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A We now know a lot about what food does to the body and the importance of a healthy diet. But what if modern intensive farming methods have affected the mineral and vitamin content of what we eat? Donald Davis, at the University of Texas, has found notable declines in nutrients in crops including tomatoes, eggplants and squash. Davis blames agricultural practices that prioritize quantity over quality. High-yielding crops produce more food, more rapidly, but they can't make or absorb nutrients at the same pace, so the nutrition is diluted. 'It's like taking a glass of orange juice and adding water to it. If you do that, the concentration of nutrients that was in the original juice drops,' he says. But the idea that modern farming produces less nourishing crops remains controversial, since nutrient levels can vary widely according to the variety of plant, the year of harvest and the time of harvest.
B But intensive farming has also led to a huge increase in food supply, which has undoubtedly had a positive effect on our diet and health. 'Evidence suggests that some nutrients have fallen, particularly trace elements such as copper in vegetables,' says Paul Finglas, at the Institute of Food Research in Norwich. "Foods are now bred for yield, and not necessarily nutritional composition. But I don't think that is a problem, because we eat a wider range of foods today than we did 10 years ago, let alone 40 years ago." Eric Decker, professor of food science at the University of Massachusetts in Amherst, agrees. If nutrients are declining, the losses are insignificant, he says. 'Over the last century, lifespans have got longer, people are bigger and stronger, and a lot of that has to do with the food supply being better.' Even Davis agrees that any differences in nutrient levels are relatively small. Despite their decline, fruit and vegetables are still our richest source of many nutrients, and you can make up for it by eating more,' he says. 'But we know that many people don't get the recommended amounts of nutrients such as iron, magnesium, and calcium. They aren't overt deficiencies in the usual sense, but they increase susceptibility to lots of different problems.'
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