NUTRITIONAL ASPECT OF MACRONUTRIENT

CARBOHYDRATES

Dept of NutritionMedical School Padjadjaran University

INTRODUCTION

Compounds composed of carbon, hydrogen, oxygen arranged as monosaccharide or multiple monosaccharide

Cn (H2O)n. Main energy sources for Asia people 65-80% energy of food intake of Indonesian

people. As mix food ingredients (sweetener & flavor)

Recommendation

60-65% energy demand come from carbohydrates:– 50-55% complex carbohydrates– 10% simple carbohydrates

CLASSIFICATION

1. Simple CH: Monosaccharide

– Glucose: one of the two sugars in disaccharides.

– Fructose: sweeteners of sugars, naturally in fruits and honey.

– Galactose: binds with glucose to form the sugar in milk.

CLASSIFICATION

Disccharide:

A pair of monosaccharide linked together– Sucrose: consist of glucose and fructose,

found in fruits, vegetable, and grains.– Maltose: consist of two glucose units, comes

from starch digestion and fermentation.– Lactose: consist of glucose and galactose,

lactose is the main carbohydrates in milk.

CLASSIFICATION

2. Complex CH / polysaccharides:Many monosaccharide linked together.

Glycogen:– An animal polisaccharide composed of glucose– Stored in liver and muscles as a storage form of

glucose.

Starches:

Plant polisaccharide composed of glucose: grains, tubers, legumes.

CLASSIFICATION

3. Fibers:

Soluble fibers: Pectin, gum, mucilage, some hemicellulose,

psilium.

Insoluble fibers:

Cellulose, many hemicellulose, lignin.

Metabolism

Digestion process breaks carbohydrate

down to a simpler one so it can be easily

absorbed.

Monosaccharide (glucose, fructose,

galactose):

end products of carbohydrate digestion.

carbohydrate is absorbed in this form.

Digestion

In the mouth: The salivary enzyme amylase starts to work,

hydrolizing starch to shorter polisaccharides and to maltose.

In the stomach: To a small extent, continue breaking starch

down.

Digestion

In the small intestine:– Perform most of the work of carbohydrates

digestion.– Pancreatic amylase continues breaking down

the polysaccharides to shorter glucose chains and disaccharides.

– On the outer membrane of the intestinal cell, the specific enzymes dismantle specific disaccharides (lactase, sucrase, maltase).

Absorption

Absorption to enterocyt by active transport. The blood then circulates through the liver. All monosaccharides are transform to

glucose. Some of glucose are utilized by liver cell and

the rest of them distributed to cell organs.

Metabolism in cell organs

Glucose transforms to glucose-6 phosphate. If the cell lack of energy (ATP):

Metabolism glucose will product energy. If energy (ATP) adequate:

Glucose will metabolized to:

1. Glycogen (limited)

2. Fatty acid, lipid and cholesterol.

3. Non essential amino acid

4. Glycoprotein and glycolipid ( cell structure)

Function

Glucose:Main energy source for brain, nerve, blood and adrenal gland.

Protein sparring/ prevent protein utilization as an energy sources.

Prevent lipid utilization as an energy source in large amount, thus glucose could prevent ketosis.

Muscle, liver and glycogen:Energy reserve

Function

Glycolipid and glycoprotein:Cell structure.

Dietary fibers:Add volume and meal portion and prolonging food in the stomach, provides senses of fullness. It use to manage DM patient and weight control in obese/overweight patients.

Water holding, increase fecal bulk.

Function

Soluble fibers: Reduce glucose absorption.

Reduce blood cholesterol through two mechanisms:

Bound to bile acid in intestin prevent bile reabsobtion therefore promotes the production of bile from cholesterol endogen.

Reduce cholesterol absorption.

Normal level of glucose per 100 cc (dL) plasma

Fasting (+12 hours after last meal): < 100 mg/dL plasma

2 hours post prandial: 100-120 mg/dL plasma.

To maintain of glucose supply to the brain therefore the body will keep the stability of glucose.

In hyperglycemia, insulin hormone will reduce glucose level through: increasing glucose uptake by the cell. increasing glycogenesis in muscle and liver. increasing lipogenesis and protein synthesis.

Hormones that increase glucose level in hypoglycemia

Glucagon improves glycogenolysis and gluconeogenesis in the liver.

Epinephrin enhances glycogenolysis and gluconeogenesis in stress condition.

Glucocorticoid promotes proteolysis and gluconeogenesis

Carbohydrates food sources

Monosaccharides Food sources

Glucose/dextrose Fruits, honey, sweet corn, carrot, hydrolized sucrose, maltose, lactose

Fructose Fruits, honey, hydrolized sucrose, corn syrup

Galactose hydrolized lactose, milk

Manitol Canned fruits, soft drink

Xylitol Artificial sweetener of chewing gum

Sorbitol Artificial sweetener of sugar free candy

Carbohydrates food sources

Disaccharides Food sourcesSucrose

(Glucose + fructose)

Sugar (99,5%), red sugar (90-95%),

Candy, chocolate, soft drink, sweetened tea, cake, biscuit, ice cream, cendol, kolak, rujak, etc.

Lactose

(Glucose + galactose)Milk

Maltose

(Glucose + glucose)Bean sprouts

Carbohydrates food sources

Polysacharides Food sourcesStarch, amylum (plant) Rice: cooked rice, porridge,

bihun, serabi.

Flour: noodle, bread, pizza, biscuit, etc.

Potato, tapioca.

Bean soybean, peanut.

Corn: popcorn, corn flakes.

Fruits: salak, sawo, banana, etc.

Glycogen

(animal)

Live, meat, kidney.

Carbohydrates food sources

Fibers Food sources

Cellulose Vegetables cell membrane, fruits, peanuts

Hemicellulose Unfiltered flour, rice, pelt

Gum/pectin Fruits: apple pelt, inside orange pelt, peanut, bean, soybean, guava

Lignin (Non CH) Branches of plants

Glycaemic Index (GI)

Physiological measurement which can be used to estimate the relative rates of glucose absorption from various foods

(Jenkins et all, 1981).

Subject ingest a portion of the test food containing 50 g carbohydtare, and blood glucose levels in peripheral blood are measured every 30 min for 3 hr. Compared with the same subject who is given 50 g carbohydrate from glucose or white bread.

Glycaemic Index Value

White bread 100 Rice 81 Boiled potato 80 Corn 80 Cornflakes 99 Bean 43 Peanut 15 Soybean 20 Banana 84 Apple 52 Orange 51 Orange juice 71

Factors that affect GI

Food absorption: Easier to absorb, higher GI value

Lipid, protein and fiber contains: The larger lipid or protein or fiber contain

the lower GI value.

Food form: solid, soft, liquid: The more liquid the higher the GI

Diseases related to carbohydrate metabolism disorder

Reactive hypoglycemia: Metabolic disturbance by abnormal insulin

activity

Caries dentis: Refined carbohydrates >>

Lactose intolerance: Lack/ deficient of lactase

Diseases related to carbohydrate metabolism disorder

Diabetes mellitus:

Metabolic disturbance by insulin resistant

Obesity:

High risk for degenerative disease that affecting by atherosclerosis