A new report from the US Centers for Disease Control and Prevention (CDC) concludes that 90 per cent of adult Americans
are eating too much salt, mostly from processed and restaurant foods. It shows that even foods inherently low in salt, such as fruit and vegetables, end up being one of the main contributors to high sodium intake because of the salt that is added in processing and preparation, for instance in soups, sauces, canned vegetables, french fries and salads.
You can read the full report, which took data from the National Health and Nutrition Examination Survey (NHANES) for 2005-2006 and contrasted it with the Dietary Guidelines for Americans 2005, online in the CDC's latest Morbidity and Mortality Weekly Report (MMWR), published 25 June.
In line with the 6th edition of the Dietary Guidelines for Americans 2005, published by the US Department of Health and Human Services and US Department of Agriculture, the report splits the American adult population into two groups according to maxium level of sodium consumption per day to avoid risks to health.
The first group includes all blacks, the middle-aged, and people with high blood pressure (hypertension), who according to the guidelines should consume no more than 1,500 mg of sodium per day, and the second group is all other adults, who should consume no more than 2,300 mg of sodium per day (about 6 grams or 1 teaspoonful of table salt).
(Incidentally, in contrast to these limits, the American Heart Association recently recommended American adults should limit their daily sodium intake to less than 1,500 mg.)
The CDC report found that for 2005-2006:
- Overall, only 9.6 per cent of all US adults met the applicable 2005 guideline recommended daily limit for sodium.
- 5.5 per cent of the 1,500 mg and 18.8 per cent of the 2,300 mg per day group met the applicable daily limit.
- The average daily sodium consumption per US adult was 3,466 mg per day.
- The average daily consumption of sodium and calories in the 1,500 mg per day group was 3,366 mg and 2,068 kcal.
- For the 2,300 mg per day group this was 3,691 mg and 2,272 kcal.
- Most of the sodium consumed overall came from food categories for which the most calories were consumed.
- 36.9 per cent of the sodium consumed came from grains, 27.9 per cent from meats, poultry, fish, and mixtures, and 12.4 per cent from vegetables.
- Although the 1,500 mg per day group consumed statistically less sodium and calories than the 2,300 mg per day group, for 8 out of 9 categories of foods, there was no difference in the overall sodium density (mg of sodium per 1,000 kcal of food) of their consumption (suggesting the foods they ate had the same level of sodium but they just ate less of it).
- Small but significant differences between the groups were found in sodium density of their consumption in a couple of subcategories (grain mixtures and breads).
The high contribution of meats to sodium intake is rather surprising, but this could be because that category includes lunchmeats and sausages where salt is added in the processing.
There is a similar story behind consumption of fruits and vegetables, which the CDC finds is the third largest contributor of sodium intake, despite these foods being naturally low in sodium. Again, this could be partly because this category includes processed versions such as canned vegetables, vegetable-based soups and sauces, potato chips, fries and prepared salads.
Also, the report did not include salt added at the table or while cooking at home, so it is likely that considerably fewer than 10 per cent of adult Americans meet the national guideline for dietary salt.
In the US, dietary sodium comes mostly from processed and restaurant food. You can taste the salt in some foods such as canned soups and cured meats, but in many foods consumed on a daily basis, such as breads and cookies, you can't, so the implication of this report is that in view of the effect of too much sodium on health (it increass blood pressure, which in turn increases risk of heart disease, kidney disease and stroke), policy and environmental changes are necessary to reduce sodium intake across the US population as a whole.
Some progress is being made.
In April this year, a the New York City-led National Salt Reduction Initiative published its first set of voluntary benchmarks for reducing sodium in specific foods. Sixteen companies agreed to meet at least one of the benchmarks.
Also in April, the Institute of Medicine called for mandatory national standards and tighter regulation for the sodium content of food, with an interim strategy of voluntary action and improved surveillance of sodium.
"Sodium Intake Among Adults --- United States, 2005-2006."
CDC, Morbidity and Mortality Weekly Report (MMWR), 25 June 2010; 59(24); 746-749
Written by: Catharine Paddock, PhD