A key national health group today recommended relaxing sodium guidelines for half of Americans, but a Creighton University scientist says the organization could have loosened them more.
The Institute of Medicine's report represented a rare shift in standards affecting sodium, the main component of table salt, after years of ratcheting them more tightly.
The institute, an independent body that provides scientific advice to the public, continued to maintain that Americans generally consume too much sodium. High sodium intake may lead to high blood pressure and heart disease, the institute said.
But large groups of Americans — those 51 years of age and older, African Americans, and people with high blood pressure, diabetes and chronic kidney disease — have been told for several years to aim for daily sodium intake at an extremely low 1,500 milligrams per day.
The report Tuesday said those groups, who make up more than half of the nation, could strive for 2,300 milligrams per day, just like everyone else.
Dr. Robert Heaney, a Creighton scientist who maintains people may consume from 3,000 to 6,000 milligrams, said Tuesday that the institute's upward recommendation to 2,300 milligrams is a good step.
“It says (there's) no point in trying to go below” 2,300 milligrams, he said. “And that's a major, major change, in my judgment.”
Studies don't prove a need to lower levels below 2,300 in the general population, the institute said. There is some evidence that intake below 2,300 is harmful for diabetics and people with heart and kidney disease, the report said, but proof of either benefit or harm at low levels isn't strong enough to treat those groups differently from the general population.
More research is needed to recommend a range for sodium intake, said Dr. Brian Strom, institute committee chairman. What is excessive sodium and what is too little isn't clear.
“That's what we need more research about,” Strom, of the University of Pennsylvania, said in an interview Tuesday.
The Institute of Medicine influences recommendations by the federal government, American Heart Association and other groups and affects school lunch programs, military meals and other government nutrition programs.
The institute said in 2004 that 1,500 milligrams was the minimum amount necessary to create a balanced diet and 2,300 was the highest amount with no evidence of harmful effect on blood pressure. The American Heart Association now recommends that people strive for 1,500 milligrams.
The institute previously said that restaurants and food manufacturers need to gradually wean Americans off high sodium diets. The institute said in 2010 that the “preference for salty taste can be changed” through a coordinated effort by the food industry.
Heaney, a longtime researcher and professor at Creighton University, said sodium guidelines gradually became more stringent beginning in the 1980s when public health officials recommended sodium intake “in moderation.”
Heaney, who was on an Institute of Medicine nutrition panel in the mid-1990s, said the concern about excessive salt intake is overblown.
“I would say don't worry about it,” said Heaney, a professor and former vice president for health sciences at Creighton.
Based on his review of sodium studies, he said, less than 3,000 milligrams of sodium daily generally is too little and more than 6,000 milligrams is too much. Americans typically consume 3,400 milligrams or more a day, which is about one-and-a-half teaspoons of salt.
He said there is “risk at both extremes” of sodium intake.
But Dr. Troy Plumb, a University of Nebraska Medical Center kidney specialist, said he doubted the new report would change how he deals with patients. He already encourages patients not to add salt, to read labels on packaging and to aim for 2,000 to 3,000 milligrams a day.
He wouldn't suggest that 3,000 to 6,000 is a satisfactory range, Plumb said. High amounts of sodium contribute to high blood pressure and water retention, he said.
“We know that lowering sodium in the diet can be one of the things that we do to lower blood pressure, specifically in people with kidney disease,” Plumb said.
Cindy Brison, an extension educator with University of Nebraska-Lincoln Extension in Douglas and Sarpy Counties, said the only people who might have to worry about low sodium intake would be workers who lose sodium by sweating a great deal.
Sodium is present in so many foods — from breads to beets, fast food to processed food — that it's hard to have too little sodium, she said.
“Watching people use salt shakers before they even taste their food — those are the people I would be most concerned about,” Brison said.
For reports such as that released Tuesday, the institute typically convenes a panel of experts in the field. The panel then reviews relevant studies to determine whether recommendations need to be adjusted.
Dan Schober, a research scientist with the Gretchen Swanson Center for Nutrition in Omaha, said the institute bases its recommendations purely on science and is highly credible.
“The Institute of Medicine is very careful about what they put out,” Schober said. “They're not a biased group.”
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