Diet and lifestyle risk factors associated with incident hypertension in women

Abstract

Context: Hypertension is an important preventable risk factor for death among women. While several modifiable risk factors have been identified, their combined risk and distribution in the population have not been assessed.

Objective: To estimate the hypothetical fraction of hypertension incidence associated with dietary and lifestyle factors in women.

Design, setting, and participants: Prospective cohort study of 83,882 adult women aged 27 to 44 years in the second Nurses' Health Study who did not have hypertension, cardiovascular disease, diabetes, or cancer in 1991, and who had normal reported blood pressure (defined as systolic blood pressure of < or = 120 mm Hg and diastolic blood pressure of < or = 80 mm Hg), with follow-up for incident hypertension for 14 years through 2005. Six modifiable lifestyle and dietary factors for hypertension were identified. The 6 low-risk factors for hypertension were a body mass index (BMI) of less than 25, a daily mean of 30 minutes of vigorous exercise, a high score on the Dietary Approaches to Stop Hypertension (DASH) diet based on responses to a food frequency questionnaire, modest alcohol intake up to 10 g/d, use of nonnarcotic analgesics less than once per week, and intake of 400 microg/d or more of supplemental folic acid. The association between combinations of 3 (normal BMI, daily vigorous exercise, and DASH-style diet), 4 (3 low-risk factors plus modest alcohol intake), 5 (4 low-risk factors plus avoidance of nonnarcotic analgesics), and 6 (folic acid supplementation > or = 400 microg/d) low-risk factors and the risk of developing hypertension was analyzed.

Main outcome measures: Adjusted hazard ratios for incident self-reported hypertension and population attributable risks (PARs).

Results: A total of 12,319 incident cases of hypertension were reported. All 6 modifiable risk factors were independently associated with the risk of developing hypertension during follow-up after also adjusting for age, race, family history of hypertension, smoking status, and use of oral contraceptives. For women who had all 6 low-risk factors (0.3% of the population), the hazard ratio for incident hypertension was 0.22 (95% confidence interval [CI], 0.10-0.51); the hypothetical PAR was 78% (95% CI, 49%-90%) for women who lacked these low-risk factors. The corresponding hypothetical absolute incidence rate difference (ARD) was 8.37 cases per 1000 person-years. The PARs were 72% (95% CI, 57%-82%; ARD, 7.76 cases per 1000 person-years) for 5 low-risk factors (0.8% of the population), 58% (95% CI, 46%-67%; ARD, 6.28 cases per 1000 person-years) for 4 low-risk factors (1.6% of the population), and 53% (95% CI, 45%-60%; ARD, 6.02 cases per 1000 person-years) for 3 low-risk factors (3.1% of the population). Body mass index alone was the most powerful predictor of hypertension, with a BMI of 25 or greater having an adjusted PAR of 40% (95% CI, 38%-41%) compared with a BMI of less than 25.

Conclusions: Adherence to low-risk dietary and lifestyle factors was associated with a significantly lower incidence of self-reported hypertension. Adopting low-risk dietary and lifestyle factors has the potential to prevent a large proportion of new-onset hypertension occurring among young women.