The Multifaceted Nature of Dietary Fiber

Key Takeaways:

  • Not all dietary fibers function in the same way, and the effects of fiber supplements can differ greatly among individuals.
  • Different fiber supplements such as arabinoxylan and inulin have distinct effects on blood sugar and cholesterol. Arabinoxylan intake was found to significantly reduce cholesterol levels while inulin did not have the same effect.
  • The study demonstrated that the greatest changes were in relation to gut bacteria, all tested supplements altered the microbiome to some extent.
  • In an unexpected discovery, the method of cholesterol removal by arabinoxylan was through its conversion into bile acids and not via binding, involving the microbiome in a new mechanism for cholesterol reduction.
  • While fiber supplements may play a role, primary factors promoting heart health include regular exercise, sufficient rest, and keeping blood pressure, cholesterol, and blood sugar under check with lipid-improving dietary patterns like DASH, vegetarian, and Mediterranean.

Understanding the diverse world of dietary fiber is no simple task. A recent analysis points out that not all fibers function the same way.

“Considering fiber as a solitary concept is akin to stating that all animals are homogeneous,” said Michael Snyder, senior author and Genetics Department chair at Stanford University School of Medicine. “There’s an immense difference.”

Different Fiber Supplements and Their Effects

Snyder’s team examined two widely used fiber supplements to determine the effects they could have on blood sugar and cholesterol levels. A significant majority of individuals do not consume sufficient fiber in their diets – these supplements could potentially bridge the gap, the researchers mention in their reports.

Common grain fiber arabinoxylan is contained in Popular supplements such as Metamucil and Psyllium husk. Inulin is naturally present in fruits and vegetables such as bananas and asparagus.

“There is a significant reduction in cholesterol levels with arabinoxylan intake,” says Snyder.

However, inulin did not have the same effect on lowering cholesterol in most participants. In certain situations, inulin caused an inflammation increase and, in higher doses, a rise in the indicators of possible liver damage.

Surprisingly, neither arabinoxylan nor inulin lowered blood sugar.

Not Every Response is Created Equal

“Responses can differ greatly among individuals,” Snyder points out. “While some did not experience lowered cholesterol with arabinoxylan, they experienced this with inulin. At least one participant reported this.”

Details on the Process

The research team studied 18 healthy volunteers through three separate sessions, each lasting three weeks. In one session, participants consumed 10 grams per day of either chicory inulin or arabinoxylan for a week, followed by 20 grams for the next week, and finally 30 grams for the final week.

After this three-week session, participants took a break of six to eight weeks, during which they followed their usual diet. Upon return, the same process was repeated, this time with the other supplement.

In the final session, the participants consumed a supplement that contained a mix of five types of fiber, including inulin and arabinoxylan.

Throughout these cycles, participants recorded their food intake and provided blood, urine, and stool samples, which allowed the researchers to measure the variations in gut bacteria, genes, proteins, and lipids. This process aimed to understand the comprehensive metabolic and microbiological impacts of the particular fibers.

Findings of the Study

The research findings, published in Cell Host & Microbe, demonstrated that the greatest changes were seen in relation to gut bacteria.

Some of the gut bacteria levels increased when larger amounts of arabinoxylan were consumed, some reduced, while others elevated irrespective of the arabinoxylan intake. All the tested supplements altered the participant’s microbiome to some extent. The microbiome refers to the collection of microbes that reside in our bodies.

Most of the participants who consumed larger amounts of arabinoxylan observed a decrease in ‘bad’ LDL cholesterol levels. Those who took a mixed supplement also observed a reduction, albeit smaller.

In a surprising revelation, the researchers discovered that arabinoxylan’s method of cholesterol removal was through its conversion into bile acids and not via binding as previously believed. “This discovery brings forth a whole new mechanism for cholesterol reduction and it also involves your microbiome,” comments Snyder.

How Dietary Components Interact with the Microbiome

Dr. Natalie Bello, hypertension research director at the Smidt Heart Institute at Cedars-Sinai in Los Angeles, emphasizes the importance of individualized treatment strategies and the necessity for further study into the interaction between dietary patterns and fiber supplementation.

Earlier data has indicated potential benefits of a high-fiber diet in lowering blood pressure, but a high intake of fiber might not be suitable for everyone, Bello clarifies.

Ultimately, regular exercise, sufficient rest, and keeping blood pressure, cholesterol, and blood sugar under check are the primary factors for promoting heart health, says Bello. Lipid-improving dietary patterns include DASH, vegetarian, and Mediterranean.

For more information on preventing high cholesterol, check the information provided by the U.S. Centers for Disease Control and Prevention.


Greetings from the trails and tracks! I'm Tim, but most folks know me as TJ. I've spent the last 5 years diving deep into the world of content writing, with a particular penchant for nutrition and the intricate science behind it. Every bite we take, every nutrient we consume, tells a unique story – and I'm here to unravel it for you.Beyond my keyboard, you'll often find me on a winding hiking trail or pushing my limits on a long-distance run. These pursuits not only keep me fit but constantly remind me of the vital role nutrition plays in fueling our passions and adventures.Through my writings, I aim to bridge the gap between complex nutritional science and everyday eating habits. Whether you're looking for the latest research updates, practical diet tips, or stories from the running track, I'm committed to serving you content that's as engaging as it is enlightening.So, lace up your shoes, grab a healthy snack, and join me in this exploration of food, science, and the great outdoors. Together, we'll journey towards better health and incredible experiences!
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