December 10, 2014

expert reaction to article comparing sugar with salt as causes of hypertension and CVD

Researchers publishing in the journal Open Heart have suggested that it might be sugar rather than salt which has greater effects on hypertension and cardiovascular disease. These comments were accompanied by a Before the Headlines analysis.

Prof. Francesco Cappuccio, Professor of Cardiovascular Medicine & Epidemiology at the University of Warwick, said:

“I would agree with the authors on some important points: that high-sugar diets may contribute substantially to cardiovascular disease, and that added sugars are the problem.

“However the emphasis on reducing sugar, and not salt, is disingenuous. Both should be targeted at population level for an effective approach to cardiovascular prevention.

“Unlike sugar, salt is not a nutrient but a chemical added to food in recent evolutionary time. Our bodies need no more than a tenth of the salt than we currently eat. All the arguments offered in support of the ‘physiological homeostasis’ of salt have been counteracted by numerous publications that the authors carefully avoid citing.

“The authors claim that ‘lowering sodium levels in processed foods could lead to an increase consumption of starches and sugars’. But there is absolutely no evidence to support this statement from a physiological or nutritional viewpoint. This shift in attention from salt to sugar is scientifically unnecessary and unsupported, and it reminds me of a well-rehearsed tactic used by industry and pseudoscience to divert public attention. It is inappropriate in a scientific publication.

“The authors also claim that there is ‘controversy’ on the efficacy of a moderate reduction in salt intake for the prevention of cardiovascular disease.  I am surprised that the editor has allowed the citations of references 12 to 15, as the existence of the raw data and the validity of the results published in those papers have been questioned to the point that Heart journal had to withdraw a paper by the same author (DiNicolantonio) in 2013 [1]. Furthermore, the Cochrane Centre also withdrew a Cochrane Review based on those articles [2]. It is important to be fully aware of these facts as they raise issues about the scientific rigour applied on this occasion.

“The conclusion I draw from this study is that we must stop this false argument about reducing either salt or sugar. Both must be reduced if we are to meet the UN targets of a reduction of cardiovascular disease of 25% by 2025.”

[1] DiNicolantonio JJ et al. Low sodium versus normal sodium diets in systolic heart failure: systematic review and meta-analysis. Heart 2012; on-line 21 August; retracted in Heart 2013; on-line 12 March.

[2] Taylor RS, et al. Reduced dietary salt for the prevention of cardiovascular disease. Cochrane Database of Systematic Reviews 2011, Issue 7. Art. No.: CD009217. Withdrawn in June 2013 http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD009217.pub2/full

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

“In my opinion the effects of added sugars are exaggerated in this article. Cutting salt intake and losing weight will lower blood pressure, but the evidence for a direct effect of added sugar is tenuous.

“Most of the salt in the diet comes from bread, processed meat, pickled foods and salt added during food preparation and at table. Salt intake has fallen in the UK as manufacturers have reduced the amount of salt added to food. This has also been accompanied by a fall in blood pressure.

“Added sugar intake is derived mainly from sugar-sweetened beverages, confectionery, cereal products (cakes and biscuits). The easiest way to reduce added sugar intake is to limit sugar-sweetened beverage and confectionery consumption. However, as far as I am aware there is no evidence to show that blood pressure is lowered when sugar-sweetened beverages are replaced by artificial sweeteners.

“To add to the Christmas cheer, alcohol definitely increases blood pressure and is probably a bigger cause for concern!”

Gaynor Bussell, Dietitian and Public Health Nutritionist, said:

“The authors appear to have built an argument to support a particular view: that fructose is bad and salt may be ok. It is not based on original work, nor has the evidence presented been balanced to include all evidence on the causes of hypertension etc. Their stance does not have the backing of a broader evidence base.

“It needs to be stated that it is the whole diet that’s important when addressing implications to health; it’s not just sugar or salt that need addressing but also issues such as total calorie intake, fibre, fats and vitamin and mineral intake also. Excessive intake of any macro or even micronutrients are not conducive to health, which is why in the UK, for example, we advocate a limit of 6g salt a day (certainly not 3g claimed to be advocated in this study) and currently about 90g of total sugars a day.

“It is difficult to define a processed food as most food we eat is processed to some extent, such as bread or tins of beans, but are not necessarily unhealthy. However, we do suggest that eating too many overly processed foods may mean we miss out on other healthy aspects of the diet such as fibre and wholegrains.”

Prof. Susan Fairweather-Tait, Professor of Mineral Metabolism at the University of East Anglia (UEA), said:

“In 2010 the European Food Safety Authority (EFSA) published a Scientific Opinion on Dietary Reference Values for carbohydrates and dietary fibre and concluded that although there is some evidence that high intakes of sugars may increase serum triglyceride and cholesterol concentrations, the available data were not sufficient to set an upper limit for (added) sugar intake. Further, there was no evidence for an association between intake of sugars and blood pressure.”

‘The wrong white crystals: not salt but sugar as aetiological in hypertension and cardiometabolic disease’ by DiNicolantonio & Lucan published in Open Heart on Wednesday 10 December 2014. 

Declared interests

Prof. Cappuccio: I am Head of the WHO Collaborating Centre for Nutrition and unpaid advisor to the WHO HQ Geneva; WHO Office for Europe; EMRO WHO and PAHO/WHO Office. I am an unpaid member of the following charitable organizations: UK Health Forum, CASH, WASH and unpaid Trustee of the Student Heart Health Trust, a charity with the mission to increase awareness of cardiovascular disease risk amongst young people.