It is well known that high blood pressure increases the risk of stroke - the fourth leading cause of death in the US. The threshold for high blood pressure diagnosis, or hypertension, is 140/90 mmHg. But new research suggests that even people with blood pressure lower than this - but higher than normal - have an increased stroke risk.
The research team, including Dr. Dingli Xu of Southern Medical University in Guangzhou, China, recently published their findings in the journal Neurology.
For the study, the investigators analyzed all existing research that looked at the risk of stroke in people with prehypertension. This is when blood pressure is higher than normal (120/80 mmHg) but below the high blood pressure diagnosis threshold.
The analysis included 19 studies involving more than 760,000 participants. All subjects were followed for between 4 and 36 years, and 25-54% of them had prehypertension.
Findings 'may have important takeaways for public health'
The researchers found that individuals with prehypertension were 66% more likely to have a stroke than those who had normal blood pressure, and almost 20% of strokes that occurred in the study population were in those with prehypertension.
As part of the study, the researchers divided individuals with prehypertension into two groups. Participants in the "high" group had blood pressure over 130/85 mmHg, while those in the "low" group had blood pressure under this but above normal.
This analysis revealed that participants in the high group were 95% more likely to have a stroke than those with normal blood pressure, while those in the low group were 44% more likely to have a stroke.
According to the Centers for Disease Control and Prevention (CDC), around 1 in 3 American adults have prehypertension, meaning these findings are of great importance.
Dr. Xu says:
"These findings, if confirmed, have important takeaways for the public.
Considering the high proportion of the population who have higher than normal blood pressure, successful treatment of this condition could prevent many strokes and make a major difference in public health."
Diet and exercise best for prehypertension
Patients with high blood pressure can use various medications, such as diuretics and beta-blockers, to help lower it. But Dr. Xu recommends against patients with prehypertension using such medications, as not enough research has been done to determine the safety and effectiveness in this population.
He notes that the best way people with prehypertension can reduce their risk of stroke is by following a healthy diet and exercising regularly.
As weight increases, so does blood pressure. But the Mayo Clinic state that losing just 10 pounds (4.5 kg) can help reduce blood pressure.
Following a diet rich in whole grains, fruit, vegetables and low-fat dairy products, and low in saturated fat and cholesterol can reduce blood pressure by up to 14 mmHg. Reducing sodium intake, even by a small amount, can also reduce blood pressure by 2-8 mmHg.
Medical News today recently reported on a study suggesting that following a vegetarian diet may help lower blood pressure.
Furthermore, exercising for at least 30 minutes to 1 hour most days of the week can lower blood pressure by 4-9 mmHg. Last year, a study revealed that participants who exercised 4 hours or more each week in their free time had a 19% lower risk of high blood pressure.