The researchers suggest that replacing one serving a day of boiled, baked, or mashed potatoes with one serving of a non-starchy vegetable is associated with a lower risk of developing hypertension.
They followed over 187,000 men and women from three large US studies for more than 20 years. Dietary intake, including frequency of potato consumption, was assessed using a questionnaire. Hypertension was reported by participants based on diagnosis by a health professional.
After taking account of several other risk factors for hypertension, the researchers found that four or more servings a week of baked, boiled, or mashed potatoes was associated with an increased risk of hypertension compared with less than one serving a month in women, but not in men.
Higher consumption of French fries was also associated with an increased risk of hypertension in both women and men. However, consumption of potato chips (crisps) was associated with no increased risk.
The authors point out that potatoes have a high glycaemic index compared with other vegetables, so can trigger a sharp rise in blood sugar levels, and this could be one explanation for the findings.
They also acknowledge some study limitations and say that, as with any observational study, no firm conclusions can be drawn about cause and effect.