Carbohydrate nutrition Flashcards
Explain the basis for dividing carbohydrates into available
carbohydrates and dietary fibre.
The differences come from digestibality, and impact on blood glucose levels
- Available Carbohydrates: These are digestible and absorbable, providing energy and affecting blood sugar levels. They include sugars and starches found in foods like grains, fruits, and vegetables.
- Dietary Fiber: This includes the indigestible parts of plant foods that pass through the digestive system largely intact. Fiber is beneficial for digestive health, helps regulate blood sugar, and can reduce the risk of chronic diseases. It’s found in fruits, vegetables, whole grains, and legumes.
- how are carbohydrates measured for nutrition labeling?
100-% water-% protien-%fat-%ash and then from within that starch and dietary fiber is measured and the rest is starch, this method has a large margin of error tho
- What are the two main digestiable carbohydrates?
starch and sugar
- what are the specific digestable and absroable carbohydrates in the human diet?
-
starch (D)
- sucrose (D)
- lactose (D)
- glucose, fructose and galactose can be asborbed
- where does digestion happen and what are the enzymes involved at each place
- mouth: salivary amylase breaks down starch
- Stomach: salviary amylase still works until pH in the stomach drops
- Small intestine: Pancreatic amylase secreted and starch will be hydrolzed to maltose the end goal for it, this is the location where monosachrides will be absorbed
- Large intestine (colon): this is where some slowly digestble starch will go and be quickly fermented
- what are the carboydrases that break down disacchrides at the brush border called and what do they work on?
- MALTASE (glucoamylase) for maltose
- SUCRASE for sucrose
- LACTASE for lactose
what is glycemic response
Relative blood glucose response after a meal
- What do blood glucose concentrations depend on?
- rate of absorbtion of glucose into blood stream
- rate of insulin production since it reduces blood sugar since it makes it enter cells
- Describe a Hi GI and a low GI
a high GI comes from a rapid increase in blood glucose [] which would cause in turn a strong insulin response which would rapidly decrease blood glucose [] so low often below the baseline and this will initiate hunger
A low GI will be a slow absorbtion of glucose that results in a lower peak [] and a more moderate response in insulin production
- what does insulin do with excess glucose and how can that cause insulin resistance if repeated
it will depoist glucose in adipose cells, and is used to make fat and if there are repeated spikes in blood glucose and insulin over time cells will become insulin resistant meaning they don’t respond as well and cant take up glucose as well
- what are factors that affect glycemic response
- rates of gastric emypting which is impacted by fat, protien and alchohol
- viscosity of intesetinal contents (especially soluble fiber which will slow gastric emptying)- physical form and chemical nature of food so ripness, pH, amylose;amylopectin ratio etc
- processing and prep of food
- time of consumption
- meal frequency
- if fiber was consumed in prevois meal
- the person consuming the meal
- what is glycemic index
it is a ranking of carbohydraytes from 1-100 based on the extent in which they raise glucose blood levels after eating
- describe the internation standard GI method
-
Participants: At least 10 healthy individuals fast overnight and participate in the test.
- Test Food: Participants consume a food portion containing 50 grams of available carbohydrate (excluding fiber).
- Blood Glucose Measurement: Blood glucose is measured at intervals over two hours post-consumption.
- Reference Food: On a different day, the process is repeated with a reference food (like glucose or white bread) for comparison.
- Calculating the GI: The area under the blood glucose response curve (AUC) for the test food is calculated and compared to the AUC for the reference food. The GI is the percentage of the test food’s AUC relative to the reference food’s AUC.
- Final GI Value: The final GI is the average of values from all participants, classifying foods into low, medium, or high GI.
- explain what the engylst starch test is
The Englyst Starch Test is an in vitro (laboratory) method developed that is basically the glycemic index test but in vitro and it is used to categorize carbohydrates, particularly starches, based on their rate of digestion. This test classifies starches into three main categories: rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS).
- describe the procedure of the engylst starch test
Process:
1. **Sample Preparation**: A food sample is prepared and mixed with a digestive enzyme solution that simulates the enzymatic digestion process occurring in the human small intestine. 2. **Digestion Simulation**: The mixture is incubated at body temperature (37°C) for a fixed time period, often 2 hours, to mimic the typical digestive process time in the human small intestine. 3. **Measurement**: The amount of glucose released during the first 20 minutes of incubation is measured to quantify the rapidly digestible starch (RDS). The glucose released between 20 minutes and 120 minutes is used to determine the slowly digestible starch (SDS). The starch not digested within 120 minutes is considered resistant starch (RS).
