| WHEAT/WHEAT BRAN |
| Costabile et al. (11) | UK 31 adults (15 M & 16 F)
Av age 32 y
BMI 20–30 | Prebiotics, probiotics, high bran or whole grain breakfast cereals, GI drugs, antibiotics (6 m), laxatives, substance or alcohol abuse, major illness, GI disease | Wholegrain wheat breakfast cereal vs. Wheat bran breakfast cereal | Randomized crossover | FISH | 3 weeks Washout 2 weeks | ① 48 g WG wheat breakfast cereal ( g fiber/serve)
② 48 g wheat bran breakfast cereal (13 g fiber/serve) | ① & ② sig ↑ in bifidobacteria, lactobacilli, enteroccoci & aptobiumHowever, ↑'s were sig greater with WG compared to WB cerealSig ↑ clostridium with ② | ① & ② sig↑ plasma ferulic acid with both cereals but greater increase with WB WB sig ↑ stool frequency WG sig improved stool form | This study demonstrates a differential impact of prebiotic action for WB and WG cereal, with a sig higher increase in bacterial no's effect for WG within the measured time frame |
| Vitaglioni et al. (12) | Italy
68 adults overweight/obese
Av Age y
Av BMI 30 | Pregnancy/lactation, medication (3 m), chronic illness, high fiber diet, probiotics, vitamins/minerals supplements, or complementary, and alternative medicines; fruit and vegetables >3 servings/d, > min exercise/wk | Whole grain wheat (Shredded Wheat) vs. refined wheat | Randomized parallel | 16S rRNA gene sequencing | 8 weeks | ① 70 g/d (3 biscuits/d −8 g fiber)
② 70 g refined wheat crackers and toast ( g fiber) | ① Sig↑ Bacteroidetes and Firmicutes & sig ↓ Clostridium | ① Sig 4-fold ↑serum dihydroferulic acid (DHFA) and 2-fold ↑ fecal ferulic acid (FA) with WG | WG wheat consumption significantly ↑ excreted FA and circulating DHFA. Bacterial communities influenced fecal FA & were modified by WG wheat consumption. |
| Freeland et al. (13) | Canada 40 adults—pre-diabetic (↑ insulin) Av age 29 y Av BMI 26 | Antibiotics (3 m)GI, diabetes, hyperlipidaemia or a high-fiber diet. | Wheat bran fiber | Randomized parallel | n/a | 1 year | ① 60 g All Bran Original (24 g fiber)
② 49 g Rice Krispies ( g fiber) | Not measured | ① Sig ↑ plasma butyrate, acetate & GLP-1 in participants between 9 and 12 months. | Sustained ↑ in wheat fiber intake ↑ plasma butyrate & GLP-1 concn in hyperinsulinaemic participants, but it takes 9–12 months for these changes to occur. |
| Neacsu et al. (14) | UK 8 healthy adults Age 18–55 y BMI 18–30 | Prescribed medication, use of nutritional supplements, smoking, antibiotics (3 M) | Wheat Bran breakfast cereal | Non-randomized acute | n/a | Single test meal
2 week washout | ① 40 g All Bran Original (11 g fiber)
② g All Bran original (33 g fiber) | Not measured | Sig ↑ plasma, urine and fecal SCFA & butyrate from ①&②
Sig ↑ plasma ferulic acid by 5 h
No sig differences between treatments | Significant increase in fecal butyrate after consumption of a 40 g bowl All Bran suggest that regular consumption of a wheat bran breakfast cereal will help support a healthy gut environment. |
| Deroover et al. (15) | Belgium
10 adults
Age 18–65 y
BMI 18–27 | Pregnancy/lactation, GI disease, Anemia, Antibiotics, prebiotics, and probiotics (1 M) | Wheat bran effect | Randomized crossover | n/a | 1 day each
Washout 4 weeks | 10 g labeled inulin plus
① 20 g wheat bran
② 20 g wheat bran ↓ particle size
③ 20 g pericarp enriched wheat bran | Not measured | Labeled fermentation markers appeared in breath & plasma around 3 h 45 min after consumption & continued for 8 h. No effect of bran particle size | Fermentation of a readily fermentable substrate increased plasma SCFA for about 8 h, suggesting that a sustained increase in plasma SCFA concentrations can be achieved when a moderate dose of fermentable carbohydrate is administered 3x per day |
| McIntosh et al. (16) | Australia
28 adult males
Age 40–65y | Regular use of drug therapy, medication, or supplements that may interfere with bowel function, major illness | High fiber intake from wholegrain wheat vs. wholegrain rye—bread, crispbreads, and breakfast cereals | Randomized crossover | n/a | 4 weeks each
Washout—length not stated | ① 21 g wheat fiber from cereal foods
② 21 g rye fiber from cereal foods
③ 6 g fiber as refined cereal foods | Not measured | Sig ↑ fecal weight with ① & ② & small sig ↓ fecal pH.
Sig ↑ Butyrate with ②
Sig ↑ propionate with ①
Sig ↓ insulin & glucose response to breakfast meal with both ① & ② | Both high-fiber rye and wheat foods were equally effective in improving measures of bowel health.
Rye foods ② more effective at ↑ plasma enterolactone and fecal butyrate |
| BARLEY |
| Martinez et al. (17) | USA
28 adults (11 M and 17 F) | Antibiotics (3 M) GI disorder, antihypertensives, lipid lowering or other regular drug therapy | Barley vs. brown rice or combination of the two | Randomized cross over | 16 S rRNA gene sequencing
Joint Genome Institute database used to identify large-bowel associated bacteria with b-glucanase encoding activity. | 4 weeks eachWashout 2 weeks | ① 60 g whole grain barley flakes ( g fiber)
② 60 g brown rice flakes ( g fiber) ③ 60 g equal mix of the two (30 g fiber) | All ↑ bacterial diversity with Sig ↑ Firmicutes (Roseburia, Dialister, Eubacterium) & actinobacteria (Bifidobacteria) & Sig ↓ Bacteroidetes | No effect on SCFA
Substantial individual variation in response
Sig improvement in inflammatory responses & glycaemia with WGB & BR combined | Short-term intake of whole grains induced compositional alterations of the gut microbiota that coincided with improvements in physiological measures related to metabolic dysfunctions in humans |
| Nilsson et al. (4) | Sweden
20 adults (10 M and 10 F)
Age 19–30 y
Av BMI | Not reported | Barley vs. refined wheat | Randomized crossover
Washout 1 week | n/a | 1 evening test meal followed by standard white wheat bread breakfast | ① WWB + Barley Dietary Fiber (BDF) ( g fiber)
② Spaghetti + BDF ( g fiber)
③ Spaghetti + BDF ( g fiber)
Spaghetti + oat DF ( g fiber)
Barley porridge ( g fiber) | Not measured | Sig higher breath H2 after ②,③ &
③ with double BDF produced sig higher breath H2 cp to or ②
Plasma SCFA sig higher after compared to barley porridge | Plasm propionate & butyrate -ve related to glucose response suggesting that SCFA derived from colonic fermentation are likely to be involved in modulating glucose response. |
| Nilsson et al. (18) | Sweden
15 adults (10 M and 5 F)
Av age y
Av BMI | Antibiotic or probiotic use (2 W) | Barley vs. white bread | Randomized crossover
Washout 1 week | n/a | 8 individual meals | 8 evening test meals with kernel based barley breads providing varying amounts of dietary fiber (–30 g fiber) | Not measured | Sig ↑ plasma butyrate -measured following morning with High amylose barley and high ß-glucan barley
Sig reduction in blood glucose response to test breakfast between 28 and 36% | The results of this study show that it is possible to increase the colonic production of SCFA in a semi-acute perspective (i.e., from an evening meal to the following morning) by choice of cereal foods rich in barley DF and RS. |
| Nilsson et al. (19) | Sweden
20 adults (3 M and 17 F)
Av age 64 y
Av BMI | Non-smoker, no metabolic disorder or illness
Antibiotics (2 w) or probiotics (2 w) | Barley bread vs. white wheat bread | Randomized crossover | n/a | 3 daysWashout 2 weeks | ① g white wheat bread ( g fiber)
② g barley bread ( g fiber) | Not measured | ② sig ↑ gut hormones, sig ↓ glucose & insulin response to test breakfast
② sig ↑ metabolic markers of microbiota activity—breath hydrogen, plasma SCFA, and acetate | Intake of barley bread for 3 d markedly increased gut fermentation activity suggesting that the metabolic benefits are related to gut fermentation of the DF fraction in Barley bread |
| RYE |
| Graston et al. (20) | Finland
17 adults (8 M and 9 F)
Av age 42
Av BMI | Not reported | Rye bread vs. white wheat bread providing 20% energy intakes | Randomized crossover | n/a | 4 weeks
Washout 4 weeks | ① Rye bread (– servings, – g fiber)
② white wheat bread (– servings, – g fiber) | Not measured | Sig ↑ fecal weight & sig ↓ transit time on Rye bread
No sig diff in total fecal SCFA
Butyrate in feces higher in men on Rye bread phase | Consumption of rye bread in normal amounts improves bowel function. Effects on bacterial activity need evaluation in larger study population |
| Vuholm et al. (21) | Denmark
70 adults (32 M and 38 F)
Av age 51
Av BMI | Smoking, GI disorders, diabetes or CVD, pregnancy or lactation, antibiotics (3 M) pre- or probiotics (1 M) | Rye wholegrains or wheat wholegrains vs. refined grain control | Randomized parallel | 16S rRNA gene sequencing using The Greengenes database for reference | 6 weeks | ① Rye ( g whole grains)
② Wheat ( g whole grains)
③ Refined grains (5g wholegrains) | No effect | Fecal Butyrtae sig ↑ with both ① & ② | Regular consumption whole grain rye or wholegrain wheat affected fecal butyrate & GI symptoms in overweight adults and can be included in the diet equally to maintain gut health |
| Lee et al. (22) | Sweden
21 adults
Av. age y
Av BMI | Diabetes, hyperlipidaemia, thyroid or metabolic disease, eating disorders, pregnancy, lactation, allergies, smoking | Wholegrain rye porridge + inulin/wheat gluten | Randomized crossover | n/a | Single test meal | ① 40 g rye ( g fiber)
② 55 g rye ( g fiber)
③ 40 g rye + g inulin/gluten ( g fiber)
40 g rye + g inulin/gluten ( g fiber)
40 g rye + g inulin/gluten ( g fiber) | Not measured | Sig higher breath H2 with compared to wheat bread or | Whole grain rye suppressed hunger compared to wheat bread but there were no additional effect from adding inulin or gluten. Large dose dependent ↑ breath H2 in response to fiber |
| RICE |
| Nemoto et al. (23) | Japan
36 adults (14 M, 22 F)
Age 22–67 years | Food allergy, serious illness, antibiotics or agent known to influence bowel condition | FBRA-Fermented Brown Rice and rice bran | Randomized crossover | 16S rRNA gene sequencing | 2 weeks each
Washout 12 weeks | ① 21 g FBRA (5 g fiber)−7 g after each meal
② 21 g control ( g fiber) | Change to total bacterial no's not sig diff between group ① & ② or after any test period. SCFA production also failed to show any sig differences. | No significant effects. In vitro testing from 6 participants showed ↑ bifidobacteria & ↑ total SCFA, lactate & acetate with FBRA | FBRA increased production of SCFA and bifidobacteria in vitro, however it remains unclear as to whether this has prebiotic effects in the intestinal environment. |
| Sheflin et al. (24) | USA
7 adults
Av age 42 y
BMI 22–29 | No history food allergy, no cholestertol lowering medication of NSAID's, pregnancy or lactation, smoking, antibiotics (3 M), probiotics (3 M) | 30 g heat stabilized rice bran | Randomized parallel | 16S rRNA gene sequencing | 28 days | ① 1 study meal & 1 study snack daily (30 g rice bran) | Sig ↑ bifidobacteria, ruminococcus species and 6 others | Sig ↑ branched chain fatty acids & butyrate | This pilot study supports that consumption of 30 g rice bran can positively affect the gut microbiota & its metabolites |
| OAT |
| Connolly et al. (25) | UK 30 adults (11 M, 19 F) mild hyperglycaemia or mild hypercholesterolaemia Av age. 42 y Av BMI | Pregnancy/lactation, food allergy, antibiotics (6 w), chronic illness, lipid lowering drugs, GI disorder, Drugs affecting GI, substance misuse, alcoholism | Whole grain Oat (WGO) Granola | Randomized crossover | 16S rRNA gene sequencing & FISH | 6 weeks each
Washout 4 weeks | ① 45 g of WGO granola ( g fiber, g ß-glucan)
② 45 g non-whole grain (NWG) breakfast cereal (flaked corn, g fiber/serve) | ① Sig ↑ bifidobacterial, lactobacilli & total bacterial count
② Sig ↓ bifidobacteria & total bacterial count | No Sig effect fecal SCFA
① Sig ↓ total chol, near sig ↓ fasting glucose
② Sig ↑ total & LDL chol | Dietary WGO ingestion had an appreciable
Impact on the composition of the human gut microbiota, and significantly reduces plasma TC & LDL-C |
| Valeur et al. (26) | Norway
10 adults
22–49 y
Av BMI 23 | Pregnancy, Chronic illness
Gi disease Antibiotics (1 M) | Oatmeal porridge | Non-randomized single arm | n/a | 8 days | 60 g oatmeal (8·5 g fiber, including 4·7 g β-glucans) | Not measured | No sig effect of fecal SCFA
Sig ↓ fecal levels of β-galactosidase & urease suggesting impact on microbial activity | Ingestion of oatmeal porridge daily for 1 week
↑ some metabolic markers of increased microbiota activity however colonic fermentation capacity & fecal SCFA were unaltered. |
| MAIZE |
| Carvalho-Wells, (27) | UK 32 adults (11 M, 21 F) Av. age 32 y Av BMI | Pregnancy/lactation, antibiotics (6 m), GI drugs or laxatives, anemia, hyperlipidaemia | Whole grain maize cereal | Randomized crossover | 16S rRNA gene sequencing | 3 weeks each
Washout 3 weeks | ① 48 g WG maize breakfast cereal ( g fiber)
② 48 g maize cereal ( g fiber) | ① Sig ↑ bifidobacteria and non-sig ↑ lactobacilli & Atopobium levels.
② Non-sig changes to bifidobacteria, lactobacilli, and Atopobium levels | Treatment effects not sustained following wash out period. No sig changes to fecal SCFA, bowel habit data, fasted lipids/glucose, and anthropometric measures | Present study showed a prebiotic effect from a WG maize cereal, which resulted in a beneficial shift in the fecal microbiota |
| MIXED WHOLE GRAIN DIETS (PREDOMINATELY WHEAT) |
| Walker et al. (28) | UK
14 obese males
Av age 54 y
Av BMI | No GI disease
Antibiotics (6 M)
No weight loss (4 M) | Resistant Starch vs. NSP (wheat bran) or High protein weight loss diet | Randomized crossover | 16S rRNA gene sequencing and qPCR | 3 weeksWashout not stated | ① Maintenance (g NSP, 5g RS)
②RS III (g RS, 16g NSP)
③NSP (g NSP, 2g RS)
HP WL (25g NSP, 2g RS) | ② Sig ↑ ruminococcus & eubacterium
③ No major change in fecal microbiota
sig ↓ eubacterium & collinsella | Fermentation metabolites not measured.
RS almost totally digested (96%) in 12 of 14 participants
Soluble NSP 90% digested Insoluble NSP 66% digested | Increased intake of RS gave substantial increases in species in colonic microbiota. However the lack of change resulting from NSP may be due to smaller increase in NSP intake (x) compared to a fold increase in RS intake on test diets. |
| Salonen et al. (29) | UK
14 males metabolic syndrome
Av age 53 y
Av BMI | GI disease
Antibiotics (6 m) | Resistant starch vs. wheat bran | Randomized crossover | 16S rRNA gene sequencing & qPCR | 3 weeks eachWashout 1 week | ① Control diet g fiber
② High RS
③ High NSP (wheat bran)
Low carb weight control | Diversity of microbiota was sig lower ① & ② but ↑ sig with ③ (wheat bran)
Firmicutes fell ~3-fold on
Changes to bacterial abundance were Smaller increase in abundance on NSP diet but may be due to smaller ↑ in fiber intake cp to control diet (x cp to x on RS) | Fecal acetate, Propionate & butyrate ↑ on ③
Chemical analysis of fecal samples showed soluble NSP digestibility to be around 88–90%
Insoluble NSP digestibility = 66% | NSP and RS, affect distinct bacteria, and have different impact on the community ecology of the human gut. RS reduced diversity while increasing specific bacterial types while wheat bran had a more modest impact on bacterial abundance while increasing diversity of the microbiota. |
| Christensen et al. (30) | Denmark
79 overweight/obese post-menopausal women
Age 45–70 y
BMI 27–37 | Not reported | Whole grain vs. refined grain on energy restricted diet | Randomized parallel | 16 S rRNA gene sequencing | 12 weeks
2 week run in | ① g of whole grain products
② g refined grain products | Sig ↑ Bifidobacterium with ① whole wheat groupSig ↓ Bacteroides with ② RW group | Fermentation metabolites not measured.
Sig -ve correlation between bacteroides abundance & % fat mass & trunk fat
Sig +ve correlation between Bifidobacterium & % fat mass & trunk fat | This study, consistent with other studies, supports the prebiotic potential of whole wheat grain products. |
| Vetrani et al. (5) | Italy
54 adults overweight/obese (23 M, 31 F)
Av age 58 y
Av BMI 32 | Diabetes, renal failure, liver abnormalities, anemia, chronic disease, alcohol abuse | Wholegrain products, e.g., bread, breakfast cereals, pasta etc. Mainly wheat some rye | Randomized parallel | n/a | 12 weeks | ① Wholegrain (40g total fiber, 29g cereal fiber)
② refined grain (22g total fiber, 12 g cereal fiber) | Not measured | Sig ↑ plasma propionate with ① which was +vely & sig associated with cereal fiber intake | Habitual consumption wholegrain foods may promote colonic fermentation of fiber, and increased propionate levels may help to modulate insulin response. |
| Cooper et al. (31) | USA
46 adults (21 M and 25 F)
Av age y
Av BMI | Diabetes, GI disease/IBS, laxatives, antibiotics (3 M) smoking, pregnancy, lactation | Wholegrain products e.g., bread, breakfast cereals, pasta etc.
Mainly wheat some corn & rice | Randomized parallel | 16S rRNA gene sequencing | 6 weeks | ① 6 servings wholegrains (g fiber)
② 6 servings refined grains (g fiber) | No sig changes but trends toward ↑Akkermansia & lactobacillus& Erysipelotrichales
N.B. Fecal samples analyzed from only 28 participants | Not measured | Microbial analysis lacked power due to small sample size and requires further research |
| Ampatzoglou et al. (32) | UK
33 adults (12 M, 21 F) | Chronic illness/medication
Substance/alcohol misuse
Antibiotics(3 m)
Probiotics (3 m)
Habitual high fiber/wholegrain | Commercially available whole grain pasta, rice, snacks, and breakfast cereals | Randomized crossover | FISH | 6 weeks
Washout 4 weeks | ① High whole grain (>80 g/d)
② low whole grain (<16 g/d) | No sig effect | Fermentation metabolites not measured.
No sig effects
Trends toward ↓ BMI, blood glucose, & ↑ fecal weight with ① | Little effect of WG consumption on blood biochemical markers, body composition, BP, fecal measurements, or gut microbiology. This may be due to impact commercial production processes on levels of undigestible fermentable carbohydrates |
| Ross et al. (33) | Switzerland
17 adults (6 M and 11 F)
Age 20–50 y
BMI 19–28 | Healthy, no medication, normal blood lipids, no recent antibiotics, non-smilers | Commercially available wholegrain foods inc. wheat, oats, and brown rice | Randomized crossover | Quantitative PCR | 2 weeks
Washout 5–7 weeks | ① g wholegrain foods (34 g fiber)
② g refined grain foods (19 g fiber)
Both 2/3 wheat
+ oats & rice | ① sig ↑ clostridium leptum
Trend toward ↑enterococcus | Fermentation metabolites not measured.
① sig ↑ stool frequency & trend toward ↓ LDL cholesterol
2 weeks too short to see full effects on gut microbiota. | Small changes in fecal microbiota after 2 weeks suggest that longer term wholegrain diets could have greater effects on gut microbiota. This requires further study in longer trials with greater no's participants |
| Tap et al. (34) | France
19 adults (9 M and 10 F)
Age 18–30 y
BMI –25 | Antibiotics (3 M)
Laxatives (3 M)
No history GI problems or taken GI medications (3 M) | High vs. low fiber intake mixed diet | Randomized crossover | 16S rRNA gene sequencing & qPCR | 5 days
Washout 2 weeks | ① 40g fiber ② 10g fiber | ① Sig ↓ Escheria coliLow level of microbial richness at outset was associated with sig microbiota change with ① | Fermentation metabolites not measured. | Short-term change in dietary fiber impacts gut microbiota differently within participants—sig change seen in all individuals. |
| Vanegas et al. (35) | USA
81 adults (49 M and 32 F postmenopausal)
Age 40–65 y
BMI <35 | Supplement use, weight loss diet,
NB. probiotics/supplements stopped 30 days prior to trial
Alcohol abuse
Antibiotics (3 M)
Medication use | Whole grains vs. refined grains
Wheat main source WG | Randomized parallel | 16S rRNA gene sequencing—Greengenes reference database & USEARCH program | 6 weeks | ①WG diet 40 g fiber/day (16 g fiber/1, kcal) ②RG diet 21 g fiber/day (8 g fiber/1, kcal) | ① sig ↑ Lachnospira & ↓ Enterobacteriaceae | ① ↑ bowel movement freq & stool weight
① Sig ↑ in stool total SCFA's & acetate | Short-term consumption of wholegrains improves bowel function and has modest positive effects on gut microbiota, SCFA and innate immune response. Prolonged intervention may give more pronounced changes in microbiota &inflammatory markers. |
| IMPACT OF REDUCING CARBOHYDRATE/FIBER INTAKE |
| Lappi et al. (36) | Finland
51 adults (25 M and 26 F) with metabolic syndrome
Av Age 60 y
Av BMI 31
+ at least 3 other features metabolic syndrome | BMI >40
Very high blood lipids
Diabetes, liver, thyroid, renal disease
Alcohol abuse
IBS. | Replacement rye bread with refined wheat bread
Same total grain intake but different quality | Randomized parallel | 16S rRNA gene sequencing and qPCR analysis | 12 weeks | ① High fiber Rye bread (24 g fiber)
② refined wheat bread (19 g fiber) | ② Sig 16% ↑ Bryantella Formatexigens
② 37% ↓ in Bacteroidetes—due to removal of rye breads
A substantial individuality characterized microbiota responses—most unidirectional but some not responders | Fermentation metabolites not measured. | Intentional modulation of the gut microbiota by withdrawal or supplementation is not straightforward due to individual variations in microbiota. Changing from high to low wholegrain diet did not produces difference sin gut microbiota in individuals with metabolic syndrome |
| Duncan et al. (37) | UK
19 obese but healthy adults
Av. Age y
Av BMI | No history of gastrointestinal problems. No antibiotics or drugs known to influence microbiota | Reduction in carbohydrate and fiber intake | Randomized crossover | FISH and 16S sRNA gene sequencing | 4 weeks
Washout 3 days | ① High protein/medium CHO ( g CHO & g NSP/day) (HPMC)
②High protein/low CHO (24 g CHO & g NSP/day) (HPLC)
③ Maintenance (M) ( g CHO & g NSP/day) | Sig change in bacterial no's
Roseburia >>
Eubacterium rectale >>
Bifidobacteria
>> | Sig ↓ in fecal total SCFA (50%) & butyrate (75%) with decreasing CHO & fiber
>>
Total fecal SCFA correlated positively with fiber intake | Butyrate production Is largely determined by fermentable carbohydrate in the diet. Long term consequences of low SCFA in colon are unknown however consideration to adequate supply of fermen table substrates should be given if low carb diet to be followed for long periods |
| Brinkworth et al. (38) | Australia
91 overweight or obese adults
Age 24–64 years
BMI 26–44 | Liver, cardiovascular, peripheral vascular, respiratory, GI, renal or hepatic disease or a malignancy.
Regular use drug therapy, medication or supplements such as laxatives or antibiotics | Comparison high or low carb energy restricted diets | Randomized parallel | Selective plating for bifidobacteria, lactobacilli, total anaerobes, and E. coli, coliforms and total aerobes & visual counting | 8 weeks | ① High carb (46% CHO, 32 g fiber)
② Low carb (4% CHO, 13 g fiber) | Sig ↓ fecal bifidobacteria in low CHO group | Fecal acetate & butyrate sig ↓ (30–60% lower) on the LC diet | Short term consumption of a low carb diet had a negative impact on bowel health: including lower stool mass, less frequent bowel movements, reduced large-bowel fermentation (↓concn) & excretion of fecal SCFA inc butyrate, & unfavorable shift in fecal microflora composition (↓ bifidobacteria) |
| WHEAT BRAN EXTRACT—ARABINO-XYLAN-OLIGOSACCHARIDE (AXOS) |
| Maki et al. (39) | USA
55 adults
Age 18–75 y
BMI – | Lipid lowering medication | Wheat bran extract AXOS | Randomized crossover | FISH | 3 weeks
Washout 2 weeks | AXOS at 0 (control), g, or g/d as part of wheat based ready-to-eat cereal −2 × 44 g servings cereal daily | Sig ↑ bididobacteria with g AXOS provided as 2 × g doses in a wheat based breakfast cereal
Bifidobacteria levels ↑ in a dose-dependent manner > g>control | Sig ↑ in plasma ferulic acid with and g AXOS—again dose dependent trend > g
No change to Acetic acid or proprionic acid, butyric acid ↓ with increasing AXOS | Sig ↓ LDL cholesterol with g/d |
| Johansson Boll et al. (40) | Sweden
19 adults (9 M and 10 F)
Av age 23
Av BMI 22 | Smoking
Antibiotics (2 w)
Probiotics (2 w)
Food allergise
Metabolic disorders | Wheat Bran extract AXOS | Randomized crossover | n/a | Single test meal
Washout 1 week | ①White wheat bread (WWB) ( g RS)
②WWB + AXOS ( g) + RS ( g)
③WWB + hiAXOS ( g), RS (1 g)
WWB + RS (15 g RS) | Not measured | Sig dose dependent ↑ breath Hydrogen with AXOS ② & ③
Sig dose dependent ↑ SCFA & Butyrate with ② & ③
No sig diff in post prandial glucose or insulin after breakfast meal but improved insulin sensitivity index with AXOS | An AXOS rich substance has the potential to influence overnight glycaemic regulation and gut fermentation in healthy young adults. |
| Windey et al. (41) | Belgium
29 adults
Age 19–44y
BMI – | Abdominal surgery, Liver or kidney failure, GI conditions. Pregnancy, lactation, Drugs affecting GI tract (14 days), Antibiotics (1 M) | Wheat bran extract (75% AXOS) | Randomized crossover | DGGE, plus real-time PCR
GenBank DNA database | 3 weeks
Washout 3 weeks | ①WBE 10 g/day (2 × 5 g sachet) AXOS = g avDP5
② 10 g (2 × 5 g sachet) maltodextrin (placebo) | Sig ↑ bifidobacteria with ① WBE
No diff in fecal SCFA | Sig ↓ colonic fermentation protein with ① WBE | Supplementing the diet with WBE clearly altered fermentation in the colon & selectively stimulated growth of bifidobacteria. |
| Cloetens et al. (42) | Belgium
12 adults (6 M and 6 F)
Av age 24
Av BMI | No GI disease Antibiotics (3 M)Medication affecting GI tract (3 M) | AXOS avDP 15 in varied doses + 3 stable isotopes to measure gastric emptying, transit time & colonic NH3 metabolism | Randomized crossover | n/a | Single test meal
Washout 1 week | ①AXOS g,
② AXOS g
③AXOS g
AXOS g
control
Given in single daily test meal | Not measured | Gut motility not affected. Both ③ & ( g and g AXOS) resulted in: Sig ↑ breath hydrogen & sig ↓ urinary nitrogen Tendency to ↑ fecal nitrogen | A minimal does of g AXOS favorably modulates colonic bacterial metabolism with increases in indicators of fermentation and bacterial growth. |
| Cloetens et al. (43) | Belgium
22 adults | Not reported | AXOS—same dose g but different degree polymerisation | Randomized parallel | RT PCR—bifidobacteria, lactobacteria, and eubacteria | 2 weeks | ①AXOS g av DP 9 ② AXOS g avDP 15 | Sig ↑ bifidobacteria with ① g AXOS avDP9Trend to ↑ Bifidibacteria with ② but not significant change from baseline | Not measured | Bifidogenic properties of AXOS are affected by the degree of polymerisation with shorter molecules being more bifidogenic. |
| Cloetens et al. (44) | Belgium
20 adults (6 M and 14 F)
Av age 24
Av BMI | GI complaints, antibiotics (3 M), drugs influencing GI transit (3 M), Abdominal surgery, pregnancy | Wheat bran extract (AXOS av DP 6) in orange juice | Randomized crossover | RT PCR—Bifidobacterium, Bifidobacterium adolescentis, total bacteria, Lactobacillus, Roseburia–Eubacterium rectale, and enterobacteria | 3 weeks
Washout 4 weeks | ① AXOS 10g (2 × 7 g sachet)
② 10 g maltodextrin (2 × 7 g sachet) | Sig ↑ bifidobacteria at 2 & 3 weeks of AXOS intake
Bifidobacteria also ↑on placebo but AXOS effect was sig > than placebo effect
Increase most pronounced in participants with lowest starting levels of bifidobacteria | Fecal SCFA not measured.
No influence of plasma folate, Vit A or minerals.
No sig diff blood lipids. |
