Adult women 50 and younger should consume at least 25 grams of fiber a day. Women 51 and older should have at least 21 grams a day. Adult men need at least 38 grams of fiber a day if they are younger than 50 and at least 30 grams of fiber a day if they are 51 and older.
Ninety percent of the U. Fiber-rich foods include fruits, vegetables, whole grains and legumes. Many cereals, such as bran flakes, are good sources of fiber. Although fiber supplements can fill the daily fiber gap, they usually have only one type of fiber, rather than a variety of fibers and micronutrients, and they may not provide all the health benefits associated with fiber in food.
Therefore, boost your fiber intake in your diet first by eating a wide variety of high-fiber foods. Many fiber supplements can be used regularly long term. Fiber is classified as soluble or insoluble. Soluble fibers are more fermentable and may cause gas. Insoluble fibers move through the digestive system largely intact, and that can increase stool bulk. The fixed effect of fiber was tested. Time was considered a random effect. Hydrogen and methane were analyzed in the log 10 scale and then back transformed.
No statistical analysis was completed on microbiota results due to the small sample size. The digestion pretreatment had a significant effect on gas volume and pH levels, whereas no differences were seen in concentration of hydrogen, methane, or SCFA with or without a digestion pretreatment data not shown. The following results pertain to findings among digested fibers since they more closely mimic an in vivo system.
Figure 1 shows gas volume produced during fermentation at different time points. No gas was detectable at 0 and 4 h.
Inulin was the only fiber to produce gas at 8 h. Control did not produce detectable gas levels at any time point. Gas volumes. Gas production at 0 and 4 h was undetectable. At 12 h, there was no difference in methane among fibers. All fiber treatments had significantly lower pH values than the control at every time point. Table 2 summarizes the production of acetate, propionate, butyrate, and total SCFA.
At 8 h, there were no differences in propionate among fibers. By 24 h, only PHGG had significantly higher propionate concentration than the control. By 8 h, there were no differences in total SCFA among fibers. At 24 h, all fibers had similar total SCFA concentrations. No baseline Bifidobacteria or Lactobacillus measures were taken due to the high cost of the analysis, but after 24 h of fermentation results can been seen in Table 3. No statistical analysis was done due to insufficient sample size.
The objective of the present study was to compare fermentation profiles of three soluble and fermentable fibers WD, PHGG and inulin after in vitro digestion with salivary amylase, porcine pepsin, and porcine pancreatin to predict physiological benefits and tolerance in vivo. The digestion step was meant to degrade any digestible carbohydrate or remove sugars used as anti-caking agents added to commercial fiber supplements, which may influence the fermentation profile.
In vitro gas production is of interest as discomfort and poor tolerance have been experienced from rapidly fermented fibers in vivo. Determinants of discomfort may depend on volume and distribution of gas in the gut [ 12 ]. A volume of gas in the proximal colon may be perceived more than the same volume in the distal colon suggesting that rate of fermentation may affect tolerance based on location of fermentation within the colon and slower fermenting fibers may be less likely to cause discomfort than more rapidly fermented fibers [ 13 ].
The present study measured gas volume by the overpressure developed in sealed serum bottles by a syringe, which yields a relative volume of gas produced that is useful for comparisons among fibers, but values are not absolute and explains the lack of measureable gas production at 4 h, despite SCFA production. Therefore, our in vitro findings align with the in vivo tolerance literature that WD produced less gas and is better tolerated at higher doses than inulin and PHGG.
Hydrogen and methane are measured during in vitro fermentation as an indirect estimate of metabolic pathways utilized by microbiota as colonic bacteria can convert hydrogen into hydrogen sulfide, methane, and acetate [ 2 ]. Among these, methane and acetate are preferable products as the presence of hydrogen sulfide is potentially damaging to the colonic epithelium [ 16 ]. As hydrogen can be converted into methane, the two have an inverse relationship in the present study between 12 and 24 h where methane increases as hydrogen decreases.
Inulin produced significantly greater hydrogen than WD at 12 and 24 h in the present study, which is consistent with previous in vitro findings [ 17 ]. Differences in concentration ranges compared to a previous in vitro study are likely due to disparities in the amount and number of hydrogen producing and methanogenic bacteria present in the donor samples, but we are unable to confirm this since no microbial analysis was done on the donor feces.
The pH of the colonic lumen is an indicator of fermentation and also plays a role in the modulation of the gut ecosystem. It has been previously shown that low pH 5.
All three fibers had pH values significantly lower than the control; however, they were not as low as 5. There was no difference in total SCFA at 24 h among the fibers and this finding is somewhat expected as the same amount 0. Acetate levels were similar among the fibers at 24 h, although inulin produced more acetate at early time points, which has been seen previously in vitro when compared to WD and PHGG [ 18 ].
PHGG favored propionate production resulting in significantly more than inulin at 24 h, whereas WD had an intermediate value between the two, which supports previous in vitro results where PHGG increased propionate production compared to the control and other fibers [ 19 ].
Interestingly, propionate from inulin decreased between 8 and 12 h. Although not well understood, this decrease at 12 h was also found previously with in vitro fermentation of inulin and is likely an artifact of this fermentation model [ 17 ]. This finding is consistent with previous research showing inulin favors butyrate production [ 18 ].
Butyrate provides energy for colonic epithelium and can induce apoptosis in cancer cell lines [ 20 ]. SCFA tend to be less prevalent in the distal colon due to rapid absorption in the proximal colon. Colonic diseases are often found in the distal colon; therefore, a fiber that is slowly fermented throughout the colon may be beneficial. Fibers stimulate the growth of Bifidobacteria or Lactobacillus , which may lead to enhanced regulation of the microbial balance in the colon as Bifidobacteria produce SCFA and anti-microbial compounds that may protect against increased growth of potentially pathogenic bacteria such as E.
A preliminary microbial analysis was conducted on samples after an in vitro digestion and fermentation in the present study. Inulin is classified as a prebiotic fiber that selectively stimulates bacteria such as Bifidobacteria and Lactobacillus [ 21 ]. Nonetheless, it is important to note results in the present study are preliminary as only one time point of 24 h was examined due to the high cost of microbial analysis and should not be over interpreted.
Future studies should include rigorous designs including molecular microbiological techniques to identify microbiota present at baseline and throughout fermentation to identify changes. Another limitation of this study is that we pooled the three fecal samples to create the inoculum to initiate fermentation.
This practice has long been accepted as a standard procedure for in vitro fermentations; however a shift toward three separate inoculums may be preferable [ 23 ]. In conclusion, we found differences in the rate of fermentation as demonstrated by differences in gas production and pH values at different time points.
Microbial levels observed at 24 h suggest a possible prebiotic effect of WD reported in vivo and warrant further investigation. Overall, in vitro batch fermentations provide a useful and economical way of determining estimates of fermentation and microbiota profiles of fibers. This study was supported by a research grant from Novartis Consumer Health Inc. Also the authors would like to thank Kelly Swanson from the University of Illinois for running the microbial analysis on the samples.
National Center for Biotechnology Information , U. Journal List Nutrients v. Published online May 3. Find articles by Jackie Noack. Find articles by Derek Timm. Find articles by Joanne Slavin.
Author information Article notes Copyright and License information Disclaimer. Indigestible dextrin is a water-soluble dietary fiber extracted and prepared from the indigestible components in the resulting mush. Citrucel methylcellulose is mainly insoluble fibers that are nonfermentable, so it's less likely to contribute to bloating and gas. Psyllium husk Metamucil and Konsyl is rich in both soluble and insoluble fiber. Generally, fiber supplements with mainly insoluble fiber may be a better option for constipation.
Inulin is available in powder form. It is a white powder and in most cases extracted from chicory. However, I have always felt that inulin and psyllium work better when taken together. The presence of psyllium clearly has the potential to enhance the prebiotic effect of inulin. Almost all patients on dialysis take laxatives and stool softeners to promote regularity and prevent constipation.
Psyllium or Metamucil is not recommended for patients on dialysis since it has to be taken with large amounts of fluid to work well. There are several health benefits of dextrin , not only because it is a high source of soluble fiber.
A high fiber diet has been linked to numerous health benefits, including weight loss, better skin health, higher bone density, and lower cholesterol. Citrucel is usually taken 1 to 3 times per day. Use exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.
Overuse of a laxative may cause damage to the nerves, muscles, or tissues in your intestines. Dosage and how to take Begin by adding some inulin -rich foods to your diet on a regular basis. If you decide to supplement, begin with no more than grams a day for at least weeks. Then, slowly increase your intake by grams at a time, until you're taking grams a day. Five Metamucil Capsules are approximately equivalent to one serving of Metamucil Powder.
For maintaining regularity or healthy blood sugar levels and helping to lower cholesterol, one will need more grams of soluble fiber from psyllium husk per serving. Too much fiber in the diet can cause bloating, gas, and constipation. A person can relieve this discomfort by increasing their fluid intake, exercising, and making dietary changes.
These uncomfortable side effects of excessive fiber can occur when someone eats more than 70 grams g of fiber a day. In previous studies, the effects of inulin were investigated in a variety of gastrointestinal disorders, including constipation and irritable bowel syndrome. Chicory-derived inulin has been shown to improve bowel motor function in patients with functional constipation.
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