Fast food fans beware: even if you're being kilojoule-conscious, you are very likely getting far too much sodium with that burger and fries-or even that chicken salad.
A survey of thousands of lunchtime patrons of 11 different fast food chains found their meals contained an average of more 1 700 milligrams (mg) of sodium.
Sodium content too high
US health guidelines recommend most people eat no more than 1 500 mg of sodium daily.
"Sodium was high across all of the chains that we looked at, and in particular the sodium density is high," said Christine M. Johnson of the Cardiovascular Disease Prevention and Control Program of the New York City Department of Health and Mental Hygiene.
Eating too much salt is a well-established risk factor for high blood pressure, Johnson added. But it's tough for people to keep their sodium intake under control, especially since more than three quarters of the salt people eat comes from restaurant meals and packaged foods, she and her colleagues point out in a research letter in the Archives of Internal Medicine.
US guidelines state that adults should consume less than 2,300 mg of sodium daily, and that limit shrinks to 1,500 mg for blacks, people with high blood pressure, and people over 40, who represent seven in 10 US adults.
How the study was done
To examine how much sodium people might be consuming with fast food meals, the researchers quizzed people leaving 167 different New York City fast food chain restaurants about what they'd purchased for lunch, gathering a total of 6,580 receipts.
Nearly 60% of purchases contained more than 1,500 mg of sodium.
The US Food and Drug Administration states that 600 mg of sodium per meal is "healthy"; just 3% of the meals met this guideline, while 20% contained more than 2,300 mg of sodium.
Meals averaged around 2,100 mg of sodium for every 4 200kJ.
One strength of the study is that it isn't based on a person's memory of what he or she ate, Johnson noted; "This is really what people are purchasing to eat for lunch right then. It's what they actually have in their hands."
New York City restaurants are now required to list the calorie content of all the food and drink they sell, but there aren't requirements for listing sodium content. Johnson recommends that people who enjoy fast food and want to limit their sodium intake check for this information online, for example at a restaurant's Web site.
"Really being able to see that information before you make the decision is so key," she said. Something that may seem like a healthier, low-sodium choice-like a chicken salad-may still be packed with salt, she explained.
While the city has no plans to start requiring restaurants to list the sodium contents of their products, according to Erin Brady, deputy press secretary with the NYC Health Department, it has launched a national initiative to reduce the sodium content of packaged and restaurant foods by 25% by 2014; so far, 16 companies have signed on to the voluntary effort, along with dozens of cities and states and 18 national health organisations (Reuters Health, May 2010).