An adult contains around one kilogram of calcium, which is the most abundant mineral in the human body. Bones and teeth store around 99% of our calcium and 1 per cent is used to support metabolic functions. Levels of calcium in the blood are tightly controlled, as the slightest deviations may result in serious symptoms of the nervous system and the heart.

Iodone is an essential trace element. An adult contains around 20-50 micrograms of iodine with 2/3 of the total supply being stored in the thyroid gland. The only known function of iodine is that it supports the two thyroid hormones that control all metabolic processes in the body. The thyroid hormones are named T3 (triiodothyronine) and T4 (thyroxine), depending on how many iodine atoms they contain. T3 functions substantially faster than T4, which is considered a precursor. Selenium is also an essential constituent of enzymes that regulate thyroid hormonal activity. Among other things, it works by removing an iodine atom, whereby the passive T4 hormone is converted to the active T3 hormone. If too little T3 hormone is produced, the metabolic rate slows down. If too much T3 is produced, the metabolic rate speeds up. For that reason, it is vital that there is enough iodine and selenium to ensure the right balance.

Manganese is an essential nutrient. An adult contains around 10-20 mg of manganese that is evenly distributed throughout the body. Only around five per cent of dietary manganese is absorbed, possibly by means of the same mechanisms as those involved in the uptake of iron. Manganese is mainly involved in different enzymatic systems such as pyruvate carboxylase and superoxide dismutase (SOD) that support the metabolism of macronutrients such as carbohydrate, protein, and fat and also work by neutralising free radicals.

Vitamin B6, also known as pyridoxine, is converted to the active forms, pyridoxal phosphate and pyridoxamine phosphate. Vitamin B6 is water-soluble and because it does not get stored in the body we depend on regular intake of the nutrient. Vitamin B6 is destroyed by heating and light.

- but is heavily overrated in energy beverages and breakfast cereals

Vitamin B6 is essential for the energy turnover, nervous system, hormone balance, and a number of other important functions. Vitamin B6 has been added to many energy beverages and breakfast cereals as an “energy booster” or a way of telling consumers that the product is healthy. But don’t be fooled. The same products often contain loads of sugar and caffeine, which burdens the blood sugar balance and the nervous system. It is therefore far better to get vitamin B6 by eating a balanced and healthy diet, possibly topped off with a supplement if necessary. Those who are likely to benefit from a supplement are strict vegetarians and vegans, pregnant and breastfeeding women, and seniors.