Carbohydrate quality and human health: a series of systematic reviews and meta-analyses

May combine two claims. The quote only partly states this claim.

Dose response curves for total dietary fibre intake and total mortality, CHD incidence, type 2 diabetes and colorectal cancer are linear with no sign of a plateau within available data.

“Figure 2 shows dose response relationships for total fibre intake and total mortality, incidence of coronary heart disease, type 2 diabetes and colorectal cancer, many of which are linear with no sign of a plateau within the available data.”

May combine two claims.

The risk estimates for glycaemic index, other than for stroke mortality, are modest compared with those for dietary fibre and following sensitivity analyses were reduced and associated with confidence intervals which included 1.

“However the risk estimates, other than for stroke mortality, are modest when compared with those for dietary fibre and following sensitivity analyses were reduced and associated with confidence intervals which included 1.”

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The observed reductions in risk for whole grains are considerable, typically around 20% with significant dose response relationships.

“As with dietary fibre the observed reductions in risk are considerable, typically around 20% with significant dose response relationships.”

• AssumptionThe authors state this as an assumption: The dose-response analysis assumes a linear relationship between intake and outcome.

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Prospective studies show reductions in all-cause mortality, coronary heart disease, cancer deaths, and incidence of type 2 diabetes with higher whole grain intake.

“Prospective studies showed a reduction in allcause mortality, coronary heart disease, cancer deaths, and incidence of type 2 diabetes.”

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Clinical trials show significantly lower body weight, systolic blood pressure and total cholesterol when comparing higher with lower dietary fibre intakes.

“Clinical trials show significantly lower body weight, systolic blood pressure and total cholesterol when comparing higher with lower intakes.”

• Also stated in: § Discussion · plain

  “In randomised trials higher intakes of dietary fibre reduce body weight, lower blood cholesterol and systolic blood pressure.”

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For all-cause mortality and coronary heart disease incidence, higher whole grain intake translates into 26 fewer deaths (95%CI 14 to 39) and 7 fewer cases (95%CI 3 to 10) per 1000 participants over the duration of the studies.

“For all-cause mortality and coronary heart disease incidence this translates into 26 fewer deaths (95%CI 14 to 39) and 7 fewer cases (95%CI 3 to 10) per 1000 participants over the duration of the studies.”

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Diets with a lower overall glycaemic index appear to be associated with a reduced risk of stroke and type 2 diabetes.

“We have found that diets with a lower overall glycaemic index appear to be associated with a reduced risk of stroke and type 2 diabetes.”

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Dose response curves show clear associations with increasing whole grain intake and all-cause mortality or risk of coronary heart disease, type 2 diabetes, and colorectal cancer incidence.

“Dose response curves showing clear associations with increasing wholegrain intake and all-cause mortality or risk of coronary heart disease, type 2 diabetes, and colorectal cancer incidence are shown in Figure 3.”

• AssumptionThe authors state this as an assumption: The dose-response analysis assumes a linear relationship between intake and outcome.

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For all-cause mortality and coronary heart disease incidence, higher total dietary fibre intake translates into 13 fewer deaths (95%CI 8 to 18) and 6 fewer cases of CHD (95%CI 4 to 7) per 1000 participants over the duration of the studies.

“For all-cause mortality and coronary heart disease incidence this translates into 13 fewer deaths (95%CI 8 to 18) and 6 fewer cases of CHD (95%CI 4 to 7) per 1000 participants over the duration of the studies.”

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In the present study, sensitivity analyses due to high heterogeneity reduced risk reduction and confidence intervals included 1.

“In the present study sensitivity analyses due to high heterogeneity reduced risk reduction and confidence intervals included 1.”

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The quality of evidence contributing to meta-analyses of trial data relating to body weight is high and total cholesterol and systolic blood pressure moderate because of unexplained heterogeneity between trials.

“The quality of evidence contributing to the meta analyses of the trial data relating to body weight is high and total cholesterol and systolic blood pressure moderate because of unexplained heterogeneity between the trials.”

Classified as probably not a substantial claim.

Searches, data extraction, and bias assessment were duplicated independently.

“Searches, data extraction, and bias assessment were duplicated independently.”

• Also stated in: § Methods · plain

  “Literature searches, identification of eligible studies, data extraction and bias assessment were undertaken independently by at least two researchers, with discrepancies resolved with an additional reviewer.”

Probably not a substantial claim: may not pass S3 (load-bearing).

For prospective studies, analyses excluding those that scored less than six out of nine on NOS were conducted.

“For prospective studies analyses excluding those that scored less than six out of a possible nine with the NOS were conducted.”

Probably not a substantial claim: may not pass S2 (checkable).

The approach enabled the authors to provide a stronger justification than previously available for a quantitative recommendation relating to dietary fibre intake.

“Our approach has enabled us to use these indicators of carbohydrate quality to provide a stronger justification than had previously been available for a quantitative recommendation relating to dietary fibre intake.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Funders except WHO had no role in study design, data collection, data analysis, data interpretation, or writing.

“With the exception of WHO, the funders of the study had no role in study design, data collection, data analysis, data interpretation, or writing the report.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Publication bias was assessed with Egger's and Begg's tests, and the trim and fill method.

“Publication bias was assessed with Egger's and Begg's tests, 18 and the trim and fill method.19”

• cites [18] Duval, 2000, Trim and fill: a simple funnel-plot–based method of testing and adjusting for publication bias in meta-analysis, Biometrics sourceNot checked yet

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• cites [19] Guyatt, 2008, GRADE: an emerging consensus on rating quality of evidence and strength of recommendations, BMJ sourceNot checked yet

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Higher intakes of total dietary fibre or whole grains result in reduced incidence and mortality from several NCDs.

“Higher intakes of total dietary fibre or whole grains result in reduced incidence and mortality from several NCDs.”

May combine two claims.

The quality of evidence relating to colorectal cancer incidence for whole grains is moderate, whilst for other critical outcomes it is low due to high heterogeneity not fully explained by sensitivity analysis.

“The quality of evidence relating to colorectal cancer incidence is moderate, whilst for other critical outcomes it is low due to high heterogeneity not fully explained by sensitivity analysis.”

May combine two claims.

Higher dietary fibre intakes may confer even greater benefit for cardiovascular diseases, type 2 diabetes, and colorectal and breast cancer.

“Dose response curves suggested that higher intakes may confer even greater benefit with regard to protection against cardiovascular diseases, type 2 diabetes and colorectal and breast cancer.”

• Also stated in: § Discussion · hedged

  “These findings together with the comparisons of clinical outcomes amongst those with different intakes of dietary fibre suggest that individual adult intakes of total dietary fibre should be no less than 25 to 29 grams per day with additional benefits likely to accrue with higher intakes.”

• AssumptionThe authors state this as an assumption: The dose-response analysis assumes a linear relationship between intake and outcome.

Probably not a substantial claim: may not pass S3 (load-bearing).

For clinical trials, analyses excluding trials with high risk of bias for at least one criterion were conducted.

“For clinical trials, analyses excluding trials with a high risk of bias for at least one criterion were conducted to examine the influence of potential bias on outcomes.”

Classified as probably not a substantial claim.

The use of GRADE criteria typically requires evidence from randomised controlled trials with disease endpoints to be rated as 'high'.

“However this is an inevitable consequence of the use of GRADE criteria for assessment which typically require evidence from randomised controlled trials with disease endpoints in order to be rated as being of 'high'.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Meta regression analyses examined effects of potential explanatory factors including trial design, duration, global region, differences in fibre intake achieved, source of fibre or starch and nutrition status.

“Meta regression analyses further examined effects of potential explanatory factors including trial design (crossover or parallel), study or trial duration, global region, differences in fibre intake achieved, source of fibre or starch and nutrition status of participants.”

Probably not a substantial claim: may not pass S3 (load-bearing).

When using GRADE, downgrading frequently occurs as a consequence of unexplained heterogeneity amongst results of different studies, even when all trend in similar direction.

“Furthermore when using the GRADE approach downgrading frequently occurs as a consequence of unexplained heterogeneity amongst the results of the different studies, even when all trend in a similar direction.”

May combine two claims.

Overall certainty of evidence regarding relationships between carbohydrate quality and critical outcomes was graded as moderate for dietary fibre, low to moderate for whole grains, and low to very-low for glycaemic index.

“Overall the certainty of evidence regarding the relationships between carbohydrate quality and critical outcomes was graded as moderate for dietary fibre, low to moderate for whole grains, and low to very-low for glycaemic index.”

Classified as probably not a substantial claim.

GRADE protocols were used to judge quality of body of evidence as high, moderate, low, or very-low.

“We used GRADE 22 protocols, to judge the quality of the body of evidence as either high, moderate, low, or very-low.”

• cites [22] Aune, 2016, Whole grain consumption and risk of cardiovascular disease, cancer, and all cause and cause specific mortality: systematic review and dose-response meta-analysis of prospective studies, BMJ sourceNot checked yet

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Classified as probably not a substantial claim.

For prospective studies, the most adjusted values for effect size were extracted, where that value did not also specifically include adjustment for other carbohydrates.

“For prospective studies the most adjusted values for effect size were extracted, where that value did not also specifically include adjustment for other carbohydrates.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Where there were multiple publications from the same cohort, data for the longest follow-up period were used.

“Where there were multiple publications from the same cohort, we used data for the longest follow-up period.”

Classified as probably not a substantial claim. May combine two claims.

Risk of bias was assessed using ROBIS for systematic reviews and meta-analyses, NOS for prospective studies, and Cochrane criteria for clinical trials.

“We used the ROBIS assessment tool 8 to assess systematic reviews and meta analyses for quality and risk of bias, and the Newcastle Ottawa Scale (NOS) 9 to assess risk of bias of each prospective study.For clinical trials we used Cochrane criteria.10”

• cites [8] Whiting, 2016, ROBIS: a new tool to assess risk of bias in systematic reviews was developed, J Clin Epidemiol sourceNot checked yet

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• cites [9] Wells, 2011Not checked yet

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• cites [10] Higgins, 2011, The Cochrane collaboration's tool for assessing risk of bias in randomised trials, BMJ sourceNot checked yet

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May combine two claims.

The study related key markers of carbohydrate quality to total mortality and mortality and incidence of major nutrition-related NCDs and considered prospective studies alongside randomised controlled trials.

“A major strength of the present study is that it has related key markers of carbohydrate quality to total mortality and mortality and incidence of the major nutrition-related non-communicable diseases and that prospective studies have been considered alongside randomised controlled trials.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Quality of evidence was assessed by research team and revised if required after discussion with NUGAG Subgroup.

“Quality of the evidence was assessed by the research team and revised if required after discussion with the NUGAG Subgroup on Diet and Health.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Data were extracted using pre-tested forms.

“Data were extracted using pre-tested forms.7”

• cites [7] Te Morenga, 2013, Dietary sugars and body weight: systematic review and meta-analyses of randomised controlled trials and cohort studies, BMJ sourceNot checked yet

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Probably not a substantial claim: may not pass S3 (load-bearing).

The study followed reporting standards for systematic reviews and meta-analyses.

“We followed reporting standards for systematic reviews and meta analyses.6”

• cites [6] Moher, 2009, Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement, PLoS Med sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The corresponding author had full access to all data and final responsibility for decision to submit.

“The corresponding author had full access to all the data in the study and had final responsibility for the decision to submit for publication.”

The quote only partly states this claim.

The high heterogeneity of the pooled effect size (>50%) for stroke incidence and total cholesterol is unexplained by sensitivity analyses.

“** The high heterogeneity of the pooled effect size (>50%) is unexplained by sensitivity analyses.”

May combine two claims.

Diets high in total dietary fibre, especially from whole grains and vegetables and fruits, are associated with a significant reduction in a range of NCDs when compared with lower dietary fibre and refined rather than whole grain intakes.

“Diets high in total dietary fibre especially from whole grains and, on the basis of another recent systematic review, 36 vegetables and fruits, are associated with a significant reduction in a range of NCDs when compared with lower dietary fibre and refined rather than whole grain intakes.”

• cites [36] Cummings, 1973, Dietary fibre, Gut sourceNot checked yet

  Not checked in the free run.

Classified as probably not a substantial claim.

Our study does not exclude the value of these indicators of carbohydrate quality in this clinical context.

“Our study does not exclude the value of these indicators of carbohydrate quality in this clinical context.”

May combine two claims.

Whole foods that require chewing and retain much of their structure in the gut are more likely to increase satiety through a variety of mechanisms leading to weight loss and to modulation of carbohydrate and lipid metabolism.

“Whole foods that require chewing and retain much of their structure in the gut are more likely to increase satiety through a variety of mechanisms leading to weight loss and to modulation of carbohydrate and lipid metabolism.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

There is a considerable body of evidence relating to the adverse consequences of high intakes of sugar sweetened beverages and strong recommendations to reduce the intake of free sugars.

“There is a considerable body of evidence relating to the adverse consequences of high intakes of sugar sweetened beverages and strong recommendations to reduce the intake of free sugars.3”

• cites [3] 2015Not checked yet

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Classified as probably not a substantial claim.

Benefit will accrue from implementation of quantitative recommendations regarding dietary fibre intake.

“Our complementary findings from randomised controlled trials and prospective studies together with the dose response effects, supported by much experimental work, are evidence that diets characterised by a low content of dietary fibre contribute to the cause of a number of NCDs and that benefit will accrue from implementation of quantitative recommendations regarding dietary fibre intake.”

May combine two claims.

We excluded trials which involved only people with diabetes or marked hyperlipidaemia, who were the participants in the majority of trials reporting reduction in these important risk indicators.

“However we excluded trials which involved only people with diabetes or marked hyperlipidaemia who were the participants in the majority of trials reporting reduction in these important risk indicators.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Other studies have reported a lower incidence of stroke and CHD amongst those consuming low glycaemic index or glycaemic load diets.

“Other studies have reported a lower incidence of stroke and CHD amongst those consuming low glycaemic index or glycaemic load diets, 29,[33][34][35][36]”

• cites [29] Turati, 2015, High glycemic index and glycemic load are associated with moderately increased cancer risk, Mol Nutr Food Res sourceNot checked yet

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• cites [33] Rossi, 2015, Relation of dietary glycemic load with ischemic and hemorrhagic stroke: a cohort study in Greece and a meta-analysis, Eur J Nutr sourceNot checked yet

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• cites [34] Aune, 2017, Fruit and vegetable intake and the risk of cardiovascular disease, total cancer and all-cause mortality—a systematic review and dose-response meta-analysis of prospective studies, Int J Epidemiol sourceNot checked yet

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Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Aune et al. report risk reductions of around 10% per 200g fruit and vegetables combined for CHD, stroke and total mortality and smaller but still significant reductions for total cardiovascular disease and cancer.

“They report risk reductions of around 10% per 200g fruit and vegetables combined for CHD, stroke and total mortality and smaller but still significant reductions for total cardiovascular disease and cancer.”

• cites [37] Spiller, 2001Not checked yet

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May combine two claims.

Foods containing added fructose or sucrose and composite foods containing both saturated fat and carbohydrate (e.g. confectionary products) may have a low glycaemic index.

“Foods containing added fructose or sucrose and composite foods containing both saturated fat and carbohydrate (e.g.confectionary products) may have a low glycaemic index.50”

• cites [50]Not checked yet

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Probably not a substantial claim: may not pass S3 (load-bearing).

The benefits of fibre reported in the present and other papers are supported by over 100 years of research into its chemistry, physical properties, physiology and metabolic effects.

“The benefits of fibre reported in the present and other papers are supported by over 100 years of research into its chemistry, physical properties, physiology and metabolic effects.23,[38][39][40]”

• cites [23] Aune, 2011, Dietary fibre, whole grains, and risk of colorectal cancer: systematic review and dose-response meta-analysis of prospective studies, BMJ sourceNot checked yet

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• cites [38] Clark, 2013, The effect of fiber on satiety and food intake: a systematic review, J Am Coll Nutr sourceNot checked yet

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• cites [39] Wanders, 2011, Effects of dietary fibre on subjective appetite, energy intake and body weight: a systematic review of randomized controlled trials, Obes Rev sourceNot checked yet

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May combine two claims.

Whole grains offer a useful means of increasing dietary fibre intake and reducing risk of NCDs.

“Whole grains offer a useful means of increasing dietary fibre intake and reducing risk of NCDs.”

Probably not a substantial claim: may not pass S3 (load-bearing).

A review of prospective studies by Turati et al. suggested a small but significant increase in colorectal cancer incidence associated with high glycaemic index or glycaemic load.

“A review of prospective studies by Turati et al. 32 suggested a small but significant increase in colorectal cancer incidence associated with high glycaemic index or glycaemic load.”

• cites [32] Mirrahimi, 2012, Associations of glycemic index and load with coronary heart disease events: a systematic review and meta-analysis of prospective cohorts, J Am Heart Assoc sourceNot checked yet

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May combine two claims. The quote only partly states this claim.

Egger's test for bias for CHD mortality was p=0.0040; trim and fill analysis did not change the direction or significance of the pooled estimate.

“* Egger's test for bias p = 0•0040. Trim and fill analysis did not change the direction or significance of the pooled estimate.”

Classified as probably not a substantial claim.

Our findings based on a series of systematic reviews and meta-analyses provide strong evidence for the importance of including advice regarding the nature and source of other carbohydrates in dietary guidelines aimed at reducing the risk of NCDs.

“Our findings based on a series of systematic reviews and meta analyses provide strong evidence for the importance of including advice regarding the nature and source of other carbohydrates in dietary guidelines aimed at reducing the risk of NCDs.”

May combine two claims.

The principal function of the microbiome is digestion of fibre and other carbohydrates that escape breakdown in the small bowel and it is the availability of fibre in the diet that dominates the metabolism of the gut microbiome and leads to protection from conditions such as colorectal cancer.

“However the principal function of the microbiome is digestion of fibre and other carbohydrates that escape breakdown in the small bowel and it is the availability of fibre in the diet that dominates the metabolism of the gut microbiome and leads to protection from conditions such as colorectal cancer.44,45”

• cites [44]Not checked yet

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• cites [45] Järvi, 1999, Improved glycemic control and lipid profile and normalized fibrinolytic activity on a low-glycemic index diet in type 2 diabetic patients, Diabetes Care sourceNot checked yet

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May combine two claims.

Intakes in the range of 25 to 29 g daily are optimal, whilst the dose response data show that amounts greater than 30 g per day confer additional benefits.

“Intakes in the range of 25 to 29g daily are optimal whilst the dose response data show that amounts greater than 30g per day confer additional benefits.”

May combine two claims.

Three systematic reviews have shown a reduced incidence of type 2 diabetes associated with the consumption of diets of lower glycaemic index or glycaemic load, though the effect was modest when compared with the protective effect of total dietary fibre or wholegrains.

“Three systematic reviews have shown a reduced incidence of type 2 diabetes associated with the consumption of diets of lower glycaemic index or glycaemic load, [29][30][31] though the effect was modest when compared with the protective effect of total dietary fibre or wholegrains.”

• cites [29] Turati, 2015, High glycemic index and glycemic load are associated with moderately increased cancer risk, Mol Nutr Food Res sourceNot checked yet

  Not checked in the free run.

• cites [30] Cai, 2015, Carbohydrate intake, glycemic index, glycemic load, and stroke: a meta-analysis of prospective cohort studies, Asia Pac J Public Health sourceNot checked yet

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• cites [31] Fan, 2012, Dietary glycemic index, glycemic load, and risk of coronary heart disease, stroke, and stroke mortality: a systematic review with meta-analysis, PLoS One sourceNot checked yet

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May combine two claims.

High intakes of dietary fibre and whole grains may be associated with deleterious effects in populations with borderline iron/mineral status, amongst whom very high whole grain intakes may further compromise iron status.

“However high intakes may be associated with deleterious effects in populations with borderline iron/mineral status, amongst whom very high whole grain intakes may further compromise iron status.49”

• cites [49]Not checked yet

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