By Nanci Hellmich
If people cut their salt intake and increased their intake of potassium by eating more fruits and vegetables, millions of lives around the world could be saved every year, says research out today.
These dietary changes would lower people's blood pressure, which would reduce their risk of having a stroke or heart attack, according to the findings published on bmj.com.
To take an in-depth look at the topic, British researchers and other experts from around the world analyzed dozens of international studies on salt and potassium and high blood pressure. High blood pressure is defined as a reading greater than or equal to 140/90.
Among the findings:
• A modest reduction in salt intake for four or more weeks lowered systolic pressure (the top number) by an average of 5mm Hg (millimeters of mercury). Blood pressure reductions from reduced salt intake were greater in people with hypertension.
• Reduced salt intake did not have adverse effects on cholesterol or renal function.
• Increased potassium intake also helped lower blood pressure.
An estimated 2.5 million deaths could be prevented each year worldwide by cutting salt intake in half, says Graham MacGregor, the senior author on one of the research papers and professor of cardiovascular medicine at Barts and London School of Medicine. He's also chairman of World Action on Salt and Health.
The ideal thing is to lower salt intake and increase potassium intake, he says. To do the latter, people would need to eat another three servings of fruits and vegetables a day - such as an orange, banana and a serving of spinach - on top of what they are eating now, MacGregor says
"Salt reduction by the food industry is by far the most attractive policy," he says. "It doesn't cost much, and it would result in huge health care improvements and costs."
Food companies in the U.K. have reduced the salt added to processed foods, and the salt intake in the U.K. has fallen without people changing what they buy, MacGregor says.
"Many of the branded food companies in the U.K. are the same ones that operate in the U.S., and they need to reduce the huge amount of unnecessary salt they are putting into food in the U.S. in the same way that they have in the U.K."
He says this is a win-win for everyone. "People who eat less salt will live longer so the food companies will be able to make more money."
Elliott Antman, a spokesman for the American Heart Association and a professor of medicine at Harvard Medical School, says the new research is a "very detailed review of the medical literature which shows that too much sodium is harmful, and potassium is actually helpful."
He points out that another recent study, published in the journal Hypertension, concluded that a gradual reduction of sodium intake in the U.S. could save 280,000 to 500,000 lives over 10 years.
Currently about 67 million American adults (31%) have high blood pressure, according to the Centers for Disease Control and Prevention. Only about half have the condition under control.
High blood pressure means the blood running through your arteries flows with too much force and puts pressure on your arteries, stretching them past their healthy limit and causing microscopic tears, the heart association says. The scar tissue that forms to repair those tears traps plaque and white blood cells, which can lead to blockages, blood clots and hardened, weakened arteries, the group says.
About 69% of people who have a first heart attack, 77% of people who have a first stroke, and 74% of people with chronic heart failure have high blood pressure, the CDC says.
Americans currently consume about 3,400 milligrams of sodium a day, mostly from processed foods and restaurant fare. The government's dietary guidelines advise reducing daily sodium intake to less than 2,300 milligrams for most people 2 and older, and cutting back to 1,500 milligrams for people 51 and older and those of any age who are African American or have hypertension, diabetes or chronic kidney disease. The American Heart Association recommends that everyone cut back to 1,500 milligrams a day.
"We know that reductions of this magnitude translate to a reduction in stroke and heart attacks," Antman says.
"The food industry is making modest reductions of the amount of sodium in their products," he says. "While this is commendable, it still leaves too much sodium in the U.S. food supply. More substantial reductions in the sodium content of our foods need to take place and they need to occur more quickly than they have to date."
People in this country have grown up with high-sodium foods and need to be weaned off the taste, he says. If they eat lower-sodium foods for a period of time, their taste buds get used to it, and it tastes fine to them, Antman says.
Morton Satin, vice president of science and research for the Salt Institute, an industry group, says, "There is no evidence that salt reduction improves overall health outcomes."
Salt reduction reduces blood pressure by a couple of points in people with high blood pressure, he says. If your systolic blood pressure is at 160 and drops a few points, that's no great benefit, nowhere near a comparable benefit from standard blood pressure medication, he says.
"On the other hand, there is a large body of clinical evidence linking negative health outcomes, such as insulin resistance, with salt reduction.
"I cannot understand how our entire public health establishment can go on talking about salt reduction and ignoring every single peer-reviewed publication that counters the salt-restriction agenda," Satin says.