Salt and Health: Old Myths and a Controversy Based on Denial
NEW analysis calls on journal editors to uphold scientific standards by ensuring that unfounded claims about salt and cardiovascular disease are rigorously and independently challenged
Read the full paper: Cappuccio, F.P., Campbell, N.R.C., He, F.J. et al. Sodium and Health: Old Myths and a Controversy Based on Denial. Curr Nutr Rep (2022). https://doi.org/10.1007/s13668-021-00383-z
The scientific consensus on which global health organisations base public health policies is that high salt intake increases blood pressure in a linear fashion, which in turn leads to increased risk of cardiovascular disease (CVD) – including stroke and heart disease. Reducing salt intake to 5g per day helps maintain blood pressure at a healthy level to reduce the burden of CVD.
NEW analysis from leading academics in salt reduction published today in Current Nutrition Reports (Sodium and Health: Old Myths and a Controversy Based on Denial) reviews eight articles published in the European Heart Journal in 2020 and 2021 where a small group of researchers, some funded by the food industry, have propagated a myth that reducing salt does not consistently reduce CVD but that lower salt might increase the risk of CVD.
The authors discuss how these European Heart Journal articles are based on science that is biased, incomplete, and inaccurate. The limitations identified include:
- Inaccurate dietary assessment tools e.g. using food diaries to estimate salt intake rather than the gold standard method of 24-hour urinary salt excretion;
- Using spot urine samples with discredited conversion formulas to estimate 24-hour urinary salt excretion – research shows that these formulas introduce bias, so that both low and very high salt intake are linked with increased risk of death;
- Potential for reverse causality (i.e. including data from ill participants who, due to their illness, are not able to eat much and therefore have a low salt intake. It is not the low salt intake that is the cause of ill health or death for these participants – it is the illness they are suffering with);
- Use of sick populations and patient groups to study the implications of a moderate reduction in salt consumption in the general population;
- Unmeasured confounding factors e.g. linking salt intake and health outcomes at a country level, rather than at an individual level.
These issues highlight the need to develop, implement and enforce higher research quality and publishing standards to protect public health interests and halt the spread of misinformation about salt and health.
Hattie Burt, Policy and Communications Office at World Action on Salt, Sugar, and Health says, “Vigorous scientific evidence is at the heart of our work to reduce salt intake and save lives. It is vitally important that strong and comprehensive public health policies are put in place worldwide to reduce population salt intake, blood pressure and cardiovascular disease risk. A small group of industry-funded researchers should not be allowed to derail this.”
