In exploring the “Health Benefits of Different Dietary Fibers in Common Foods,” this article delves into the intricate world of dietary fibers, ranging from soluble types like β-glucans, found in oats and barley, to insoluble fibers like arabinoxylans in cereals.
We’ll examine the health impacts of these fibers, their role in managing diseases such as diabetes and cardiovascular health, and how they contribute to obesity management.
Additionally, the article sheds light on the latest research advancements in dietary fibers and the importance of proper nutritional documentation for a holistic understanding of these essential diet components.
TABLE OF CONTENTS
Main Findings
- Dietary fibers are classified into soluble and insoluble types, with distinct health impacts.
- Different fiber subtypes, like β-fructans, β-glucans, pectin, and arabinoxylans, have unique molecular structures and functions.
- These fibers play significant roles in managing diseases like diabetes, cardiovascular diseases, obesity, gastrointestinal diseases, and colon cancer.
- The study stresses the need for more detailed research and documentation of dietary fiber sources and their effects on health.
- It advocates for a more nuanced understanding of dietary fibers, beyond just classifying them as high or low fiber, or soluble or insoluble.
Understanding Dietary Fibers: What Are They?
Dietary fibers, complex carbohydrate polymers comprising at least three monomeric units, defy digestion in the small intestine 1 2.
Sourced primarily from grains, cereals, legumes, fruits, vegetables, and nuts, they are categorized based on solubility, viscosity, and fermentability 3 .
Clinical studies have predominantly explored total fiber content or soluble (SDF) and insoluble (IDF) dietary fibers 4 .
However, specific dietary fiber subtypes have demonstrated distinct impacts on host health and disease 5 .
Insoluble fibers, like cellulose and lignin, hasten intestinal transit and increase fecal bulk, alleviating constipation 6 .
Conversely, soluble fibers (e.g., pectin, arabinoxylan, β-glucans, fructooligosaccharides, galactooligosaccharides, inulin, and xyloglucans) undergo fermentation in the large intestine by gut microbiota, yielding beneficial byproducts, including short-chain fatty acids (SCFA), gases (CO2, CH4, and H2), and lactic acid 7 .
Predominant SCFAs produced are acetate, propionate, and butyrate, serving as signaling molecules and host energy sources 8 .
Fermentable or prebiotic fibers, such as galactooligosaccharides and fructooligosaccharides, benefit host microorganisms via fermentation 9 .
Although other fibers can be fermented, their role in promoting beneficial microbes remains uncertain, labeling them as fermentable but not prebiotic (e.g., pectins and cereal mixed linkage beta-glucans).
Scarce information exists on how fiber molecular parameters, such as sugar composition, molecular size, glycosidic linkage profile, and associated components like phytates and phenolic compounds, influence human health 10 .
Regrettably, most clinical studies persist in focusing on vague “high-fiber” vs. “low-fiber” diets or “soluble” vs. “insoluble” fibers, overlooking the physiologically relevant impact of these fibers in gut fermentation and the generation of “bioactive peptides.”
This review underscores the need to assess the intake and influence of specific dietary fibers in health and disease, surpassing mere examination of total fiber intake or solubility.
Exploring Various Fibers Found in Everyday Foods
Total Dietary Fiber in Foods
The amount of total dietary fiber (TDF) in various foods can vary significantly.
In fruits, TDF content ranges from 0.4 to 10.4g/100g of total food volume 11 12.
Passion fruit boasts the highest TDF content among fruits at 10.4g/100g 13.
Vegetables, on the other hand, have TDF content ranging from 0.5 to 15.5g/100g 14, with black beans leading the pack at 15.5g/100g 15.
Cereal grains, including wheat bran, also contain substantial TDF, ranging from 1.2 to 44.6g/100g 16, with wheat bran having the highest TDF content at 44.6g/100g 17.
While apples are considered a significant source of TDF, reported values vary due to differences in measurement methods and food growth conditions.
For example, a study in Australia reported TDF in rye as 15.2–20.9g/100g 18, while a European study calculated it as 13.1g/100g 19 .
TDF content in bananas also varies with ripeness, ranging from 18g/100g in unripe bananas to 2.2g/100g in overripe ones 20.
The geographical location of studies further influences TDF content.
For instance, a Brazilian study found that raw peas contain 10.4g/100g of TDF, but freeze-dried cooked peas have 8.98g/100g 21 .
Different cooking processes also affect TDF in legumes like beans, chickpeas, and lentils, with values decreasing after cooking 22.
Wheat grains show variations in TDF content between countries, such as Italy (11.6–17g/100g), Finland (10.2–15.7g/100g), and Serbia (9.2g/100g) 23 .
Barley and oats also exhibit varying TDF content depending on the location of cultivation 24 .
Inulin and Fructooligosaccharides (FOS)
Chicory root contains the highest amounts of measured β-fructans at 41.6g/100g inulin and 22.9g/100g FOS, followed by Jerusalem artichokes (18g/100g inulin and 13.5g/100g FOS) and garlic (12.5g/100g inulin and 5g/100g FOS) 25 .
Bananas and nectarines display variable amounts of β-fructans, while nectarines have the highest FOS content in fruits at 0.89g/100g 26 .
The FOS content in apples varies based on cultivars, with values ranging from 0.07g/100g to 0.29g/100g 27 .
β-Glucans
β-glucans are primarily found in cereal grains (Henrion, Francey, Lê, & Lamothe, 2019).
The content of β-glucans varies across different grains, including wholegrain wheat (0.2–4.7g/100g), rice (0.13g/100g), maize (0.8–1.7g/100g), sorghum (1.1–6.2g/100g), rye (1–2g/100g), and oats (3.8–6.1/100g) 28.
Barley also shows variability in β-glucan content, ranging from 2 to 20 g/100g of flour 29 .
Different varieties of hulless barley exhibit varying β-glucan percentages 30 .
The processing method can influence β-glucan digestibility in hulless barley, with certain methods reducing starch digestibility 31.
Pectin
Pectin, commonly found in fruits and vegetables, varies in content across different types of produce.
Citrus fruits, carrots, and sweet potatoes contain notable amounts of pectin 32 .
Pectin content in apples, for example, ranges from 0.28g/100g to 0.63g/100g in different samples from various locations33 .
Pectin content in bananas varies between 0.44g/100g and 1.02g/100g in different countries (Wade, Kavanagh, Hockley, & Brady, 1992; Kawabata, Sawayama, & Uryu, 1974; Kertesz, 1951) and depends on ripeness 34.
Arabinoxylans
Arabinoxylan (AX) is predominantly found in cereal grains.
Its content varies, with wheat whole grain containing 4–9g/100g, wheat bran 19.4g/100g, rice bran 4.8–5.1g/100g, rye bran 12.06–14.76g/100g, and oat 2.2–4.1g/100g 35 .
Bread preparation methods can influence AX content, with leavened bread showing a small reduction (6–10%) in AX during preparation 36 .
Yeast-free bread contains more fructans and AXs compared to leavened bread 37.
The type of flour also affects soluble fiber content in products like biscuits 38 .
Wheat AXs impact biscuit dough elasticity, while wheat bran influences product stiffness 39.
Health Benefits of Different Dietary Fibers
Dietary fibers have been a hot topic since the 1980s, drawing significant attention as a valuable food ingredient with substantial health benefits.
Extensive evidence highlights the positive impact of dietary fibers on a range of health issues, including cardiovascular disease, diabetes, metabolic syndrome, inflammatory bowel diseases (IBD), diverticular disease, obesity, and cancer.
For instance, insoluble dietary fibers (IDFs) exhibit anti-carcinogenic properties by binding mutagens and toxins 40, while soluble dietary fibers (SDFs) contribute to reducing total and low-density lipoprotein (LDL) cholesterol levels and slowing the increase in blood glucose 41 .
Cereal-based dietary fiber has shown promise in reducing the risk of IBD and colorectal cancer by fermenting in the gut, producing beneficial short-chain fatty acids (SCFAs), notably butyrate 42.
Moreover, a meta-analysis indicates that a daily increase of 7 grams in fiber intake can lower the risk of cardiovascular disease, strokes, diabetes, colorectal cancer, and rectal cancer 43.
However, despite these insights, the specific amounts of different dietary fibers in foods and the mechanisms governing their interactions with host and microbial cells remain poorly understood.
Additionally, existing studies employ various approaches, ranging from examining isolated fibers to observing whole foods (correlational studies) to conducting randomized control trials (RCTs) using isolated fiber supplements, collectively contributing to our understanding of the health benefits of dietary fibers.
How Different Fibers Benefit Your Health
Beta-Glucans: A Diverse Group of Immune-Boosting Fibers
Beta-glucans, present in fungal cell walls, plants, and some bacteria, are soluble dietary fibers composed of glucose subunits 44.
Their various physiological effects are tied to structural properties like polymerization degree, linkage type, and solubility, influencing their biological impact 45 .
These fibers can activate immune receptors such as Dectin-1, complement receptor (CR3), and TLR-2/6, engaging host immune cells 46 .
Importantly, their binding affinity to Dectin-1 varies depending on their structure, with beta-(1,4) structures showing lower binding than beta-(1,3) and beta-(1,6) structures Brown & Gordon, 2001.
Furthermore, beta-(1,3)glucans from microbial sources stimulate cytokine production more effectively than those from barley and oats 47 .
Factors like linkage type, molecular mass, and solubility influence the immune-modulatory capacity of beta-glucans 48.
Beyond their direct effects on host cells, beta-glucans are fermented by gut microbiota, yielding health-promoting short-chain fatty acids (SCFAs) 49.
The fermentation process involves various gut microbes like Enterococcus, Lactobacilli, and Bifidobacteria, producing variable SCFAs.
Studies exploring beta-glucans from different sources, including microbes, oats, barley, and mushrooms, have shown varying effects on immune responses, cancer, cholesterol, triglyceride levels, and blood glucose homeostasis 50 .
Pectins: Complex Polysaccharides with Immune Activation Properties
Pectins, water-soluble dietary fibers found in fruits and vegetables, are intricate polysaccharides mainly consisting of α-1,4-linked d-galacturonic acid residues, partly esterified with methyl and acetyl groups 51.
Their structural properties, such as methylation degree and chain length, impact their biological effects, including immune responses 52 .
Pectins interact with host immune cells, such as macrophages, stimulating the production of immune cytokines like IFNγ and TNFα 53 54.
The removal of side chains from sweet pepper pectin can modify the secretion profile of cytokines 55
Pectins are also subject to fermentation by microorganisms like Bacillus, Agrobacterium, Pseudomonas, Bacteroides, Prevetella, Ralstonia, Dickeya, and yeast species 56 .
SCFAs generated from pectin fermentation play a role in regulating intestinal inflammation and maintaining gut epithelial barriers 57.
Pectins offer protective effects by preserving the intestinal mucus layer, reducing cholesterol and serum glucose levels, and decreasing the risk of cancer 58 59.
Beta-Fructans: Soluble Fiber with Immune Modulation
Beta-fructans, soluble dietary fibers with varying degrees of polymerization, influence immunity in chain-length-dependent ways 60.
Low-degree beta-fructans enhance anti-inflammatory responses by promoting IL-10 secretion 61.
However, unfermented beta-fructans and FOS, particularly from chicory root, can trigger gut inflammation via TLR2 and NLRP-3 inflammasome pathways 62 63.
These fibers are fermented by microorganisms like Bifidobacteria, Streptococcus, Flavobacterium, and Lactobacillus, with fermentation rate depending on their degree of polymerization 64 .
Beta-fructans are well-studied and recognized as prebiotic fibers, offering protection against constipation, inflammation, and supporting the growth of gut microbiota 656667.
Arabinoxylans: Hemicellulose Polysaccharides with Immune Benefits
Arabinoxylans (AX) are hemicellulose polysaccharides in cereal grain cell walls, containing xylose units and phenolic acids 68 69.
Arabinoxylan oligosaccharides (AXOS) result from AX hydrolysis 70 .
Structural variations in AX, including sugar composition, molecular weight, and linkage, are associated with diverse physiological effects, metabolism, and immune responses.
AXs can activate T and B cells, enhancing humoral and cell-mediated immunity 71.
Additionally, ferulic acid in AXs acts as an antioxidant 72 .
The antioxidative properties are linked to phenolic acid composition, esterified ferulic acid content, and relative xylose residue ratios 73.
AXs are fermented by various gut microbes, but the rate depends on source and structure.
Fermentation of AXs from maize and rice bran differs from wheat bran due to branch structures, impacting their fermentation rates 74 .
AXs protect the immune system by reducing the risk of cardiovascular disease, diabetes, obesity, and colon cancer, along with their beneficial effects on cholesterol, glucose levels, and antioxidant activities.
The Role of Fiber in Fighting Common Health Issues
Heart-Healthy Wonders of Dietary Fibers
Promoting Cardiovascular Health
Dietary fibers play a remarkable role in promoting cardiovascular health, as evidenced by numerous studies 75 .
Research has consistently shown that increasing total dietary fiber intake is directly linked to a reduced risk of cardiovascular disease 76.
For instance, a recent study on mice models demonstrated that a deficiency in dietary fibers, such as resistant starch, led to hypertension and immune pathway suppression, highlighting the protective effects of dietary fibers 77.
In human studies, the source of dietary fiber also matters.
Cereal fibers, found in grains, have shown strong protective effects against cardiovascular diseases 78.
However, a study in an Iranian population found that fibers from fruits, vegetables, legumes, and nuts reduced cardiovascular risk, while grain fibers did not show the same benefits 79.
β-Glucans Take the Spotlight
β-glucans, found in yeast and barley, have demonstrated their cardiovascular benefits.
In a mouse study, a combination of β-glucans led to reduced blood pressure and increased sodium excretion, contributing to antihypertensive effects 80 .
Clinical trials have shown that barley β-D-glucan can reduce total cholesterol levels 81 .
Oat fibers, primarily composed of mixed linkage β-D-glucan and arabinoxylan fibers, significantly reduce total blood cholesterol 82 .
A meta-analysis of trials on barley β-D-glucan observed decreased total and LDL cholesterol levels83 .
Pectin’s Lesser-Known Role
Pectin, although less studied in the context of cardiovascular health compared to β-glucans, shows promise.
Apolipoprotein E-deficient (apoE−/−) mice supplemented with pectin exhibited increased butyrate production, reduced serum cholesterol, and a lower risk of atherosclerosis 84 .
In a human trial, lemon peel, rich in pectin, didn’t significantly affect biochemical factors but showed a slight reduction in LDL 85 .
Fruits like apples and oranges, containing pectin, have been associated with a reduced risk of cardiovascular disease 86 87.
β-Fructans and Inulin
β-fructans, including inulin, hold potential for cardiovascular health.
A study with inulin supplementation in a Western-type diet didn’t reduce atherosclerosis risk in mice but modulated gut microbiota 88.
In humans, isomalto-oligosaccharides (IMO) supplementation led to reduced total cholesterol and LDL-cholesterol levels 89 .
AX Fibers Show Promise
Ax fibers, found in brown rice bran and psyllium seed husk, have shown heart-protective properties.
Psyllium seed husk reduced myocardial infarction in rats 90 .
A study in post-menopausal women found that acylated steryl glucosides (PSG) from brown rice bran reduced LDL-cholesterol levels and inflammatory biomarkers (TNF-α) 91.
Diabetes-Fighting Potential of Dietary Fibers
Dietary Fibers and Diabetes
Dietary fibers have emerged as potential champions in the battle against diabetes.
Numerous studies suggest a link between higher fiber intake and a reduced risk of diabetes.
While specific impacts of different dietary fibers are still under investigation, some promising findings have been uncovered.
β-Glucans: Taming Blood Sugar
Studies in animals have shown significant associations between barley β-D-glucan intake and improved glycemic status in diabetic rats 92 .
In rats with diabetes, supplementation of β-(1,3)glucan (Saccharomyces cerevisiae) led to a 30% reduction in blood glucose concentration 93.
In humans, prospective cohort studies have highlighted that higher intakes of grains, whole grains, total dietary fiber, and cereal fiber containing β-glucan, arabinoxylan, and β-fructans were associated with a reduced risk of diabetes in older women 94.
Furthermore, clinical trials have shown that whole grain oat intake can reduce post-meal blood glucose, insulin resistance, total cholesterol, and LDL cholesterol 95.
A 5g daily β-glucan supplement in individuals with Type 2 Diabetes (T2D) improved glycemic control, regulated appetite hormones, and modulated gut microbiota over three months 96 .
In healthy subjects, intake of β-D-glucan from oats improved glycemic and insulin responses over two months 97.
The effectiveness of β-glucans appears to be influenced by the quantity consumed, duration, and physiochemical properties, primarily due to their gel-forming ability, which helps regulate glucose and insulin release in the intestines 98 .
Pectin’s Hidden Potential
Although pectin fibers have received less attention in diabetes research, intriguing findings have surfaced.
Citrus pectin, derived from orange peels, has demonstrated anti-diabetic effects in Type 2 Diabetes (T2D) rats, reducing fasting blood glucose and improving glucose tolerance, hepatic glycogen levels, and blood lipids 99 .
Low methoxyl pectin supplementation in non-obese diabetic rats limited the development of Type 1 Diabetes (T1D).
Low methylated pectins have shown protective effects against diabetes-induced oxidative stress in insulin-producing β-cells, potentially by inhibiting toll-like receptor (TLR)2/1 100 .
While clinical trials are yet to be conducted, these animal and biochemical studies suggest the diabetes-fighting potential of pectin.
β-Fructans: A Diabetes Ally
Inulin-type fructans, a subset of β-fructans, have demonstrated their anti-diabetic prowess.
In T2D rats, consumption of inulin-type fructans reduced fasting blood glucose, glucose intolerance, and pro-inflammatory cytokines, including IL-6 101.
Long-chain inulin-type fructans from chicory root slowed diabetes progression in non-obese T1D mice 102 .
In humans, inulin-type fructan supplements reduced fasting blood glucose, glycosylated hemoglobin, fasting insulin, and insulin resistance in prediabetic and T2D patients 103 .
However, a study in healthy adults showed no significant effects on fasting blood glucose or fasting insulin after 6 months of inulin-type fructan intake 104 .
Interestingly, supplementation with inulin alone in T2D patients displayed no effects on fasting blood glucose and insulin resistance, suggesting potential benefits of mixed fiber supplementation 105 .
Arabinoxylans: A Multi-Faceted Approach
Arabinoxylans, another group of dietary fibers, have revealed their potential in diabetes management.
In rats with T2D, arabinoxylan consumption normalized bile acid levels, decreased opportunistic pathogens, increased beneficial fiber-degrading bacteria, and raised short-chain fatty acid (SCFA) production 106.
In humans with T2D, a high-arabinoxylan diet improved glycemic control 107.
Weight Management Benefits of Dietary Fibers
Dietary Fibers and Obesity
Dietary fibers have a potential role in weight management, offering insights into how they might help curb obesity by regulating feelings of fullness and more.
Appetite Regulation with SCFA
The fermentation of dietary fibers by gut microbes produces short-chain fatty acids (SCFA), which can cross the blood-brain barrier and reduce appetite 108.
This suggests that increasing the consumption of easily fermentable dietary fibers could lead to reduced daily calorie intake and a decreased risk of obesity.
β-Glucans: Battling Fat
Animal studies have shown that β-glucans from sources like Agaricus bisporus can lower fat levels, limit fat deposits, and reduce obesity 109.
In humans, intake of barley β-D-glucan for 12 weeks significantly decreased visceral fat area, waist circumference, body weight, and body mass index 110.
Yeast β-glucan supplements also had protective effects on pro-cytokines, blood pressure, and waist circumference in obese and overweight individuals 111 .
Pectin’s Impact on Obesity
Pectin, found in various foods, showed promising results in alleviating obesity.
Studies demonstrated that pectin consumption led to reduced visceral fats, triglycerides, total cholesterol, LDL-cholesterol, and fat accumulation in the liver and heart in obese rats 112 .
Apple pectin also contributed to weight reduction in obese rats 113.
Furthermore, apple pectin altered gut microbiota, reduced inflammation, and inhibited weight gain and fat accumulation in obese rats 114.
A randomized control trial in obese patients showed that daily pectin intake elevated satiety and slowed gastric emptying 115 .
β-Fructans: Aiding Weight Loss
Obese rats treated with β-fructan for 8 weeks displayed reduced energy intake, body weight, and liver triacylglycerol accumulation compared to controls 116.
In obese women, β-fructan treatment for 3 months resulted in reduced serum lipopolysaccharide levels, fat mass, plasma lactate, and phosphatidylcholine levels, associated with changes in gut microbiota composition 117.
Another study found that inulin-type fructans reduced appetite and altered microbial communities in obese and overweight adults 118.
Consumption of agave fructans in obese individuals over 12 weeks led to reduced body mass index (BMI), hip and waist circumferences, triglycerides, and decreased total body fat 119 .
Arabinoxylans: Countering Obesity
Supplementing high molecular weight wheat arabinoxylans (AX) in obese mice for 4 weeks reduced diet-induced adiposity, body weight gain, cholesterol accumulation, and insulin resistance 120.
Wheat bran arabinoxylan oligosaccharides over 8 weeks reduced obesity in mice by increasing satietogenic peptide production 121.
In obese and overweight individuals, a 6-week supplementation with long-chain corn bran arabinoxylan modulated gut microbiota and SCFAs production 122.
Another study showed that 15g/day of AX for 6 weeks in obese individuals increased SCFA production, reduced fecal pH, and decreased inflammatory cytokines production 123.
Gastrointestinal Health with Dietary Fibers
Dietary Fibers and Gastrointestinal Disorders
Dietary fibers offer therapeutic potential in various gastrointestinal disorders, including irritable bowel syndrome (IBS), inflammatory bowel diseases (IBD), diverticular disease, and constipation.
Both soluble and insoluble fibers play a crucial role in enhancing stool consistency and weight, thereby addressing issues like constipation.
IBD and Dietary Fiber
Studies have revealed a strong connection between diet and inflammatory bowel diseases (IBD).
Many IBD patients identify diet as a trigger for their condition, leading to dietary restrictions 124 .
Research has shown significant correlations between the consumption of fruits, vegetables, and Crohn’s disease, with long-term dietary fiber intake from fruit sources reducing the risk of Crohn’s disease by 40% 125.
Interestingly, dietary fiber types like β-glucans, β-fructans, and others have varying effects on intestinal barrier integrity and inflammation.
Beneficial Effects of β-Glucans
Supplementing high molar mass oat β-D-glucan for 30 days in individuals with chronic gastritis reduced mucosal damage and C-reactive protein 126.
In mice, oat β-D-glucan mitigated colitis by producing short-chain fatty acids (SCFA) and regulating microbial metabolites 127.
Similar results were observed with Lentinus edodes-derived β-(1,3)glucan and highland barley β-D-glucan, but unfermented barley β-D-glucan caused intestinal barrier damage, highlighting the role of gut microbiota 128 129.
In remission ulcerative colitis patients, oat bran consumption increased stool butyrate levels, improving gastrointestinal symptoms.
Effects of β-Fructans
Oligofructose-enriched inulin supplements reduced fecal calprotectin levels in active ulcerative colitis patients 130.
However, the impact of β-fructans depends on SCFA production via microbe-mediated fiber fermentation.
β-fructans supplements improved clinical remission and reduced fecal calprotectin in some patients but worsened symptomatic relapse and increased pro-inflammatory cytokines in others 131 132.
In a study involving active Crohn’s disease patients, FOS (fructooligosaccharides) showed no significant clinical impact and even increased disease severity 133.
Disease severity and gut microbiota play crucial roles in mediating the effects of β-fructan fibers.
Dietary Fibers from Pectin
Different pectin types had varying effects on gastrointestinal health.
Orange pectin reduced clinical symptoms and colon damage, lowering IL-1β and IL-6 levels in mice 134 .
Artichoke pectin decreased IL-1β and IL-6 in DSS-induced colitis mice 135.
Consumption of pectin following fecal microbiota transplantation in ulcerative colitis patients improved microbiota diversity and decreased the Mayo score 136.
Dietary Fibers and Colon Cancer
Dietary Fibers: Your Ally Against Colon Cancer
Colorectal cancer (CRC) is a significant concern, but dietary fibers offer a protective shield against it.
The link between inflammatory bowel disease (IBD) and CRC suggests the potential benefits of dietary fibers 137 138 .
These benefits hinge on fiber fermentation and the production of short-chain fatty acids (SCFA) like butyrate.
The Fiber Puzzle in CRC Prevention
Understanding the specific impact of different fiber types on CRC remains a challenge.
While many studies have shown an inverse relationship between fiber intake and CRC risk, there’s variation in which fiber-rich foods significantly reduce this risk 139 140 141.
β-Glucans: Immune Warriors
β-glucans emerge as potential CRC defenders due to their immune-modulating and anti-inflammatory properties 142.
In animal studies, β-glucans have shown protective effects against CRC and reduced mortality rates 143 .
Combining β-glucans and quercetin (a flavonoid) in a mouse study led to reduced CRC mortality by 12% through alterations in gut bacteria and gene expression 144.
β-(1,3)glucan from Lentinus edodes induced anti-tumor effects in CRC cell lines.
Clinical trials have also supported the protective effects of β-D-glucans in CRC and reduced chemotherapy side effects 145.
Barley β-D-glucan has shown promise in reducing CRC risk in high-risk individuals 146.
Pectins: Nature’s Shield
Pectins have demonstrated potential in CRC prevention through animal studies and cell lines, although human studies are limited.
For example, both citrus and apple pectin reduced tumor numbers in rat studies 147.
In another study, pectin significantly reduced colon cancer incidence in mice 148.
Sweet potato pectin inhibited CRC cell proliferation and induced apoptosis in vitro 149 .
β-Fructans: A Complex Story
β-fructans show promise in animal models but yield conflicting results in clinical trials 150 .
In mice, combining β-fructans with butyrate-producing bacteria reduced tumor numbers 151.
Inulin, a β-fructan, reduced colon cancer incidence and altered gut bacteria composition in another study 152.
Clinical trials, however, offer mixed results.
While some studies showed increased fecal butyrate levels with FOS (fructooligosaccharides), others found no significant impact on colonic cell proliferation 153.
Arabinoxylans: Taming Inflammation
Arabinoxylan fibers reduce pro-inflammatory cytokines in CRC cell lines.
In humans, wheat bran rich in arabinoxylans reduced DNA synthesis and cell proliferation in individuals at risk of CRC 154.
More research is needed to assess the potential of BioBran/MGN-3 Arabinoxylan as an immunomodulator for cancer patients 155 .
Beyond CRC: Other Cancer Connections
Dietary fibers may also play a role in preventing other cancers.
For instance, endometrial cancer risk inversely correlates with total dietary fiber (TDF) and vegetable intake.
This highlights the importance of exploring different fiber subtypes and their unique bioactivities in the context of cancer prevention.
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