Milk's poor reputation as being an unhealthy drink may be unjustified, research suggests.

Scientists found drinking milk does not increase the risk of heart disease and stroke - in fact it may even have a protective effect.

The researchers, from the University of Bristol, found men who consumed at least 200ml a day were less likely to develop ischaemic heart disease.

The study is published in the Journal of Epidemiology and Community Health.

Writing in the journal, the researchers say that milk has had a bad press as it increases cholesterol levels.

Also, research has suggested rates of fatal heart disease are highest in countries who drink the most milk.

However, they say: "The present perception of milk as harmful, in increasing cardiovascular risk, should be challenged, and every effort should be made to restore it to its rightful place in a healthy diet."

The findings are based on data from 665 men from south Wales, aged 45-59, who kept detailed diaries of their food and drink consumption, and who underwent regular health checks over a period of 20 years.

During the study period, 54 had a stroke and 139 developed symptoms of ischaemic heart disease, such as a heart attack or angina. In total 225 died.

Men who drank the most milk had a lower risk of ischaemic heart disease, and a significantly lower risk of stroke than those who drank the least.

Energy

The researchers also found men who consumed the most milk every day had a higher energy intake - suggesting that they were more active.

Cholesterol levels and blood pressure readings were similar in high and low milk consumers.

However, those men who drank the least milk - less than 200ml a day - tended to drink the most alcohol.

Researcher Dr Andy Ness told the BBC News website it was possible, but unlikely, that the differences uncovered in the study were nothing to do with milk consumption.

Alternatively, although milk contained saturated fats, which are known to be bad for health, it could be that this negative effect was counter-balanced by beneficial ingredients. For instance, calcium has been shown to lower blood pressure.

Dr Ness said it was also possible that milk displaced other, potentially more damaging food and drink, in some people's diets.

Starting young

Finally, it was also possible that men enjoyed milk as adults also drank significant quantities as child - when it is known to play a crucial role in healthy development.

He said: "I would not encourage people to drink pints and pints of milk, but as part of balanced diet some milk does not appear to be harmful."

Claire Williamson, a nutrition scientist at the British Nutrition Foundation, said milk and dairy foods were an important part of a balanced diet.

"Milk is an important source of several nutrients including protein, calcium, zinc and vitamin B12.

"Currently around 5% of men and 8% of women aged between 19-24 years are not consuming enough calcium to meet their needs."

She recommended two to three servings per day - a serving is a 200ml glass of milk, a small pot of yogurt or a 30g portion of cheese.

At the start of the study, virtually all milk consumption was whole (full fat) milk.

But a random sample of the surviving men in 2000, showed that almost all had switched to skimmed or semi skimmed milk.