Fiber supports digestive health, promotes regular bowel movements, and prevents constipation. It helps with weight management by providing a lasting feeling of fullness. (1) A higher fiber intake has been linked to a reduced risk of type 2 diabetes, cardiovascular disease, and certain types of cancer.
If you don’t want to die young, eat fiber.
—Dr. Layne Norton
August 2025 Umbrella Study on Fiber & Health
Extensive evidence highlights fiber’s role in improving numerous health markers across diverse populations. A comprehensive umbrella review of multiple meta-analyses offers a broad range of insights and recommendations. Analyzing data from 17,155,277 participants, it examines the impact of fiber on cardiovascular disease, cancer, mortality, and various other health indicators. (2)
The study revealed strong, high-quality evidence indicating that increased fiber intake significantly reduces the risk of cardiovascular disease and related mortality. In umbrella studies, researchers categorize findings by assigning quantitative ratings to different levels of evidence:
- Class One — Convincing Evidence
- Class Two — Highly Suggestive Evidence
- Class Three — Suggestive Evidence
- Class Four — Weak Evidence
Reduced Risk of Cardiovascular Diseases, Pancreatic Cancer, & Diverticular Disease — Class One
Scientists uncovered compelling class one evidence linking dietary fiber intake to reduced cardiovascular mortality, pancreatic cancer, and diverticular disease risk.
“Diverticular disease…is where the portions of the intestine form pouches that food can get trapped in and cause massive inflammation,” Dr. Norton explained.
Reduced Risk of Coronary Heart Disease & Ovarian Cancer — Class Two
During the study, scientists identified two pieces of evidence linking fiber intake to reducing all-cause mortality. Their findings suggest that consuming fiber lowers the risk of coronary heart disease and ovarian cancer.
Not class one, but class two…there is strong evidence suggesting a beneficial effect.
—Dr. Layne Norton
Class Three & Class Four
Class three evidence suggests potential benefits across 16 diverse outcomes. Meanwhile, class four evidence, which is considered weaker, indicates benefits in six additional outcomes.
Other Studies
Numerous studies on fiber intake and health consistently show that higher fiber consumption is linked to a reduced risk of various health issues. This represents a dose-response relationship, where greater fiber intake leads to greater benefits.
One study showed that for every 10-gram increase in fiber, the risk of mortality decreases by 10%.
—Dr. Layne Norton
Dietary fiber seems like a biohack for longevity. It is consistently linked to a lower risk of death across diverse groups, including those with type 2 diabetes, cancer, and cardiovascular disease.
Effects of Fiber on Stroke
Researchers confirmed that a higher fiber intake is linked to a reduced risk of stroke. (3) Across various statistical models, individuals consuming less than 10 grams of fiber per day faced a 20% to 25% higher risk of stroke compared to those who consumed 10 to 18 grams daily.
Dietary fiber intake reduces the risk of mortality for individuals who have experienced a stroke. Consuming 10 to 18 grams of fiber daily is associated with a 20% to 30% lower risk of death. Increasing fiber intake beyond 18 grams further enhances this benefit, reducing mortality risk by 30% to 40%.
Incorporating more fiber into your diet can contribute to a longer, healthier life with improved overall well-being. “I’m not even talking about the gut microbiome benefits. Fiber is the biggest lever you can pull for gut microbiome health,” Dr. Norton added.
Carnivore Dieters
Carnivore enthusiasts’ claims that fiber causes inflammation are questionable, as studies involving participants consuming fiber did not measure C-reactive protein (CRP) levels to support such assertions. “Eating something with fiber and getting a tummy ache does not equate to inflammation. They’re not the same,” Dr. Norton explained.
Avoiding sources that may trigger gastrointestinal discomfort is best for individuals sensitive to certain fiber types. “To live longer, have a higher quality of life, lower your risk of type 2 diabetes, cardiovascular disease, and cancer, then you should eat enough fiber,” Dr. Norton stated. “Aim for at least 20 grams of fiber daily as an absolute minimum. Shoot for about 14 grams of fiber per thousand calories of intake.”
Sources of Fiber
Fiber can be found in various foods, including fruits, vegetables, legumes, beans, and whole grains. “I’m not talking about Lucky Charms or Fruit Loops,” Dr. Norton clarified. “I’m talking about the cereal fiber that can be present in breakfast cereals.”
Whole grains are a source of fiber that has been shown to significantly lower the risk of cardiovascular disease.
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References
- Barber, T. M., Kabisch, S., Pfeiffer, A. F. H., & Weickert, M. O. (2020). The Health Benefits of Dietary Fibre. Nutrients, 12(10), 3209. https://doi.org/10.3390/nu12103209
- Veronese, N., Gianfredi, V., Solmi, M., Barbagallo, M., Dominguez, L. J., Mandalà, C., Di Palermo, C., Carruba, L., Solimando, L., Stubbs, B., Castagna, A., Maggi, S., Zanetti, M., Al-Daghri, N., Sabico, S., Nucci, D., Gosling, C., & Fontana, L. (2025). The impact of dietary fiber consumption on human health: An umbrella review of evidence from 17,155,277 individuals. Clinical nutrition (Edinburgh, Scotland), 51, 325–333. https://doi.org/10.1016/j.clnu.2025.06.021
- Lai, S., Zhou, G., Li, Y., Zhang, Y., An, Y., Deng, F., Wu, K., Liu, P., Chu, Q., & Peng, R. (2025). Association Between Dietary Fiber Intake and Stroke Among US Adults: From NHANES and Mendelian Randomization Analysis. Stroke, 56(7), 1786–1798. https://doi.org/10.1161/STROKEAHA.124.049093
Featured image via Shutterstock/Antonina Vlasova
