Fiber Flashcards
What is Fiber?
Health Canada Definition:
• non-digestible carbohydrate and lignin
(of plant origin)
U.S./Cdn Definition Institute of Medicine
‘Dietary Reference Intakes’ (2002):
Dietary Fiber: non-digestible carbohydrate and lignin that are
intrinsic and intact in plants.
Functional Fiber: isolated, non-digestible carbohydrate
that have beneficial effects in humans.
Total Fiber: sum of Dietary and Functional Fiber.
Insoluble Fibers:
cellulose (β-[1,4]-linked glucose) wheat bran
some hemicelluloses (glucose, arabinose, mannose, xylose)
vegetables and fruit (associated with cellulose)
lignin (polyphenolics) all plant foods (‘woody’ plant cell walls)
Soluble Fibers:
some hemicelluloses (glucose, arabinose, mannose, xylose)
vegetables and fruit (associated with cellulose)
pectin (galacturonic acid and rhamnose) fruits and vegetables
gums (galactomannans–highly viscous) seeds
β-glucans (highly branched β-linked glucose) oats, barley
Physiological Effects
Insoluble Fibers:
Slowly fermented - fecal bulking [laxation, colonic health, ulcerative
colitis, colon cancer]
e.g., wheat bran: fecal bulking 5.7 g / g bran
Physiological Effects
Soluble Fibers:
Fermented - produce short chain fatty acids
(butyrate, propionate, acetate) [colonic health, CHD?]
High Viscosity - increases bile acid excretion [CHD]
- slows carbohydrate absorption [diabetes, CHD]
Glycemic Index / Glycemic Load
GI: the relative blood glucose response to dietary CHO (compared to control food – usually white bread or pure glucose) • GL: takes into account the quality and quality of CHO in a food. Calculated by multiplying the glycemic index by the amount of CHO in grams provided by a food and dividing the total by 100
Cardiovascular Disease, Canadian
Statistics (1999)
Cardiovascular Deaths: 79,000 per year
• 35% of all deaths for men
• 38% of all deaths for women
48% of men & 43% of women have elevated
cholesterol
Health Agencies
First line of intervention to reduce cholesterol
and CHD risk is through lifestyle change
(diet, ↑physical activity, weight control)
↓ Cholesterol 1% = ↓ CHD
2%
What is a Heart-Healthy Diet?
Working Group on Hypercholesterolemia and Other
Dyslipidemias (Canadian):
• <30% total fat
• <10% saturated fat and trans fatty acids
• <300 mg/d dietary cholesterol
• 25-30 g/d fiber
• healthy whole foods (Canada’s Food Guide)
• whole grains (5-10 servings per day)
• fruit and vegetables (5-10 servings per day)
• low-fat milk products (2-4 servings per day)
• low-fat meat and alternatives (2-3 servings per day)
What is a Heart-Healthy Diet?
National Cholesterol Education Program (Step III):
25-35% total fat
• <7% saturated fat; <10% PUFA; <20% MUFA
• <200 mg dietary cholesterol
• 20-30 g/d fiber
• healthy whole foods (whole grains, fruit & vegetables)
• viscous (soluble) fiber (10-25 g/d)
• plant stanol/sterols (2 g/d)
What is a Heart-Healthy Diet?
American Heart Association:
American Heart Association:
• Balance calorie intake and physical activity to achieve or maintain a
healthy body weight
• Consume a diet rich in vegetables and fruits
• Choose whole-grain, high-fiber foods
• Consume fish, especially oily fish, at least twice a week
• Limit your intake of saturated fat to <7% of energy, trans fat to <1% of
energy, and cholesterol to <300 mg per day
• Minimize your intake of beverages and foods with added sugars
• Choose and prepare foods with little or no salt
• If you consume alcohol, do so in moderation
Current FDA Health Claims
for CHD Risk Reduction
Vegetable Proteins • Soy Viscous Fibers Phytosterols • Oat ß-glucan • Sterols • Psyllium • Stanols Nuts (under consideration)
Key Mechanisms of Action
- Viscous fibers = increase Bile acid loss
- Soy Protein = decrease Cholesterol synthesis
increase LDL receptor uptake - Phytosterols = decrease Cholesterol absorption
Nuts
MUFA HDL -> increase hdl, decrease LDL
Vegetable Protein decrease LDL
Vitamin E
& Phenolics -> decrease oxidized LDL
Combination Diet for
Cholesterol Reduction
Viscous Fibres
• Vegetable Protein (soy)
• Phytosterols
• Nuts
