Is it better for people to intake more dietary fiber?
Dietary fiber has many benefits for human body, such as moistening the intestines to relieve constipation, improving intestinal function, regulating blood sugar and blood lipid, controlling weight, regulating acid-base balance and so on.
So is it better to eat more dietary fiber? Do different dietary fibers play the same role in the human body?
Recently, a team of researchers at Stanford University in the United States has found that each fiber is related to the biochemical and microbial reactions that depend on the fiber. Therefore, the health benefits of dietary fiber vary from individual to individual, and also depend on the specific fiber type and fiber intake.
The two fibers are arabinoxylan (AX), which is commonly found in whole grains, and long-chain inulin (LCI), which is commonly found in onions and chicory roots. They recruited 18 participants to regularly supplement with both types of fiber.
Participants increased their fiber supplementation from 10 grams per day for breakfast in week 1 to 20 grams per day for week 2 (10 grams for breakfast and 10 grams for dinner) and then to 30 grams per day during week 3 (10 grams each for breakfast, lunch and dinner).
The researchers used fecal metagenomics, plasma proteomics, metabolomics and lipidomics to analyze serum cytokines and clinical values of 18 participants. The results showed fiber and dose-dependent microbiological and systemic responses.
On average, arabinoxylan (AX) improved the lipid profile in a dose-dependent manner, lowering low-density lipoprotein cholesterol, total cholesterol, and other lipids, and was associated with an increase in bile acids, which contributed to the observed cholesterol reduction. However, individual responses varied, with some participants having little change in their cholesterol levels.
At the same time, moderate long-chain inulin (LCI) intake was associated with a slight decrease in inflammatory markers and an increase in bifidobacterial abundance. Bifidobacterium is an intestinal probiotic that produces healthy short-chain fatty acids.
The results of this study show that the benefits of fiber depend on the type of fiber, dosage and individual itself, that is, a series of factors generated by the interaction between fiber, intestinal flora and host.
Two limitations of the study were the short duration and the small number of subjects. However, it is certain that proper intake of dietary fiber does have some benefits for the human body. The recommended fiber intake in the United States is 20 to 35 grams a day. The Chinese Nutrition Society recommends that adults consume 25-30g of dietary fiber per day.