Focus on minerals

Dr Joan Ransley

Minerals in our diet are often an afterthought but they are as important to health as vitamins. But which foods contain the minerals we need? How much do we need of them? Can we overdose on minerals? And are mineral supplements advised? These are all important questions which need to be considered carefully.

What are minerals?

Minerals are essential nutrients which we can’t live without. We can’t make them in our body and so we must obtain them from the food we eat. Without minerals our bodies can develop serious illness such as iron deficiency anaemia, goitre, and rickets.

How many minerals does the body need?

There are ten key minerals and they are: calcium, iron, sodium, fluoride, iodine, magnesium, phosphorous, potassium, selenium, and zinc.

Which foods contain the minerals we need?

All the minerals we need can be obtained from five key food groups which are:

1. fruit and vegetables
2. potatoes, bread, rice, pasta and other starchy, wholegrain carbohydrates
3. beans, pulses, fish, eggs, meat and other proteins
4. dairy and alternatives (like Oat Drink)
5. oils and spreads

Different foods provide us with different minerals in varying amounts, which is why it is important to aim for a varied and balanced diet.

How much do we need of each mineral?

Minerals are known as ‘micronutrients’ because they are needed by the body in small amounts. The amount we need per day is known as the Reference Intake (RI) and can be found on the nutrition label of some products.

Requirements for minerals vary depending on age, body size, sex and stages in the life cycle e.g. pregnancy.

Full details can be obtained here.

Can we overdose on minerals?

Yes, it is possible but rare. It is important not to take more than the RI of a mineral. For example, too much iron can damage the lining of the gut. ([1] It is important not to leave vitamin and mineral supplements in a place where children can eat them. They can be toxic if eaten in large amounts. )

Are mineral supplements necessary?

Most people should get all the minerals they need by eating a varied diet. Supplements are not a substitute for a healthy diet, which provides other important dietary components such as vitamins and fibre. If you are concerned about your health speak to a GP before self-medicating with dietary supplements.

Ten important minerals in your diet

1. Calcium

What does it do? Builds and maintain strong bones and teeth. Helps blood to clot and, nerves and muscles to function.

Food sources Dairy food and calcium-fortified dairy- alternatives e.g. Oat Drink. Canned fish, green leafy vegetables, fish, and bread.

Reference intake 800 mg

2. Iron

What does it do? Helps make red blood cells, which carry oxygen around the body. It also helps the immune system and brain function.

Food sources Red meat, beans, pulses, nuts and seeds, fish (such as canned sardines), wholemeal bread, and dried fruit.

Reference intake 14mg

3. Sodium

What does it do? Regulates the water content in the body.

Food sources Small amounts are found naturally in many foods. Often added as salt (sodium chloride) during processing and cooking.

Reference intake 6g of salt (equivalent to about 2.4g of sodium)

4. Fluoride

What does it do? Helps the formation of strong teeth and reduces the risk of tooth decay.

Food sources Tap water, tea (and toothpaste).

Reference intake 3.5mg

5. Iodine

What does it do? Helps make thyroid hormones and brain function. Food sources Milk, yogurt, cheese, eggs, fish, shellfish and sea vegetables such as nori.

Reference intake 150 μg

6. Magnesium

What does it do? Helps release energy from food, maintain strong bones and helps normal muscle and nerve function.

Food sources Nuts and seeds, wholegrain cereals.

Reference intake 375mg

7. Phosphorus

What does it do? Helps build strong bones and teeth and helps to release energy from food.

Food sources Red meat, poultry, fish, milk, cheese, yogurt, eggs, bread, and wholegrains.

Reference intake 700mg

8. Potassium

What does it do? Helps regulates the water content in the body and maintain normal blood pressure. Helps the nerves and muscles to function normally.

Food sources Bananas, blackcurrants, avocado, spinach, parsnip and beetroot, dried fruit, poultry, red meat, fish, milk and wholegrains

Reference intake 200mg

9. Selenium

What does it do? Used to make DNA and protects against cell damage and infections. Helps normal fertility in males.

Food sources Brazil nuts, cashews, and sunflower seeds, eggs, poultry, fish, and shellfish

Reference intake 55µg

10. Zinc

What does it do? Used to make DNA, builds proteins, heals damaged tissue, and supports a healthy immune system. Zinc is also involved with the senses of taste and smell and normal fertility.

Food sources Meat, cheese, some shellfish, nuts, pumpkin seeds and pine nuts, wholegrain cereals and bread.

Reference intake 10mg