Fiber: Using Food as Medicine for Long-Term Health

Dietary fiber remains one of the most extensively researched nutrients, which has accumulated extensive evidence showing its protective effects against various chronic diseases. Despite this evidence, most Americans consume only half the recommended daily intake. 

Taking small steps to improve intake is a great opportunity for anyone to work toward disease prevention and maintaining optimal health.

What is Fiber?

Fiber includes the non-digestible components of plant foods that resist digestion in the small intestine. Upon reaching the colon, fiber exerts its beneficial effects through multiple mechanisms. Soluble fiber dissolves in water to form a viscous gel, slowing gastric emptying and nutrient absorption, while insoluble fiber increases fecal bulk and accelerates intestinal transit time.

The gut microbiome plays a key role in the health benefits of dietary fiber. Beneficial bacteria in the colon ferment soluble fiber, producing short-chain fatty acids (SCFAs) that serve as fuel for colon cells. SCFAs also enhance insulin sensitivity, promote satiety through hormonal signaling (GLP-1 and peptide YY), and exhibit anti-inflammatory properties throughout the body. I often like to support this process when working with someone with eczema or acne!

Current Recommendations & Intake Goals

The Dietary Guidelines for Americans recommend 14 grams of fiber per 1,000 calories consumed, translating to approximately 25-28 grams daily for women and 28-34 grams for men. 

Despite these recommendations, average American fiber intake remains approximately 14-16 grams daily, highlighting a significant dietary gap.(1)

Emerging evidence suggests that intakes of 35-40 grams daily may provide optimal protection against all-cause mortality.(2)

What are the Health Benefits of Increasing Fiber?

Cardiovascular Protection and Metabolic Health

A meta-analysis from 2016 of 15 studied revealed that individuals consuming the highest amounts of dietary fiber experienced a 23% reduction in cardiovascular disease mortality and a 24% reduction in coronary heart disease mortality. The authors suggest that every 10g increase in fiber intake corresponds to a 9% reduction in cardiovascular mortality.(3) Wow!

Type 2 Diabetes Management

Soluble fiber improves blood sugar regulation and insulin sensitivity by reducing the glycemic index of foods, slowing glucose absorption, and modulating the production of inflammatory molecules. A study from 2023 confirmed that both food-based and supplemental fiber sources (particularly psyllium husk) enhance glycemic control and mitigate cardiovascular risk factors in those living with diabetes.(4)

For those living with diabetes, I often recommend 1/4 avocado be eaten with a main meal for this reason. This offers not only healthy fats to slow gastric emptying but 3g of fiber to improve postprandial glucose balance.(5)

Cholesterol Reduction & Lipid Management

Soluble fiber effectively lowers low-density lipoprotein cholesterol (LDL-C) without negatively affecting high-density lipoprotein cholesterol (HDL-C). The cholesterol-lowering mechanism involves increased viscosity in the small intestine, which binds bile acids containing cholesterol and prevents their reabsorption. This process drives synthesis of new bile acids in the liver which further reduces circulating cholesterol levels. See my article on cholesterol management here. 

Weight Management & Satiety

The gel-forming properties of soluble fiber prolong gastric emptying time and extend feelings of fullness. This also helps to reduce overall caloric intake. Fiber supplementation in individuals living with obesity has been shown to enhance weight loss outcomes, reduce body fat percentage, and visceral or internal adipose accumulation.

Gastrointestinal Health & Cancer Prevention

Both soluble and insoluble fibers provide distinct and direct benefits to gastrointestinal health, including risk of colon cancer.(6) Both forms of fiber reduce bowel transit time which means they also can ease constipation. See my article here on constipation!

Inflammation Reduction & Immune Function

The SCFAs produced during fiber fermentation, particularly butyrate, reduce inflammatory mediators and support intestinal barrier integrity. A 2024 study on crushed flaxseed consumption in menopausal women demonstrated significant reductions in high-sensitivity C-reactive protein (hs-CRP), a key inflammatory biomarker.(7)

Which Foods are High in Fiber?

This is certainly not an exhaustive list, but a great place to start:

Food Source	Serving Size	Total Fiber
Chia Seeds	2 tbsp	8-10
Ground Flax Seeds	2 tbsp	3-5g
Lentils	1/2 cup cooked	6-7g
Black Beans	1/2 cup cooked	6-8g
Oats	1 cup cooked	4g
Avocado	1/2 Medium Avocado	5-6g
Broccoli	1 cup cooked	4-5g

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References:

1. Over time, racial and ethnic gaps in dietary fiber consumption per 1,000 calories have widened | Economic Research Service. Accessed January 16, 2026. https://www.ers.usda.gov/data-products/charts-of-note/chart-detail?chartId=106189 

2. Ramezani F, Pourghazi F, Eslami M, et al. Dietary fiber intake and all-cause and cause-specific mortality: An updated systematic review and meta-analysis of prospective cohort studies. Clin Nutr. 2024;43(1):65-83. doi:10.1016/j.clnu.2023.11.005

3. Kim Y, Je Y. Dietary fibre intake and mortality from cardiovascular disease and all cancers: A meta-analysis of prospective cohort studies. Arch Cardiovasc Dis. 2016;109(1):39-54. doi:10.1016/j.acvd.2015.09.005

4. Gholami Z, Paknahad Z. The beneficial effects of psyllium on cardiovascular diseases and their risk factors: Systematic review and dose-response meta-analysis of randomized controlled trials. Journal of Functional Foods. 2023;111:105878. doi:10.1016/j.jff.2023.105878

5. Senn MK, Goodarzi MO, Ramesh G, et al. Associations between avocado intake and measures of glucose and insulin homeostasis in Hispanic individuals with and without type 2 diabetes: Results from the Hispanic Community Health Study/Study of Latinos (Hchs/sol). Nutrition, metabolism, and cardiovascular diseases : NMCD. 2023;33(12):2428. doi:10.1016/j.numecd.2023.08.002

6. Kunzmann AT, Coleman HG, Huang WY, Kitahara CM, Cantwell MM, Berndt SI. Dietary fiber intake and risk of colorectal cancer and incident and recurrent adenoma in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. The American Journal of Clinical Nutrition. 2015;102(4):881. doi:10.3945/ajcn.115.113282

7. Wang LY, He LH, Xu LJ, Li SB. Short-chain fatty acids: bridges between diet, gut microbiota, and health. J Gastroenterol Hepatol. 2024;39(9):1728-1736. doi:10.1111/jgh.16619