Fiber
Fiber refers to the indigestible plant carbohydrates found in fruits, vegetables, legumes, whole grains, nuts, and seeds. It exists in two main forms — soluble and insoluble — each playing distinct roles in digestive and metabolic health. Most adults consume well below the recommended 25–38 grams per day, making it one of the most common nutrient shortfalls.
Expert Evidence
13 references from 3 experts
“A meta-analysis published in the Lancet links higher fiber intake with a 15 to 30% decreased risk in deaths from all causes, heart disease, and strokes.”
The Healthiest Diet Says Harvard
12:108 references in 8 episodes from 2025–2026
Brad Stanfield strongly advocates for fiber based on large meta-analyses showing reduced all-cause mortality and heart disease risk, and favors fiber supplements over alternatives like spirulina for lowering LDL cholesterol. There is no evidence of personal use, no specific dosing guidance, and no cautions discussed.
Benefits
Fiber intake is linked to a 15-30% decrease in all-cause mortality, heart disease, and strokes per a Lancet meta-analysis. Fiber supplements lowered LDL cholesterol by about 8 units across 181 RCTs, and fiber may reduce blood pressure by around 4 units in hypertensive adults.
“Your gut likes fiber. It likes fiber because it metabolizes it into something that regulates your immune system. That's scientifically proven and shown in dozens of studies. We don't talk enough about fiber. Most people are walking around fiber deficient.”
Rhonda Patrick interviews Rich Roll on the Environmental Impact of Food, and a Plant-Based Diet
32:444 references in 4 episodes from 2015–2024
Rhonda Patrick strongly advocates for fiber, emphasizing that gut bacteria metabolize it into immune-regulating metabolites and that most people are fiber deficient compared to hunter-gatherer societies who consumed roughly 10x more. She highlights specific mechanisms including soluble fiber feeding the gut wall to strengthen the gut barrier and immune system, and fiber binding to toxins like BPA and phthalates to promote their excretion. No personal usage, specific dosage recommendations, or cautions are discussed.
“Carbs are such a great source of fiber, and it's probably one of the only things we know in nutrition that if you have a certain amount of fiber for a certain period of time for a long period of time, it's hugely beneficial to your health. No matter what your views are on carbs, use the amount of carbs to get at least 25 to 30 grams of fiber a day.”
Jordan Sullivan: Fueling for Sports Performance & Body Composition
35:051 reference in 1 episode
Galpin recommends consuming at least 25-30 grams of fiber daily, calling it one of the few nutritional factors with strong long-term health benefits. He frames carbohydrates primarily as a vehicle for meeting fiber intake. No personal supplementation routine, specific fiber supplement recommendations, or cautions are discussed.
Side Effects
- Bloating and gas, especially when increasing intake too quickly
- Abdominal cramping
- Loose stools or diarrhea at high doses
- Potential reduced absorption of certain medications if taken simultaneously