The risk of high blood pressure might increase in some men even after one or two drinks a day, say researchers.

Much research suggests that moderate drinking does no harm - and may even offer health benefits in some cases.

However, the latest studies of Japanese men may mean that this may not be true for everyone.

The researchers, from Osaka University Graduate School of Medicine, looked at more than 1,000 men from a suburban town over a 10-year period.

It found that, compared with non-drinkers, any man who drank alcohol, regardless of quantity or frequency, had an increased risk of high blood pressure.

The more alcohol drunk, the higher the risk of increased blood pressure.

Heart disease

Even moderate drinking had an adverse effect - men who averaged just one drink a day had a 20% to 30% increased incidence of high blood pressure.

No such added risk was noted in women in the study.

High blood pressure is a problem because, over time, it can increase the chance of developing heart disease, as well as raise the risk of stroke.

There is no obvious explanation for the wide disparity between the results of these studies and previous results from other research.

However, it was suggested that general differences between Japanese and western males might be to blame.

US men, for example, are far more likely to be obese or overweight - which would reduce the blood alcohol level produced by each unit of drink.

In addition, about 50% of Japanese people have a genetic mutation which affects the metabolism of alcohol.

Lifestyle

The studies also did not look into the lifestyle or diet of the men in the study, so cannot rule out these as a factor.

A spokesman for Alcohol Concern in the UK said that as long as men, or women, did not exceed the Department of Health's guidelines for safe alcohol consumption, there should be no problem.

She said: "An extra glass of wine is no substitute for a trip to the gym."

The current safe limits are three to four units of alcohol a day for men, and two to three for women - with at least one day's abstinence a week.

A unit of alcohol is approximately half a pint of beer, a glass of wine or a measure of spirits.

The studies were published in the journal Alcohol: Clinical Experience and Research.