Confused? Just take it with fewer grains of salt
IF YOU’RE confused about salt, I’m not surprised. There’s been a steady back-and-forth on claims that reducing dietary sodium (which represents 40 percent of the salt molecule) is crucial to our well-being, countered by claims that following this advice can sometimes be a health hazard.
While some studies have concluded that only people with hypertension on high-salt diets need to reduce salt intake, the overwhelming strength of scientific findings bolsters advice from major health organisations that most Americans should cut back on sodium. Excess sodium is responsible for most cases of hypertension in Western societies, and hypertension is a leading risk factor for heart attacks, strokes and kidney failure.
Because salt added to our foods by processors and restaurants, not that from our saltshakers, is the main source of sodium in our diets, protecting the health of the most vulnerable requires a society-wide reduction in sodium.
The recommended daily intake for healthy American adults – 2,300 milligrams of sodium a day, or the amount in about one and an eighth teaspoons of salt – will be reflected in the new nutrition facts label, scheduled to take effect in mid-2018. Currently, the average American consumes more than 3,400 milligrams a day, an amount often found in a single restaurant meal. A lunch of soup and a sandwich can easily add up to a day’s worth of sodium.
However, an expert team reported last year in the New England Journal of Medicine that an average reduction of just 400 milligrams of sodium a day could save 28,000 lives and $7 billion in health care costs a year.
Seventy-five countries, including the United States, have adopted or advocated salt-lowering goals, and wherever this is happening, rates of hypertension and deaths from cardiovascular disease are declining.
To be sure, sodium is an essential nutrient, as is chloride that makes up the rest of the salt molecule. We evolved from ocean-dwellers, and human tissues still swim in a salty sea. Our kidneys are fine-tuned machines for keeping blood levels of sodium within a physiologically healthy range; when there’s too much sodium on board, the kidneys dump it into urine for excretion, and when more is needed, they reabsorb it from urine and pump it back into the blood.
Unfortunately, faced with a chronic excess of sodium to deal with, the kidneys can get worn out; sodium levels in the blood then rise along with water needed to dilute it, resulting in increased pressure on blood vessels and excess fluid surrounding body tissues (read, swelling).
So why, you may wonder, is there any controversy? Shabby science, resulting in claims that is it unsafe to reduce sodium intake below 1,500 milligrams a day, is one reason, according to Bonnie Liebman, director of nutrition at the Center for Science in the Public Interest, a health advocacy organisation in Washington.
“Very few people consume so little sodium, and most of those who do are sick to begin with, so they eat less and consume less sodium,” she explained. “It’s a phony issue.”
But when a study is published that runs counter to prevailing beliefs, it tends to get undue media coverage. “The media like ‘man bites dog’ stories, and studies with surprising results make headlines,” Liebman said.