VMBO Year 2 · HAVO/VWO Years 2–3 · Nutrition and digestion · Section 2.1

Foods and nutrients

Plant-based or animal-based

Everything you eat and drink is a food or drink product. Products may come from plants or from animals, such as meat, eggs and milk.

Plant-based alternatives include reduced-fat spreads made from vegetable oils and soya drinks made from soya beans.

Functions of nutrients

Nutrients are substances in food that the body needs. This course groups their roles into four functions:

• Fuel: Supplies energy for body functions.
• Building material: Supports growth and the repair of tissues.
• Stored reserve: Can be stored for later use.
• Protective role: Helps maintain normal body functions and prevent deficiency diseases.

A nutrient may have more than one function.

Six groups of nutrients

The six groups studied here are proteins, carbohydrates, fats, water, minerals and vitamins.

Proteins

Proteins mainly provide materials for building and repairing cells, including muscle tissue. They can also be used as fuel. The body does not have a special protein store; excess energy from food can contribute to fat storage.

Carbohydrates

Carbohydrates include sugars such as glucose, starch, glycogen and dietary fibre. Digestible carbohydrates mainly supply energy and can also contribute to building or storage functions.

Glucose can be stored as glycogen in the liver and muscles. Excess energy can also contribute to fat storage.

Fats

Fats supply energy and provide building materials, including components of cell membranes. They can be stored as reserves, for example in the fat layer beneath the skin.

Water

About 60% of a typical adult's body mass is water, although this varies. Water is an important component of cells and is needed for transporting substances, for example in blood.

Minerals

Minerals, including calcium, magnesium, sodium and iron, have structural and regulatory roles. Calcium, for example, helps build bones.

Vitamins

Vitamins are needed in small amounts for normal body functions. Deficiencies and, for some vitamins, excessive intakes can cause harm.

Vitamin A supports vision and healthy tissues; vitamin D helps the body absorb calcium and maintain bones. Vitamins include A, the B group, C, D, E and K.

Dietary fibre

Dietary fibre consists mainly of plant carbohydrates that human digestive enzymes cannot break down. Sources include vegetables, fruit, wholegrain foods and pulses.

Fibre supports bowel function and can help you feel full. Some fibre is broken down by gut bacteria.