"If we were to eliminate prehypertension, we could potentially prevent about 47 percent of all heart attacks," said the study's lead author Adnan I. Qureshi, M.D., professor and director of the Cerebrovascular Program in the Zeenat Qureshi Stroke Research Center at the University of Medicine and Dentistry of New Jersey in Newark.
Normal blood pressure is lower than 120/80 millimeters of mercury (mm Hg). Prehypertension is systolic blood pressure between 120 and 139 and/or diastolic pressure between 80 and 89 mm Hg. (Systolic pressure is the force in the arteries when the heart beats and diastolic pressure is the force when the heart is at rest.) Hypertension is blood pressure 140/90 mm Hg or higher.
"There is a gray zone, where you are not hypertensive but your blood pressure is not normal either," he said.
More than a year ago, a national committee coined the term "prehypertension" for this gray area. But until this study, Qureshi said, physicians and the public knew little about what this term meant. About 59 million people in the United States are prehypertensive.
Researchers examined existing data from the Framingham Study and found that a prehypertensive person is more than three times more likely to have a heart attack and 1.7 times more likely to have heart disease than a person with normal blood pressure.
They did not find a significantly increased risk of stroke among those with prehypertension. "This is somewhat surprising, but it may be related to the small number of stroke events in the study," Qureshi said. "The differential effect in this gray zone may be mediated through factors other than blood pressure, such as insulin resistance."
Researchers also investigated the population's attributable risk, which determines how a disease will be impacted if that risk factor were eliminated.
"While we classically recommend lifestyle modifications such as weight control, regular physical activity and changes in diet for people with prehypertension, these findings raise the question of whether we should treat prehypertensive patients more aggressively."
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Henry Scowcroft, a senior information officer at Cancer Research UK, puts the findings in perspective and says regularly drinking milk is linked to a very tiny increase in the absolute risk of ovarian cancer, which is equivalent to about 0.2 per cent.
As a woman's lifetime ovarian cancer risk is about 2.1 per cent, Cancer Research UK strongly advises 'people not to change their diet to avoid these foods given the health benefits of drinking skimmed milk and eating low-fat dairy products'.
Dr Alice Cotter, a nutritionist and spokeswoman on behalf of the Dairy Council, says the great majority of studies do not support a link between dairy foods and the risk of ovarian cancer.
She says a similar research paper which analysed 22 studies in this area and published in February, did not find any association between milk and dairy foods and ovarian cancer risk, and other studies have shown that milk and dairy foods may have a protective effect against some forms of cancer.
Although studies of this type contribute to scientific research about ovarian cancer, says Cotter, the authors themselves point out several limitations of the study.