Researchers from the University of Leuven in Belgium found no link between high urinary sodium and risk of hypertension, cardiovascular events or death. This suggests models have overvalued the benefit of lowering salt intake in saving lives and health costs at a population level, they argued.
Elsewhere, Dutch researchers said low sodium levels in the blood increase the risk of fracture in elderly people.
Recent research predicted that cutting salt intake by around 3g per day could reduce cardiovascular events and healthcare costs.
But researchers led by Dr Jan Staessen said such predictions ignored the inconsistency of evidence linking BP to salt intake. Neither did these consider whether the results could be applied to the general population, nor the possible dangers of sudden salt reduction, they said.
Researchers used data from 3,681 participants without cardiovascular disease who had urinary sodium and BP measured over eight years.
They found systolic BP increased by 1.71mmHg for every 100mmol per day increase in urinary sodium, although there was no link with diastolic BP.
But higher urinary sodium levels did not predict hypertension or increase risk of cardiovascular events or death. In contrast, they found low sodium was linked to higher cardiovascular mortality.
The researchers concluded: 'Taken together, our findings refute the estimates of computer models of lives saved and healthcare costs reduced with lower salt intake.' The findings did not support 'generalised and indiscriminate reduction of salt intake at the population level', they added.
In the Dutch study, researchers found patients with hyponatraemia, or low blood sodium, were 40 per cent more likely to experience a non-vertebral fracture. They were also more likely to fall than those without the condition. Screening may be warranted in elderly patients with fractures, the researchers added.