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Dietary Fibre…
Still Going Strong
Dietary fibre is the non-digestible component
of plant foods – fruit, vegetables, legumes and grains.
As far back as Hippocrates, dietary fibre has been identified
as beneficial to human health. In modern times, the association
between dietary fibre and health continues to be explored by
the scientific community. Nevertheless, Canadians continue
to consume inadequate amounts of dietary fibre. In this
newsletter, we describe the importance of fibre to overall
health, including recent research that demonstrates the
association between diets containing high levels of fibre and
a reduction in the risk of a variety of chronic diseases.
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The Impact of Dietary Fibre
on Chronic Disease States
A diet high in fibre has been linked to a decreased risk of many chronic diseases, including obesity, coronary heart
disease, diabetes, metabolic syndrome and cancer. Using diet records from 1526 subjects, Newby and colleagues
measured the impact of whole grains, refined grains and cereal fibre on risk factors for chronic disease.1 The intake
of refined grains was positively correlated with fasting insulin levels. However, both whole grains and cereal fibre
were shown to be inversely related with body weight, BMI, cholesterol levels
and postprandial glucose response; and the magnitude of the association
Studies suggest that the
was similar for whole grains and cereal fibre. These results suggest that
health benefits of whole grain
cereal fibre is the bioactive component of whole grains that helps to facilitate
are primarily attributed to its
reductions in chronic disease.
fibre component
Body Weight Maintenance
Health care professionals recommend a variety of strategies for obesity prevention and treatment, including to
increase levels of fibre in the diet. In a review exploring the relationship between fibre intake and body weight, Slavin
concluded fibre intake is inversely associated with body weight and body fat.2
More recently, a prospective cohort study (n=89,432) by Du and colleagues3 demonstrated that total fibre and cereal
fibres were inversely associated with body weight and waist circumference; and although reductions were small, an
effect of dietary fibre on weight management was demonstrated over time.
Heart Disease
Heart disease and stroke are among the top three leading causes of death in Canada. In 2008, cardiovascular
disease (CVD) accounted for 29% of all deaths.4 The evidence for fibre’s role in reducing the risk of heart disease is
consistent and robust. In fact, the DRI recommendations for dietary fibre are based on levels found to be protective
against heart disease. 5 A systematic review of 15 cohorts by Mente and colleagues found that fibre was associated
with a significantly lower risk (22%) of coronary heart disease.6 Fibres from oat and psyllium in particular have been
studied extensively for their impact on blood cholesterol levels.
Most recently, Health Canada has approved health claims for use in nutrition labelling of foods containing these fibres,
including statements such as “oat [or psyllium] fibre helps lower blood cholesterol, a risk factor for heart disease.” 7,8
Diabetes
In 2008-2009, approximately 2.4 million Canadians (6.8% of the population) were living with diabetes.9 Moreover,
individuals with diabetes experienced mortality rates at least two times higher than those without. Schulze and
colleagues performed a meta-analysis on nine prospective cohort studies and found that a median cereal fibre intake
of 16.6g/day reduced the risk of developing type 2 diabetes by 33% (RR 0.67), while intakes of vegetable or fruit fibres
were not significantly associated with diabetes risk.10
The Canadian Diabetes Association recommends people with diabetes to “increase dietary
fibre to 25-50 grams per day from a variety of sources, including soluble and cereal fibres”
(CDA 2008 Clinical Practice Guidelines)
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Metabolic Syndrome
Metabolic syndrome is a constellation of various
biomarkers and conditions associated with an
increased risk of heart disease and diabetes.11
Using the most commonly accepted criteria
(see inset), approximately one in five Canadian
adults have metabolic syndrome.
Diagnosing Metabolic Syndrome
Any three or more of the following:
1. Waist circumference: Men > 120 cm; Women > 88 cm
2. Triglycerides: > 1.7 mmol/L
3. HDL-cholesterol: Men < 1.03 mmol/L, Women < 1.30 mmol/L
4. Blood Pressure: > 130/85 mmHg
Recent work by Carlson and colleagues
5. Fasting glucose: > 6.1 mmol/L
examined the associations between the intakes
of fibre, saturated fat and cholesterol and
Third Report of the National Cholesterol Education Program (NCEP) Expert
Panel on Defection, Evaluation, and Treatment of High Blood Choleaterol in
prevalence of metabolic syndrome in adolescents
Adults (Adult Treatment Panel III) Final Report. Circulation 2002, 106:3143
(12-19yr, n=2,128).12 Analyzing 24-hr dietary recall and
anthropometric data collected from NHANES 1999-2002, results showed a graded inverse association between
dietary fibre g/1,000kcal and prevalence of metabolic syndrome. Fibre intakes of 3g/1,000kcal (lowest quintile)
showed a 9.3% metabolic syndrome prevalence rate versus a rate of 3.2% at fibre intakes of 11g/1,000kcal
(highest quintile). Neither intakes of cholesterol or saturated fat were associated with the prevalence of
metabolic syndrome.
Colorectal Cancer
An estimated 22,200 Canadians were diagnosed with colorectal cancer in
2011 and overall, it is the second leading cause of death from cancer in men
Health Canada uses wheat bran
and women combined.13 Although a high fibre diet is often discussed as
fibre as the benchmark which
being protective against certain cancers, epidemiological evidence regarding
other fibres are measured
the association between fibre and cancer is mixed. Nevertheless, a recent
against for regularity effects
meta-analysis of results from 19 prospective studies demonstrated that
(Health Canada Guidelines for Planning and Statistical Review of
compared with low fibre intakes, a high total dietary fibre reduced the risk for
Clinical Laxation Studies, 1994)
colorectal cancer by 12% (RR 0.88).14
In the same study, using data from
16 prospective studies and eight cohort studies, a dose response analysis
showed that for each 10g/day intake of either total or cereal fibre, the risk of
colorectal cancer decreased by 10% (RR 0.90).
Latest News: Fibre Intake a
Lowered Risk of Mortality
A recent study by Park and colleagues examined the role of dietary fibre
and mortality in men and women (50-71yr, n=388,122) over nine years
of follow up. Results showed that dietary fibre was associated with a
significantly lower risk of death from all causes, by 24-54% and 34-56% in
men and women, respectively.15
The association remained strong after adjustments for many factors
such as age, sex, race, marital status, BMI, smoking status, physical
activity level, hormone therapy in women, intakes of alcohol, red
meat, fruit, vegetables and total energy, aspirin use, high cholesterol
and high blood pressure. However, the authors acknowledge that
despite controlling for numerous factors that have been linked to
premature death, it is unlikely that dietary fibre intake is the only
nutritional marker for a healthy diet or lifestyle. Further research is
needed to understand better the relationship between dietary fibre
intake and life expectancy.
1. Newby PK et al. Intake of whole grains, refined
grains, and cereal fiber measured with 7-d diet
records and associations with risk factors for chronic
disease. Am J Clin Nutr 86:1745-53 (2007)
2. Slavin JL. Dietary fiber and body weight. Nutrition
21:411-18 (2005)
3. Du H et al. Dietary fiber and subsequent changes in
body weight and waist circumference in European
men and women. Am J Clin Nutr 91:329-36 (2010)
4. Statistics Canada. Morality, Summary List of Causes
2008. www.heartandstroke.com
(accessed 23 Jan 2012)
5. Institute of Medicine, Food and Nutrition Board.
Dietary Reference Intakes: Energy, Carbohydrates,
Fibre, Fat, Fatty Acids, Cholesterol, Protein, and
Amino Acids. National Academies Press,
Washington DC (2002)
6. Mente A et al. A systematic review of the evidence
supporting a causal link between dietary factors and
coronary heart disease. Arch Intern Med
169(7):659-69 (2009)
The Bottom Line
Research has linked diets high in dietary fibre, particularly cereal fibre to
the reduced risk of many chronic diseases affecting a large portion of the
Canadian population. Most recently, fibre has also been linked to overall
mortality, perhaps through its associations with chronic disease. Overall
the evidence demonstrates that fibre is a nutrient too important to ignore.
As dietitians, we can help Canadians meet recommended levels of fibre
to ensure their optimum health.
7. Bureau of Nutritional Sciences, Food Directorate,
Health Products and Food Branch. Oat Products and
Blood Cholesterol Lowering: Summary of
Assessment of a Health Claim about Oat Products
and Blood Cholesterol Lowering. Health Canada,
Ottawa ON (2010)
8. Bureau of Nutritional Sciences, Food Directorate,
Health Products and Food Branch. Psyllium Products
and Blood Cholesterol Lowering: Summary of
Assessment of a Health Claim about Food Products
Containing Psyllium and Blood Cholesterol
Lowering. Health Canada, Ottawa ON (2011)
9. Public Health Agency of Canada. Diabetes in
Canada: Facts and figures from a public health
perspective. Health Canada, Ottawa ON (2011)
10.Schulze MB et al. Fiber and magnesium intake and
incidence of type 2 diabetes. Arch Intern Med
167:956-65 (2007)
11.Riediger ND & Clara I. Prevalence of metabolic
syndrome in the Canadian adult population. CMAJ
183(15):E1127-34 (2011)
12.Carlson JJ et al. Dietary fiber and nutrient density
are inversely associated with metabolic syndrome in
US adolescents. J Am Diet Assoc
111(11):1688-95 (2011)
Visit kelloggs.ca to:
Try the interactive Fibre Tracker
tool to see how food choices
contribute to daily fibre intake.
13.Canadian Cancer Society. Canadian Cancer
Statistics 2011 Featuring Colorectal Cancer.
Canadian Cancer Society, Toronto ON (2011)
14.Aune D et al. Dietary fibre, whole grains, and risk of
colorectal cancer: Systematic review and
dose-response meta-analysis of prospective studies.
BMJ 343:d6617 (2011)
15.Park Y et al. Dietary fiber intake and mortality in the
NIH-AARP diet and health study. Arch Intern Med
171(12):1061-68 (2011)
Kellogg Canada publishes quarterly newsletters on topics that are relevant to healthcare professionals.
The newsletters are available at www.kelloggnutrition.ca/professional.
The editor of the Kellogg’s* Nutrition newsletters is Loretta DiFrancesco, PhD, RD, MBA of Source! Nutrition®.
* © 2012, Trademark of Kellogg Company used under licence by Kellogg Canada Inc. | Spring 2012
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