Can a healthy diet be sufficient in today's world?

There was a time when simply eating a healthy diet and avoiding all anti-nutrients ensured that we got all the minerals needed to stay healthy Research today shows that this may no longer be the case as the nutrient content of our food is on the decline.

Most of the blame lies with artificial chemical fertilisers. We now know that plants absorb 70 to 80 different minerals from the soil, while the number returned to it by plants grown with commercial fertilisers can be counted on the fingers of one hand. Every crop that is cut or animal that is sent to market marks a further depletion in the mineral status of the soil on which it was raised. Organic wastes that in former times would have been composted and returned to the land are nowadays mostly consigned to landfill sites or incineration.

There are many other ways in which the move to chemical farming prevents crops from taking up even the sparse amounts of trace minerals left in the soil. Soil contains bacteria, fungi, plant and animal life, in a state of constant interaction and balance. Every one of these organisms needs dozens of different minerals to survive and play its part in the ecosystem. Some bacteria have a vital role in converting soil minerals into chemical forms that plants can use. NPK fertilizers (fertilizers used in modern farming that only contain nitrogen, phosphorous and potassium) gradually change the soil pH towards acidic conditions in which these bacteria can not survive. To combat soil acidification farmers lay lime on the land adding back calcium and magnesium to raise the soil pH, but it also converts manganese and some other trace minerals into chemical forms that plants are unable to absorb.

Pesticides and herbicides also reduce the uptake of trace minerals by plants. Plants have an important relationship with certain fungi that can form networks covering several acres. The fungus obtains carbohydrates from the plant root, at the same time supplying the plant with nutrients it draws from the soil. This gives the plant access to a vastly greater mineral extraction system than is possible by their roots alone. Chemical fungicide sprays destroy these beneficial fungi and so again reduce the ability of plants to absorb soil minerals. Insecticides can also reduce trace mineral uptake by inactivating chlorine-containing enzymes in plants, essential for the absorption of manganese and other minerals.

The combined effect of soil mineral depletion and the reduced availability of those minerals that remain is that most of the food that we eat is mineral deficient. The table below summarizes the reductions in the average mineral content of 27 vegetables and 17 fruits, between 1940 and 1991. The results of the latest research are expected to show mineral values in continual decline.

A new study published earlier this year shows that, as might be expected, mineral levels in animal products reflect the picture in plant foods. Comparing levels measured in 2002 with those present in 1940, the iron content of milk was found to be 62% less, calcium and magnesium in parmesan cheese had each fallen by 70% and copper in dairy produce had plummeted by a remarkable 90%.

The UK government is putting resources into improving health by encouraging people to eat a healthy diet, including 5 portions of fruit and vegetables per day, but you scarcely hear a word about the problem of soil mineral depletion. Food seems to be considered as something quite separate from its source and means of production. But this is not rocket science – the foundation of human health is the quality of the food we eat, which relies ultimately on the vitality of the soil on which it is raised.

Minerals are needed for the proper formation of blood and bone, the maintenance of healthy nerve function, heartbeat regulation, reproduction and foetal development. They are essential to the process of growth, healing and energy release. And it is not just the presence of the mineral in the body that is important – they must be in the correct ratio to each other. The level of each mineral has an effect, directly or indirectly, on every other, so if one is out of kilter the whole system is affected.

Minerals are an essential part of our natural diet and a lack of them may in part account for our increasing susceptibility to the “diseases of civilisation” – such as heart disease (magnesium), cancer (selenium), diabetes (chromium) and mental illnesses (zinc). Every one of us should take care to get the minerals we need, for the good of our health.