Salt
reduction only important in some people with high blood pressure
Date:
May
21, 2016
Source:
McMaster
University
Summary:
A
large worldwide study has found that, contrary to popular thought, low-salt
diets may not be beneficial and may actually increase the risk of
cardiovascular disease (CVD) and death compared to average salt consumption.
The study suggests that the only people who need to worry about reducing sodium
in their diet are those with hypertension (high blood pressure) and have high
salt consumption.
Risks
associated with low-sodium intake -- less than three grams per day -- are
consistent regardless of a patient's hypertension status.
Credit:
© Sebastian Studio / Fotolia
A
large worldwide study has found that, contrary to popular thought, low-salt
diets may not be beneficial and may actually increase the risk of
cardiovascular disease (CVD) and death compared to average salt consumption.
In
fact, the study suggests that the only people who need to worry about reducing
sodium in their diet are those with hypertension (high blood pressure) and have
high salt consumption.
The
study, involving more than 130,000 people from 49 countries, was led by
investigators of the Population Health Research Institute (PHRI) of McMaster
University and Hamilton Health Sciences.
They
looked specifically at whether the relationship between sodium (salt) intake
and death, heart disease and stroke differs in people with high blood pressure
compared to those with normal blood pressure.
The
researchers showed that regardless of whether people have high blood pressure,
low-sodium intake is associated with more heart attacks, strokes, and deaths
compared to average intake.
"These
are extremely important findings for those who are suffering from high blood
pressure," said Andrew Mente, lead author of the study, a principal
investigator of PHRI and an associate professor of clinical epidemiology and
biostatistics at McMaster's Michael G. DeGroote School of Medicine.
"While
our data highlights the importance of reducing high salt intake in people with
hypertension, it does not support reducing salt intake to low levels.
"Our
findings are important because they show that lowering sodium is best targeted
at those with hypertension who also consume high sodium diets."
Current
intake of sodium in Canada is typically between 3.5 and 4 grams per day and
some guidelines have recommended that the entire population lower sodium intake
to below 2.3 grams per day, a level that fewer than five per cent of Canadians
and people around the world consume.
Previous
studies have shown that low-sodium, compared to average sodium intake, is
related to increased cardiovascular risk and mortality, even though low sodium
intake is associated with lower blood pressure.
This
new study shows that the risks associated with low-sodium intake -- less than
three grams per day -- are consistent regardless of a patient's hypertension
status.
Further,
the findings show that while there is a limit below which sodium intake may be
unsafe, the harm associated with high sodium consumption appears to be confined
to only those with hypertension.
Only
about 10 per cent of the population in the global study had both hypertension
and high sodium consumption (greater than 6 grams per day).
Mente
said that this suggests that the majority of individuals in Canada and most
countries are consuming the right amount of salt.
He
added that targeted salt reduction in those who are most susceptible because of
hypertension and high salt consumption may be preferable to a population-wide
approach to reducing sodium intake in most countries except those where the
average sodium intake is very high, such as parts of central Asia or China.
He
added that what is now generally recommended as a healthy daily ceiling for
sodium consumption appears to be set too low, regardless of a person's blood
pressure level.
"Low
sodium intake reduces blood pressure modestly, compared to average intake, but
low sodium intake also has other effects, including adverse elevations of
certain hormones which may outweigh any benefits. The key question is not
whether blood pressure is lower with very low salt intake, instead it is
whether it improves health," Mente said
Dr.
Martin O'Donnell, a co-author on the study and an associate clinical professor
at McMaster University and National University of Ireland Galway, said:
"This study adds to our understanding of the relationship between salt
intake and health, and questions the appropriateness of current guidelines that
recommend low sodium intake in the entire population."
"An
approach that recommends salt in moderation, particularly focused on those with
hypertension, appears more in-line with current evidence." The study was
funded from more than 50 sources, including the PHRI, the Heart and Stroke
Foundation of Canada and the Canadian Institutes of Health Research.
Story
Source:
Materials provided by McMaster
University. Note: Content may be edited for style and length.
Journal
Reference:
1. Andrew Mente et
al. Associations of urinary sodium excretion with cardiovascular events
in individuals with and without hypertension: a pooled analysis of data from
four studies. The Lancet, 2016 DOI: 10.1016/S0140-6736(16)30467-6
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