Myths and guidance abound about which food or drink is healthy and which is not. The news on individual products changes regularly as the latest scientific research is published.
An entirely unscientific straw poll of 10 colleagues and relatives between the ages of 25 and 72 on the caffeine content of tea and coffee illustrates the effect of the conflicting news on our perceptions.
Six people said they believed that tea contained more caffeine than coffee. One person believed they contained the same amount, and three thought tea contained less caffeine. One of the latter assured me that most people in Britain are convinced that tea contains no caffeine whatsoever.
The answer: an ordinary cup of tea contains half as much caffeine as an ordinary cup of coffee, according to the UK Tea Association.
It says tea intake would reach a potentially harmful level for most people - 400mg - only if an individual drank 12 to 14 cups in a couple of hours, which is most unlikely. An average cup brewed for three minutes contains 30 to 60mg. For coffee, six cups in two hours could be overdoing it, but that is probably achievable.
The caffeine debate has raged since decaffeinated coffee was introduced in America in the mid-1980s.
It was promoted as the healthy alternative to coffee, which seems to have been variously charged with increasing the likelihood of heart attacks and cancer, raising cholesterol levels, decreasing all of the above, and improving one's brain power.
'No one has given caffeine a bad bill of health if it is consumed in moderation,' said Illtyd Lewis, executive director of the UK Tea Council. Many people don't realise they are taking in caffeine when they have confectionery, analgesics and colas.
Because of our increasing awareness of the influence of diet on health, public perceptions of what is good or bad for us (regardless of the underlying scientific facts) have become critical for retail sales of food and drink. The British salmonella scare a few years ago and the slump in egg sales that followed is a good case in point.
Consumer concerns about whether caffeine could affect development of chronic diseases have hit coffee and tea sales, while decaffeinated coffee has zoomed in popularity. Decaf now accounts for 10 to 15 per cent of the coffee drunk in the US and 6 to 7 per cent of the coffee consumed in the UK. Decaf tea is not making much headway here, though sales of herbal infusions are growing fast.
Ever-increasing competition means that beverage makers are anxious to promote the health attributes of their products. The tea industry, a mature business whose dominant market share is declining as new types of drink pour on to the supermarket shelves, is no exception.
This week, at an international tea convention in the Channel Islands, the tea world unveils what it hopes will give it a competitive edge.
Britain, the US and Canada are jointly launching a pounds 1m international research programme, focusing on the cancer- and heart disease-preventing properties of black tea, the type of tea drunk here.
The tea industry is optimistic about the findings it could produce, because a scientific study conducted in Japan has discovered that components of the green tea drunk there function in the body as an anti-oxidant. Studies indicate that anti-oxidants in the cell can inhibit development of cancer, and may reduce the development of heart disease by reducing the oxidation of fat and cholesterol.
Carole Greenwood, a professor at Toronto University, points out that several nutrients are known to function as anti-oxidants in the cell, including Vitamins C, E, and beta-carotene. 'However, other food components including tea polyphenols are felt to have similar anti-oxidant properties,' she said.
The tea industry is making no claims until the scientific research is under way and producing results.
Keeping in mind public weariness of dietary advice, and the fact that campaigns can backfire and put consumers off a product, the international tea trade aims to present a responsible, united front with whatever information the study produces. Ms Greenwood said the message should be that tea is a good choice in the context of a healthy diet and lifestyle.
But clearly, the tea industry is excited with the possiblities. The results of a well managed marketing campaign pushing good news about tea's health benefits would be increased profits.
Even hardened tea lovers might be comforted by such positive findings. Statistically, tea is Britain's national drink, making up 43 per cent of all beverages drunk, including water. Even the biggest sceptic may be subliminally affected by advertising and news about what is good or bad for us.
On average, we drink 3.56 cups a day (costing 2 1/2 p per cup) in Britain, compared with 1.74 cups of coffee. Mr Lewis put it more graphically: 'If you live to be three-score (years) and ten, that's 90,000 cups of tea down the chute.'Reuse content