Understanding Carbohydrates

• Carbohydrates are organic compounds composed of carbon, hydrogen, and oxygen.
• Examples of prevalent carbohydrates include glucose, fructose, and sucrose.

Carbohydrate Classification

• Carbohydrates get classified based on the number of saccharide units and their structural arrangement.
• The main classifications are:
• Monosaccharides
• Disaccharides
• Polysaccharides
• Oligosaccharides

Monosaccharides

• These are the simplest carbohydrates that cannot be further broken down through hydrolysis.
• Monosaccharides consist of 2-6 carbon units.
• Glucose, also known as dextrose, is a monosaccharide.
• Fructose, primarily found in fruits, is referred to as fruit sugar and is a monosaccharide.
• Galactose is another example of a monosaccharide.

Disaccharides

• Disaccharides comprise two monosaccharide units.
• Hydrolysis of a disaccharide yields two monosaccharide units.
• Examples of disaccharides include sucrose, maltose, and lactose.

Polysaccharides

• Polysaccharides, also known as compound sugars, yield over ten molecules of monosaccharides upon hydrolysis.
• Starch, glycogen, dextrin, and dietary fiber are examples of polysaccharides.

Oligosaccharides

• Oligosaccharides consist of a relatively small and defined number of monosaccharides linked together.
• Lactose, maltose, and sucrose are examples of oligosaccharides, each composed of two simple sugars.

Recommended Dietary Allowance (RDA)

• RDA signifies the average daily dietary intake required to fulfill the nutrient requirements of most healthy individuals within specific demographics and life stages.
• Carbohydrates should constitute 60-70% of total calorie intake.
• The RDA of energy for a healthy, sedentary female worker is 1875 kcal/day.
• Therefore, RDA for Carbohydrates= 60% of 1875 kcal/day= 281 g/day

Dietary Sources of Carbohydrates

• Common dietary sources:
• All cereals, such as rice, wheat, bajra, jowar, and ragi.
• Roots and tubers like potato, tapioca, and sweet potato.
• Sugarcane, honey, jaggery, and sago.
• Pulses and legumes.
• Fruits.

Functions of Carbohydrates

• Energy Source: Primary source of energy, offering 4 kcal per gram.
• Protein Sparing Action: Sufficient carbohydrate intake allows protein to focus on body building.
• Fat Metabolism: Essential for the complete oxidation of fats.
• Reserve Food Material: Stored as glycogen and utilized as energy during fasting.
• Conversion to Fat: Excess carbohydrates convert into fat when storage capacity is reached.
• Central Nervous System Function: Crucial energy source for proper brain function. Prolonged hyperglycemia can damage brain tissue.
• Heart Function: Glucose supports consistent heart muscle function; prolonged fasting can harm heart muscles.
• Intestinal Flora: Milk sugar encourages beneficial bacteria growth in the small intestine.
• Dietary Fiber: Aids normal bowel function without providing nutritive value.

Basal Metabolic Rate (BMR)

• BMR measures the energy needed for essential involuntary bodily functions.
• These include heart, brain, liver, lungs, kidney activities, body temperature maintenance, gastrointestinal movements, and oxidation during rest.

Factors Affecting BMR

• Body Composition: Metabolically active organs (liver, heart, lungs, brain, muscles) consume more oxygen and produce more heat than less active tissues (like bone). Higher muscle proportion increases BMR per unit of body weight.
• Surface Area: Taller, thinner individuals have higher surface area, leading to a higher metabolic rate compared to shorter individuals of the same weight.
• Sex: Women generally have lower BMRs due to less muscle tissue and more adipose tissue compared to men. BMR varies with menstrual cycle phases, increasing before menstruation and decreasing afterward.
• Age: BMR is highest in the first two years of life due to rapid growth, then gradually declines, averaging a 2% decrease per decade after age 21.
• Sleep: BMR drops approximately 10% during sleep compared to wakefulness, varying with movement during sleep.
• Climate: BMR tends to be lower in hot climates because the body expends less energy to maintain temperature compared to cold climates.
• Body Temperature: Elevated body temperature increases BMR.
• Endocrine Glands: Thyroid hormones regulate energy metabolism; overactive thyroid (hyperthyroidism) can increase metabolism by 75-100%, while underactive thyroid (hypothyroidism) decreases it. Growth hormones elevate BMR during infancy, childhood, and adolescence.
• Pregnancy: BMR rises each trimester, increasing by 15-20% by the end of the last trimester to support weight gain and fetal growth.
• State of Nutrition: Higher food consumption raises BMR, while prolonged fasting lowers BMR as the body conserves energy.
• Diseased Conditions: BMR often increases in conditions like fever, burns, and tumors.