Dietary Carbohydrates Flashcards Preview

DEMS: Unit II > Dietary Carbohydrates > Flashcards

Flashcards in Dietary Carbohydrates Deck (17):
1

How to calculate number of grams of carbohydrate consumed per day by an individual in energy balance

  • [Weight (kg) * 30kcal/kg/day] * 50% carbs / 4kcal/gram.
  • Ex. 70kg person * 30 kcal/kg/day
    • = 2100 kcal/day * 50% carbs
    • = 1050 kcal carbs / 4kcal/gram
    • = 262.5g carbs/day.
  • With diabetes, adjust insulin accordingly (1 unit/15g carbs - varies by person)

2

Carbohydrate classes in sugars

  • (1-2 molecules)
  • Monosaccharides, disaccharides, polyols (sugar alcohols)

3

Components of monosaccharides

  • Glucose
  • Galactose
  • Fructose

4

Components of disaccharides

  • Sucrose
  • Lactose

5

Components of polyols

  • Sorbitol
  • Mannitol
  • Xylitol
  • Hydrogenated starch hydrolysates

6

Carbohydrate classes in oligosaccharides

  • (3-9 molecules)
  • Malto-oligosaccharides, other oligosaccharides

7

Components of malto-oligosaccharides

Maltodextrins

8

Components of other oligosaccharides

  • Raffinose
  • Stachyose

9

Carbohydrate classes in polysaccharides

  • (>9 molecules)
  • Starch, fiber

10

Components of starch

  • Amylose
  • Amylopectin

11

Components of fiber

  • Cellulose
  • Hemicellulose
  • Pectins

12

Unique metabolic properties of fructose

  • Enters cell via hexose transporter
  • Skips PFK; enters glycolysis after pFK and speeds through to become pyruvate
  • Rapidly cleared by liver --> increased TAG + insulin resistance
  • If you eat too much, you may get fat
    •  if EI > EE

13

Properties of resistant starch

  • Ex. corn starch.
  • Used as thickening agent in many foods.
  • Slowly absorbed due to crystal structure.
  • Effects similar to those seen with high amylose carbohydrates.
  • Used in children with inborn errors of metabolism that predispose them to hypoglycemia
    • (Problems with hepatic glucose production during fasting)

14

Properties of fiber

  • Complex carbohydrate not digestible by human intestinal enzymes --> pass through GI tract largely unaltered
  • Increase stool volume, may lower cholesterol levels
  • Higher levels of dietary fiber associated with lower risk of cancer
  • Contained in husk of grains, source of some of the beneficial effects of whole grain products

15

Glycemic index

  • Looks at glucose (but not fructose, which is an issue with GI)
  • Indicator of the ability of different types of foods that contain carbohydrate to raise blood glucose within 2 hours
  • Foods containing carbohydrates that break down most quickly during digestion have highest glycemic index.
  • Also called dietary index
  • White bread has GI of 100 --> standard
  • Higher glycemic index = larger glucose excursion (and vice versa)

16

Glycemic load

  • Glycemic index in consumed food
  • Glycemic load = glycemic index of a given food * amount of food eaten

17

Types of studies that can be used to inform nutritional recommendations

  • Cellular/molecular studies
    • controlled and accurate
    • may lack applicability
  • Animal studies
    • can control diet completely
    • but doesn't necessarily translate to people
  • Epidemiological studies
    • self-reported dietary intake correlated with disease
    • powerful due to large sample size
    • but not great because people lie
  • Small RCTs with soft endpoints/surrogate markers
    • hard to get a lot of people to do things
    • may not be as powerful
  • Large RCTs with hard endpoints
    • gold standard
    • but still not perfect because we don't know that people are doing what they're supposed to
    • Ex. Finnish Diabetes Study