Dietary Carbohydrate Flashcards
Sorbitol
Sugar alcohol
Glucose (instead of ketone, has an alcohol)
Used as thickening/bulk agents
Classes of Carbohydrates
- Simple sugars (mono or disaccharides-food sugars, polyols-sugar alcohols)
- Oligosaccharides (3-9 molecules)
- Polysaccharides (9+, starch - amylose or amylopectin (food equivalent of glycogen); or fiber - indigestible carbohydrate)
Starch vs. Cellulose
Starch: 1-4 bonds
Cellulose: 1-6 bonds (stereochemistry, cannot absorb)
Glycemic index/Glycemic load
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
2 scales for GI
- Pure glucose
- 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)
What is important about diet and health?
- overall mortality
- CV disease
- Diabetes
- Cancer
- Weight
- Enjoyment of eating
Does some aspect of the diet cause insulin resistance and DM?
- Relative amounts of fat or carbohydrate
- Type of carbohydrate
- Total calories
Types of studies
- Animal or In Vitro studies - can provide the most detailed mechanistic info (but does it apply to humans?)
- Epidemiologic studies - population based intake data; issues: validity of intake data, reliability of IR (insulin resistance) diagnosis, interrelationship of factors
Carb intake data
- Increased simple carb and total carb in diet correlated to increased diabetes
- Decreased intake of fiber
BUT correlation does not mean causation
Dietary intake data
- 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
Sucrose and Fructose Mixed data
- 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
Fructose and glycolysis
Comes in at the level of glyceraldehyde P. Glycolysis is regulated above the level at which fructose comes in (fructose bypasses regulatory steps)
Effects of dietary fructose on body fat in humans
- Gained weight drinking either glucose or fructose
- Fructose gained more weight than glucose
- Increased TG levels with fructose
- Decreased insulin sensitivity
But no gold standard intervention trial
Epidemiological studies Fiber, GI, GL
- increased fiber intake associated with lower insulin levels and less diabetes
- Lower GL = lower insulin levels and diabetes
In other words, low fiber, high GL = LOTS of diabetes (meaningful endpoint)
Issues with GI
- 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
3 structures of sugars that he wants us to know
- Glucose
- Fructose - 2 C outside the ring
- Galactose - isomer, swapped OH group orientation
All 6 carbon sugars
Circulate in a ring structure around oxygen
Best things to talk about with patients, best diets?
- 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
Diabetes prevention program
- 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)
When to intervene?
- Born happy thin and healthy but then we get habits…
- Weight is the central factor.. try to get in earlier.
Aspartame
- aspartate + phenylalanine
- no evidence that non-nutritive sweeteners are harmful. Present in diet in high quantities from other food.
Diet and Diabetes
- Review meal pattern: no meal, no meal insulin
- Carbohydrate awareness: more carbs, more insulin or higher sugars
- Carb counting: calculating how many units of insulin for each gram of carb
