A RECENT study is questioning the World Health Organization's (WHO) dietary guidelines for sodium and potassium, saying it has set targets that are out of reach in many cultures.

In the interest of reducing heart disease and stroke, the WHO recommends consuming less than 2,000 milligrams of salt per day, an amount roughly equal to less than a teaspoon.

On the flipside, the WHO's recommended daily potassium intake is 3,510 milligrams per day, which would require eating about six potatoes per day, or drinking nine cups of milk per day.

Potassium-rich foods are well known to reduce heart disease and stroke, yet individuals are unlikely to consume enough of them to reach WHO target levels.

An international team of researchers based at the University of Washington examined dietary statistics obtained from surveys conducted by the governments of France, Mexico, the UK and the US.

They were not surprised to find that only a tiny portion of the population in each country -- a fraction of a percent in all cases -- are meeting the recommended daily guidelines for sodium and potassium.

"The chances that a majority of a population would achieve these goals is near zero"

Dr. Adam Drewnowski of UW said he would be shocked if any nation the world over came even close to achieving these goals.

"The data confirm that we eat too much sodium and not enough potassium," he says. "But they also suggest that the numbers being proposed by WHO and other health agencies are completely unfeasible."

Sodium and potassium are found in many of the same foods, according to Dr. Drewnowski, and this creates conflict when it comes down to a question of how much milk to drink, for it contains both.

Potassium-rich foods that don't contain sodium such as greens, citrus and fish are expensive, he says, adding approximately $1.49 per day or $42 per week to an individual's food bill.

Sprinkling potassium over food as a supplement isn't the answer, either, according to Dr. Drewnowski, for the substance has a metallic, bitter taste.

Global guidelines need to take global food patterns into account

Consumer education won't be enough to lower sodium intake, says Dr. Drewnowski.

To make a difference, processed foods -- the bearers of most of the sodium in the US diet -- would have to be reformulated.

Yet different strategies would apply to other countries and the bottom line according to Dr. Drewnowski is that global dietary guidelines need to set targets that are not only attainable but also affordable in developing countries.

The study was published in the British Medical Journal.