Fibre, Vitamins & Minerals

What is fibre?

Fibre is a type of carbohydrate found in plant foods that isn't digested in the small intestine (see Lesson 4). Instead, it passes to the large intestine, where some of it is fermented by gut bacteria.

Fibre helps keep the digestive system working normally, and diets higher in fibre are associated with a lower risk of some health conditions. At a beginner level, fibre is often described in two broad groups:

• Soluble fibre partly dissolves in water. Oats, beans, lentils and some fruit are sources.
• Insoluble fibre doesn't dissolve in water and helps add bulk. Wholegrains, nuts and the skins of vegetables and fruit are sources.

Most plant foods contain a mix of both.

Where fibre comes from

Fibre is found only in plant foods: wholegrain bread, pasta and cereals, oats, beans, lentils and peas, vegetables, fruit, nuts and seeds, and potatoes with their skins. Meat, fish, eggs and dairy contain no fibre. UK NHS guidance suggests most adults in the UK don't eat enough fibre and gives practical ways to include more; recommended amounts differ between countries.

What are vitamins?

Vitamins are nutrients the body needs in small amounts to work properly. Each has different functions, and how much a person needs varies with age, sex, life stage and health. They are often grouped by how they dissolve:

Because water-soluble vitamins can be affected by heat and cooking water, how you prepare vegetables matters a little too. See how raw and cooked vegetables compare.

What are minerals?

Minerals are elements the body needs to build tissues and to work properly. A few examples:

• Calcium helps build and maintain bones and teeth. Sources include dairy foods, calcium-fortified plant drinks, and some green leafy vegetables.
• Iron is needed to make red blood cells. Sources include meat, beans, lentils, nuts and fortified cereals.
• Potassium helps control the balance of fluids in the body. Sources include many fruits, vegetables and pulses.
• Iodine is needed to make thyroid hormones. Sources include fish, dairy foods and, in some countries, iodised salt.

Some nutrients can be harmful in large amounts, which is one reason not to take high-dose supplements without advice. Some national health bodies give specific advice for particular groups, such as during pregnancy. Check guidance where you live and speak to a healthcare professional for individual advice.

Why variety matters

No single food provides every vitamin and mineral. A varied diet with plenty of vegetables, fruit, wholegrains, pulses and a range of protein foods (see Lesson 1) gives most people the vitamins and minerals they need.

Fibre, vitamins and minerals on labels

Fibre is listed on many labels in grams. In the UK, fibre may be included on the nutrition panel but isn't one of the nutrients that must be shown; on US Nutrition Facts labels, dietary fibre is required. Vitamins and minerals are often shown as a percentage of a reference amount. These reference amounts are set differently by different authorities (for example, “%RI” in the UK/EU and “%DV” in the US), so percentages aren't directly comparable between countries. Lesson 7 covers labels in detail.