Nutrition and Digestion: Enzymes & Dietary Fibre

• Nutrition involves obtaining nutrients from food to sustain life functions.
• Digestion is breaking down complex food molecules into smaller, absorbable units.
• Overall well-being is influenced by nutrition and digestion.

Enzymes

• Enzymes are biological catalysts that accelerate chemical reactions within the body.
• Crucial for digestion, they simplify complex molecules.
• Each enzyme has a specific substrate.
• Enzymes function by reducing the activation energy required for reactions.
• Temperature and pH levels affect enzymatic activity.
• Amylase, protease, and lipase are examples of enzymes.

Dietary Fibre

• Dietary fibre is the indigestible component of plant-based foods.
• It introduces bulk to the diet, facilitating healthy bowel movements.
• Fibre exists in soluble and insoluble forms.
• Soluble fibre dissolves in water, creating a gel-like substance.
• It aids in blood sugar regulation and reduces cholesterol.
• Insoluble fibre increases stool bulk, preventing constipation.
• Sources include fruits, vegetables, and whole grains.
• The recommended daily intake is 25-30 grams.

Digestion of Carbohydrates

• Digestion starts in the mouth with salivary amylase.
• Salivary amylase breaks down starch into smaller polysaccharides.
• Pancreatic amylase continues the breakdown in the small intestine.
• This breaks down polysaccharides into disaccharides.
• Maltase, sucrase, and lactase break down disaccharides into monosaccharides.
• Monosaccharides (glucose, fructose, galactose) are absorbed into the bloodstream.
• Undigested carbs pass into the large intestine and may be fermented by bacteria.

Digestion of Protein

• The process starts in the stomach with pepsin.
• Pepsin breaks proteins into smaller peptides.
• Pancreatic proteases (trypsin, chymotrypsin) continue digestion in the small intestine.
• They break down peptides into smaller peptides and amino acids.
• Peptidases in the small intestine further break down peptides into amino acids.
• Amino acids are absorbed into the bloodstream.
• Protein digestion provides amino acids, essential for building proteins.

Lipids, Oils, and Fats

• They are essential nutrients providing energy and supporting cell structure and function.
• Fat digestion primarily occurs in the small intestine.
• Bile emulsifies fats into smaller droplets.
• Pancreatic lipase breaks down triglycerides into monoglycerides and fatty acids.
• These components, along with cholesterol and fat-soluble vitamins, form micelles.
• Micelles transport digested fats to intestinal cells for absorption.
• Within intestinal cells, triglycerides are re-synthesized into chylomicrons.
• Chylomicrons enter the lymphatic system before the bloodstream.
• Fats provide energy, insulation, and support hormone production.
• Essential fatty acids, like omega-3 and omega-6, must come from the diet.