Can Reduced Salt Intake Be Harmful?
By Edward C. Geehr, M.D., Lifescript Chief Medical Officer
Published February 18, 2011
The greatest salt restrictions are recommended for people 51 and older, African-Americans, people with high blood pressure, and diabetics of any age. Daily intake should be reduced to less than 1,500 milligrams (mg) of sodium, or the equivalent of 2/3 teaspoon. All others are recommended to limit their daily sodium intake to 2,300 mg, equal to a single teaspoon.
The guidelines are a severe restriction compared to the average American consumption of 3,400 mg of sodium per day. Those of you who have been subjected to a hospital low-salt diet already appreciate the difference. The average male between ages 30 and 39 is by far the largest consumer of sodium, ingesting an average of about 4,500 mg per day, or three times the lower sodium threshold.
Processed foods are the primary source of salt consumption, according to the guidelines. Pizza alone accounts for 6% of the salt in American diets. Salad dressings, cold cuts and hamburgers are other high-sodium foods targeted for reduction.
The guidelines assume that Americans are eating more salt, which in turn drives up blood pressure rates.
Not so, say two Harvard researchers. A 2010 American Journal of Clinical Nutrition study reports that sodium consumption has remained flat over the last 40 years.
While salt consumption hasn’t changed, average calorie consumption has skyrocketed during that period. The number of obese and overweight Americans has nearly doubled. The guidelines overlook recent research that indicates obesity is the principle factor behind rising blood pressure rates. Salt sensitivity affects between 10%-20% of the population, leading to increased blood pressure or stiffening of the vessels. While some people with hypertension are sensitive to the amount of salt intake, not all respond to decreased sodium. But obesity highly correlates with blood pressure.
A recent study on thousands of people across 33 different countries showed that people consume sodium within a narrow range of 2,700 mg to 4,900 mg per day. The new guidelines, if followed, would make the U.S. the only modern nation with salt consumption at such low levels.
Ironically, reduction in salt could aggravate the tendency to overeat. Many nutritionists feel the sodium guidelines will lead people to consume more calories to satisfy taste and their innate salt appetite.
To make matters worse, a dramatic reduction in salt intake can interfere with blood sugar metabolism. A recent Harvard study found a correlation between low-salt diets and acceleration of insulin resistance, a precursor to type 2 diabetes.
While many of the new guidelines are sensible recommendations, the new salt reduction targets are likely to generate much controversy in coming years. Before any radical change in your salt intake, talk to your physician about a diet that’s right for you.
Today, if you eat nothing but unprocessed foods—plenty of fruits, vegetables, whole grains, and nuts, with a smattering of wild fish and naturally raised beef, chicken, eggs, and milk—that you prepare yourself with a light hand on the salt shaker, you are taking in far more potassium than sodium (not to mention plenty of vitamins, minerals, fiber, phytonutrients, healthy fats, and other elements of a healthful diet).
More potassium than sodium is a good thing. But few Americans eat this way. Instead, our reliance on fast and prepared foods tips the balance in the other direction. Most of us get far more sodium than we need while averaging just 2,500 mg of potassium, about half of what is recommended for adults. Equally worrisome, our hunger for salt appears to be growing. In the United States, there has been a 55 percent increase in the average sodium intake since the 1970s.
Hazards of Too Much Sodium
Higher salt intake was associated with a 23 percent increase in stroke and a 14 percent increase in heart disease. Several dozen studies have explored connections between salt, sodium, or salty foods and cancer. The data from these studies show that, in general, higher intakes of salt, sodium, or salty foods is linked to an increase in stomach cancer. The World Cancer Research Fund and American Institute for Cancer Research concluded that salt, as well as salted and salty foods, are a “probable cause of stomach cancer.”
The more salt you take in, the more calcium your body flushes out in the urine, leaching out of the bones. So a diet high in sodium could have an additional unwanted effect—the bone-thinning disease known as osteoporosis. A study in post-menopausal women showed that the loss of hip bone density over two years was related to salt as much as calcium. Other studies have shown that reducing salt intake causes a positive calcium balance, suggesting that reducing salt intake could slow the loss of calcium from bone that occurs with aging.
It’s clear that an abundance of salt in our food is a silent killer, responsible for thousands of deaths each year. The real question is, what can be done to help people reduce their intake? The answer is simple. Become the producer of your own foods rather than the consumer of processed foods. You can do something about your, and your family’s, salt intake, simply by cutting back on processed foods and choosing more fresh foods.
The New England Journal of Medicine modeled what would happen if Americans cut back their average daily sodium consumption by 1,200 milligrams—an amount that would still leave many people above the recommended intake, but would be a significant decrease from current levels. Such a cutback would prevent up to 120,000 new cases of heart disease each year, researchers estimate, and would save up to 92,000 lives and $24 billion in health costs.