But too little salt may also cause health problems, report authors add
TUESDAY, May 14, 2013 (HealthDay News) -- Most Americans should consume less salt, but too little salt can also cause health problems for some, a new report says.
The problem is that there is scant evidence for determining exactly how much salt is too much and how little is too little, according to the Institute of Medicine (IOM) committee that penned the report, which was released Tuesday.
"Studies have looked at efforts to lower excessive salt intake, but raised questions about harm from too little salt," explained IOM committee chair Dr. Brian Strom, a professor of public health and preventive medicine at the University of Pennsylvania Perelman School of Medicine in Philadelphia.
So, although the report supports current U.S. dietary guidelines on salt consumption, it does not determine whether those suggested limits could or should be lower.
"Unfortunately, the message is a mixed message, which is deliberate on our part and reflects the mixed data," Strom said. "We clearly support that, in general, eating too much salt is harmful. [But] we are raising questions about the harm from too little salt."
The right balance of salt, however, isn't known. "As a committee, we did not provide a target range of what the right amount should be," Strom said.
Specifically, the committee looked at the amount of salt recommended by the U.S. Dietary Guidelines for Americans, which say most people aged 14 to 50 should limit their daily salt intake to 2,300 milligrams (mg).
However, for more than 50 percent of Americans -- those aged 51 or older, blacks and people with high blood pressure, diabetes or chronic kidney disease -- those same guidelines say that salt intake should be limited to 1,500 mg a day.
"Most Americans come nowhere near the low end of salt consumption," Strom noted.
Despite efforts by the public health community to get people to use less salt, most Americans still consume an average of 3,400 mg or more of salt a day. That is about 1.5 teaspoons of salt, according to the IOM committee.
Only about 11 percent of the salt people eat comes from the salt shaker, added IOM committee member Dr. Joachim Ix, an associate professor of medicine at the Veterans Affairs San Diego Healthcare System in California.
"The lion's share of salt that's consumed is in the food people are taking in already. A large part of that is in processed foods and foods eaten outside of the home," Ix noted.
Another expert agreed.
"We usually think of sodium as table salt," said Samantha Heller, a senior clinical nutritionist at NYU Langone Medical Center in New York City. "But many foods are unexpectedly high in sodium, including sweets, breads and cereals," she noted.
"Over two-thirds of the sodium in our diet comes from processed foods like canned soups, frozen pizzas, baked goods, frozen meals, instant anything, and deli and restaurant foods," Heller added.
The U.S. Centers for Disease Control and Prevention states that lowering sodium intake could prevent thousands of deaths a year, Heller said.
"Choosing more whole, unprocessed foods that we cook at home can go a long way towards cutting the salt," Heller suggested. "Compare labels. For example: some breakfast cereals have as much as 290 mg of sodium per serving compared with others that have 0 mg per serving. Instead of salt, perk up at-home meals with lemon, vinegars, herbs, spices, jalapenos, garlic and onions."
However, after reviewing the evidence for the current salt intake recommendations, the committee found there were problems with the studies, including how they were conducted and the small number of cases where salt actually played a role in a health outcome, Strom said.
The IOM committee did, however, conclude:
- High salt consumption is linked to an increased risk for heart disease.
- There is no conclusive evidence that consuming 2,300 mg of salt a day either increases or decreases the risk for heart disease, stroke or death.
- Too little salt could raise the risk for further heart problems among those being treated for heart failure.
- There is no compelling evidence that people with diabetes, kidney disease, heart disease, hypertension or borderline hypertension, or those who are aged 51 or older or who are black should reduce their salt consumption to 1,500 mg or less a day.
- More research is needed to determine whether 1,500 to 2,300 mg of salt a day is optimal.
The Salt Institute welcomed the finding that too little salt might actually harm health.
"It is good to see that this report cautions against drastic sodium reduction efforts to get people to consume dangerously low levels of sodium of 1,500 mg a day," Morton Satin, vice president of science and research at the institute, said in a statement. "There is no scientific justification for population-wide sodium reduction to such low levels, and the recognition by the IOM experts that such low levels may cause harm may help steer overzealous organizations away from reckless recommendations."
The Institute of Medicine provides independent, objective, evidence-based advice to policymakers, health professionals, the private sector, and the public.
For more on salt, visit the U.S. Centers for Disease Control and Prevention (http://www.cdc.gov/salt/ ).
SOURCES: Brian Strom, M.D., George S. Pepper Professor of Public Health and Preventive Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia; Joachim Ix, M.D., associate professor, medicine, Veterans Affairs San Diego Healthcare System, California; Samantha Heller, M.S., R.D., senior clinical nutritionist, NYU Langone Medical Center, New York City; Morton Satin, vice president, science and research, Salt Institute; May 14, 2013, Institute of Medicine, report Sodium Intake in Populations: Assessment of Evidence