Fiber material

The microbiome may be the key

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According to a recent study, the health benefits of consuming dietary fiber may depend on the fiber type, dosage, and individual microbiome. Jeff Wasserman/Stocksy
  • High-fiber diets have many health benefits, including reducing the risk of heart attack and stroke.
  • Many types of dietary fiber can be consumed as part of a varied diet or as dietary supplements.
  • Different fibers can have different effects on our gut microbiome.
  • A new study suggests that the use of targeted dietary fiber may benefit health.

Fiber is an essential part of our diet. Otherwise known as roughage, it is the indigestible part of plant foods that helps reduce the risk of health problems such as heart disease and type 2 diabetes.

There are two types of fiber, both of which are non-starch polysaccharides that people cannot digest:

  • Insoluble fiber provides bulk to food and moves waste through the body, keeping the gut healthy and helping to prevent constipation.
  • Soluble fiber forms a gel-like substance that is broken down by gut bacteria. It can lower cholesterol levels and help regulate blood sugar.

But not all dietary fiber is created equal. A new study published in Cell host and microbe found that the health benefits vary from individual to individual and may depend on the type of fiber, the dose consumed and the microbiome of the individual.

Stanford School of Medicine researchers tested how two purified soluble fibers — arabinoxylan (AX) and long-chain inulin (LCI) – affected a group of 18 participants.

AX is found in whole grains, such as rye, wheat, oats, and rice; LCI is found in onions, chicory root, garlic and Jerusalem artichokes. Both types of fibers can also be considered as food supplements.

Study participants had an average age of 56.9 years. Of the 8 men and 10 women, 14 were overweight or obese and 11 were insulin sensitive. The researchers randomly separated them into 2 groups for three cross tests. One group started with AX, the other with LCI then switched. Both groups ended up with a fiber mix consisting of AX, LCI, acacia gum, glucomannansand resistant starch.

Each trial lasted 3 weeks. During the first week, participants consumed 10 g of fiber per day, increasing to 20 g in the second week and 30 g in the third. The participants then had a break of 6 to 8 weeks between the 3 trials.

“This is a VERY small study of 18 participants who are free-living – which means their food is not controlled – so between the food and the sample size it is extremely difficult to draw any conclusions. significant findings. Like almost all good research I’ve read on the microbiome, it raises as many questions as it answers.

– Kate Cohen, MS, RDN, of the Ellison Institute for Transformative Medicine at Providence Saint John’s Health Center in Santa Monica, CA, speaking to Medical News Today.

The researchers took plasma, serum and stool samples from all participants at the start of the trial and then at the end of each week. They also measured their heart rate and blood pressure.

They measured changes in lipids, including cholesterol, genetic material in stool samples (to identify gut bacteria), plasma proteins, metabolites and cytokines. Cytokines are inflammatory markers indicating inflammation in the body.

While taking AX, most participants had a significant drop in low-density lipoprotein (LDL), or “bad” cholesterol, and an increase in bile acids. The authors suggest that increasing bile acids may contribute to LDL reduction. However, some participants saw no change in LDL levels.

For LCI, most, but not all, people saw a slight decrease in inflammatory markers and an increase in Bifidobacterium. This gut microbe is generally considered beneficial for gut health. However, the highest dose of LCI (30 g per day) reversed this effect. At this dose, participants saw increased inflammation and elevation of alanine aminotransferase, an enzyme associated with liver damage.

Blended fiber supplementation produced fewer significant changes.

The authors note that the responses were not consistent for all people for both fiber types, suggesting that each person’s microbiome may determine the responses.

“Our results demonstrate that the physiological, microbial and molecular effects of individual fibers differ significantly.”

– Dr. Michael Snyder, lead author of the study, said in a press release.

Kate Cohen was excited to see where the authors would go next: “Discovering how different fibers interact with the microbiome is an essential step in making personalized nutrition a reality. This research also lays the groundwork for a truly normative use of food as medicine. This study confirms once again that the microbiome holds enormous potential for understanding human health.

The current recommended fiber intake is 14 grams per 1,000 calories consumed, according to the American Academy of Nutrition.

Experts say it’s best to get your fiber from food sources before using supplements.