As it’s Salt Awareness Week, I thought I’d look at some more evidence from the Cochrane Collaboration on the impact of salt in our diets.
A recently-updated Cochrane review presents evidence from 167 randomised controlled trials (RCTs) comparing the short term impact of a low versus high sodium (salt) diet on blood pressure (BP) and on a number of hormones and lipids. Blood pressure was examined separately in three groups by race: Caucasians, Blacks and Asians, and according to whether people had high or normal blood pressure. Here’s what they found:
- Low versus high sodium diet in white people with normal BP decreased BP by 1% and in people with high blood pressure by 3.5%
- In the small number of non-white people studied the effect was greater, but more studies are needed before conclusions can be drawn
- There were increases in some hormones and lipids which could be harmful if they continued over time, but these studies were not designed to measure long-term health effects
- The authors identified many methodological problems in the included studies. Almost all the studies lacked information on how people were allocated to treatments and how that allocation was concealed
The reviewers concluded –
- for white people with normal BP: “due to the relatively small effects and due to the antagonistic nature of the effects (decrease in blood pressure, increase in hormones and lipids), these results do not support that sodium reduction may have net beneficial effects.”
- for white people with high BP: “sodium reduction may be used as a supplementary treatment for hypertension.”
Graudal NA, Hubeck-Graudal T, Jurgens G. Effects of low sodium diet versus high sodium diet on blood pressure, renin, aldosterone, catecholamines, cholesterol, and triglyceride. Cochrane Database of Systematic Reviews 2011, Issue 11. Art. No.: CD004022. DOI: 10.1002/14651858.CD004022.pub3.
A Cochrane summary is available for this review.