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HomeBlogAre all fibers created equal? A new study says no.
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Fiber is good for you.

It helps with digestion, weight management, blood sugar, heart health, and cancer prevention. Every country does not eat enough fiber.  Recommended intake is 28-42 grams/day, and Americans only get 12-14 grams/day (Europeans are better at 18-24 g/d). The traditional discussion has been soluble fiber and insoluble fiber.

Soluble fiber

dissolves in water, absorbing water and forming a gel like substance in the digestive tract, and is more easily fermented.

  • Sources: Common sources include oats, legumes (beans and lentils), fruits (especially apples and citrus), psyllium, and barley.
  • Health Benefits:
    • Helps lower blood cholesterol levels, potentially reducing heart disease risk.
    • Regulates blood sugar levels, aiding in diabetes management.
    • Slows digestion, contributing to longer feelings of fullness and aiding weight management

Insoluble fiber

does not dissolve in water. It adds bulk to your stool to promote regular bowel movements.

  • Sources: Found in whole grains, nuts, seeds, and the skins of fruits and vegetables (e.g., cauliflower, green beans, and potatoes).
  • Health Benefits:
    • Prevents constipation by enhancing stool bulk and facilitating bowel movements.
    • Supports colon health and may lower the risk of diverticulitis and other intestinal conditions
Some fiber is dietary- you get it naturally in whole foods, so you get nutrients along with the fiber. Other fiber is functional, where it is extracted from natural sources or made. You see this often in supplements to boost fiber content, inulin and sugar alcohols.

But not all fiber is equal.

Turns out different kinds of fiber may help with different things. There is more research into “prebiotic fibers,” which feed beneficial bacteria in the gut to promote fermentation. This is thought to improve gut health and reduce inflammation. Examples of good prebiotic fibers are onions, garlic, and asparagus.

A new study

published in Food Research International March 2025 did an in depth look at fiber, “Beyond soluble and insoluble: A comprehensive framework for classifying dietary fibre’s health effects.” They proposed a new classification based on five features:
  1. Backbone Structure: This feature refers to the fundamental composition of the fiber molecules and how they are constructed. Different backbone structures can influence the fiber’s functionality and health impacts.
  2. Water-Holding Capacity: This characteristic describes how much water a fiber can absorb, impacting digestion and satiety. Fibers with high water-holding capacities may aid in maintaining gut health by promoting bioprocesses in the intestines.
  3. Structural Charge: The ionic properties of dietary fibers can affect their interactions with other macromolecules and gut microbiota, influencing digestion and nutrient absorption.
  4. Fiber Matrix: This feature pertains to the overall organization of fiber within foods and how it interacts with other components, potentially affecting gut microbiota dynamics and health outcomes.
  5. Fermentation Rate: This defines how quickly a fiber can be fermented by gut bacteria, which is crucial for determining its health effects, particularly concerning gut health and nutrient absorption

They then talk about what is your goal?

I really liked their talk about the gut microbiome. We have seen so much advancement in our understanding of how the microbiome affects your health- diabetes, Crohn’s, heart disease, MS, and more. It is an area we believe in and expect new advancements to come. They had an exciting section (yes, you too can get excited about fiber and your bowels), where they discussed different fibers and what it would do, with links to the original studies. Examples:

  • Higher water holding capacity? It will decrease food intake and make your stool bulkier and regular.
  • Glucose absorption capacity? It binds and captures glucose,  helping with diabetes and insulin resistance.
  • Cholesterol bonding? lowers serum cholesterol
  • Immune modulation
  • Absorption of toxic ions, like lead and arsenic
  • Reduce cancer metastasis

How can Biohackr Health help?

We created our own probiotic, focused on regularity and using bacterial strains known to help with glucose control. We will watch this area closely to see how we should tweak our probiotic, or even more likely, create different lines of fiber/probiotics targeting different issues. SHOP

Medical Sources: 

This was truly a great deep dive into fiber. For more reading go to the original publication: RMIT fiber classification publication link

The information provided on this website is for general informational purposes only and does not constitute medical advice, diagnosis, or treatment. Always seek the advice of a qualified healthcare provider for any questions regarding your health or medical condition.
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