Effects of dietary induced postprandial glycemia and

related diseases: emphasis on carbohydrate, glycemic index and

glycemic load

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Detmold, Germany, April 2005

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AGENDA

• Trends in carbohydrate intake

• What is glycemic index (GI)/glycemic load (GL) ?

• Food factors influencing the GI

• Clinical evidence in favor of GI

• No consensus on the importance of GI in human H&N

• New trends

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Trends in carbohydrates intake... (FAO/WHO report)

20-30 % < starch < 50% and over(as a % of energy)

15-30 % > sweeteners > 9-15 %(as a % of energy)

15-20 g/d < dietary fibres < 25-40 g/d

45-55 % < total carbohydrate < 60-80%(as a % of energy)

Developed countries Developing countries

Western Europe :- Belgium- United Kingdom

North America :- USA- Canada

Australia

Asia :- Bangladesh- Vietnam

Africa :- Malawi- South Africa

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Changes in carbohydrate consumption... (Gross et al., 2004)

total CHO

fiber intake

whole grains

refined CHO

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CHO are pointed out … (Gross et al., 2004)

CHO intake

Prevalence of obesity

CHO intake

Prevalence of type 2 diabetes

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Western chronic diseases …In United States :

- 2 of every 5 deaths are attributed to CVD or diabetes (Hoyert et al,1999)

- Type 2 diabetes mellitus (DM) : ≈ 8% of the US population(Harris et al., 1998)

- World: 300 millions individuals in 2025 (King et al., 1998)

The problem is…- high GL diets have been positively associated with a greater risk of type

2 diabetes (Salmeron et al., 1997; Salmeron et al., 1997) and CVD (Liu et al., 2000)

Low GI and GL diets are associated with lower risk of CVD (-25%) (Liu et al., 2000; Jacobs et al., 2000; McKeown et al., 2002) and type 2 DM (-30%) (McKeown et al., 2002; Fung et al., 2002)

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What is GI ?

GI is a method of assessing and classifying the glycemic response to foods

AUC of the test foodAUC of the standard food

GI = x 100

Glyc

emia

( mm

ol/L

)

Time (min)

Incremental area = A + B + C + D + E + F

AB C

DE F

Very low < 4040 < low < 55

56 < moderate < 70high > 70

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What is GL ?

GL = (GI x available carbohydrate content per food serving)/100

• Orange juice, GI 50, serving of 250ml contains 26g CHO GL 13

• French Baguette, GI 72, serving of 70g contains 37g CHO GL 26

• Carrots, GI 47, serving of 80g contains 6g CHO GL 3

Example of GI values from GI tables .... Item GI Item GI Bakery products Dairy products Croissant 67 Ice cream 61 French baguette 95 Milk, full fat 27 Coarse rye kernel bread 41 yogurth 36 Whole meal rye bread 58 Fruits White wheat bread 70 Plum/Pear/Apple 38 Beverages Peach/Orange 42 Coca-cola 58 Kiwi 53 Lucorade (sparkling glucose drink)

95 Legumes

Apple juice 40 Baked beans 48 Orange juice 50 Kidney beans 28 Gatorade 78 Lentils 30 Breakfast cereal Soya beans 18 All-bran 42 Vegetables Chocapic 84 Carrots, raw 16 Corn flakes 81 Baked potato 60 Porridge 58 Snack foods Cereal grains Chocolate milk 43 Barley, pearled 25 Mars bar 65 Rye, whole kernel 34 Snickers 55 Sweet corn 53 Jelly beans 78 (Foster-Powell and coll., 2002)

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Food factors influencing GI ...

Stomach

Small intestine

CARBOHYDRATESLimitations: Rate of gastric emptying

Limitations: Rate of digestion and absorption

Blood circulationEffect on glycemic response

Liver

Nature of starch(amylose/amylopectine)

Starch/nutrients interaction

Types and amounts of others nutrients(viscous fibers, antinutrients)

Food processing(particule size, starch

gelatinization)

Nature of the monosccharides

(glucose, fructose, galactose)

insulin Protein

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Dietary factors which influence GI of foods ....

GI

3. Food processing/cooking- Degree of starch gelatinisationGI instant rice, boiled 1min = 46GI instant rice , boiled 6 min = 87

- Food form/ Particle sizeGI wheat (whole kernel) = 41GI whole wheat flour = 70

GI steamed potatoes = 57GI mashed potatoes = 74

2. Nature of starch- Amylose- AmylopectinWaxy rice (GI=88)>Basmati (GI=58)

1. Nature of the monosaccharides- Glucose → Maltose : 100- Galactose → Lactose: 46- Fructose → Sucrose: 68

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New types of carbohydrates which influence GI of foods ....

6. Type of sweeteners added in diet- isomaltulose: 56- low glycemic syrups: 35

GI

5. Types and amounts of other nutrients - Proteins- Dietary fibers

- Antinutrients- Organic acids

GI white wheat bread = 70GI white bread + 15g psyllium = 53

4. Starch-nutrient interaction- Starch/fat- Starch/proteinGI white wheat bread (WB)= 70GI gluten-free bread (GFB)= 90

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Clinical evidence in favor of GI (Augustin et al , 2002)

• Decrease rise in blood sugar and improve the body's sensitivity to insulin Decrease the risk of insulin resistance, type 2 diabetes mellitus

• Help control hunger, appetite Help lose weight

• Help lower blood lipids (LDL-c and TG) Decrease CVD risk

• Help decrease glycated fructosamine, haemoglobin (HbA1C) 1% reduction of HbA1C : reduction in risks of 21% for diabetes, 14% for myocardial infections, 37% for microvascular complications

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Availability of GI foods (Feord, Leatherhead)

Symbol programmes

Low GI

USA Misleading?

Canada Not permitted/ Misleading

Australia Acceptable

UK No legislation or guidance

France Not permitted/ Misleading

Germany Not permitted/ Misleading

Switzerland Not permitted/ Misleading

South Africa Acceptable

Netherlands Not permitted/ Misleading

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Foods associated with GI

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Foods associated with GI

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No consensus on the importance of GI to human Health & Nutrition

• Proponents:– FAO/WHO– European Association for the Study of Diabetes– Canadian Diabetes Association– Diabetes UK– Dieteticians Association of Australia

• Opponents:– American Diabetes Association – American Heart Association– American Dietetic Association

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A lot of conflicting results (Kelly et al, 2004; Opperman et al, 2004)

• Outcomes:

– Significant heterogeneity

– None of the comparisons detected any evidence of a difference in effect on:

• HDL-c, LDL-c, TG between the low and high GI diet in all types of subjects

• body weight, fasting glucose, fasting insulin between the low and high GI diet in subjects with CHD

– There is some evidence of a reduction in total cholesterol (-0.17 mmol/L) and in HbA1C (-0.45%) with low-GI diets compared to high GI diets in diabetic subjects

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A lot of conflicting results (Kelly et al, 2004; Opperman et al, 2004)

•Conclusion:

– Evidence low GI reduce CHD and CHD risk factors is weak →recent studies (Tavani et al, 2003 and Frost et al, 2004)

– Low-GI diets improved blood glucose control (corroborated by the meta-analysis of Brand-Miller et al, 2003) and cholesterol in type 2 diabetic subjects

– No notable effects of a low-GI diet on lipid and CHO metabolism in healthy subjects

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Conclusion on GI

• May be an interesting tool for diabetic subjects but not for allthe population

• However, using GI as a based tool to enable selection of CHO-containing foods for diabetic subjects is still not globally recommended (American diabetes association, 2002 and Franz, 2003)

• Moreover..............GI is not an interesting tool– Very difficult to communicate to consumers– High GI foods would be seen as unhealthy foods although they are

recommended during and after exercise– Important role of the fibers in the low-GI foods on the risk factors – GI does not always give a proper idea of the real glycemic

response to foods

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00.5

11.5

22.5

high >165 medium 165-143

low 143 high >5.8g/d

low <2.5g/day

Glycemic load, cereal fiber intake and relative risk of type 2 diabetes in women (Salmeron et al., 1997, Meyer et al, 2000; Jacobs et al, 2000; Fung et al, 2002; Stevens et al, 2004; Schulze et al, 2004 )

Glycemic loadCer

eal fib

er int

ake

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Glycemic load (GL) and glycemic response (GR)

GL = (GI x available CHO content per food serving)/100

GR : expresses the ability of a food /drink to elevate the blood glucose levels after consumption

GL seem to be a better tool to predict the glycemic response to individual foods than GI alone or the amount of CHO alone (Ludwig, 2003)

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Importance of GL – meta-analysis of epidemiological studies (Livesey, in writing) 75,521 CHD Women;

Nurses Health StudyLiu et al (2001) Am J Clin Nutr 73,560-6

42,759 T2DM Men; Health Professionals Study Salmeron et al 1997 Diabetes Care 20, 545-50

0.8

1

1.2

1.4

1.6

1.8

2

50 100 150 200

Glycaemic load (g eq./d)

Rep

orte

d re

lativ

e ris

k

Coronary heart disease and type 2 diabetes mellitus – prospective studies

Better Worse

Significance vs Glycaemic load , P<0.0001 Significance vs Glycaemic index, P<0.35 only

65,713 T2DM Women;Nurses Health StudySalmeron et al 1997 JAMA 12, 472-477

91,249 T2DM Women; Nurses Health Study IISchulze et al (2004) Am J ClinNutr 80, 348-56

35,988 T2DM Women;Iowa Womens StudyMeyer et al (2000) AJCN 71, 921-30

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GL is stronger than GI as marker of dietary risk

0.5

0.75

1

1.25

1.5

1.75

2

0 1 2 3 4 5

Quintile

Fast

ing

trig

lyce

ride

(Q1

= 1)

Glycaemic LoadGlycaemic Index

Nurses’s Health Study (sample n = 280, age 45-70)Liu et al, Am J Clin Nutr 2001, 73 560-6

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GL is stronger than GI as marker of dietary risk

0

2.5

5

7.5

10

0 1 2 3 4 5

Quintile

Elev

ated

hsC

RP

(odd

s ra

tio)

Glycaemic Load

Glycaemic Index

Women’s Health Study (sample n = 244, age 45-82)Liu et al (2002) Am J Clin Nutr 75, 492-8

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New trends are emerging in the food industry ....Low GIfood /low glycemic response

• Desire to compare the glycemic response of foods or drinks based on portion size

GIfood: expresses the ability of a food/drink to elevate the blood glucose level after consumption, whatever the amount of available carbohydrates is.

Low-carb• In response to the recommendation of the WHO to reduce the consumption of sugar/rapidly available carbohydrates as well as to favor the consumption of low glycemic load foods.

Low-carb: it consists in reducing the amount of total availablecarbohydrate in the food.

Both trends REDUCE the GLYCEMIC LOAD of a food

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New trends in the food industry .... to reduce GL

- replace available CHO’s by fat or protein (nutritionally not relevant)- replace available CHO’s by non-available CHO’s (dietary fibers)- replace available CHO’s by polyols which are poorly absorbed and/or metabolised

Low-carb/Low-GIfood (low glycemic response)

Low-GIfood (low glycemic response)

- use low GI carbohydrates

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Too much Sugar, too much carbohydrate or

just too much?

(David Jenkins et al. AJCN 2004; 79, 711-712)

• There is no clear indication that obesity is directly caused by increased sugar consumption or carbohydrate intake in general!

• This raises questions about the total amount of food consumed and amount of energy expended!

• ……wake –up call for radical lifestyle change!

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General conclusions

• Reduce the overall glycemic load of the diet

• Consumption of whole grains foods and unrefined dietary fibers (around 30g/d)

• GL = GI x amount of CHO consumed fiber decrease GL of foodsThis trend will drive the market to whole grains enriched foods and

to fibers-rich foods

• GI labelling ? will certainely be evolving to GR or GL labelling