Fiber (Chapter 4)

FYI CARD 4 Characteristics of Fiber that provide physiologic benefits.

1. Solubility in water (or not) 2. Water-Holding Capacity & Viscosity 3. Adsorption or binding ability 4. Degradeability/Fermentability

A dietary & functional fiber consisting of tree & shrub exudates (aka sap from plants/trees); found in oatmeal, barley, legumes. (video posted in group)

Gums (hydrocolloids) *GI: highly fermentable by GI bacteria *be able to write this definition/discuss

A dietary fiber located in plant CELL WALLS found in bran, whole grains, nuts, legumes, some vegetables & fruits (*wide combination).

Hemicellulose *GI: soluble/insoluble & fermentable/not fermentable (b/c of backbone & side chain variety) *be able to write this definition/discuss

What are some examples of water soluble fibers? See p117 pic.

Hemicelluloses, pectins, gums, beta-glucans, fructans (inulin, fructooligosaccharides), psyllium, and some resistant starches. Ex: legumes, oats, barley, some fruits (berries, bannanas, apples, pears), and some veg (carrots, broccoli, artichokes, onion)

A dietary & functional fiber which is water soluble & highly fermentable; found in cereal brans, esp oat & barley cereals.

Beta-Glucans

A dietary & functional fiber located in plant CELL WALLS found in bran, legumes, nuts, peas, root veggies, cabbage family, outer covering of seeds, apples.

Cellulose *GI: degraded inconsistently by GI bacteria *be able to write this definition/discuss

A type of functional fiber; insoluble; similar to cellulose, found in cell walls and outside shell of crabs, shrimp, lobster.

Chitin (Dr. R: popular a while back in pill form & was used to lower cholesterol)

Name 3 fructans.

Inulin Oligofructose Fructooligosaccharides

A dietary fiber known for prebiotic attribute and found in chicory, asparagus, onions, garlic, artichokes, tomatoes, and bananas.

Fructan

A dietary & functional fiber in STEMS, SEEDS, BRAN LAYER of plants; found in wheat, mature root veggies, fruits with edible seeds.

Lignin (structural support) *GI: poorly fermented by GI bacteria *be able to write this definition/discuss

A dietary & functional fiber in the CELL WALL & MIDDLE LAMELLA that is water soluble and contains gel-forming abilities; found in apples, strawberries, citrus fruits.

Pectins (cement) *GI: can be almost entirely fermented by GI bacteria (alpha 1-4 linkages) *be able to write this definition/discuss

A functional fiber polysaccharide of glucose & sorbitol units used as a bulking agent or sugar substitute.

Polydextrose

A functional fiber; mucilage from husk of psyllium seeds with high water binding capacity and provides viscosity; used as a laxative and must ingest plenty of fluids.

Psyllium ex: Metamucil (bulking agent)

A type of starch that cannot be digested or absorbed by humans.

Resistant Starch

Which has a higher water-holding capacity? Water soluble fibers: pectins, gums, and some hemicelluloses? or Insoluble fibers: cellulose and lignin.

Water soluble fiber has a higher water-holding capacity. Soluble fibers may bind up to SEVERAL times their weight in water, producing a viscous, slow-moving solution that often traps nutrients to slow down digestion and absorption within the GIT.

Refers to the ability of fiber in food to bind water.

Water-holding or hydration capacity (of food) **Think of fiber as a dry sponge that hydrates or soaks up water and digestive juices as it moves through the GIT.

nondigestible CHO & lignin that are intact & intrinsic in plants

dietary fiber (key word: plant)

What other factors does water-holding capacity depend on.........besides just fiber's solubility in water?

pH of GIT SIZE of particle fiber Degree to which foods are processed ....all influence water-holding capacity and in turn, physiologic effects.

Describe difference b/w soluble and insoluble fiber. See p117 pic.

soluble - dissolves in hot water; feel fuller longer, delays gastric emptying insoluble - does not dissolve in hot water; moves things along quickly b/c it cleans out the colon.

There are 4 types of Resistant Starch. Discuss the two Dietary Fiber types.

(Dietary Fiber) RS1 - plant cell walls *seeds, legumes, (unprocessed) whole grains RS2 - ungelatinized starch granules *(uncooked) potato & high amylose corn

Discuss the Functional Fiber types (of Resistant Starch).

(Functional Fibers) RS3 - retrograde starch from cooking and cooling or extruding foods. *ex: cooked and cooled rice, pasta, potato RS4 - Chemically modified starch *not found in nature

Which fibers are considered dietary AND functional fiber?

(Table 4.1) Cellulose Pectin Lignin Gums Beta-Glucans Fructans Resistant starches

Which fibers are ONLY functional fiber?

(Table 4.1) Chitan & chitosan Polydextrose & polyols Psyllium Resistant dextrins

Which fibers are ONLY dietary fibers?

(Table 4.1) Hemicellulose

Ingesting FIBERS that can HOLD WATER and create VISCOUS solutions w/in the GIT causes a number of effects. List.

*Delayed (slowed) emptying from the stomach *Reduced mixing of GI contents with digestive enzymes *Reduced enzyme function *Decreased nutrient diffusion rates (and thus delayed nutrient absorption) *altered small intestine transit time (read details on each p.119)

What are examples of insoluble fibers?

cellulose, lignin, chitin/chitosan, some hemicelluloses and pectins, some resistant starches. Ex: whole grain products, wheat and corn bran, nuts, seeds, some veg, and some fruit.

The term fiber that appears on FOOD LABELS reflects ONLY ___________ fiber.

dietary

nondigestible CHO that are isolated, extracted, or manufactured & known to have physiological benefits.

functional fiber (key word: manufactured)