Nutrition

Food as Fuel

• Cells need energy to function.

• Nutrients from food are digested and circulated throughout the body.

• A nutrient is any substance that has a useful function in the body.

• Calorie: heat required to raise temperature of 1g of H2O by 1°C

Classification of Food

• Organic or Inorganic.

• Macronutrients or Micronutrients.

Organic vs. Inorganic

• Organic: Produced by living organisms.– Carbohydrates, protein, fats and vitamins.

• Inorganic: From rocks, soil and seas.– Water and minerals.

Macronutrients vs. Micronutrients

• Macronutrients - Needed in large amounts.– Carbohydrates, proteins and fats.

• Micronutrients - Needed in small amounts.– Vitamins and minerals.

Carbohydrates

• Composed of carbon, hydrogen & oxygen.

• Major source of energy.– Starches, etc.

• Made up of sugars– Ready source of glucose

• Excess stored as glycogen or as fat.

• Cellulose (fibre) indigestible but important.

Fats

• Concentrated source of energy– 2x the energy of carbs

• Also made of C, H and

O but in different ratio• Also used for insulation, forms

cell membranes, protects vital organs & increases nerve transmission.

Fats

• Unsaturated fats: Liquid at room temperature.– Easier for body to digest– e.g., olive oil, canola oil

• Saturated fats: Solid at room temperature.– Harder for the body to digest– e.g., butter, lard

Which Fat is Healthier?

Proteins

• Most abundant compound in body• Used throughout the body

– Structure for skin, organs, bones, etc. – Also enzymes and hormones

• Made of 20 amino acids– 8 are essential - get from diet

• Meat, eggs, milk, fish, etc.

Micronutrients

• Not an energy source• Consumed in small

amounts• Vitamins – Growth &

muscle function.- Often act as coenzymes.

• Minerals – e.g., iron (blood), calcium (bones), etc.

Water

• Most abundant substance in body.

• 90% of blood plasma.

• Transports all nutrients.

• Forms extracellular fluid between cells.

• Regulates body temperature