Public health
strategies should be based on best evidence
McMaster University
New research shows
that for the vast majority of individuals, sodium consumption does not increase
health risks except for those who eat more than five grams a day, the
equivalent of 2.5 teaspoons of salt.
Fewer than five per
cent of individuals in developed countries exceed that level.
The large,
international study also shows that even for those individuals there is good
news.
Any health risk of sodium intake is virtually eliminated if people improve their diet quality by adding fruits, vegetables, dairy foods, potatoes, and other potassium rich foods.
Any health risk of sodium intake is virtually eliminated if people improve their diet quality by adding fruits, vegetables, dairy foods, potatoes, and other potassium rich foods.
The research, published in The Lancet, is by scientists of the Population Health Research Institute (PHRI) of McMaster University and Hamilton Health Sciences, along with their research colleagues from 21 countries.
The study followed
94,000 people, aged 35 to 70, for an average of eight years in communities
from18 countries around the world and found there an associated risk of
cardiovascular disease and strokes only where the average intake is greater
than five grams of sodium a day.
China is the only
country in their study where 80 per cent of communities have a sodium intake of
more than five grams a day. In the other countries, the majority of the
communities had an average sodium consumption of 3 to 5 grams a day (equivalent
to 1.5 to 2.5 teaspoons of salt).
"The World Health
Organization recommends consumption of less than two grams of sodium -- that's
one teaspoon of salt -- a day as a preventative measure against cardiovascular
disease, but there is little evidence in terms of improved health outcomes that
individuals ever achieve at such a low level," said Andrew Mente, first
author of the study and a PHRI researcher.
He added that the
American Heart Association recommends even less -- 1.5 grams of sodium a day
for individuals at risk of heart disease.
"Only in the
communities with the most sodium intake -- those over five grams a day of
sodium -- which is mainly in China, did we find a direct link between sodium
intake and major cardiovascular events like heart attack and stroke.
"In communities
that consumed less than five grams of sodium a day, the opposite was the case.
Sodium consumption was inversely associated with myocardial infarction or heart
attacks and total mortality, and no increase in stroke."
Mente added: "We
found all major cardiovascular problems, including death, decreased in
communities and countries where there is an increased consumption of potassium
which is found in foods such as fruits, vegetables, dairy foods, potatoes and nuts
and beans."
The information for
the research article came from the ongoing, international Prospective Urban
Rural Epidemiology (PURE) study run by the PHRI. Mente is also an associate
professor of the Department of Health Research Methods, Evidence and Impact at
McMaster University.
Most previous studies
relating sodium intake to heart disease and stroke were based on
individual-level information, said Martin O'Donnell, co-author of the report, a
PHRI researcher and an associate clinical professor of medicine at McMaster.
"Public health
strategies should be based on best evidence. Our findings demonstrate that
community-level interventions to reduce sodium intake should target communities
with high sodium consumption, and should be embedded within approaches to
improve overall dietary quality.
"There is no
convincing evidence that people with moderate or average sodium intake need to
reduce their sodium intake for prevention of heart disease and stroke,"
said O'Donnell.
Besides Canada, this
research paper involved individual and community information from the countries
of Argentina, Bangladesh, Brazil, Chile, China, Columbia, India, Iran,
Malaysia, occupied Palestinian territory, Pakistan, Philippines, Poland, Saudi
Arabia, South Africa, Sweden, Tanzania, Turkey, United Arab Emirates, and
Zimbabwe.