Podcast
Questions and Answers
Which of the following is NOT a type of monosaccharide?
Which of the following is NOT a type of monosaccharide?
Which of the following enzymes is responsible for breaking down lactose into monosaccharides?
Which of the following enzymes is responsible for breaking down lactose into monosaccharides?
What process is responsible for converting excess glucose into glycogen?
What process is responsible for converting excess glucose into glycogen?
What is the primary role of insulin in blood glucose regulation?
What is the primary role of insulin in blood glucose regulation?
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Which of the following is NOT a polysaccharide?
Which of the following is NOT a polysaccharide?
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What is a key factor to consider when choosing a carbohydrate source?
What is a key factor to consider when choosing a carbohydrate source?
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What is the main limitation of the glycemic index?
What is the main limitation of the glycemic index?
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Which of the following foods tend to have a lower glycemic index?
Which of the following foods tend to have a lower glycemic index?
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What happens to fructose when it is ingested?
What happens to fructose when it is ingested?
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What is a result of high fructose intake on the gut microbiome?
What is a result of high fructose intake on the gut microbiome?
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What is a limitation of the fructose animal studies?
What is a limitation of the fructose animal studies?
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What is the 'fructose survival hypothesis'?
What is the 'fructose survival hypothesis'?
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Study Notes
Classification of Carbohydrates
- Monosaccharides: single sugar molecules, including glucose, fructose, and galactose
- Disaccharides: sucrose (glucose + fructose), lactose (glucose + galactose), and maltose (2 glucose)
- Oligosaccharides: raffinose and stachyose
- Polysaccharides: starch (plant-based), glycogen (stored energy in muscles and liver), and cellulose (plant-based)
Carbohydrate Digestion and Absorption
- Amylase in saliva breaks down carbohydrates
- Lactase, maltase, and sucrase break down their respective disaccharides into monosaccharides
- Carbohydrates are broken down into monosaccharides before being absorbed into the bloodstream
Metabolism of Carbohydrates
- Excess glucose is converted to glycogen via glycogenesis, which requires energy and occurs in the liver or muscles
- When energy is needed, glycogen is broken down into glucose via glycogenolysis, producing lots of ATP
Blood Glucose Regulation
- High blood sugar promotes insulin to stimulate glucose uptake
- Low blood sugar promotes glucagon to stimulate glycogen breakdown to form glucose for energy
Choosing a Carbohydrate Source
- Nutrient density: the amount of nutrients per amount of food
- Glycemic index: measures how quickly a food raises blood sugar levels
- Glycemic load: takes into account the amount of carbohydrates consumed
- Fructose content: high fructose intake is associated with negative effects
- Fibre content: foods high in fibre are lower in GI and reduce the risk of negative effects
Glycemic Index Studies
- Low and high GI foods have similar outcomes when caloric intake is controlled
- Fibre is a significant confounder
- Baseline characteristics and variability in findings affect outcomes
- GI studies have limitations, including assessment on an empty stomach and variability in preparation and lifestyle
Fructose Metabolism
- Fructose has a different metabolic fate than glucose
- Fructose goes straight to the liver to be transformed to glucose via fructolysis
- Fructose has no negative feedback loop and can deplete energy stores
- Fructose is associated with increased blood pressure, type 2 diabetes, and obesity
Fructose Animal Studies
- High fructose intake leads to increased body weight, food intake, blood glucose, and decreased insulin
- Fructose intake is associated with increased uric acid and triglycerides
Fructose Survival Hypothesis
- Fructose turns on a survival switch to prepare for periods of starvation
- Increased fructose intake leads to increased blood pressure, eating, fat storage, insulin resistance, and low-grade inflammation
Fructose Human Studies
- High fructose intake increases visceral adiposity and leads to weight gain
- Fructose intake is associated with negative health effects, including increased blood pressure, type 2 diabetes, and obesity
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Description
Learn about the different classifications of carbohydrates including monosaccharides, disaccharides, oligosaccharides, and polysaccharides. Discover examples of each type and how carbs are transformed into glucose to produce energy.
