Maintenance of a lean body weight into adulthood could prevent hypertension in women, a long-term study suggests. Using data from the Nurses' Health Study, researchers found that excess weight and even modest adult weight gain substantially increased risk for hypertension.
Consistent with previous findings linking weight at middle-age and risk for hypertension, the analysis found that a higher body mass index (BMI) at early adulthood is also a significant factor.
A cohort of 82,473 female nurses aged 30 to 55, all involved in the ongoing Nurses' Health Study, were included in the analysis. Investigators, who used follow-up information obtained biennially for 16 years, did not include women who at baseline had reported high blood pressure or a history of myocardial infarction (MI), angina pectoris, stroke, coronary artery surgery, diabetes mellitus, or any cancer other than nonmelanoma skin cancer. Women were excluded from subsequent follow ups if those conditions developed during the study period.
The measure of obesity used in the analysis was BMI. Long-term weight changes, from 1 8 years of age to the beginning of each 2-year follow up, and medium-term weight changes, from 1976 to the beginning of each follow up, were calculated.
At the end of 16 years, 16,395 incident cases of hypertension had been diagnosed in the analysis group.
BMI was strongly associated with increasing risk of hypertension, lead author Zhiping Huang, MD, PhD, from Harvard Medical School, and his colleagues wrote in Annals of Internal Medicine. That association was not altered when adjustments were made for height, family history of MI, parity, use of oral contraceptives, menopausal status, postmenopausal hormone use, and cigarette smoking.
Higher BMI at 1 8 years of age was linked to an increased risk for hypertension later in life. Women with a BMI greater than 25 kg/m2 at age 1 8 had a relative risk of 2.28 when compared with women whose BMI at 18 was 18.2 kg/m2 or less. Researchers found that for every 1 kg/m2 increase in BMI at 1 8 years of age, the risk for hypertension increased by 8%.
There was a five-fold increase in risk among women who gained more than 25 kg after age 18, a 29% increase in risk for women who gained between 2.1 and 4.9 kg, and a 74% risk for those who gained 5.0 to 9.9 kg.
"Although the association of BMI at 18 years of age with subsequent hypertension seemed weaker than the association between BMI at midlife and hypertension, it was still appreciable after we controlled for weight change later in life," said Huang (1998).
Long-term and medium-term weight loss, investigators found, are associated with a substantially reduced risk for subsequent hypertension. The effect of weight loss was much greater for women who had a higher baseline BMI. Women who had a lower baseline BMI showed little reduction in risk for hypertension if they lost weight, with researchers asserting that any weight lost in those women may be loss of lean mass rather than fat mass.
But women leaner at baseline saw their risk elevate if they gained weight as they aged.
"The prospective data in women offer strong support for the 1995 United States weight guidelines to avoid adult weight gain with increasing age," said Huang and colleagues (1998).
- Huang, Z., Willett, W.C., Manson, J.E., et al. (1998). Body weight, weight change, and risk for hypertension in women. Annals of Internal Medicine, 128, 81-88.