Diets Often Fail to Supply Sufficient Minerals

Tom Stockdale offers an historical – and rural – perspective

Most breakfast cereals, fortified by the addition of vitamins, are suitable foods with which to start the day. By law bread flour is fortified with vitamins B1 and B6, iron and calcium.

It has to be a matter of opinion, but many diets may fail to provide sufficient iodine, selenium, boron, iron and zinc. In addition many people fail to obtain sufficient vitamin C and D to support robust good health.

Before antibiotics became available most medicine chests contained tincture of iodine (a bactericide) and zinc ointment (to encourage healing) to be used on cuts and abrasions. It was common practice for farmers to dip the teats of their dairy cows into iodine to protect them from mastitis, so a certain amount of iodine must have entered the milk through the skin. It was also customary to spray potatoes with a copper solution to protect them from fungal disease; this increased the dietary intake of copper.

It is, however, necessary to be cautious in the use of copper and zinc supplements because they are absorbed by cells through the same pathway, so that an increase in the uptake of one can induce a deficiency of the other.

In the past far more turnips were grown and used for food than today. These turnips were fertilised with borronated phosphatic manure which prevented them going rotten.

It has been observed that hot springs are a good source of boron and that those who live near hot springs seldom suffer from arthritis. In the tropics, where heavy rainfall washes boron from the soil and where boron is removed from the soil by intensive cropping with sugar cane, the local inhabitants develop arthritis at an early age. Osteoarthritis is described as an autoimmune disease despite the evidence for it being caused by boron deficiency.

Selenium was not identified as an essential element until 1973 when it was found to be a component of an enzyme called glutathione peroxidase. It has since been identified in other enzymes, notably in deiodinase 1, which is of vital importance in its ability to activate thyroxin.

The thyroid gland is situated at the base of the neck and releases thyroxin (T4) and triiodothyronine (T3) in response to thyroid stimulating hormone (TSH) released from the pituitary gland. Each molecule of T4 contains four atoms of iodine and one of them needs to be removed to form the active T3.

When insufficient T3 is being produced, due to deficiency of iodine or selenium, additional TSH is synthesised, deiodinase II is inhibited, and selenium is withdrawn from peripheral tissue to be concentrated in the thyroid gland. An indication of this is the presence of cold feet.
In some circumstances iodine deficiency causes the thyroid gland to grow into a goitre. By stimulating the production of TSH it can also initiate an auto-immune response with the productions of thyroid tissue anti- bodies. The presence of either iodine or selenium deficiency more commonly decreases the rate of metabolism by depressing the rate at which adenosine troposphere (ATP) is synthesised.

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First Published in 2009