Dietary Carbohydrate

Question 1

Sorbitol

Answer 1

Sugar alcohol

Glucose (instead of ketone, has an alcohol)
Used as thickening/bulk agents

Question 2

Classes of Carbohydrates

Answer 2

1. Simple sugars (mono or disaccharides-food sugars, polyols-sugar alcohols)
2. Oligosaccharides (3-9 molecules)
3. Polysaccharides (9+, starch - amylose or amylopectin (food equivalent of glycogen); or fiber - indigestible carbohydrate)

Question 3

Starch vs. Cellulose

Answer 3

Starch: 1-4 bonds

Cellulose: 1-6 bonds (stereochemistry, cannot absorb)

Question 4

Glycemic index/Glycemic load

Answer 4

Area under the curve of change in blood glucose vs. time = GI and you can compare foods

White bread = if you eat 100g, then blood glucose goes up by x amount (high GI)

Pumpernickel bread = if you eat 100g, then maybe not as much of a rise or not as fast of a rise (low GI)

GL = GI * # grams of whatever food

Question 5

2 scales for GI

Answer 5

1. Pure glucose
2. White bread as a gold standard of 100

Note: coca-cola does not have a high GI because it is fructose, not glucose –> doesn’t mean it’s good for you.

High glycemic foods are refined carbohydrates (get rid of the husk), Low GI (basmati rice, pumpernickel)

Question 6

What is important about diet and health?

Answer 6

• overall mortality
• CV disease
• Diabetes
• Cancer
• Weight
• Enjoyment of eating

Question 7

Does some aspect of the diet cause insulin resistance and DM?

Answer 7

• Relative amounts of fat or carbohydrate
• Type of carbohydrate
• Total calories

Question 8

Types of studies

Answer 8

1. Animal or In Vitro studies - can provide the most detailed mechanistic info (but does it apply to humans?)
2. Epidemiologic studies - population based intake data; issues: validity of intake data, reliability of IR (insulin resistance) diagnosis, interrelationship of factors

Question 9

Carb intake data

Answer 9

1. Increased simple carb and total carb in diet correlated to increased diabetes
2. Decreased intake of fiber

BUT correlation does not mean causation

Question 10

Dietary intake data

Answer 10

• worrisome
• correlation does not mean cause
• increased total energy intake, reduced energy expenditure … maybe it had to do with positive energy balance

Why are people eating this way?

• food industry/government is making them do it
• they are just dumb
• palatability is priority

Question 11

Sucrose and Fructose Mixed data

Answer 11

• Thought is that because fructose does not raise glucose levels, it’s better (not true)
• However, unique metabolic effects on liver
• Causes insulin resistance in rats independent of weight gain in rats

Question 12

Fructose and glycolysis

Answer 12

Comes in at the level of glyceraldehyde P. Glycolysis is regulated above the level at which fructose comes in (fructose bypasses regulatory steps)

Question 13

Effects of dietary fructose on body fat in humans

Answer 13

1. Gained weight drinking either glucose or fructose
2. Fructose gained more weight than glucose
3. Increased TG levels with fructose
4. Decreased insulin sensitivity

But no gold standard intervention trial

Question 14

Epidemiological studies Fiber, GI, GL

Answer 14

1. increased fiber intake associated with lower insulin levels and less diabetes
2. Lower GL = lower insulin levels and diabetes

In other words, low fiber, high GL = LOTS of diabetes (meaningful endpoint)

Question 15

Issues with GI

Answer 15

• High fat/sucrose/fructose foods have low GI
• Can’t read it on the label
• Complexity with sugar alcohols, amylose and resistant starch
• GI altered by method of preparation and time of day

Question 16

3 structures of sugars that he wants us to know

Answer 16

1. Glucose
2. Fructose - 2 C outside the ring
3. Galactose - isomer, swapped OH group orientation

All 6 carbon sugars
Circulate in a ring structure around oxygen

Question 17

Best things to talk about with patients, best diets?

Answer 17

• Fructose, Fiber, carbs (the data is too mixed on GI to talk)
• High carb/reduced fat and calorie restricted diets prevent diabetes in those at risk. We don’t know if there is anything better out there because it hasn’t been tested
• Low carb diet good for fat loss.
• Finnish diabetes prevention study = decrease incidence of diabetes with interventions. More interventions you did, the more likely you did not get diabetes

Question 18

Diabetes prevention program

Answer 18

• 3000 people randomized to metformin, lifestyle, or control
• High fat diet, lifestyle = exercise
• Very modest weight loss = dramatic reduction of diabetes incidence (reduced by almost 60% for just a 4% weight loss)

Question 19

When to intervene?

Answer 19

• Born happy thin and healthy but then we get habits…

- Weight is the central factor.. try to get in earlier.

Question 20

Aspartame

Answer 20

• aspartate + phenylalanine

- no evidence that non-nutritive sweeteners are harmful. Present in diet in high quantities from other food.

Question 21

Diet and Diabetes

Answer 21

1. Review meal pattern: no meal, no meal insulin
2. Carbohydrate awareness: more carbs, more insulin or higher sugars
3. Carb counting: calculating how many units of insulin for each gram of carb