Minerals

Unlike vitamins, which are organic substances (containing the element carbon), minerals are inorganic and are found in rocks and soil. Vegetables absorb minerals as they grow, while animals digest it through their diet. Like vitamins, minerals can be divided into two groups - those needed in larger quantities (major minerals) and those only required in tiny amounts (trace elements).

Minerals needed daily include calcium, magnesium, phosphorus, potassium and sodium. These minerals are present in virtually all cells of the body, ensuring our internal systems function efficiently. Acute imbalances of these minerals can be potentially fatal. Such cases are rarely caused by a poor diet, but usually the result of an illness or other unusual factor.

Without minerals, the body would be unable to

• Build new tissues.
• Contract muscles.
• Process nerve reactions.
• Clot your blood.
• Keep your body pH neutral.
• Regulate body processes.
• Release energy from food.

Mineral deficiencies

Dietary mineral intake must be sustained to maintain physical health.

• Calcium deficiency can lead to hypocalcaemia (an abnormally low level of calcium in the blood) and osteoporosis.
• Severe magnesium deficiency can result in low levels of calcium in the blood.
• Clinical features of copper deficiency include failure to thrive in babies, impaired immunity, anaemia with altered iron metabolism and bone marrow changes.
• Poor selenium status is linked to a poor immune system and increased susceptibility to illness. It has been suggested that it may be linked to an increased risk of cancer and heart disease.
• In the UK, iodine is added to salt so deficiency is rarely a problem but disorders include goitre (swelling of the thyroid gland in the neck) and poor fetal growth.
• A deficiency of phosphorus can lead to severely low phosphate levels, also known as hypophosphatemia.

Excessive intake

Consuming too many dietary minerals can harm your body. Too much calcium in the blood may cause nausea, vomiting, loss of appetite, increased urination, kidney toxicity, confusion and irregular heart rhythm. High levels of magnesium in the blood can lead to heart problems or difficulty breathing.

Copper poisoning can arise from contamination of water and drinks from metal utensils, and contact with copper coins, plumbing fixtures and industrial applications, causing vomiting and diarrhoea. Toxic levels of selenium are rare but can result in gastrointestinal upset, hair loss, fatigue, irritability and mild nerve damage.

Consult your GP if concerned about any of these issues.

The MRC Human Nutrition Research wrote this article in August 2008.