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Pass on the salt? Study says you don’t need to

Research method is under fire by scientists
A new international study challenges the conventional wisdom about reducing salt consumption. Earlier this year, Boston Market had removed the salt shakers from the tables in their restaurants nationwide.

A large, international study questions the conventional wisdom that most people should cut back on salt, suggesting the amount most people consume is OK for heart health – and too little may be as bad as too much. The findings came under immediate attack by other scientists.

Limiting salt is still important for people with high blood pressure – and in fact, a second study estimates too much sodium contributes to up to 1.65 million deaths each year. The studies both have strengths and weaknesses and come as the U.S. government is preparing to nudge industry to trim sodium in processed and restaurant foods.

The first study’s leader, Dr. Salim Yusuf of McMaster University’s Population Health Research Institute in Hamilton, Ontario, urged keeping an open mind.

“There are those who have made a career out of promoting extreme sodium reduction that will attack us,” he said. It’s better to focus on healthy lifestyles and overall diets instead of a single element, “and that is something everyone can rally around.”

No one should view this as permission to eat more salt, he said, adding that “most people should stay where they are.”

The studies appear in The New England Journal of Medicine.

Yusuf’s is observational, rather than a strict experiment, and has big limitations in its methods. But its size lends strength – more than 100,000 people in 17 countries, the largest on this topic. It’s also from a general population, not just people at high risk of heart disease, as many past studies have been.

“These are now the best data available,” Dr. Brian Strom said of the new study. Strom, the chancellor of Rutgers Biomedical and Health Sciences, led an Institute of Medicine panel last year that found little evidence to support very low sodium levels.

“Too-high sodium is bad. Too low also may be bad, and sodium isn’t the whole story,” Strom said. “People should go for moderation.”

The study was sponsored by the McMaster Institute, nonprofit and government groups and industry. The countries included Canada but not the United States; China accounted for 42 percent of participants. About 40 percent had high blood pressure.

Sodium levels were estimated from a single urine test instead of the preferred method of over 24 hours at multiple times, which Yusuf said was impractical in such a big group.

That drew criticism from a host of scientists.

“This is a fundamental flaw” that undermines of confidence in the results, said Dr. Elliott Antman, a Brigham and Women’s Hospital cardiologist who is president of the Heart Association.

Dr. Martin O’Donnell of McMaster University, one of the researchers, said potatoes, bananas, avocados, leafy greens, nuts, apricots, salmon and mushrooms are high in potassium, and “it’s easier for people to add things to their diet than to take away” something like salt.

The second study in the journal – on how much sodium contributes to heart-related deaths – was led by Dr. Dariush Mozaffarian of Tufts University and the Harvard School of Public Health and funded by the Bill and Melinda Gates Foundation. Researchers looked at dozens of studies around the world on sodium intake, calculated its relationship to high blood pressure and then the relationship of high blood pressure to cardiovascular deaths.

There were 1.65 million deaths from intake of more than 2 grams of sodium a day, they estimate, and half a million deaths based on current worldwide consumption of 4 grams a day, said Mozaffarian, who has consulted for some food makers.

His study is less controversial and shows why policies to curb salt are important, Michael Jacobson of the consumer group Center for Science in the Public Interest, wrote in an email.



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