Once, meat, milk and eggs were good for us and drink was the demon. But now, as scientific knowledge of nutrition grows, the messages have changed, Oliver Gillie writes
Meat, milk and eggs for many years were recommended as prime foods vital for health. They are good sources of protein, vitamins and minerals - the elements of food that nutritionists have always considered important. But over the past 10 years everything has changed. We are now told to eat more vegetables, fruit and fish, while milk, eggs and meat are given a secondary position - or even discouraged. Why?

The science of nutrition began with simple observations: lime juice was found to cure scurvy; milk, butter and egg yolk were found to encourage the growth of rats. It was also observed that children on high carbohydrate diets did not grow well - protein was important.

Big improvements in agriculture in Western countries have made meat, milk and eggs plentiful. The majority of British children now grow well and the average height of the nation is greater than it has ever been. Unemployment in the Thirties interrupted the trend but consumption of meat, dairy products and fat has steadily increased this century. It was not until heart-disease deaths rocketed in the Sixties and Seventies that deeper questions began to be asked.

Doctors pointed out that American and British men were six times as likely to die of heart disease as Japanese men. Everything pointed to diet and the three to four times greater consumption of fat by those in the West. Meat, eggs and milk are high in fats - the nutritionists' favourite products came under attack. At first many nutritionists refused to consider the medical findings - and they were backed up by the vested interests of farmers and the food industry.

Study of heart-disease deaths in Britain during the war, when meat, eggs and butter were rationed, showed a clear decline. Evidence mounted up, but it was not until 1984 that a government report fully acknowledged the newly discovered relationship between heart disease and diet. The report recommended a decrease in the amount of saturated fat such as butter and animal fat in the diet and an increase in the intake of polyunsaturated fats that come from seed oils such as soya and sunflower.

As a result of these new ideas, there has been a slow reduction in the number of premature deaths from heart disease in Britain. However, the decrease has been much greater in the US and Finland, where greater publicity has been given to the problem. And heart-disease deaths in Britain are still about three times those in France, where their greater consumption of vegetables, seed oils and wine gives greater protection.

Consumed in moderation, alcohol is good for the heart: a dramatic reversal of the common view, maintained for more than 100 years by the Temperance movement, that alcohol is an indulgence without any merits.

The benefits of moderate drinking were first recognised by science in 1926 but it took another 65 years to obtain proof. In 1991 Sir Richard Doll and Professor Richard Peto showed that British doctors who had two or three alcoholic drinks a day suffered less heart disease than total abstainers. Since then medical experts have agreed that three drinks a day is a safe limit for men over 40 and two drinks a day is safe for women over 40.

The Government has gone even further: in December, it not only emphasised the "significant health benefits" of alcohol but, against most medical advice, put up safe limits to four drinks daily for men and three for women, laying it open to claims of creating a "boozers' charter".

But most experts now agree that a moderate amount of alcohol lowers harmful cholesterol in the blood, reduces blood clotting and so reduces the risk of heart attacks. But after three or four drinks a day, alcohol begins to have more risks than benefits. High blood pressure and the associated risk of stroke is one of the principal dangers, but regular drinking can also cause liver disease, - a common cause of death in France - affect fertility in both sexes and bring on incipient breast cancer. In pregnant women it can induce abortion and foetal defects.

The risks are greater for those who are overweight. And there is no safe limit for the under forties. Younger people have a very low risk of dying from heart disease. But they have a high risk of injury and death from violence, road accidents, and suicide - all exacerbated by even small amounts of alcohol.

Is red wine better for the heart than other forms of alcohol? Some studies indicate that this is the case, but other research has found that the type of alcohol makes no difference.

What probably makes a difference is the style of drinking: your average Scotsman on a bender has a drinking style quite different from the average Frenchman. For the best health it is important to drink slowly - and to eat.