The research team asked a representative sample of 764 men to weigh and record every item of food and drink they consumed for seven consecutive days. Just under 90% of the sample (665) produced complete and detailed diaries.
The men, who were all aged between 45 and 59, were taking part in the Caerphilly Cohort Study, which was set up between 1979 and 1983.
They were given comprehensive health check-ups, including a heart tracing (ECG) at the start of the study and subsequently every five years for a period of 20 years. Hospital and family doctor records were also checked.
During the study period, 54 men had a stroke and 139 developed symptomatic ischaemic heart disease (heart attack or angina), and 225 died.
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 of them had switched to skimmed or semi skimmed milk within the preceding eight years.
Men who consumed the most milk every day (a pint or more) 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 (less than half a pint), and men who drank the least milk tended to drink the most alcohol.
Men who drank the most milk had a lower risk of ischaemic heart disease or stroke than those who drank the least, and in the case of stroke this risk was significantly lower. The findings held true even for those men who had started out drinking full fat milk.
The authors suggest that milk has had something of a bad press in respect of its impact on cholesterol, and they conclude: "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."