Relationship of potato consumption, total and by preparation method with blood pressure and body mass index: The International Population Study on Macronutrients and Blood Pressure (INTERMAP) US study

Abstract

Background: Limited evidence from prospective US cohort studies suggests that higher potato intake is associated with a higher risk of hypertension and obesity. Different preparation methods affect the nutritional composition of potatoes and are related to different dietary choices that may influence associations with blood pressure and body mass index (BMI). Objective: To investigate potato consumption, total and by preparation method, in relation to blood pressure and BMI. Methods: We used cross-sectional data of 2,195 participants aged 40 to 59 in 1996-1997 from the United States samples of the population-based INTERMAP study. During four visits, four in-depth multipass 24-hour dietary recalls and eight blood pressure measurements were collected. Reported potato intakes were categorized as fried and non-fried potatoes, using the USDA food grouping system. Potato intakes (g/1000 kcal) were averaged over four days. Regression coefficients per 2SD higher intake were estimated using multivariate linear regression analyses with adjustments for age, sex, sample, lifestyle and disease factors, and other food groups. To assess influence on the association, diet quality (by Dietary Approaches to Stop Hypertension adherence score), BMI, urinary sodium and potassium were added separately to the previous model. Results: Median intake of total, non-fried, and fried potatoes were 40 g/d, 23 g/d and 8 g/d, respectively. Total and non-fried potato intakes were not associated with blood pressure. The association between fried potatoes and blood pressure varied by sex (P for interaction=0.03). In women, higher fried potato intake (2SD: 20 g/1000 kcal) was associated with a +3.00 mmHg (95%CI: 1.29, 4.71) higher systolic and +1.26 mmHg (95%CI: 0.15, 2.38) higher diastolic blood pressure, which prevailed after additional, but separate, adjustments for BMI, diet quality, urinary sodium and potassium. Potato chips contributed predominantly (79%) to fried potato intake and accounted for the direct association of fried potatoes and blood pressure (+3.77 mmHg systolic (95%CI: 1.92, 5.62), and +1.80 mmHg diastolic (95%CI: 0.62, 2.98)). The association between fried potatoes and blood pressure was not found in men. In the total population, higher fried potato intake was positively associated with BMI (+0.62, 95%CI: 0.14, 1.09) but attenuated after adjustment for diet quality. Total and non-fried potatoes were not associated with BMI. Conclusions: In contrast to non-fried potato intake, fried potato consumption was directly related to blood pressure in women. This finding is in line with results of previous US cohort studies and suggests that the association of potatoes with blood pressure may depend on preparation method.