♥ New study associates raised blood pressure or hypertension with eating potatoes.
Very often, specific foods are associated with particular risk factors rather than the more serious situation of ‘cause and effect’ . One such situation relates to the consumption of potatoes and chips but surprisingly not crisps and presumably other potato snacks.
A new study looking at nutrition in health suggests that eating potatoes generally is associated with a rise in blood pressure or hypertension. It would appear that having four or more servings of potato be they mashed, boiled or baked in a week was linked to an 11 per cent increased risk of high blood pressure when compared to just one serving in a month. A similar result for both men and women found that if they ate four or more servings per week of chips or French fries there was a 17 per cent higher risk of high blood pressure.
The study was reported in the British Medical Journal (BMJ) and looked at the dietary habits of people at the Brigham and Women’s Hospital and at the Harvard Medical School in Boston, Massachusetts. The research team assessed the intake of various forms of potato with the incidence of hypertension in three populations; 62,175 women 62,175 women in the Nurses’ Health Study, 88,475 women in the Nurses’ Health Study II, and 36,803 men in the Health Professionals Follow-up Study. The total number of participants was 187,453 and none had hypertension as their baseline.
The study was based on dietary questionnaires which involved the collection of data on their consumption of various forms of potato: boiled, mashed, as crisps, etc. They were checked by doctors over a period of at least 20 years on whether they had high blood pressure. The researchers reached their conclusions following assessment of a range of risk factors and statistically eliminating them from their findings e.g. overall weight, body mass index (BMI), age etc.
The suggestion was that potatoes have a higher glycaemic index (GI) than other vegetables which leads to the condition. Generally, high GI foods raise blood sugar levels more quickly and the phenomenon is linked to risk of poor health including diabetes, inflammation and promoting other mechanisms that lead to raised blood pressure or hypertension. A study report from earlier in 2016 had found independently that women consuming potatoes were at a raised risk of suffering diabetes during pregnancy. In that study eating between two and four servings of potatoes per week was associated with a rise of 27% greater likelihood of developing diabetes during pregnancy even accounting for factors such as weight. Apparently, just one serving a week could increase the risk by 20% compared to women eating less than one serving a week.
The researchers in the BMJ paper calculated that replacing one serving a day of baked, boiled, or mashed potatoes with one serving a day of non-starchy vegetables was associated with a 7% decreased risk of hypertension. What wasn’t explained thoroughly was why crisps for example were not associated with the increased risk of hypertension.
The overriding conclusion was:
”These 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 programmes but instead support a harmful effect that is consistent with adverse effects of high carbohydrate intakes seen in controlled feeding studies.”
The government food programme related to advice coming from the US government about the general consumption of vegetables and potatoes.
However, the authors of a linked editorial countered that a whole meal’s glycaemic load depends on several factors including its protein and fibre content, and the glycaemic index of any other carbohydrate-containing foods in that meal.
There are a number of critical elements cited by nutritionists and other researchers concerning the linking of food groups to specific disease states or various risk factors. The first relates to the use of dietary questionnaires and the accurate measurement of dietary behaviour and consumption patterns. The second concerns the use of statistical techniques to extrapolate findings for specific foodstuffs when so many other factors are at play. However, cohort studies remain a valuable source of data given the size of the groups and their length of examination.
Reference
Borgi, L., Rimm, E.B., Willett, W.C., Forman, J.P. (2016) Potato intake and incidence of hypertension: results from three prospective US cohort studies. BMJ; 353: i2351. doi:10.1136/bmj.i2351
Leave a Reply