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Nutritional Biochem 2 > Fiber > Flashcards

Fiber Flashcards

1
Q

What is the difference between dietary and functional fiber?

A
  • Dietary: nondigestible carbs and lignin in plants
  • Functional: nondigestible carbs, extracted or manufactured and have been shown to have beneficial physiological effects
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2
Q

Cellulose examples are…

A

plant foods, wheat bran, legumes, nuts, peas, root veggies, cabbage family, celery, broccoli, seed coverings, apples

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3
Q

Chitosan, Chitin examples are…

A

Shells of crab, shrimp, lobster

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4
Q

What are some functional fibers?

A
  • Cellulose, Lignin, Fructans, Chitin and Chitosan, Polydextrose and Polyols
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5
Q

What is the majority of the plant cell wall made out of?

A

Cellulose [insoluble in water]

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6
Q

What bonds are cellulose made up of?

A

B - (1-4) glycocytic bonds

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7
Q

Degradation of cellulose by colonic bacteria varies, but generally it is or is not fermented?

A

NOT FERMENTED

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8
Q

a - (1-4) vs. B - (1-4) which is able to be digested and which is not?

A

a - (1,4) - DIGEST

B - (1,4) - NO DIGEST

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9
Q

*****What are Pectins referred to as?

A

**Galacturonoglycans

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10
Q

Galacturonic acid is a primary constituent of pectin, and its backbone is made of unbranched chains of what?

A
  • a - (1-4) linked D-galacturonic acid units [H20 soluble]
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11
Q

Fruits and veggies provide almost equal quantities (30%) of what two functional fibers?

A

Cellulose and Pectin

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12
Q

Pectins are water soluble, are completely fermented by colonic bacteria, therefore they are not good for what?

A
  • Bulking of fecal matter
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13
Q

What is the only non-polysaccharide constituent of fiber?

A

Lignin!

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14
Q

Where are Lignin’s found?

A

Stems, seeds fruite and veggies

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15
Q

Lignins are hydrophobic or hydrophillic? Are they fermentable or not fermentable?

A
  • Hydrophobic - INSOLUBLE

- Not fermentable - by colonic bacterial microflora

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16
Q

Intestinal microflora can convert some lignins into what?

A

Enterolactone and enterodiol (both weak phytoestrogens) may provide protection against hormone-related cancers, diabetes and heart disease….

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17
Q

What are gums?

A

Water soluble substances also called hydrocolloids

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18
Q

Gum Arabic are what?

A

Tree exudates (protection from wounds) secreted at the site of plant injury by specialized secretory cells, highly fermentable by colonic bacteria [ex. xanthan gum, guar gum, as thickeners due to H20 binding]

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19
Q

Guar gum has what type of bond?

A

mannose B- 1,4 to galactose a- 1,6

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20
Q

Xantham gum is comprised of what bonds, and what makes it special?

A

B-1,4 just like cellulose, but every second glucose unit is attached to a TRISACCHARIDE consisting of mannose and glucuronic acid,

[xantham gum can be sunthesized by microorganisms…]

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21
Q

B-Glucans are similar to cellulose but every third glycosidic bond is what type of bond?

A

B-1,3 [this is highly H20 soluble and fermentable]

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22
Q

B-glucans are found in what dietary food?

A

Cereal bran like oats and barley

[they reduce serum cholesterol and postprandial blood glucose concentrations]

23
Q

Fructans which are sometimes called polyfructose are bonded together using what type of bond?

A

B- 1,2 glycosidic bonds

24
Q

Fructans are found naturally in plants with what being the most common sources?

A

Asparagus, leeks, onions, garlic, tomatoes, bananas

25
Q

Are fructans water soluble and fermentable?

A

YES

26
Q

Fructans can be divided into three groups, they are based on the number of fructose units…

A
  1. Inulin
  2. Oligofructose
  3. Fructooligosaccharides (FOS)
27
Q

What is inulin used for?

A

Replacement of fat fillings/dressings/frozen desserts [Nephrologists use to measure GFR]

28
Q

What is Oligofructose used for?

A
  • Added in cereals, yogurt, dairy products and frozen desserts
29
Q

What are Fructooligosaccharides (FOS) used for?

A
  • Promote growth of bifidobacteria, FOS is classified as a PREBIOTIC
30
Q

How an one define the pre-biotic?

A
  • take care of what you already have in your intestinal flora…
31
Q

Chitin is linked with what type of bond? How is it different from Cellulose?

A
  • B-1,4

- Acetylated amino group

32
Q

Is Chitin fermentable/H20 soluble?

A

NNNOOOOOOO!

33
Q

What is the difference between Chitosan and Chitin?

A

Chitosan IS WATER SOLUBLE
Chitin is not water soluble

[Chitosan is the deacetylated form of Chitin]

34
Q

What has Chitosan been shown to lower?

A

Serum cholesterol concentrations by binding with negatively charged unesterfied fatty acids and cholesterol which PROMOTES EXCRETION!

35
Q

Psyllium structure is similar to what other type of fiber?

A

Gums [husk of psyllium seeds]

36
Q

Is Psyllium water soluble?

A

YES, has high water-binding properties and provides viscosity

37
Q

Psyllium is NOT FERMENTABLE, what OTC medication is this found in?

A

Laxative Metamucil

38
Q

Soluble fiber is…

A
  • Fructans
  • Psyllium (viscous)
  • B-Glucans (viscous)
  • Pectins (viscous)
  • Gums (viscous)
  • Hemicelluloses (some)
39
Q

Insoluble fiber is…

A
  • Lignin (non-viscous)
  • Cellulose (non-viscous)
  • Hemicelluloses (non-viscous) (some)
40
Q

GI responses to soluble and insoluble fibers… There are 4 primary mechanisms of action…

A

Soluble:

  1. Can absorb or bind nutrients or selected substances such as…
  2. Can cause gel formation leading to…
  3. *Can bind water (increase water-holding capacity)

Insoluble:

  1. Can be degraded/fermented
  2. *Can bind water (increase water-holding capacity)
41
Q

Fiber gives you what? and many of them are said to be what?

A

CALORIES!

FERMENTABLE!

42
Q

There has been consistent evidence for a moderate inverse relationship between intake of fruits and vegetables to what disease(s)?

A

Heart attack and stroke

43
Q

Increase fiber, what 3 things will decrease?

A
  1. Stroke
  2. CVA
  3. Heart disease
44
Q

Minimum dose of 3g/day of oat or barley B-glucan can lower what?

A

Total and LDL cholesterol (5.4%, 8.7% respectively)

[decrease carbs, to decrease trigs!]

45
Q

Diets rich in fiber and fiber supplementation have been shown to improve glycemic control through reduced rates of ____ absorption and _____ secretion, as well as improved _______ sensitivity…

A
  • glucose absorption
  • insulin secretion
  • insulin sensitivity
46
Q

Persons with high dietary fiber have what % reduced rate of developing what disease?

A

25% - Type II diabetes

47
Q

Fiber tends to lower energy density and a higher volume which can promote which few things…

A
  • Promote satiety
  • Reduce hunger
  • Delay gastric emptying
48
Q

Fiber may induce the secretion of what satiating hormones?

A
  • Glucagon-like peptide 1 (GLP-1)
  • Peptide YY (PYY)
  • [GLP-1 has been shown to reduce gastric emptying]
49
Q

High fiber, reduced risk for what?

A

OBESITY (30% reduced risk if high fiber consumption)

50
Q

How does fiber prevent colon cancer? [hint: 6 things]

A
  1. Bile acids absorbed by fiber
  2. fiber fermentation decreases pH
  3. Fermentation may release fiber-bound calcium
    * 4. Butyrate inhibits histone deacetylases helps apoptosis of cancer cells
  4. Increase fecal bulk, shortened fecal transit time
  5. Insoluble fibers bind to carcinogens minimizing chances of interaction with colonic mucosal cells

[28% reduction in colo-rectal cancer with increased fiber intake]

51
Q

Avg fiber consumption in the US is what per day?

A

~ 15 g/day

52
Q

Fiber intake of what per day is considered excessive?

A

50 g

53
Q

What is the general rule for fiber?

A

“eat 5-9 per day”

Nutritional Biochem 2 (6 decks)

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