lecture 4b- 1 october 2014 fibre metabolism and regulation most of this lecture derived from chapter...

Lecture 4b- 1 October 2014

Fibre metabolism and regulation

Most of this lecture derived from Chapter 4 of Gropper

Outline of lectures 4a,b

Definition of Dietary Fibre

Plants and Fibre

Dietary Fibre

Outline of lectures 4a,bSome Properties-dictate physiological and metabolic effects of fibre a) Water Solubility b) Water Holding/Hydration Capacity as

well as viscosity Slowed Gastric emptying

Reduced mixing of gastrointestinal contents with digestive enzymes

Reduced enzyme function Decreased nutrient diffusion rate Altered small intestine transit time


Some Properties-dictate physiological and metabolic effects of fibre

c) Absorption or Binding Ability Diminished absorption of lipids Increased faecal bile excretion Lowered serum cholesterol Altered mineral balance

Outline of lectures 4a,bSome Properties-dictate physiological and metabolic effects of fibre

d) Degradability or fermentability Fermentable fibres Increased water and sodium absorption

in colon Mucosal cell proliferation Provision of energy Acidification of luminal environment Non-fermentable fibres Detoxification Increased faecal bulk

Outline of lectures 4a,4b

Recommended Intake of Fibre Implications in Disease Prevention and

Management

Fibre-Based Herbal Medicines


Summary

More Detailed InformationDietary Fibre

Recommended Intake of Fibre/Implications in Disease Prevention and Management

25- 35 grams per day-DRI-40 tops, 50 obstruction

soluble fibre- hypocholesterolemic-hypoglycemic

insoluble fibre- laxative

Dietary Fibre

How is fibre metabolism regulated in humans?

A few examples

-intake(form and quantity)

-food preparation

-regulation of bacterial enzymes and pathways sincewe cannot use our own enzymes to digest.


Echinacea

-few controlled studies

-immune response boost-prevention or treatment of cold, flu or other infections

active agents

-hmw polysaccharides among others

-side effects-allergic reactions may occur -use in systemic or immune system dysfunction is contraindicated

Fibre-Based Herbal MedicinesGinseng

-cancer prevention-fatigue reduction

-few controlled studies

-active agents-saponin glycosides and ginsenosides-modulate hormones and central nervous system

function

-side effects-negative interactions with warfarin


Ginkgo biloba -vascular flow -free radical scavenger

-few controlled studies-

-active agents-flavone glycosides-see above for effects

-side effects-headaches, dizziness, palpitations


Garlic -lower cholesterol -anti-platelet aggregatory - a number of controlled studies-

-active agents-allicin-see above for functions

-side effects-heartburn, flatulence-anticoagulant function synergy


St. John's Wort -depression -anxiety

a few well- controlled studies-

-active agents-MAO inhibitor-fights depression

-side effects-fatigue, allergic reactions, photosensitivity


Golden seal -canker sores

a number of controlled studies-

-active agents-alkaloids-see above for functions

-side effects-none reported


Glucosamine -rheumatoid arthritis


Chondroitin sulphate -rheumatoid arthritis


Regulatory considerations

what should be regulated, how and by who?


Summary-figure 5.2 Gropper-no satisfactory definition of fibre

-SCFAs provide energy therefore fibre is energy yielding

-varied soluble and insoluble fibre content in different foods-implications for suchdifferences?

lecture 4b- 1 october 2014 fibre metabolism and regulation most of this lecture derived from chapter...

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