OVERVIEW OF DIETARY CARBOHYDRATES & GLYCEMIC INDEX. Prof. Dr. Shameem Siddiqui JSMU SMC Biochemistry

Transcription

1 OVERVIEW OF DIETARY CARBOHYDRATES & GLYCEMIC INDEX Prof. Dr. Shameem Siddiqui JSMU SMC Biochemistry

2 Nutri;on Science Relates to Macronutrients CHO, Protein, Fats. Micronutrients Vitamins, & Trace Elements Water & Main Electrolytes Oxygen delivery Acid Base balance

3 Terminologies rela;ng nutri;on DIET Total of all kind of food and drinks that a man, animal or a community habitually eats. Eg Balanced diet, vegetarian diet, Atkins diet FOOD any nutrihous/junk substance that man/animal eat or drink eg French fries, Lays, coke, Aloo Gosht. NUTRIENT Chemically defined components required by the body essenhal for growth and maintenance of life, eg Fish, Poultry, grains, veg & fruits.

4 Six Classes of Nutrients 1. Carbohydrates 2. Fats 3. Proteins 4. Water 5. Vitamins 6. Minerals Macronutrients: Carbohydrates, Fats, Proteins, Water Micronutrients: Vitamins & Minerals No single ratio of macronutrients defines a perfect diet!

5 Dietary Reference Standards for Intake of nutrients DIETARY REFERENCE INTAKE EAR: intake that meet requirement of 50% of healthy individuals. RDA: intake that meet the requirement of 98% healthy individuals. AI: eshmates of nutrient intake by group of healthy people. UL: highest daily intake level with no risk of adverse effect

6 DRI) One of the main principals of good health is a balanced diet. Prophet Mohammed (PBUH) emphasized the behavior of ea;ng less as a method of preven;ng sickness and diseases. Prophet Mohammed (PBUH) is reported to have said: "Eat less you will be healthier." (Hadith) "Nothing is worse than a person who fills his stomach. It should be enough for the son of Adam to have a few bites to sagsfy his hunger. If he wishes more, it should be: one- third for his food, one- third for his liquids, and one- third for his breath." (Tarmazi, ibn Majah and Hakim)

7 Energy Requirement

8 Dietary Carbohydrates (70-85%)

9 Carbohydrate Basics Primary role: Provide body with energy Ul;mate Targets: brain and red blood cells Eye and Renal medulla Nerve cells and red blood cells rely almost exclusively on glucose as an energy source

10 Carbohydrate Basics Considered an ideal fuel (yield 4Kcal/gm) as compared to other sources of calories Less expensive than protein. MulHple health benefits High- fat diets are associated with chronic disease Constitute ¾ of biological world

11 Other General Func;ons of Carbohydrates Precursor of Glycoprotein, Glycolipids & Glyco- polysaccharides. Provide Carbon skeleton for NEAA synthesis. Involved in Fat Synthesis via Acetyl CoA. Involved in Glycogen Synthesis. Provides TCA- Cycle Intermediates. Component of Nucleo;de Sugar (Ribose)

12 Dietary Carbohydrates All carbohydrates are composed of Simple sugars & Complex Carbohydrates Includes : Refined Carbohydrates: Sucrose (sweets/drinks, or fruit juices) Complex Carbohydrates Starch (grains, potatoes) Fibers Cellulose, hemicellulose, lignin, pechn, beta glucan. (IndigesHble by the human gut). Fibers are present in cereals, legumes, vegetable and fruits.

13 Simple Vs Complex carbohydrates Simple: Mono- and Di- saccharides Complex: Oligo- and Poly- saccharides Oligosaccharides contain 3-9 monosaccharide units and are included as polysaccharides Long chains of sugars; also called polysaccharides (saccharide = sugar unit)

14 Simple Carbohydrates/Sugars: MONOsaccharides Glucose Fructose Galactose DIsaccharides l Sucrose: Glucose + Fructose l Lactose: Glucose + Galactose l Maltose: Glucose + Glucose

15 Complex Carbohydrates Polysaccharides are long chains of mono- saccharides include: glycogen found in animals starch and fiber found in plants.

16 CHEMISTRY Human Diet (~50% of Calories ingested as CHO) 10-85% Starch 160 gm Sucrose 120 gm Lactose 30 gm Glucose 05 gm Fructose 05 gm Maltose Traces

17 Sources of Carbohydrates Sources Sucrose Lactose Fructose Starch Amylose- linear AmylopecHn- br Obtained from Sugar, Drinks Milk Fruits, honey, vegetables & Corn- Syrup, Processed Food Wheat, Rice, Corn, Barley, Oat, Legumes, millet, & root vegetables like potatoes Glycogen- very br Muscle & Liver

18 New Environment DIGESTED ABSORBED TRANSPORTED & METABOLIZED

19 RDA = 130 gm

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22 Overview of Metabolism metabolic need is for glucose: ~300 g/d in humans Glucose can be made from most AAs (not Leu) Glucose can be made from propionate (SCFA) Glucose can be made from glycerol Glucose cannot be made from faxy acids CHO not strictly essengal in diet Relying solely on AAs etc. as precursor for glucose not prudent or pracgcal (except for carnivores), so...

23 BLOOD GLUCOSE LEVEL HAS TO BE MAINTAINED 4-6mmol/L (10mmol/L aier meals) High BGL= complicahons of DM Low BGL = Brain damage & death

24 URINE 10mmol/L mmol/l Muscle All Hssues Liver as Glucostat

25 Factors affechng blood glucose Tend to increase Hunger Glucose absorphon from gut HepaHc glycogenolysis Adrenaline Glucagon Gluconeogenesis in liver Insulin antagonist Growth Hormone CorHsol Insulin destroying enzymes

26 Factors affechng blood glucose Tend to decrease SaHety Glucose diffusion in ECF Muscular exercise Insulin Glucose oxidahon Glycogen deposihon Lipogenesis Gluconeogenesis { glucosuria in diabetes}

27 GLYCEMIC INDEX & GLYCEMIC OVERLOAD

28 A scale that ranks carbohydrates by how much they raise blood glucose levels compared to a reference food. Ranking Low 0 55 Moderate High 70 or more

29 Factors Influencing GI Ranking Type of starch Cooking Physical entrapment Food processing Viscosity of fiber Acid content Sugar content Fat content Protein content How does all this affect our glycemic levels? How does all this make us feel after eating carbohydrate-containing foods?

30 Glycemic Load (GL): What does it mean? Glycemic load measures the degree of glycemic response and insulin demand produced by a specific amount of a specific food. Glycemic load reflects both the quality and the quantity of dietary carbohydrates. GL = GI/100 x CHO (grams) per serving Example: GL of an apple = 40/100 x 15g = 6g

31 Glycemic Load (GL): Calculation 1/2 cup converted, LG rice 38/100 x 22g = 8 g 1/2 cup glutinous rice 98/100 x 29g = 28 g 2 1/4 Tbsp glutinous rice 98/100 x 8g = 8 g 1 2/3 cups converted, LG rice 38/100 x 73g = 28 g

32 Glycemic Load (GL): Ranking Individual food portion: Low 0-10 Moderate High 20+

33 GI vs. GL Glycemic Index: ranks carbohydrates based on their immediate blood glucose response. GI = glycemic quality Glycemic Load: helps predict blood glucose response to specific amount of specific carbohydrate food. GL = glycemic quality quantity

34 Benefits of Low GI Diet Are there any documented benefits to lowering the GI of one s diet? YES! BG levels cholesterol levels type 2 DM risk heart disease risk weight

35 HIGH GLYCEMIC INDEX (>70) Baked potato French fries Rice cakes Bagels Graham crackers Refined cereal products Sugar- sweetened beverages Jelly beans Candy bars Couscous Cranberry juice cocktail White basmah rice White- flour pasta MEDIUM GLYCEMIC INDEX (56-69) Orange juice Popcorn Corn Sweet potato Peas Brown/white rice Oatmeal Bulgur Whole grain breads Whole grain pasta No- sugar added fruitjuices LOW GLYCEMIC INDEX (<55) High- fiber fruits and vegetables (apple, pear green beans, apricots) Milk Yogurt Legumes (chick peas,kidney beans, blackbeans, lenhls, pintobeans

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38 Today s Overview Biochemistry of nutrient Explore overview of metabolism from nutrihon point of view Meet your nutrient in other perspechve GI & GL

39 Islamic way of ea;ng Habit Dua before each meal Dua aier each meal EaHng LESS DieHng EaHng slowly ModeraHon and sharing EaHng together Drink water or liquid in two or three installments

40 Table Manners 1) Sisng down while eahng. 2) EaHng together and sharing of food. 3) Serving others first, especially guests. 4) Host is the first to start eahng and the last to finish. (This is the opposite of Western table manners.) 5) Taking food in smaller porhons than needed. 6) Finishing (cleaning) the plate without leiovers

41 Table Manners 7) EaHng with the right hand. 8) WaiHng for everyone to finish before finally leaving the table or floor cloth. 9) Washing hands and mouth before and aier eahng. 10) Brushing teeth before and aier eahng (Miswak). 11) Sharing food with relahves, friends, neighbors, the needy and deshtute.

42 12) Eat from the corner of the plate from your side, don't eat from the middle or the other side of the dish. 13) As an invited guest it is permissible to ask your host for water or salt. Accept what is offered and don't request addihonal items your host may not have available. 14) When eahng in a group, if quanhhes are limited, share from your plate with the others. The Prophet Mohammed (pbuh) is reported to have said, "A plate for one is enough for two, and a plate for two is enough for four.

43 QUESTIONS?

44 Working Toward Mastery Projects Worked On Get Familiar Get Experienced Achieve Mastery Time Spent

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46 APPENDIX

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