May 17, 2016

expert reaction to potato consumption and high blood pressure

The effect of consumption of various kinds of cooked potatoes is the subject of a paper published in The BMJ in which the authors report that higher consumption was associated with an increased risk of developing high blood pressure.

Victoria Taylor, Senior Dietitian at the British Heart Foundation, said:

“This type of study can only show an association, not cause and effect. We cannot therefore conclude that potatoes cause high blood pressure and we cannot explain the cause of the effects seen in the study among higher consumers of potatoes.

“Although a higher consumption of potatoes, such as mashed potatoes or French Fries, was associated with high blood pressure, it is still possible that other factors in the diet or lifestyle are also affecting the results, especially as both the blood pressure and food frequency were self-reported.

“It is also important to note this is a study from the US where dietary guidance and recommendations vary from the UK. For example, in the UK white potatoes are not included in the 5-a-day recommendations for fruit and vegetable consumption. While potatoes are part of the starchy carbohydrates section of the Government’s Eatwell guide, we must remember that, as with all foods, it’s important to consider the overall balance of the foods we eat.

“Nearly 30 per cent of adults in the UK have high blood pressure so it is key that we understand the condition and its causes as much as possible. This is why the British Heart Foundation is currently funding research projects across the UK into high blood pressure, such as research at the University of Glasgow currently investigating the causes of blood vessel problems, which contribute to high blood pressure.”

Prof. Tom Sanders, Emeritus Professor of Nutrition and Dietetics, King’s college London, said:

“Overweight, high intake of salt and alcohol and a low intake of potassium are well known to increase blood pressure but the effects of individual foods are less certain.  Generally, fruit and vegetables are associated with lower blood pressure with the exception of pickled vegetables. This report is an observational study not a dietary intervention trial. It finds an association between the consumption of potato products and risk of developing high blood pressure in women but, surprisingly, not men, who usually consume more potatoes than women. The association in women may well be confounded by other differences in lifestyle that impact on blood pressure. Potatoes do contain small amounts of alkaloids such as chaconine and solanine but not in sufficient amounts to affect blood pressure. However, potatoes, especially chips, are often consumed with added salt which may be part of the explanation for this association with raised blood pressure.

“I don’t think this study should be used to discourage people from eating potatoes.  In the UK, potatoes are more widely consumed than in the USA and make an important contribution to the intake of vitamin C and potassium. The vitamin C and potassium content is best retained when the potatoes are baked or boiled with skins on.”

‘Potato intake and incidence of hypertension: results from three prospective US cohort studies’ by Borgi et al. published in The BMJ on Tuesday 17^th May. 

Declared interests

Victoria Taylor: Nothing declared

Prof. Tom Sanders: “Prof Tom Sanders is a Scientific Governor of the charity British Nutrition Foundation, member of the scientific advisory committee of the Natural Hydration Council (which promotes the drinking of water), and honorary Nutritional Director of the charity HEART UK. Prof. Tom Sanders is now emeritus but when he was doing research at King’s College London, the following applied: Tom does not hold any grants or have any consultancies with companies involved in the production or marketing of sugar-sweetened drinks. In reference to previous funding to Tom’s institution: £4.5 million was donated to King’s College London by Tate & Lyle in 2006; this funding finished in 2011. This money was given to the College and was in recognition of the discovery of the artificial sweetener sucralose by Prof. Hough at the Queen Elizabeth College (QEC), which merged with King’s College London. The Tate & Lyle grant paid for the Clinical Research Centre at St Thomas’ that is run by the Guy’s & St Thomas’ Trust, it was not used to fund research on sugar. Tate & Lyle sold their sugar interests to American Sugar so the brand Tate & Lyle still exists but it is no longer linked to the company Tate & Lyle PLC, which gave the money to King’s College London in 2006. Tom also used to work for Ajinomoto on aspartame about 8 years ago.  Tom was a member of the FAO/WHO Joint Expert Committee that recommended that trans fatty acids be removed from the human food chain. Tom has previously acted as a member of the Global Dairy Platform Scientific Advisory Panel and Tom is a member of the Programme Advisory Committee of the Malaysian Palm Oil Board. In the past Tom has acted as a consultant to Archer Daniel Midland Company and received honoraria for meetings sponsored by Unilever PLC. Tom’s research on fats was funded by Public Health England/Food Standards Agency.”