Overnight, Singapore will have one in three people suffering from high blood pressure instead of one in four - if it adopts a new cut-off rate recommended by the American Heart Association (AHA).

But the vast majority of these newly diagnosed hypertensives, classified as "high blood pressure stage 1", will need to make only lifestyle changes to reduce their risk of getting heart attacks and stroke.

The stricter rate recommended by the AHA is 130/80 versus the existing 140/90.

It is based on solid evidence, said Professor Tan Huay Cheem, director of the National University Heart Centre, "so there's no reason to reject these recommendations".

But he added: "We should still treat patients with stage 1 hypertension with lifestyle changes and start drug treatment only if he has multiple other risk factors (for example, diabetes mellitus, etc)".

Prof Tan also said the 130/80 cut-off is for at least two readings done at home. The cut-off at clinics stays at 140/90 as anxiety tends to raise a person's blood pressure, he said.

Dr Chee Tek Siong, a cardiologist in private practice and a board member of the Singapore Heart Foundation, shares Prof Tan's view and said treatment would be given to high-risk cases, who have issues like diabetes, high cholesterol, obstructive sleep apnea and kidney failure.

The AHA estimates that only one in five of the stage 1 hypertensives might need medication to reduce blood pressure. The rest should be given advice to make lifestyle changes and have their blood pressure checked after three to six months, he added.

Lifestyle changes include reducing salt in one's diet and eating more potassium-rich foods like bananas, potatoes, avocado and dark leafy vegetables, exercising more, drinking less alcohol and not smoking.

Dr Paul Chiam, a cardiologist at Mount Elizabeth Novena Hospital, highlighted the need for people to know the importance of strict blood pressure control "as we know that better BP (blood pressure) control does lead to fewer strokes, heart and kidney disease".

Dr Daniel Yeo, a cardiologist at Gleneagles Hospital, noted that Canada and Australia adopted the stricter cut-off last year, so the AHA's move was no surprise.