A good thing gone bad

Today's fruit and vegetables may not be as nutritious as we think they are, reports Jan Fairfa

We are all familiar with the advice that we should eat at least five portions of fruit and vegetables per day. But it seems these foods do not contain the goodness that we think they do. In the last 50 years, there has been a huge drop in the mineral levels of foods that has serious implications for our health. Research shows that the iron in spinach has dropped by 60 per cent. Broccoli has lost 75 per cent of its calcium. Carrots have lost 75 per cent of their magnesium and watercress has lost 93 per cent of its copper.

We are all familiar with the advice that we should eat at least five portions of fruit and vegetables per day. But it seems these foods do not contain the goodness that we think they do. In the last 50 years, there has been a huge drop in the mineral levels of foods that has serious implications for our health. Research shows that the iron in spinach has dropped by 60 per cent. Broccoli has lost 75 per cent of its calcium. Carrots have lost 75 per cent of their magnesium and watercress has lost 93 per cent of its copper.

Altogether, 27 varieties of vegetables assayed have lost 16 per cent of potassium, 24 per cent of magnesium, 27 per cent of iron, 46 per cent of calcium, 49 per cent of sodium and 76 per cent of copper. Seventeen varieties of fruit have lost 16 per cent of magnesium and calcium, 19 per cent of potassium, 20 per cent of copper, 24 per cent of iron and 29 per cent of sodium.

This might not seem too frightening but minerals are essential constituents of bones, teeth, muscle, soft tissue, blood and nerve cells. Most vitamins cannot be assimilated without the aid of minerals. And minerals are involved in almost all of the body's metabolic processes.

There are now over 18,000 clinical papers showing that shortages of the recognised vitamins, minerals and fatty acids are linked to disorders and diseases as diverse as bipolar manic depression and Alzheimer's Disease, to heart disease and cancers. The vital role that these nutrients play in human health has only become clear in the last 75 years, and they are probably the tip of an iceberg yet to be discovered.

The dramatic loss of minerals only came to light because David Thomas, a chiropractor with a special interest in minerals, noticed some of his patients showing signs of mineral deficiency despite eating a healthy diet. He suspected the nutritional quality of their food, and that led him to compile a comparative "study on the mineral depletion of the foods available to us as a nation over the period 1940 to 1991". He used data from five editions of The Chemical Composition of Food, written by McCance and Widdowson and published under the auspices of the Medical Research Council, and later the Ministry of Agriculture, Fisheries and Food (MAFF), and the Royal Society of Chemistry.

But Thomas was interested in the rate of change, so he compared figures from 1978 with those of 1991 and found, as he feared, that the depletion of minerals is accelerating. For instance, vegetables lost 57 per cent of their zinc in those 13 years.

So what is going on? Before the end of the Second World War, nearly all farming was organic. Every farmer knew that different crops absorb different minerals from the soil, which is why they used to rotate crops and regularly replace the lost minerals by using mineral-rich manure, organic plant material and ground-up animal bones. Now artificial fertilizers, which only include nitrogen, phosphorus and potassium (NPK = the chemical symbols) are routinely used to speed up the growth and productivity of crops, but NPK fertiliser was developed before the mineral requirements of plants and humans were fully recognised.

As well as NPK, plants need magnesium, calcium and sulphur, plus the trace elements: iron, zinc, manganese, boron, copper, molybdenum and chlorine. Without these essential nutrients plants are vulnerable to mould, fungus and insects and so require large quantities of pesticides.

Unfortunately the minerals plants gain from fertilisers may not be bio-available. For example, potassium, which is added as potassium chloride, inhibits the plant absorption of magnesium, calcium, zinc and selenium. Phosphorus also binds zinc, so the plant take-up is severely reduced and there is little that remains bio-available to the consumer. Zinc is an important precursor for sexual development and healthy sperm and it is interesting to note that the sperm count for the Western male has deteriorated sharply in the last five decades.

Naturopaths keep stressing that the only way to remain healthy is to eat a diet focussing on a wide variety of seasonal, fresh, local, organically-grown fruits and vegetables, nuts, pulses, lentils, seeds, some dairy foods, fish and game. This is basic, good nutrition which should be everybody's birthright.

This article is taken from the April edition of ' Medicine Today'. For subscription details send sae to: Alexander House, Hampstead Hill Gardens, London NW1 2PL