    • Diarrhea: Soluble fiber absorbs excess water in the intestines and adds bulk to the stool, which can help slow down diarrhea. Foods rich in soluble fiber include oats, bananas, and apples. Insoluble fiber, on the other hand, can speed up bowel movements and might not be helpful for treating diarrhea. [PMID: 11827762]
  • Supports Weight Management: Soluble fiber can help you feel full, reducing overeating. Research data from 345 participants over six months showed that fiber intake was the most influential predictor of weight loss. Higher fiber intake led to more weight loss and better adherence to the diet, regardless of other dietary elements like fats and carbohydrates. [PMC6768815]
  • Lowers Cholesterol Levels: Soluble fiber specifically can bind to cholesterol and help remove it from the body as it travels through the digestive tract. A study reviewed the ability of soluble fibers to lower LDL cholesterol levels showing that water-soluble, viscous-forming fibers can decrease total and bad cholesterol levels by about 5-10%. Medium to high molecular weight fibers are the most effective and include fiber-rich foods like whole oats, legumes, and apples also show similar cholesterol-lowering benefits. [PMID: 27807734] Psyllium husk is the best fiber supplement source for this type of fiber.
  • Regulates Blood Sugar: Soluble fiber slows down the absorption of sugar, helping to control blood sugar levels. A review of the research showed that for patients with diabetes, taking psyllium, a soluble fiber, led to a significant reduction in triglycerides, LDL, fasting blood sugar, and hemoglobin A1c. [PMID: 31919936]
  • Boosts Heart Health: Both soluble and insoluble fiber contribute to a healthier heart. Research in cardiology shows that a balanced intake of both types is associated with a reduced risk of heart disease. [PMID: 16407729]
  • Enhances Microbiome Health: Soluble fiber serves as a prebiotic, nourishing good bacteria in the gut. “Oligosaccharides”, like inulin and fructo-oligosaccharides, are considered prebiotics that can benefit gut health. They resist digestion in the small intestine and are fermented in the colon, positively affecting gut bacteria. Various studies confirm that multiple types of fiber, including resistant starch and various oligosaccharides, meet the definition of being beneficial prebiotics. [PMC3705355]
  • Reduces Risk of Certain Cancers: A large body of research shows that eating a variety of foods containing high fiber has a protective effect against colon cancer as well as being protective against breast, ovary, endometrial, and gastrointestinal cancer. [PMID: 1851150]
  • Increases Longevity: Both types of fiber are associated with a longer lifespan. Longitudinal studies have found a correlation between a balanced intake of soluble and insoluble fiber and increased longevity. [PMC3513325] Some researchers have proposed increasing dietary fiber intake to 50 g/day is likely to increase lifespan, improve the quality of life during the added years, and reduce health-care costs. [PMC6944853]

How Much Fiber Do You Need?

The daily recommended intake of fiber varies depending on age and sex. Generally, adult women should aim for 25 grams of fiber per day, while adult men should aim for 38 grams. Another handy rule of thumb is to eat 14 grams of fiber for every 1,000 calories eaten. This recommendation aligns with dietary guidelines that suggest about 28 grams of fiber per day for a 2,000-calorie diet. Keep in mind that these are general recommendations and may vary depending on age, sex, and health status. Consuming a variety of plant-based foods, including fruits, vegetables, whole grains, legumes, nuts, and seeds, can help ensure adequate fiber intake.

Food Sources of Fiber

Food SourceServing SizeFiber (grams)Fiber Type
Chia seeds1 oz (28g)10.6Soluble
Ground flaxseeds2 tbsp4Soluble
Lentils (cooked)1 cup15.6Soluble
Black beans (cooked)1 cup15Soluble
Chickpeas (cooked)1 cup12.5Soluble
Kidney beans (cooked)1 cup11.3Soluble
Artichoke (cooked)1 medium10.3Both
Avocado1 medium10Both
Raspberries1 cup8Both
Blackberries1 cup7.6Both
Whole wheat spaghetti (cooked)1 cup6.3Both
Barley, pearled (cooked)1 cup6Both
Quinoa (cooked)1 cup5.2Both
Carrots (cooked)1 cup5.2Both
Broccoli (cooked)1 cup5.1Both
Pear1 medium5.5Both
Apple (with skin)1 medium4.4Both
Spinach (cooked)1 cup4.3Both
Brussels sprouts (cooked)1 cup4Both
Sweet potato (cooked)1 medium3.8Both
Blueberries1 cup3.6Both
Almonds1 oz (28g)3.5Both
Orange1 medium3.1Both
Pistachios1 oz (28g)2.9Both
Pecans1 oz (28g)2.7Both
Walnuts1 oz (28g)1.9Both
Amounts are Approximate

Types of Fiber Supplements

  • Fiber Supplements: Fiber supplements, such as psyllium husk (Metamucil), methylcellulose (Citrucel), or wheat dextrin (Benefiber), can help increase daily fiber intake. These supplements work by adding bulk to stool, making it softer and easier to pass.
    • Psyllium Husk (Metamucil): Psyllium husk is a soluble fiber that absorbs water in the gut, forming a gel-like substance. Psyllium husk is gentle and well-tolerated by most people. It can also help lower cholesterol levels and stabilize blood sugar, making it beneficial for heart health and diabetes management. [PMC6358997]
    • Methylcellulose (Citrucel): Methylcellulose is another soluble fiber that works similarly to psyllium husk by increasing stool bulk and softness. It’s known for its gentle and non-fermentable nature, which means it’s less likely to cause gas or bloating. Methylcellulose can be a suitable option for individuals with sensitive stomachs or those prone to digestive discomfort.
    • Wheat Dextrin (Benefiber): Wheat dextrin is a soluble fiber derived from wheat starch. It dissolves easily in liquids and can be added to various beverages and foods without altering their texture. Wheat dextrin is a convenient way to increase daily fiber intake. It supports regularity and aids in maintaining digestive health.
    • Calcium Polycarbophil (FiberCon): Calcium polycarbophil is a synthetic fiber that absorbs water, softening stool and promoting bowel movements. It may be less likely to cause bloating or excessive gas compared to some other fiber supplements. Calcium polycarbophil is a suitable choice for those looking for a well-tolerated option.
    • Inulin and FOS (Fructooligosaccharides): Inulin and FOS are prebiotic fibers that support the growth of beneficial gut bacteria. While they may not directly soften stool, they contribute to overall gut health. These fibers can improve the balance of the gut microbiome, which is essential for digestive and immune health.
    • Glucomannan (Konjac Root): Glucomannan is a water-soluble fiber derived from the konjac root. It has a high viscosity and can absorb a significant amount of water, creating a feeling of fullness in the stomach. Glucomannan is sometimes used as a weight loss aid due to its appetite-suppressing properties.
    • Oat Bran: Oat bran is rich in both soluble and insoluble fiber. It can help soften stool and promote regular bowel movements. Oat bran is also known for its heart-healthy benefits, as it can help lower cholesterol levels.
    • Acacia Gum (Acacia Fiber): Acacia gum, also known as gum arabic or acacia fiber, is primarily soluble fiber. Around 80-90% of its carbohydrate content is fiber, making it highly beneficial for digestive health. It forms a gel-like substance in the gut, aiding in bowel regularity and potentially soothing irritable bowel syndrome symptoms. Acacia gum is known for being gentle on the digestive system, reducing the likelihood of gas and bloating. Additionally, it acts as a prebiotic, promoting the growth of beneficial gut bacteria, thereby supporting overall gut health.

Are Fiber Supplements Safe?

Fiber supplements are widely regarded as safe for most people when used as directed. They are an over-the-counter solution for those looking to add more fiber to their diet. Many people use them for digestive health, and they often come from natural sources like psyllium husk, inulin, or wheat dextrin. Side effects are usually mild and can include bloating or gas, which often resolve as your body adjusts. However, it’s important to follow the guidelines on the packaging for proper dosage and consider medication interactions.

Medication Interactions with Fiber Supplements

  • Warfarin (Coumadin) – General high fiber intake may lower the effectiveness of this blood thinner, as fiber can affect vitamin K metabolism. Adding fiber slowly and keeping a consistent fiber intake is important, but consult your physician.
  • Carbamazepine (Tegretol) – Fiber in the same meal can reduce the absorption of this seizure medication.
  • Digoxin – Absorption can be affected if fiber is consumed in the same meal, reducing the effectiveness of this heart medication.
  • Metformin – Fiber in the same meal can decrease the absorption of this diabetes medication, leading to reduced effectiveness.
  • Antacids (Aluminum and Magnesium) – If taken together, fiber can bind to these antacids, reducing their effectiveness.
  • Calcium Channel Blockers (e.g., Diltiazem, Verapamil) – Fiber in the same meal may reduce the absorption of these heart medications.
  • Thyroid Medications (e.g., Levothyroxine) – Absorption may be affected by fiber in the same meal, reducing the medication’s effectiveness.
  • Oral Contraceptives – Fiber in the same meal could potentially affect the absorption, though more research is needed.
  • Certain Antibiotics (e.g., Ciprofloxacin) – If fiber-rich foods are consumed in the same meal, absorption of the antibiotic can be reduced, affecting its effectiveness.

Supplement Interactions with Fiber

  • Calcium – Fiber can bind with calcium, potentially affecting its absorption if taken in the same meal.
  • Magnesium – Fiber in the same meal may reduce the absorption of magnesium supplements, impacting their effectiveness.
  • Zinc – Taking fiber and zinc together in the same meal can inhibit zinc absorption, affecting the supplement’s efficacy.
  • Iron – High-fiber meals can interfere with iron absorption from supplements, reducing its bioavailability.
  • Vitamin D – While not directly interacting, high fiber intake may affect the metabolism of vitamin D, though more research is needed.
  • Omega-3 Fatty Acids – While not a direct interaction, a high fiber diet may affect how the body processes these fatty acids.
  • Folic Acid – Fiber in the same meal can interfere with the absorption of folic acid supplements, reducing their effectiveness.
  • Coenzyme Q10 – High fiber intake may affect the absorption of this supplement if taken in the same meal.
  • Selenium – Fiber can potentially reduce the absorption of selenium if consumed in the same meal.
  • B-Vitamins – High fiber intake can bind with B-vitamins, potentially affecting their absorption if taken in the same meal.

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Psyllium Fiber

Suggested Dose: 5 grams with each meal.

Psyllium is a soluble fiber that comes from the Plantago ovata plant. Psyllium has also been shown to be effective in chronic constipation, chronic diarrhea, hemorrhoids, ulcerative colitis, enteral nutrition–induced diarrhea, fecal incontinence, and irritable bowel syndrome. [PMC4415962, PMC4415970]

Psyllium Husk Powder by NOW Foods

Soluble fiber from foods such as psyllium seed husks, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease. A serving of Psyllium Husk Powder supplies 6 grams of the 7 grams soluble fiber necessary per day to have this effect.

Vigorously mix 1 level tablespoon daily into at least 12 oz. of water or juice and consume immediately. Be sure to drink plenty of additional fluids throughout the day. Start with smaller amounts and gradually increase over several weeks.

Amount Per 1 TBSP Serving

Dietary Fiber … 7g
Soluble Fiber … 6g
Insoluble Fiber … 1g

Psyllium Husk Powder (Husk/Seed)

Inulin Fiber

  • Nourishes Friendly Bacteria*
  • Very Low Glycemic Index*

Inulin, a fructooligosaccharide (FOS), is a soluble prebiotic fiber that is resistant to digestion and reaches the large intestine essentially intact.* Intestinal probiotic bacteria consume Inulin and in turn, produce the short-chain fatty acids that nourish the cells lining the colon.* Inulin thus helps to maintain intestinal health and function.* Inulin has a pleasant flavor that adds a mild sweetness to foods and drinks, but has a very low glycemic index and will not negatively impact serum glucose levels.*

Take 1 level teaspoon 1 to 3 times daily. Mix into your favorite beverage or food. Begin with 1 teaspoon a day and slowly increase dosage to limit GI discomfort.

Serving Size: 1 Level Teaspoon (approx. 2.8g)

Amount Per Serving
Calories … 5  
Total Carbohydrate … 2.7g
Dietary Fiber … 2.5g
Organic Inulin … 2.8g (FOS) (from Blue Agave)

Acacia Fiber

Acacia fiber, also known as gum arabic or acacia gum, is a dietary fiber extracted from the sap of the Acacia Senegal tree, commonly found in Africa, Pakistan, and India. It is a soluble fiber, which dissolves in water, and offers numerous health benefits. Primarily, it serves as a prebiotic, supporting the growth of beneficial gut bacteria and thus promoting digestive health. This makes it particularly beneficial for alleviating symptoms of irritable bowel syndrome (IBS) and aiding in regular bowel movements.

Additionally, acacia fiber is known for its role in appetite control; as a soluble fiber, it forms a gel-like substance in the gut that slows digestion and prolongs the feeling of fullness, which can be helpful in weight management. It also plays a role in blood sugar management by slowing carbohydrate absorption, which is helpful for people with diabetes or those at risk. Furthermore, regular intake of acacia fiber has been associated with reduced blood cholesterol levels, contributing positively to heart health. Notably, acacia fiber is gentle on the digestive system, making it a preferable option for those who may experience gas and bloating from other fiber types. It can be easily incorporated into various foods and beverages due to its tasteless nature, but always start with small doses to test how well you tolerate it.

Acacia Fiber Organic Powder by NOW Foods

Acacia powder is harvested from the sap of the acacia tree, which is native to parts of Africa, Pakistan, and India. It acts as a prebiotic that supports the vitality of the microorganisms that help maintain a healthy GI environment.* Acacia powder is generally well tolerated and can be used daily.

  • Highly Soluble, Mixes Easily
  • Prebiotic*

Suggested Use: Mix 1 level tablespoon daily into at least 8 oz. of water or juice. Be sure to drink plenty of additional fluids throughout the day. For sensitive individuals, start with 1 teaspoon daily, and gradually increase to 1 tablespoon.

Serving Size: 1 Level Tablespoon (appx 6.5g)

Amount Per Serving

Total Carbohydrate … 6g** (Approximately 80-90% of the carbohydrate content in acacia gum is fiber. Approx. 5.5 g fiber per Tablespoon.)

Organic Acacia Gum Powder … 6.5g (6,500 mg)† (Acacia senegal/ Acacia seyal)

Glucomannan: A High Fiber Substitute for Corn Starch

Glucomannan is a type of soluble fiber. It’s derived from the root of the konjac plant. This fiber is known for its ability to absorb water and form a gel-like substance, making it popular for weight loss and digestive health. Research on glucomannan shows that it can lower total cholesterol, LDL cholesterol, triglycerides, body weight, and fasting blood sugar. Reference: [PMID: 18842808]

Sunfiber® by Metabolic Code

Sunfiber® is a galactomannan based soluble dietary fiber made from hydrolyzed guar gum.* Sunfiber® supports a healthy digestive tract by providing fiber, estrogen and testosterone metabolism in the GUT, healthy lipid levels, and a healthy metabolism and weight.* Supports TRIAD 2 immune/GUT, TRIAD 3 cardiovascular issues and TRIAD 5 hormonal regulation issues.*
Suggested Use:
Take 1 level scoop with a meal. Mix 6-8oz fruit juice, as a smoothie or sprinkle on food.

Serving Size: One Scoop (6 g)

Amount Per Serving
Calories
 … 13
Total Carbohydrates … 6g
Dietary Fiber … 5g
Sunfiber® Guar Fiber (partially hydrolozed Guar Gum) (Cyamopsis Tetgragonolobus)
Soluble Fiber … 6g

Shirataki Noodles * (aka Miracle Noodles) Are Made of Glucomannan (Konjak)

An 8-ounce serving of Shirataki noodles contains only 20 calories, but an impressive total of 6 grams of fiber. You can order Shirataki noodles or rice on Amazon through our affiliate link.


Food First!

Although this article discusses supplements in detail, don’t forget that we are absolutely committed to the “Food First” approach to nutrition. When it comes to your health, the totality of your eating habits far surpasses the impact of individual nutrients or any single supplement you consume. Even though this article doesn’t delve into the broader picture of your overall diet, it’s crucial to keep this element at the forefront of our minds. Your food needs to provide all the vitamins, minerals, fiber, and phytochemicals to nourish your body systems down to the cellular level.

Food choices, rather than supplements, are the most critical factors for a healthy gut microbiome. These trillions of tiny inhabitants in your gut affect your brain waves; they orchestrate your immune system. They possess the power to create molecules that can switch genes on or off and are even capable of synthesizing neurotransmitters. Opting for organic foods and steering clear of plastic packaging (including those labeled BPA-free) is a smart move to limit toxin exposure. The sum of all these parts leads to a powerful conclusion: the ultimate key to your health lies in the quality and balance of the food you consume. Supplements are secondary.

To Sum It Up

Fiber supplements offer a convenient way to boost your daily fiber intake, benefiting digestive health, lowering cholesterol, and aiding in blood sugar control. These supplements can be especially useful when you find it difficult to get enough fiber from food alone. All in all, adding fiber to your routine can be a straightforward move for a healthier lifestyle.


This Article is Not a Substitute for Medical Advice

Dietary supplements are not designed to diagnose, treat, cure, or prevent any disease. The Supplement Sciences website seeks to provide comprehensive access to the most relevant supplement information along with convenient online ordering. We do not provide medical advice and cannot guarantee that every product suggested is completely without risk. Since each person is unique in their health history and medication use, it is important to discuss supplements with your personal physician. Specifically, pregnant women and individuals being treated for cancer or liver or kidney problems must consult their physician about every nutritional supplement they plan to take. People taking medications for the treatment of HIV or with a history of organ transplant must not take supplements without consulting with their physician.


About the Author

Stephanie Figon, MS, RDN, LD

Creator of Supplement Sciences and NutriScape.NET. As a dietitian since 1992, Steph has had experiences in consulting, 15 years in clinical, and has operated a private practice nutrition counseling office for since 2011. Log in to comment and save this article on your board or send your comments to reviews@supplement-sciences.com