Pasta, Glycemic Index and Health

Dr. Cyril W.C. Kendall

Department of Nutritional Sciences, Faculty of Medicine,

University of Toronto;

Clinical Nutrition & Risk Factor Modification Center,

St. Michael’s Hospital;

Toronto, Ontario

Canada.

Traditional,

Developing

Countries

Modern,

Developed

Countries

Prevalence of Obesity and Diabetes

Diabetes on the Rise

Current prevalence of Diabetes worldwide% of Population with diabetes

Diabetes on the Rise

% of Population with diabetesPrevalence of Diabetes in 2030 worldwide

IDF Atlas

MI: 2-4x

Stroke: 2-6x

End stage renal disease: 17x

Retinopathy: 25x

Limb amputations:10-15x

Other complications:

- ↓ cognitive function

- infertility

- impotence

Hyperglycemia (High 2h Blood Glucose or HbA1c) is

Associated with All-cause and CVD Mortality

in Non-diabetic Populations

• Helsinki Policeman Study (Pyorala et al. 1979)

• The Framingham Study (Singer et al. 1980)

• The Whitehall Study (Fuller et al. 1983)

• The Chicago Heart Study (Pan et al. 1986)

• The Rancho Bernardo Study (Park et al. 1996; Barrett-Connor et l.,

1998)

• Hoorn study (De Vegt et al. Diabetologia, 1999)

• ARIC study (Vitelli et al. 1997)

• Meta-analysis DECODE study (Lancet 1999)

• EPIC-Norfolk (Khaw et al. 2001)

• The Cardiovascular Health Study (Smith et al. 2002)

•….many more now

↑Glucose/Insulin ↑Chronic Diseases

Dietary carbohydrates

are the main drivers

of blood glucose and

insulin responses

Increasing prevalence of Type 2 DM in the US with increasing

Consumption of Carbohydrates

Diabetes and Carbohydrate Consumption

300

325

350

375

400

425

450

475

500

525

0

5

10

15

20

25

30

35

60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96

Carb

ohyd

rate

(g/d

)

US D

iabe

tics

(per

thou

sand

)

Year

Total Carbohydrate Diabetics

Prevalence of Type 2 DM in the US and

Consumption of Carbohydrates

National Nutrient Databank Centers for Disease Control and Prevention

Gross et al AJCN 2004

Relationship of Saturated Fat Intake to

Coronary Heart Disease

Siri-Tarino et al Am J Clin Nutr 2010;91:535–46.

FIGURE 2. Risk ratios and 95% CIs for fully adjusted random-effects models examining associations between saturated

fat intake in relation to coronary heart disease. SAT, saturated fat intake; IV, inverse variance.

“A Call for a Low-Carb Diet That Embraces Fat”(New York Times – Sept 1, 2014)

“People who avoid carbohydrates and eat more fat, even

saturated fat, lose more body fat and have fewer

cardiovascular risks than people who follow the low-fat diet

that health authorities have favored for decades, a major

new study shows.”

Are Carbohydrates as

Unhealthy as Saturated Fat?

Carbohydrate Quality

Glycemic Index/ Load

Dietary Fiber

Whole Grains

Glycemic Index Background

• Classification of carbohydrate rich foods

based on their effect on blood glucose.

• Certain carbohydrates, by virtue of their

slow rate of digestibility and absorption,

may provide a strategy to prevent and

manage chronic diseases such as

diabetes and CHD.

Test Food

Reference Food

IAUC 50g CHO TEST FOOD x 100

IAUC 50g CHO REF. FOOD

Glycemic Index (GI)

GI =

Time (min)

Glucose

0 15 30 45 60 90 120 0 15 30 45 60 90 120

Jenkins et al. AJCN 1981; Wolever et al 1991

Glycemic Load (GL)

GL(food) = GI(food) X amount CHO(serving)

Glycemic Index

High GI FoodsLow GI Foods

GLYCEMIC INDEX RANKING

Foods grouped into high, intermediate and low classes

according to GI :

High GI (GI >90)

Most Breads

Plain Crackers

Most Breakfast Cereals

Instant Mashed Potatoes

Millet

Corn chips

Medium GI (GI 70-89)

All Bran

Oatmeal

Most biscuits or cookies

Buckwheat

Sweet Corn

Boiled New Potatoes

Yam

Sweet Potatoes

Low GI (GI <69)

Pasta

Pumpernickel Bread

Parboiled Rice

Most legumes (dried)

Nuts

Barley

Bulgur (cracked wheat)

High GI

Intermediate GI

Low GI

GI of Bread and Spaghetti

0

1

2

3

4

5

6

7

8

Blo

od

Glu

co

se

(m

mo

l/L

)

Time (h)

Blood Glucose Increments after Spaghetti,

White and Wholemeal Bread (diabetic subjects)

Spaghetti

White Bread

Wholemeal Bread

0 1 2 3

<0.05

<0.005 <0.001

<0.005

<0.02

Jenkins et al. Diab Care (1983)

4-hr Glucose Response Curves

4.00

4.50

5.00

5.50

6.00

6.50

7.00

7.50

0 30 60 90 120 150 180 210 240

Time (min)

Glu

co

se C

on

cen

trati

on

(m

mo

l/L

)

50 Bread

100 Bread

50 Pasta

100 Pasta

Bread and Pasta:

metabolic responses in healthy people

(unpublished data)

4hr-Glucose iAUC

0

50

100

150

200

250

300

Gly

ce

mic

re

sp

on

se

(min

xm

mo

l/L

)

a

b

c

da

Bread-50 Bread-100Pasta-50 Pasta-100

Columns not sharing the same letters are significantly different (p<0.05)

Bread and Pasta:

metabolic responses in healthy people

(unpublished data)

4-hr Insulin Response Curves

0

50

100

150

200

250

300

350

400

0 30 60 90 120 150 180 210 240

Time (min)

Insu

lin

Co

ncen

trati

on

(p

mo

l/L

)

50 Bread

100 Bread

50 Pasta

100 Pasta

Bread and Pasta:

metabolic responses in healthy people

(unpublished data)

Insulin IAUC (4-hr)

0

10,000

20,000

30,000

40,000

50,000

Ins

ulin

co

nc

en

tra

tio

ns

(pm

ol/L

)

50 Bread

100 Bread

50 Pasta

100 Pastaa

b

ccontrol

Bread and Pasta:

metabolic responses in healthy people

(unpublished data)

Questions

• Can we lower the GI of the diet by

recommending low GI foods?

• Would this dietary advice improve glycemic

control in type 2 diabetic subjects?

• Would markers of cardiovascular disease

risk also be improved and weight loss

promoted?

Low GI Diet in Diabetes Control:

Effectiveness Study (n=210)

Study Design

Low Glycem ic Index diet

Month

Week

1 2 3 4

1 2 3 4 5 6 7 8 9 10 12 13 14 15 16

11

High Cereal Fiber diet

Blood, BP & 7 -day diet record

Anthropometry

Figure 3. Schematic representation of the study protocol

Pretest +

Randomization

(2 months)

17 18 19 20 21 22 23 24

5 6

Low Glycem ic Index diet

Month

Week

1 2 3 4

1 2 3 4 5 6 7 8 9 10 12 13 14 15 16

11

High Cereal Fiber diet

Blood, BP & 7 -day diet record

Anthropometry

Figure 3. Schematic representation of the study protocol

Pretest +

Randomization

(2 months)

17 18 19 20 21 22 23 24

5 6

Bran flakesOatmeal

Whole wheat crackersBulgur

Vegetable soupBeans, Chickpeas,

Lentils

Whole wheat breadPumpernickel bread

(Dimpflmeier)

Rye crackersBarley

Shredded WheatRed River cereal

White / Brown riceParboiled rice

Potato (baked, mashed)Pasta (al dente)

High Cereal Fiber Diet

(Control)

Low GI Diet

(Test)

Bran flakesOatmeal

Whole wheat crackersBulgur

Vegetable soupBeans, Chickpeas,

Lentils

Whole wheat breadPumpernickel bread

(Dimpflmeier)

Rye crackersBarley

Shredded WheatRed River cereal

White / Brown riceParboiled rice

Potato (baked, mashed)Pasta (al dente)

High Cereal Fiber Diet

(Control)

Low GI Diet

(Test)

GI < 70 GI = 80

Recommended Study Foods

2

6

Low Glycemic Index Diets and

Diabetes Control

Jenkins DJ, Kendall CW et al. JAMA 2008.

Control TestEnergy (kcal) 1,648 1,664

Fat (%) 29.4 32.6

SFA 8.9 9.1

MUFA 11.6 12.9

PUFA 5.9 6.5

Cholesterol (mg/100kcal) 145 143

Protein (%) 21.0 21.5

Carbohydrate (%) 48.1 44.4

Fiber (g/1000 kcal) 16.5 19.7

GI 84 70

Compliance

Jenkins, Kendall et al. 2008

% compliance

Cereal Fiber LGI

87% 90%

GI: 80 → 70

HbA1c (intent to treat, n=210)

0 4 8 12 16 20 24

Week

6.30

6.40

6.50

6.60

6.70

6.80

6.90

7.00

7.10

7.20

7.30

Hb

A1c (

%)

Low Glycemic Index

High Cereal Fiber

P<0.001

Jenkins DJ, Kendall CW et al. JAMA 2008.

Fasting Glucose

114

118

122

126

130

134

138

142

146

Fasti

ng

glu

co

se (

mg

/dL

)

Low Glycemic Index

High Cereal Fiber

P=0.022

0 4 8 12 16 20 24

WeekJenkins DJ, Kendall CW et al. JAMA 2008.

HDL-C

38

39

40

41

42

43

44

45

46

HD

L-C

(m

g/d

L)

Low Glycemic Index

High Cereal Fiber

P=0.005

0 4 8 12 16 20 24

WeekJenkins DJ, Kendall CW et al. JAMA 2008.

LDL/HDL-C

2.1

2.2

2.3

2.4

2.5

2.6

2.7

LD

L/H

DL

-C

Low Glycemic Index

High Cereal Fiber

P=0.047

0 4 8 12 16 20 24

WeekJenkins DJ, Kendall CW et al. JAMA 2008.

Diastolic BP

68

70

72

74

76

Dia

sto

lic B

P (

mm

Hg

)

Low Glycemic Index

High Cereal Fiber

Jenkins DJ, Kendall CW et al. JAMA 2008.

0 4 8 12 16 20 24

Week

P=0.37

Body Weight (kg)

80

81

82

83

84

85

86

87

88

89

90

Bo

dy w

eig

ht

(kg

)

Low Glycemic Index

High Cereal Fiber

P=0.053

0 4 8 12 16 20 24

Week

Jenkins DJ, Kendall CW et al. JAMA 2008.

Between

Treatment

Difference

(P-value)

High Fiber

Control

Pulse Diet

Test

(n=64) (n=67)

Weight (kg) -1.7* -2.6* 0.219

Glucose (mgl/dL) -7 -11* 0.934

HbA1c (%) -0.3* -0.5* 0.001

Lipids (mg/dL)

Total Cholesterol -2 -9* 0.001

LDL-C -1 -3* 0.063

HDL-C 1* 0 0.001

Triglycerides -9* -19* 0.064

Total Chol:HDL-C ratio -0.12* -0.14* 0.360

Blood Pressure (mmHg)

Systolic 0 -4* 0.010

Diastolic 0 -3* 0.001

Low GI Pulse Based Diet in DiabetesChange Across Treatments (mean) (n=131)

10y CHD Risk (%) -0.5 -1.1* 0.010

Jenkins, Kendall, et al. Arch Intern Med (2012)

-0.30

-0.25

-0.20

-0.15

-0.10

-0.05

0.00

Ch

an

ge

in

% H

bA

1c

Full Dose Nuts

Half Dose Nuts and Muffins

Full Dose Muffins

P=0.0012

P=0.3855P=0.4834

Nuts and DiabetesChange in % HbA1c Across Treatments (n=117)

Jenkins, Kendall, et al. Diab Care (2011)

Full vs Half P=0.004

Full vs Muffin P=0.001

P-value

Treatment

DifferenceNuts Both Muffins

Characteristics (n=40) (n=38) (n=39)

Weight (kg) 79.7±2.28 86.50±2.54 82.90±2.35 0.327

Glucose (mmol/L) 7.15±0.22 7.41±0.33 7.18±0.25 0.425

HbA1c (%) 6.88±0.10 7.02±0.12 7.06±0.09 0.039

Lipids (mmol/L)

Total Cholesterol 4.16±0.18 3.98±0.13 4.32±0.17 0.002

LDL-C 2.34±0.15 2.21±0.10 2.47±0.13 0.007

HDL-C 1.10±0.04 1.09±0.04 1.14±0.06 0.701

Triglycerides 1.59±0.16 1.50±0.14 1.64±0.16 0.204

Total Chol:HDL-C ratio 3.88±0.16 3.84±0.19 3.97±0.21 0.015

LDL-C:HDL-C ratio 2.17±0.13 2.14±0.13 2.29±0.14 0.028

Blood pressure (mmHg)

Systolic 120±2 124±2 124±2 0.678

Diastolic 70±1 71±1 72±2 0.182

End of Treatment Differences for Intent-to-Treat Analyses

(n=117) (mean + sem)

Low GL Canola vs High Cereal Fiber Diet:

Effects on HbA1c, LDL-C and TG

Jenkins, Kendall, et al. Diab Care (2014)

Baseline SBP Level determines HbA1c Reduction by Canola oil-Low GL Diet

Changes from Baseline (Week 0) in HbA1c (% HbA1c unit) during Canola oil-Low GL (test) and High Wheat-Fibre (control)

Diets in Participants stratified by high and low baseline SBP. HbA1c was reduced more on the test than the control for those

with higher baseline SBP (P<0.003).

Baseline SBP<130 mmHg Baseline SBP≥130 mmHg

Week Week

Jenkins, Kendall, et al. Diab Care (2014)

Effect of a Low GL Diet vs. a High Fiber Diet on %HbA1c over 3 Months

Data are presented as ITT mean treatment difference in HbA1c ±SEM, P-values define the significance

between treatments using LS means . IR= Insulin Resistance, IR Risk Factors were defined as the following

baseline values: HbA1c≥7.2 (median baseline value of the cohort); HDL-C ≤1.3mmol/L for women and

≤1.0mmol/L for men; Triglyceride ≥ 1.7mmol/L; Systolic blood pressure ≥130mmHg or diastolic blood pressure

≥85mmHg ; Waist Circumference ≥88 for women and ≥102 for men; Age ≥ 58 (median age of cohort).

-0,80

-0,70

-0,60

-0,50

-0,40

-0,30

-0,20

-0,10

0,00

All Participants≥1 IR Risk

Factor ≥2 IR Risk Factors

≥3 IR Risk Factors

≥4 IR Risk Factors

≥5 IR Risk Factors

Bet

we

en

Tre

atm

en

t D

iffe

ren

ce(%

Hb

A1

c U

nit

)

P= 0.076 P= 0.076 P= 0.117

P= 0.084

P= 0.017

P= 0.002

n=141 n=140 n=121

n=78

n=34

n=18

Low vs High GI Diet: a Meta-Analysis

% Difference in Glycated Proteins

% -35 -25 -15 -5 5 15

Gilbertson et al. 2001Komindr et al. 2001Giacco et al 2000Luscombe et al 1999Jarvi et al 1999Lafrance et al 1998Frost et al 1993Wolever et al 1992Wolever et al 1992Fontvieille et al 1992Brand et al 1991Jenkins et al 1991Fontvieille et al 1988Collier et al 1988

Mean %difference in 14 studies = -7.4% (CI -8.8 to -6.0%)

OVERALL RESULT

Brand-Miller et al, Diabetes Care 2003;26:2261-67

2.5 2.32.05

2.171.8

1.62

1.511.28

1

0

1

2

3

High Medium Low

High

Medium

LowRelative

Risk

>165 165-143 <143

Glycemic Load

>5.8 g/day

2.5 -5.8 g/day

<2.5 g/day

(Salmeron et al,1997)

(ref)

Cereal Fiber

Glycemic Load and Cereal Fiber Intake in

Women And Risk of Type II Diabetes (75,000 Nurses over 10y)

Glycemic Index and

Type 2 Diabetes Incidence

0

0.5

1

1.5

2

1 2 3 4 5

Quintiles of increasing GI

RR

Schulze et al. AJCN 2004

Nurses Health Study; n=91,249 women; 8-yr follow-up

P < 0.001

1

1.15 1.07

1.27

1.59

Glycemic Load (GL) and Risk of CHD

Liu et al. Am. J. Clin. Nutr. 2000

Nurses Health Study

n=75,521 women

10-yr follow-up

1

1.16 1.181.31

1.01

0

0.5

1

1.5

Q1 Q2 Q3 Q4 Q5

Glycemic load

RR

p (trend) < 0.008

(1.02-1.68)

Summary

• Low GI advice can reduce the GI of the diet

• Low GI diets have shown metabolic benefits in Type 2 diabetes. Glycemic control significantly improved and CVD risk factors decreased.

• Longer-term dietary studies with harder end points are

needed (e.g. CHD, MRI and atherosclerotic plaque formation).

International Health Institutions

Supporting the GI Concept

1) World Health Organisation (WHO)

2) Food and Agriculture Organisation (FAO)

3) International Diabetes Federation (IDF):

4) Canadian Diabetes Association (CDA)

5) European Association for the Study of Diabetes (EASD)

6) Australian National Evidence-Based Guidelines for T2D

7) Dietary Guidelines for Older Australians

Parameter ADA BDA CDA EASDWeight Reduction Modest weight loss Desirable weight Healthy weight Desirable weight

(5-7%)

Physical Activity Increase Increase Increase Increase

Carbohydrate 50-60% 50-55% 50-60% 45-60%

Polysaccharides Whole grains, Fiber rich foods Whole grain cereals Low GI foods

fruits, vegetables & legumes

Sugars No limit <25 g/d ≤10% added <10% calories

Glycemic index Does not recommend Discusses Include low GI foods low GI foods

for general use recommended

Fiber As for general >30 g/d 25-35 g/d Increase population (low GI foods)

Protein 15-20% 10-15% 11% 10-20%

Total fat 25-35% 30-35% < 30% < 35%

SFA/Trans <10% <10% < 10% < 10%

MUFA 10-20% 10-15% 10-15% 10-20%

PUFA ~10% <10% < 10% < 10%

Cholesterol <300 mg/d <300 mg/d - < 300 mg

International Diabetes Associations’ Lifestyle and Dietary

Guidelines

Anderson, Randles, Kendall, Jenkins. J Am Coll Nutr (2003)

Glycemic Index, Glycemic Load and Glycemic Response:

An International Scientific Consensus Summit

Stresa, Italy • June 7th, 2013

Organizers: Oldways & Nutrition Foundation of Italy

Goal: To bring together international experts on

carbohydrates and health in order to advance

worldwide understanding of the key role of

carbohydrates in a healthy diet.

Consensus Statement

1. Carbohydrates present in different foods have distinct

physiological effects, including effects on post-prandial

glycemia (PPG), with different implications for health.

2. Reducing PPG is recognized as a beneficial physiological

effect.

3. Ways to reduce PPG include slowing carbohydrate absorption

by consuming low glycemic index (GI)* and glycemic load

(GL)* foods.

4. The GI methodology is a sufficiently valid and reproducible

5. The GI quantifies specific physiological properties of

carbohydrate containing foods as influenced by the food

matrix.

Consensus Statement

6. Convincing evidence that low GI diets improve glycemic

control in people with type 2 diabetes.

7. Convincing evidence that low GI/GL diets reduce the risk

of developing type 2 diabetes.

8. Convincing evidence that low GI/GL diets reduce the risk

of coronary heart disease.

9. The carbohydrate quality as defined by GI/GL is

particularly important for individuals who are sedentary,

overweight and at increased risk of type 2 diabetes.

10. Probable evidence exists for low GI/GL diets in body

weight management.

Consensus Statement

11. The GI complements other ways of characterizing

carbohydrate-foods, such as fiber and whole grain

content.

12. Low GI is to be considered in a context of a healthy diet.

13. Given the rapid rise in diabetes and obesity there is a

need to communicate information on GI/GL to the

general public and health professionals.

14. This should be supported by inclusion of GI/GL in dietary

guidelines and food composition tables.

15. In addition package labels and low GI/GL symbols on

healthy foods should be considered.

Glycemic Index, Glycemic Load and Glycemic Response:

An International Scientific Consensus Summit

Stresa, Italy • June 7th, 2013

An international panel of experts has formed the “International

Carbohydrate Quality Consortium (ICQC)” which met in Stresa on June

6-7, 2013 and discussed the importance of carbohydrate quality in

addition to quantity.

Thank you for your attention

Health Implications of GI

• Foods with a low GI:– Role in HEALTH

• Weight management• Acne• Physical and mental performance

(sustained energy)• Reduce risk for diabetes, heart disease and

other conditions

– Role in DISEASE• Management of diabetes

• Why is GI not better recognized?

Quality of Evidence

Excellent

Good

Some