A case-control study on potato consumption and risk of stroke in central Iran.

BACKGROUND

Potato, a high- glycemic index (GI) food, is one of the most widely used starchy foods worldwide. Previous studies on the association of dietary intakes with stroke have mostly focused on the dietary GI and there is no information regarding the association between potato consumption and risk of stroke. This case-control study was conducted to evaluate the association between potato consumption and risk of stroke in an Iranian adult population.

METHODS

In this case-control study, 195 patients with stroke, hospitalized in the Neurology Ward of Alzahra University Hospital and 195 controls from other wards of the hospital with convenience non-random sampling method were enrolled. To assess participants' dietary intakes, a validated food frequency questionnaire was used. Information on socioeconomic and demographic variables, physical activity pattern, and smoking were collected by the use of questionnaires. Logistic regression method in different models was applied to explore the associations between potato intake and stroke. First quartile of potato intake was used as a reference in all models. Mantel-Haenszel extension chi-square test was used to assess the overall trend across quartiles of potato consumption.

RESULTS

Individuals with stroke were more likely to be male (60% vs. 46%, P < 0.05) and older (68.0 ± 1.0 vs. 61.5 ± 0.8 y, P < 0.001) as compared with controls. They had lower body mass index (BMI) (25.2 ± 0.3 vs. 28.5 ± 1.0 kg/m2, P < 0.05), and were less likely to be obese (11.3% vs. 29.2%, P < 0.001) compared with controls. The mean potato consumption was 31.1 ± 3.4 and 23.4 ± 1.3 g/d for cases and controls, respectively. Participants with the highest potato consumption were younger and more likely to be physically active. High potato consumption was associated with higher intakes of energy, fruits, vegetables, pulses, and grains. After adjustment for age, sex, and total energy intake, we found that individuals with the highest potato consumption were more likely to have stroke as compared with those with the lowest consumption (OR: 1.9; 95%CI: 1.0 - 3.6). The correlation between physical activity and potato consumption was 0.03, P = 0.54 and that of smoking and potato intake was -0.004, P = 0.94. Even after additional control for smoking and physical activity, the association remained significant (OR: 1.9; 95% CI: 1.0 - 3.6). Further adjustment for dietary intakes made the associations non significant (OR: 1.1; 95%CI: 0.5 - 2.5). However, when BMI was taken into account in the final model, we found that individuals in the third quartile of potato consumption were significantly more likely to have stroke (OR: 2.2; 95%CI: 1.0 - 4.7).

CONCLUSIONS

We found evidence indicating that there is a marginally significant independent association between potato consumption and risk of stroke. Prospective studies are required to confirm this finding.