The new normal-Globe and Mail- 30 September 2012- parents do not recognise when they and/or others including kid(s) is/are overweight or obese Fat is the new normal  

Lecture 4a- 23 January 2017 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,b Some 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

Outline of lectures 4a,b 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,b Some 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,b Recommended Intake of Fibre             Implications in Disease Prevention and Management Fibre-Based Herbal Medicines

Outline of lectures 4a,b Summary

More detailed information Definition of Dietary Fibre         -not a single entity and therefore no universal definition         -one attempt at definition- "plant polysaccharides and lignin which are resistant to hydrolysis by the digestive enzymes of man"- Trowell et al quoted in Chapter 5, Gropper 3rd edition         -however, there are problems with this definition

Problems with definition-direct quote from Gropper, Chapter 5 “fails to include all the digestible residue from food that may reach the colon. It uses the ability to be digested as the basis for the definition when undigested food reaching the colon does not necessarily lack the ability to be digested nor is it necessarily unavailable to the body”

Health Canada Definition of Dietary Fibre (most recent 2012) • . Health Canada Definition of Dietary Fibre (most recent 2012) Dietary fibre consists of: carbohydrates with a DP1 of 3 or more that naturally occur in foods of plant origin and that are not digested and absorbed by the small intestine; and accepted novel fibres. Novel fibres are ingredients manufactured to be sources of dietary fibre and consist of carbohydrates with a DP of 3 or more that are not digested and absorbed by the small intestine. They are synthetically produced or are obtained from natural sources which have no history of safe use as dietary fibre or which have been processed so as to modify the properties of the fibre contained therein. Accepted novel fibres have at least one physiological effect demonstrated by generally accepted scientific evidence." 1DP: degree of polymerization or number of saccharide units.

Health Canada Definition of Dietary Fibre (most recent 2012) • . Health Canada Definition of Dietary Fibre (most recent 2012) The substances in part 1 of this definition are all edible plant materials that have a history of use as food and have been processed or cooked using conventional processes. They include fruits, vegetables, pulses, seeds, nuts, cereals, legumes, etc. Some minor substances, such as lignin, waxes, cutin, suberin, phytate, and tannin, although not carbohydrates, are an integral part of dietary fibre and are intricately tied to the plant polysaccharides, often serving as chemical cross-links between various components and increasing resistance to digestion in the small intestine. These substances, as well as some proteic fractions, are not separated from the polysaccharides in some gravimetric methods. Therefore, they are included in the definition of dietary fibre when they are part of the plant cell wall matrix, but they cannot be defined as dietary fibre if they are isolated and introduced into a food. Substances in part 2 of the definition include, for example, substances obtained from agricultural crop by-products and from raw plant materials, substances of animal or bacterial origin, chemically modified substances, synthetic products, etc. These substances are not historically used as food fibre sources. The term "novel fibre" is used only during the pre-market review process involving Health Canada, the food industry, and the Canadian Food Inspection Agency. Once a novel fibre source has been accepted by Health Canada, it is labelled as dietary fibre and is known as such.

• . Health Canada kcal/gm (metabolisable energy) for fibre (most recent 2012) Health Canada considers the energy value for carbohydrate that is not digested in the small intestine, but is fully fermented in the large intestine, is 2 kcal (8 kJ) /g. This will be the general value used for all unavailable carbohydrate, including dietary fibre, in the absence of specific values. This will also apply to inulin for which the previously calculated value was 2.2 kcal (9.2 kJ) /g. Products with energy values lower than 2 kcal (8kJ) /g, which have already been accepted by Health Canada based on scientific evidence, may carry a label declaration of these specific caloric values. Thus, the energy value of the fibre portion of wheat bran is 0.6 kcal (2.5 kJ) /g and the wheat bran itself has an energy value of 2.4 kcal (10 kJ) /g. Polydextrose, an eligible fibre source under the new definition, has been previously accepted as having an energy value of 1 kcal (4 kJ) /g given that it is only partially fermentable

Plants and Fibre        -fibre is derived from plant cells        -plant cell wall contributes more than 95 percent of dietary fibre         -figure 5.1 –Gropper         -figure 5.3-Gropper

Plants and Fibre       

Plants and Fibre       

Fibre- water insoluble and water soluble    

Fibre- water insoluble      -cellulose-bran, legumes, peas, root vegetables, cabbage family veggies, apples, outer covering of seeds          -poorly fermented generally    

Fibre- water insoluble -hemicellulose-not water soluble if do NOT have acid side chains   -bran and whole grains(not clear if water or water insoluble or both)                                             -fermentability depends on sugar and acid composition-eg hexose and uronic acid are more accessible to bacterial enzymes    

Fibre- water insoluble lignin-a non-carbohydrate component of fibre- wheat, fruits with edible seeds (eg strawberries) , mature root veggies (eg carrots)            -poorly fermented    

Fibre- water soluble -water soluble-refers to hot water             

Fibre- water soluble -water soluble-refers to hot water                  -hemicellulose-water soluble if have acid side chains                            

Fibre- water soluble -pectin-gel forming                                    -apples, strawberries and citrus fruits                       -easily fermented             

Fibre- water soluble        -gums                        -oatmeal, barley and legumes                        -eg: gum arabic                        -easily fermented             

Fibre- water soluble -mucilages           -similar in structure to gums           -synthesised by plant secretory cells           -carrageenan and agar-dervived from seaweed and algae                 -used as stabilisers in ice cream for example -degraded by colonic bacteria             

Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre             a) Water Solubility                      -generally water soluble -delay gastric emptying                                     -increase transit time                                     -decrease nutrient (glucose absorption)             

Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre             a) Water Solubility                      generally water insoluble                                     -decrease transit time -increase faecal bulk             

Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre b) Water Holding/Hydration Capacity as well as viscosity              -ability of fibre in food to bind water-ie sponge effect              -water soluble fibres have greater hydration capacity than?             

Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre b) Water Holding (whc)/Hydration Capacity as well as viscosity              -water holding capacity dependent on water solubility, pH of gastrointestinal tract, size of fibre particles and degree of food processing -increased pH increases whc              -coarsely ground bran has higher hydration capacity             

Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre b) Water Holding/Hydration Capacity as well as viscosity -water holding by fibre creates viscous solutions resulting in:                       Slowed gastric emptying-satiety                       Reduced mixing of gastrointestinal contents with digestive enzymes- physical barrier                                    

Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre b) Water Holding/Hydration Capacity as well as viscosity -water holding by fibre creates viscous solutions resulting in:                     Reduced enzyme function -eg inhibit -intestinal peptidases                                              -pancreatic lipase                                              -mechanism is unclear                                    

Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre b) Water Holding/Hydration Capacity as well as viscosity -water holding by fibre creates viscous solutions resulting in:               Decreased nutrient diffusion rate and hence nutrient absorption                        -passage through mucin layer is reduced                                                           

Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre b) Water Holding/Hydration Capacity as well as viscosity -water holding by fibre creates viscous solutions resulting in:               Decreased nutrient diffusion rate and hence nutrient absorption                        -reduced convective currents                                                           

Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre b) Water Holding/Hydration Capacity as well as viscosity -water holding by fibre creates viscous solutions resulting in:         Decreased nutrient diffusion rate and hence nutrient absorption                  -results in decreased absorption of amino acids and fatty acids due to viscous fibre                                                                            

Some Properties-dictate physiological and metabolic effects of fibre Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre b) Water Holding/Hydration Capacity as well as viscosity -water holding by fibre creates viscous solutions resulting in:                 Decreased nutrient diffusion rate and hence nutrient absorption                          -pectin, psyllium and viscous mucilaginous gums (eg guar gum) lower blood glucose and hence hormonal response to glucose                                    

Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre b) Water Holding/Hydration Capacity as well as viscosity -water holding by fibre creates viscous solutions resulting in:             Altered small intestine transit time                 -soluble -increase transit time- good- why?                 -insoluble-decrease transit time- bad-why?                                         -net effect?                                    

Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre      c) Absorption or Binding Ability                 -lignins, gums, pectins and some hemicelluloses have ability to bind(adsorb) enzymes, nutrients in gi tract                                                             -dependent on gi pH, particle size, food processing and fermentability                                                              

Some Properties-dictate physiological and metabolic effects of fibre Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre      c) Absorption or Binding Ability                -lignins, gums, pectins and some hemicelluloses have ability to bind(adsorb) enzymes, nutrients in gi tract                                                             -results in-diminished lipid absorption                                      -lowered blood cholesterol                                      -increased faecal bile excretion -changed mineral balance                                                              

Some Properties-dictate physiological and metabolic effects of fibre Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre      c) Absorption or Binding Ability                -lignins, gums, pectins and some hemicelluloses have ability to bind(adsorb) enzymes, nutrients in gi tract                                                             Diminished Absorption of Lipids                               -pectin, guar gum, oatbran, lignin- adsorb fatty acids, cholesterol, bile acids                                -consequence of such adsorption                                                                                       

Some Properties-dictate physiological and metabolic effects of fibre Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre c) Absorption or Binding Ability                 -lignins, gums, pectins and some hemicelluloses have ability to bind(adsorb) enzymes, nutrients in gi tract                                                             Diminished Absorption of Lipids Increased faecal bile excretion                       -similar mechanistic consequence seen under diminished absorption of lipid                                    

Some Properties-dictate physiological and metabolic effects of fibre Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre c) Absorption or Binding Ability                 -lignins, gums, pectins and some hemicelluloses have ability to bind(adsorb) enzymes, nutrients in gi tract                                                             Lowered serum cholesterol                                 consequently more plasma cholesterol is used to synthesise bile                                                                   

Some Properties-dictate physiological and metabolic effects of fibre Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre c) Absorption or Binding Ability                 -lignins, gums, pectins and some hemicelluloses have ability to bind(adsorb) enzymes, nutrients in gi tract                                                             Altered mineral balance                                 -fibre containing uronic acid can form cationic bridges with minerals                                                                    

Some Properties-dictate physiological and metabolic effects of fibre Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre c) Absorption or Binding Ability                 -lignins, gums, pectins and some hemicelluloses have ability to bind(adsorb) enzymes, nutrients in gi tract                                                             Altered mineral balance                                 -lignins also thought to play a role                                 -slower the fermentation the higher the ability to bind minerals by bacteria                                                                                                    

Some Properties-dictate physiological and metabolic effects of fibre Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre c) Absorption or Binding Ability                 -lignins, gums, pectins and some hemicelluloses have ability to bind(adsorb) enzymes, nutrients in gi tract                                                             Altered mineral balance                                 -more rapidly fermentable fibres eg pectin may have positive effect on mineral balance                                                                    

Some Properties-dictate physiological and metabolic effects of fibre Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre d) Degradability or fermentability                    -principal metabolites of fibre and undigested starch fermentation are lactate and short chain fatty acids (SCFAs)                   -also get some hydrogen, CO2 and methane gases                   -pectin, gums, oat and wheat bran and psyllium produce SCFAs                                                                    

Some Properties-dictate physiological and metabolic effects of fibre Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre d) Degradability or fermentability                  Fermentable fibres                      Increased water and sodium absorption in colon               -SCFA rapid absorption stimulates water and sodium absorption                                                                                         

Dietary Fibre d) Degradability or fermentability Fermentable fibres Some Properties-dictate physiological and metabolic effects of fibre d) Degradability or fermentability                  Fermentable fibres                                            Mucosal cell proliferation                                -substrates from degradation of dietary fibre                      Provision of energy                                -SCFAs                      Acidification of luminal environment                            -SCFAs-calcium more available to bile and fatty acids- may be protective against colon cancer                                                                    

Some Properties-dictate physiological and metabolic effects of fibre Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre d) Degradability or fermentability                  Non-Fermentable fibres                                             -principally cellulose and lignins-promote proliferation of colonic microbes                        Detoxification                                 via proliferation of colonic microbes                                                                                           

Some Properties-dictate physiological and metabolic effects of fibre Dietary Fibre Some Properties-dictate physiological and metabolic effects of fibre d) Degradability or fermentability                  Non-Fermentable fibres                                          Increased faecal bulk-good laxative effect                          bulk consists of undigested fibre, salts and water                        -wheat bran and especially rice bran particularly good at this