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Higher potato consumption associated with increased risk of high blood pressure
But studying dietary patterns may be more useful than individual foods or nutrients
Higher intakes of boiled, baked, or mashed potatoes, and French fries is associated with an increased risk of developing high blood pressure (hypertension) in adult women and men, according to a study published by The BMJ today.
The US-based 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.
But a linked editorial argues that studying overall dietary patterns and risk of disease is more useful than a focus on individual foods or nutrients.
Potatoes are one of the world’s most commonly consumed foods - and have recently been included as vegetables in US government healthy meals programs, due to their high potassium content. But the association of potato intake with hypertension has not been studied.
So researchers based at Brigham and Women’s Hospital and Harvard Medical School set out to determine whether higher long term intake of baked, boiled, or mashed potatoes, French fries, and potato chips (crisps) was associated with incident 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.
After further analyses, 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 decreased risk of hypertension.
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.
Nevertheless, they say their findings “have potentially important public health ramifications, as they do not support a potential benefit from the inclusion of potatoes as vegetables in government food programs but instead support a harmful effect that is consistent with adverse effects of high carbohydrate intakes seen in controlled feeding studies.”
In a linked editorial, researchers at the University of New South Wales argue that, although diet has an important part to play in prevention and early management of hypertension, dietary behaviour and patterns of consumption are complex and difficult to measure.
“We will continue to rely on prospective cohort studies, but those that examine associations between various dietary patterns and risk of disease provide more useful insights for both policy makers and practitioners than does a focus on individual foods or nutrients,” they conclude.
Expert Reaction
These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.
Scientia Professor Mark Harris is Professor of General Practice and Director of the Centre for Primary Health Care and Equity at UNSW. Harris is an author of the accompanying editorial.
Focusing on your risk of disease and the intake of single nutrients or foods, and not considering overall dietary patterns, is problematic.
The sometimes conflicting recommendations from research looking at the risks posed by specific dietary foods can also be confusing for consumers.
There is no need for consumers or people concerned about their blood pressure to completely remove potatoes from their diet, however making hot chips and potato crisps an occasional food is a healthy choice.
The best strategy for reducing your risk of diseases, such as diabetes, heart disease and high blood pressure is to consume a diet rich in fruit, vegetables, whole grains and low fat dairy foods, and limiting sugar, sweetened foods and drinks, red meat and added fats.
Dr Rebecca Reynolds is a lecturer in nutrition at the University of New South Wales
Potatoes when consumed in healthier ways such as cooked in potato salads, baked, boiled, mashed with milk and extra virgin olive oil, going easy on the salt, are a good food to be included as part of a healthy, balanced diet.
What you want to avoid eating frequently are the processed potato products like potato chips that are often deep fried in unhealthier oils, have more added salt and are more energy dense, which are factors more likely associated with hypertension.
- People focus too much on population-level studies and foods where certain nutrients and foods are demonised - it's more about a whole dietary approach, i.e. mostly and sometimes, more fruit and veg - including potatoes that are cooked in healthier ways), more Mediterranean-style.
- Population cohort association studies don't prove causation, i.e. seeing associations between hypertension and certain foods does not necessarily mean that those foods cause hypertension, partly because there are more sources of error in these types of studies compared to studies like randomised controlled trials.
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