BIBC 120 Lecture Notes - Lecture 17: High Fructose Corn Syrup, Xylose Isomerase, Corn Syrup
24 May 2018
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Week 6.3
o Glycemic Load=(food AUC/glucose AUC) x grams carbs in one serving of that
food
• high>20, low <10
o experiment:
1. fast 12 hours
2. consume 50 g pure glucose or amount of food that gives you 50 g carbs
3. Measure area under curve for both
• GI=(food AUC at 120 min/glucose AUC at 120 min) x 100
• high >70, low <55
o What is the evidence for the glycemic response of food affecting health?
• Epidemiological/intervention study evidence is mixed
• Low GI diets reported to decrease risk factors for heart disease
and diabetes
• Other studies less clear
• Potential physiologic/biochemical mechanisms
• Insulin response and effects on metabolism
• Increased carbohydrate consumption/weight gain
• Foods with low GI and GL tend to contain more fiber
o Insulin response curve is same as glycemic response curve, glycemic responses
determines insulin released
Carbohydrates in Food
• Natural: starch, some sucrose and fructose in fruits, lactose in dairy
• Added sugars: sucrose (table sugar) and high fructose corn syrup
o Corn syrup: corn starch -----a amylase + maltase (glucoamylase)-→ glucose –
lose isoerase do’t eed to kow-> some glucose to fructose. final product:
45-55% glucose, 45-55% fructose
▪ sucrose GI = 65
▪ corn syrup GI = 58-68
o not the cause of inc. diabetes/obesity but its cheaper to produce so they add it
to more things??
o New York City Proposed bill to Limit Soft Drink Cup Size, struck down
• Dietary Reference Intakes for Carbohydrates
o Recommended Dietary Allowance (RDA) = 130 grams per day
o This is based on the minimum amount of glucose utilized by the brain
o This represents a minimum intake—although this may vary depending
pregnancy/lactation and amount of physical activity
o There is no tolerable upper limit (UL) for carbohydrates
o Acceptable Macronutrient Distribution Range (AMDR) for carbohydrates is 45 –
65% of total Calories from carbohydrates
Other Dietary Guidelines
• Added sugars (sucrose and HFCS) not more than 25% of total Calories
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