Macronutrients

Question 1

What are fructans?

Answer 1

Inulin, oligofructose, fructooligosaccharides

Food sources= chicory, asparagus, leeks, onions, garlic, Jerusalem artichokes, tomatoes, banana

Wheat, barley, rye also contain some fructans

Question 2

Resistant starch? Types?

Answer 2

Starch that cannot be or is not easily enigmatically digested or absorbed
Rs1= (dietary fiber) found in cell walls; whole or partially milled grains/seeds
Rs2= (dietary fiber) packed inside granules in plant cells –> high-amylose plant foods=unripe bananas, some legumes, raw potatoes, some maize
Rs3= (functional fiber) retrograde starch
Moist heat cooking and cooling generates Rs3–> Cooked and cooled rice, pasta, potatoes
Rs4= (functional fiber) Chemical modifications of starch

Question 3

Total Fiber = sum of dietary fiber & functional fiber
— Dietary Fiber =
— Functional Fiber =

Answer 3

Total Fiber – sum of dietary fiber & functional fiber

— Dietary Fiber – Complex carbohydrates and lignins
naturally occurring & found mainly in the plant cell
wall. Dietary fiber cannot be broken down by
human digestive enzymes.

=Cellulose, hemicellulose, pectin, lignin, gums, B-glucans, fructans, resistant starches

— Functional Fiber – Nondigestable carbohydrates
including plant, animal or commercially produced

sources that have beneficial effects in humans.
=cellulose, pectin, lignin, gums, fructans, chitin/chitosan, polydextrose/polyols, psyllium, resistant starches/dextrins

Question 4

Psyllium

Answer 4

Classified as a mucilage

High water-binding capacity, considered a functional fiber

Question 5

Soluble fiber vs insoluble fiber

Answer 5

Soluble fiber = fiber that dissolves in hot water

Insoluble fiber = fiber that does not dissolve in hot water

Question 6

Foods rich in soluble fiber

Answer 6

Legumes, oats, barley, some fruits (berries, bananas, apples, pears), and some vegetables (carrots, broccoli, artichokes, onions)

Question 7

Foods rich in insoluble fiber

Answer 7

Whole-grain products, wheat and corn bran, nuts, seeds, some vegetables, some fruits

Generally –> Vegetables and most grain products contain more insoluble than soluble fibers

Question 8

Characteristics of soluble fibers:

Answer 8

Delay gastric emptying, increase transit time (through slower movement) through the intestine, and decrease nutrient (glucose) absorption (attenuation of blood glucose response)

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 digestive tract

Question 9

Characteristics of insoluble fibers:

Answer 9

Decrease (speed up) intestinal transit time, increase fecal bulk

Question 10

Some fiber components have the ability to bind/adsorb substances (such as enzymes/nutrients).
Ingesting fibers with adsorption properties may cause these physiological effects:

Answer 10

• Diminished absorption of lipids
• Increased fecal bile acid secretion
• lowered serum cholesterol concentrations
• Altered mineral, carotenoid, phytochemical absorption

Question 11

How does fiber help to lower serum cholesterol concentrations?

Answer 11

1. Some fibers adsorb fatty acids/cholesterol/bile acids in the digestive tract, do not get absorbed in the small intestine and pass into the large intestine where the are excreted in the feces –> So less bile undergoes enterohepatic re-circulation
   - A decrease inbile acids returned to the liver and decreased cholesterol absorption leads to decreased cholesterol in liver cells
   Decreased hepatic cholesterol promotes removal of LDL cholesterol from the blood.
   The decrease in bile acids returned to the liver also necessitates the use of cholesterol for synthesis of new bile acids.

Question 12

The most well-studied cholesterol-lowering high-fiber foods are B-glucan from barley and oats as well as psyllium. What quantities are needed to lower serum lipid concentrations?

Answer 12

Pectin = 12-24 g
Guar gum = 9-30g
Barley B-glucan = 5g
Psyllium and oat B-glucan = 6g

One would need to ingest 6-10 svgs /day of soluble fiber rich fruits and vegetables or 2-3 svgs/day of legumes or oat/barley-based cereals

Question 13

What amount of plant sterols/stanols is needed to decrease total and LDL plasma cholesterol concentrations in ppl with normal/high levels?

Answer 13

1.6-3g/day

Question 14

Benefits of fermentable fibers

Answer 14

Act as prebiotics, can generate short-shain fatty acids, can provide energy and other substances (nitrogen)

Question 15

Examples of prebiotics:

Answer 15

Fructans (inulin, oligofructose, fructooligosaccharides), lactulose, transgalacto-oligosaccharides, and galactose and soybean oligosaccharides

Question 16

Principal metabolites of the fermentable fibers = lactic acid and short-chain fatty acids

Primary examples of short-chain fatty acids AND their importance in the gut =

Answer 16

Acetic, butyric and propionic acids

1. Increased water and sodium absorption in the colon.
2. Mucosal cell differentiation and proliferation
3. Acidifcation of luminal environment and its effects
   -favors growth of beneficial lactobacilli and
   bifidobacteria
   
   • Promotes production of mucin (barrier over
     intestinal cells) / inhibits growth of
     pathogenic bacteria
   • Protective against colon cancer
4. Provision of energy
   
   • Over 95% of SCFA are absorbed/utilized by the
     body
   • Butyric acid -> Food for colonic cells
   • Propionic acid -> Converts to succinyl-CoA to be
     used by liver for glucose/energy production
   • Acetic acid used by skeletal, cardiac muscle,
     kidneys, brain
5. Inhibition of cholesterol synthesis
   
   • Enhances delivery of nutrients to colon and
     from colon to liver
6. Enhanced immune fxn
   
   • Over 50% of lymphocytes and other immune cells
     are found in GI tract
7. Trophic effects and prevention of abnormal cell populations (apoptosis in tumor cell lines)

Question 17

Acid vs base

Answer 17

A pH less than 7 is acidic.

A pH greater than 7 is basic.

Question 18

Benefits of nonfermentable fibers:

Answer 18

Important role in detoxification, increased fecal volume

Question 19

Cause of diverticular disease:

Answer 19

Bulging pouches of the colon wall (diverticula) form when colon’s wall weakens. This may result from years of constipation associated with low fecal bulk, and straining to pass hard fecal matter (straining increases pressure and weakens its walls).
When fecal matter becomes trapped, the pouches become inflamed (diverticulitis).

*High fiber (esp insoluble) diets increase stool weight and fecal bulk to reduce straining and pressure. Increased fecal bulk also reduce likelihood of fecal matter being trapped