- High-fiber diets have many health benefits, including reduced risk of heart attack and stroke.
- Many different types of dietary fiber can be eaten 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 specific dietary fibers may benefit health.
Fiber It is an essential part of our diet. Also 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 non-starchy. polysaccharides that people can not digest:
- Insoluble fiber provides bulk to the diet and moves waste through the body, keeping the gut healthy and helping to prevent constipation.
- Soluble fiber it forms a gel-like substance that is broken down by intestinal bacteria. It can lower cholesterol levels and help regulate blood sugar levels.
But not all dietary fibers are created equal. A new study published in Cell host and microbe has found that health benefits vary between individuals and may depend on the type of fiber, the dose consumed, and the microbiome of the individual.
Researchers at the Stanford School of Medicine tested how two purified soluble fibers: arabinoxylan (AX) and long chain inulin (LCI) — affected a group of 18 participants.
AX is located in whole grains, such as rye, wheat, oats and rice; ICL It is found in onions, chicory root, garlic and Jerusalem artichokes. Both types of fiber can also be taken as Dietary supplements.
Participants in the study 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 crossover trials. One group started with AX, the other with LCI and then switched. Both groups ended up with a fiber mix made up of AX, LCI, acacia gum, glucomannansY resistant starch.
Each trial lasted 3 weeks. In the first week, the participants consumed 10 g of fiber per day, increasing to 20 g in the second week and 30 g in the third. Participants then had a 6- to 8-week break between the 3 trials.
“This is a VERY small study of 18 participants who are ‘free-living’, meaning their food is not being controlled, so between food and sample size, it is extremely difficult to draw any meaningful conclusions. Like almost all the good research I read about the microbiome, this raises as many questions as it answers.”
– kate cohenMS, RDN, from the Ellison Institute for Transformative Medicine at Providence Saint John’s Health Center in Santa Monica, CA, speaking with Today’s medical news.
The researchers collected plasma, serum, and stool samples from all participants at the beginning 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 that indicate inflammation in the body.
When taking AXE, most participants had a significant decrease in low-density lipoprotein (LDL), or ‘bad’ cholesterol, and an increase in bile acids. The authors suggest that the increase in bile acids may contribute to the reduction of LDL. However, some participants saw no change in LDL levels.
For LCI, most, but not all, people saw a small decrease in inflammatory markers and an increase in Bifidobacteria. This gut microbe is generally considered beneficial for gut health. However, the highest dose of LCI (30 g per day) reversed this effect. With this dose, the participants observed an increase in inflammation and elevation of alanine aminotransferasean enzyme associated with liver damage.
Mixed fiber supplementation produced less significant changes.
The authors note that responses were not consistent across people for any fiber type, suggesting that each person’s microbiome may determine responses.
“Our results demonstrate that the physiological, microbial and molecular effects of individual fibers differ substantially.”
– said Dr. Michael Snyder, lead author of the study, 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 is also laying the groundwork for using food as medicine in a truly prescriptive way. This study once again confirms that the microbiome has enormous potential for understanding human health.”
The current recommended fiber intake it’s 14 grams for every 1,000 calories consumed, according to the American Academy of Nutrition.
Experts say it’s best to get fiber from dietary sources before using supplements.
