This document discusses glycemic index (GI), a measure of how foods affect blood glucose levels. It provides details on GI determination, factors that influence GI values, benefits of a low GI diet, and recommendations. Specifically, it finds that a low GI diet is associated with lower blood glucose and HbA1c levels, improved lipid profiles, weight control, and decreased risk of heart disease and diabetes. The take home message encourages choosing high-fiber whole grains and fruits/veggies while limiting refined sugars and large portions of high GI foods.

1. KNOWLEDGE FOR THE BENEFIT OF HUMANITY
ADVANCED NUTRITION (HFS4352) GLYCEMIC INDEX
Mohd Razif Shahril, PhD
School of Nutrition & Dietetics
Faculty of Medicine and Health Sciences
Universiti Sultan Zainal Abidin
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2. Outline
•What is Glycemix Index (GI)?
•Glycemix Index Determination Protocol
•Factors Influencing GI
•Benefits of Low GI Diet
•Take home message
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3. What is Glycemix Index (GI)
•A scale that ranks carbohydrate by how much they raise blood glucose levels compared to a reference food.
–Developed by Jenkins et al. 1981. Am J Clin Nutr. 34(3):362-366.
•References on GI
–Brand-Miller et al. 2006. The New Glucose Revolution. 3rd ed. New York, NY: Marlowe & Co.
–Written by experts on GI
–Atkinson et al. 2008. Diabetes Care 31(12):2281- 2283
–Most comprehensive table of the GI of foods that has been assembled to date
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4. What is Glycemix Index (GI)
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Rapidly digested or absorbed carbohydrates
Slowly digested or absorbed carbohydrates

5. What does the GI value mean?
•The glycemic index (GI) is expressed as a ratio comparing the blood glucose increase caused by a test food to that of a reference food (usually glucose) for 2 hours following ingestion.
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Area Under the Curve for Test Food
Area Under the Curve for Reference Food
× 100
= GI
GLYCEMIC INDEX
VALUE
Low GI
0 – 55
Moderate GI
56 – 69
High GI
≥ 70

6. •The glycemic load (GL) takes into account the amount of carbohydrate (CHO) in a common serving in addition to its glycemic index (GI)
–Example: Carrots (peeled, boiled) have a GI of 47 and 5 g CHO per serving
Glycemic Load (GL)?
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GL = (GI of CHO × grams of CHO per serving) ÷ 100
The GL of carrots is: (47 × 5) ÷ 100 = 2.4
GLYCEMIC LOAD
VALUE
Low GL
0 – 10
Moderate GL
11 – 19
High GL
≥ 20

7. GI Determination Protocol
25 g or 50 g CHO of test food
1st hour – Blood taken every 15 minutes
2nd hour – Blood take every 30 minutes
Glucose response value plotted in graph
Calculate Area Under Curve (AUC)
Test food response compared to reference food (glucose)
Repeat among 8 to 10 volunteers
GI value
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8. GI Determination Protocol
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9. Factors Influencing GI
Type of starch
Physical entrapment
Viscosity of fibre
Sugar content
Fat and protein content
Acid content
Food processing
Cooking
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10. [1] Type of starch
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Amylose
Absorbs less water
Molecules form tight clumps
Slower rate of digestion
LOWER GI
E.g. Kidney beans (28)
Amylopectin
Absorbs more water
Molecules are more open
Faster rate of digestion
HIGHER GI
Eg. Russet potato (85)

11. [1] Type of starch
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12. [2] Physical entrapment
•Bran acts as a physical barrier that slows down enzymatic activity on the internal starch layer.
•Lower GI
–All Bran (38)
–Pumpernickel bread (50)
•Higher GI
–Bagel (72)
–Corn Flakes (92)
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13. [2] Physical entrapment
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14. [3] Viscosity of fibre
•Viscous, soluble fibers transform intestinal contents into gel-like matter that slows down enzymatic activity on starch.
•High soluble fibre = lower GI
•Lower GI
–Apple (40)
–Rolled oats (51)
•Higher GI
–Whole wheat bread (73)
–Cheerios (74)
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15. [4] Sugar content
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16. [4] Sugar content
•Lower GI
–Frosted Flakes (55)
–Raisin Bran (61)
•Higher GI
–Golden Grahams (71)
–Rice Krispies (82)
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sugar sucrose glucose + fructose
starch maltose glucose + glucose
(GI 60) (GI 100) (GI 19)
(GI 105) (GI 100) (GI 100)

17. [5] Fat and protein content
•Fat and protein slow down gastric emptying, and thus, slows down digestion of starch.
•High fat and protein foods have lower GI
•Lower GI
–Peanut M&M’s (33)
–Potato chips (54)
–Special K (69)
•Higher GI
–Jelly beans (78)
–Baked potato (85)
–Corn Flakes (92)
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18. [6] Acid content
•Acid slows down gastric emptying, and thus, slows down the digestion of starch.
•Foods with higher acid content = lower GI
•Lower GI
–Sourdough wheat bread (54)
•Higher GI
–Wonder white bread (73)
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19. [7] Food processing
•Highly processed foods require less digestive processing.
•Processed foods = higher GI
•Lower GI
–Old fashioned, rolled oats (51)
•Higher GI
–Quick, 1-minute oats (66)
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20. [8] Cooking
•Cooking swells starch molecules and softens foods, which speeds up the rate of digestion.
•Overly cooked foods = Higher GI
•Lower GI
–Al dente spaghetti – boiled 10 to 15 minutes (44)
•Higher GI
–Over-cooked spaghetti – boiled 20 minutes (64)
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21. Low/High GI Meals/ Snacks
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GI = 60 GL = 48
GI = 42 GL = 31

22. Low/High GI Meals/ Snacks
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GI = 85 GL = 48
GI = 39 GL = 22

23. Low/High GI Meals/ Snacks
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GI = 83 GL = 19
GI = 14 GL = 1

24. Low/High GI Meals/ Snacks
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GI = 80 GL = 32
GI = 61 GL = 12

25. Low/High GI Meals/ Snacks
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GI = 57 GL = 31
GI = 32 GL = 16

26. GI Symbol
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27. Benefits of Low GI Diet
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Low GI diet helps lower blood glucose levels
Meta-analysis of 14 studies, 356 subjects (types 1 & 2 DM), 2-52 weeks duration
Mean difference
•7.4% in glycated proteins over & above reduction compared to high GI diet.
•0.43% points in HbA1c over & above reduction compared to high GI diet
Brand-Miller et al. Diabetes Care. 2003; 26; 2263.

28. Benefits of Low GI Diet
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Low GI diet helps lower blood glucose levels
EURODIAB IDDM Complications Study, 1996
2,054 people, 15-60 y, with type 1 DM
Buyken et al. Am J Clin Nutr. 2001; 73; 578.
GI
HbA1c
Lowest quartile
58-78
6.04
Highest quartile
86-112
6.60

29. Benefits of Low GI Diet
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Low GI diet improves lipid levels
NHANES III, 1988-1994
13,907 American adults, 20+ y
Ford & Liu. Arch Intern Med. 2001; 161; 572-576.
GI
HDL-C
Lowest quintile
52.51
Highest quintile
49.42

30. Benefits of Low GI Diet
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Low GI diet improves lipid levels
23 obese young adults, 18-35 y, BMI > 27, 12 mos. duration
GL
Tot. chol.
LDL
HDL
TG
Ad libitum low GL diet
53
-8.5
-9.7
12.2
-37.2
Low calorie, low fat diet
77
-6.2
-7.4
1.1
-19.1
Ebbling et al. Am J Clin Nutr. 2005; 81; 981.

31. Benefits of Low GI Diet
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Nurses’ Health Study, 1984-1996
74,091 women, 38-63 y
Lin et al. Am J Clin Nutr. 2003; 78; 923.
Calculated odds ratios (lowest > highest quintiles)
BMI (≥30)
n = 6,400
Major weight gain
(≥25kg) n = 657
Whole grains
-19%
-23%
Refined grains
+18%
+26%
Dietary fiber
-34%
-49%
Low GI diet aids in weight control

32. Benefits of Low GI Diet
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0%
25%
50%
75%
< 18.5 18.5 - 24.9 25.0 - 29.9 30.0 - 34.9 35.0 - 44.9 45.0 +
BMI
% of Subjects
Burani & Longo. Diabetes Educ. 2006; 32; 83.
Low GI diet aids in weight control
Post low GI MNT counseling, 21 subjects, 21-89 y, 3-36 mos.
pre LGI-MNT
post LGI-MNT

33. Benefits of Low GI Diet
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Low GI diet decreases risk of heart disease
Nurses’ Health Study, 1984-1994
75,521 adult women, 38-63 y, free of CHD
10 year follow-up: 761 cases of CHD
Lin et al. Am J Clin Nutr. 2000; 71; 1455-1461.
Relative risk of CHD
GL highest quintile
1.98
GI highest quintile
1.31

34. Benefits of Low GI Diet
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Low GI diet decreases risk of heart disease
Nurses’ Health Study, 1980-1999
78,779 women, 38-63 y, free of CVD
18 year follow-up: 1,020 stroke cases documented
Relative risk
CHO intake (all subjects)
2.05 for hemorrhagic stroke
CHO intake (BMI ≥ 25)
2.13 for total stroke
3.84 for hemorrhagic stroke
GL intake (BMI ≥ 25)
1.61 for total stroke
cereal fiber (all subjects)
0.66 for total stroke
0.51 for hemorrhagic stroke
Oh et al. Am J Epid. 2005; 161; 161-169.

35. Benefits of Low GI Diet
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Low GI diet decreases risk of diabetes.
Nurses’ Health Study, 1986-1992
65,173 US women 40-65 y, free of DM
6 year follow-up: 915 cases of type 2 DM
Relative risk
GI
1.37
GL
1.47
cereal fiber
0.72
GL cereal fiber
2.50
Salmeron et al. JAMA. 1997; 277; 472.

36. Take home message
•Eat high-fiber breakfast cereals (oats, bran, barley) OR add berries, nuts, flaxseed and cinnamon to high GI cereals.
•Choose dense, whole grain and sourdough breads and crackers OR add a heart-healthy protein and/or condiment to high GI breads and crackers.
•Include 5-9 servings of fruits and vegetables every day.
•Replace white potatoes with yams or sweet potatoes OR consume smaller portion of high GI potatoes.
•Eat less refined sugars and convenience foods (soda, sweets, desserts, etc.) OR combine nuts, fruit, yogurt, ice cream with commercial sweets – watch portion sizes.
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37. Thank You
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