Greener greens, browner bread, redder meat, fresher eggs; the latest costly fad for diet-conscious middle classes? Or the way ahead for the rest of the world? Ten years ago there were only a handful of health food shops in Britain. Today there are more than 1,000 and a new one opens every week. Yin, Yang, macrobiotic, biodynamic, organic, are becoming everyday words. And what we grow to eat is becoming a matter of fierce argument. Then there are the pills, potions and elixirs; remedies and stimulants making claims that wouldn't be surprising in a medieval bazaar; and the honeys and the syrups and the sugar substitutes. The people who grow and sell and eat health foods preach a message of purity and anti-pollution. Others claim that it's all a fuss over nothing. In the meantime it's a £20-million a year business boom. So are we listening to the message of those with a better way of life to offer - or the noises of those with bigger profits in mind?