How To Save a Half Million Lives

Reducing sodium intake over ten years could save hundreds of thousands of lives

(RxWiki News) Heart disease is one of the leading killers in the United States. Too much salt in your diet is a risk factor for heart disease and other heart problems. So could reducing salt save lives?

Yes, definitely. The more important question is, how many lives could lowering dietary salt save? To answer that question, researchers turned to math.

Imagine eating just one-twentieth of a teaspoon less salt each day for a year. Then, during the following year, imagine subtracting another one-twentieth of a teaspoon of salt from your diet each day.

Keep that up each year for ten years, taking away 5 percent of a teaspoon of salt each day. If every person in the US did that over the next ten years, the average daily sodium intake would be 2,200 mg daily per person.

And that could save a half million lives.

"Eat less salt."

The study, led by Pamela G. Coxson, PhD, of the Department of Medicine at the University of California San Francisco, used three different mathematical models to measure how reducing sodium in US diets might affect death rates.

A mathematical model in medicine is where the researchers create a massive set of equations that take into account different possibilities. Researchers input different data possibilities into the formulas and then see what the result would be.

Creating different equations allows some models to assume some conditions and others to assume different conditions. If three different models show similar overall results, the validity of the results increases. That is, the results are basically more trustworthy.

In all three of the models used in this study, the researchers were making calculations about how much heart-related deaths would decrease if sodium intake were reduced across the country.

For the first math model, the researchers specifically focused on the effects of reducing sodium intake on cardiovascular disease.

In the second model, they focused on the indirect effects of reducing sodium intake on individuals' blood pressure. The researchers used data from medical trials of high blood pressure medications to fill out their projections.

In the third model, the researchers made calculations based on what past epidemiological studies have found. An epidemiology study looks at disease over the long-term by comparing individuals and their habits or characteristics.

The researchers plugged three different scenarios into each of these math models. The first scenario involved gradually reducing the country's sodium intake so that it was 40 percent lower 10 years from now.

A 40 percent reduction would mean the population consumed an average of 2,200 mg of sodium a day. That reduction could be measured as eating 5 percent of a teaspoon (1/20th of a teaspoon) less salt each day per person.

Using this scenario, the combined results of the math models showed that anywhere from 280,000 to 500,000 lives would likely be saved over 10 years.

The second scenario calculated what might happen if everyone cut their sodium by 40 percent tomorrow to 2,200 mg a day and then kept that reduction for 10 years.

The third scenario was the most dramatic: what would happen if everyone cut their sodium to 1,500 mg a day tomorrow and kept that up for a decade?

For the second and third scenarios, the researchers used the models to calculate that anywhere from 700,000 to 1.2 million deaths might be prevented over 10 years.

"Under three different modeling assumptions, the projected health benefits from reductions in dietary sodium are substantial," the researchers wrote.

They suggested a number of possible public health approaches that might help lower sodium intake in the US. Among these are regulation, educating consumers and labeling food more clearly.

They also suggested voluntary partnerships with food manufacturers and local, state and federal policies that might help reinforce healthier diets with lower amounts of sodium.

According to Sarah Samaan, MD, a cardiologist with Legacy Heart Center in Dallas-Fort Worth and a dailyRx expert, this study shows "clearly and concisely the expected health benefits we could achieve by cutting the amount of salt in our diets."

"As a public health issue, this is also an issue of economics, since high blood pressure is a major contributor to strokes, heart disease and kidney failure, all of which can lead to serious disability and more expensive health care," she added.

Dr. Samaan also pointed out that it's not adding salt from the salt shaker that is really the big problem in terms of where the salt in our diets comes from.

"It's important that people understand that about 80 percent of the salt in our American diet comes from processed, prepared and restaurant food," she said.

"In addition to fast food, lunch meats, soups, pasta sauces and even bread products are typically loaded with sodium. Our taste buds have become accustomed to this high salt load, but it is possible to wean ourselves off. By committing to gradually ease the amount of salt included in their products, manufacturers and restaurants could have an enormous impact on public health."

The study was published February 11 in the journal Hypertension. The research was funded by the US Centers for Disease Control and Prevention and by the American Heart Association. The researchers declared no conflicts of interest.

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Review Date: 
February 12, 2013