Ordinary salt a killer, or not!

Excess sodium can cause heart disease (Photo: Wolf Soul)

Excess sodium can cause cardiovascular disease (Photo: Wolf Soul)

Some simple facts:

  • Cardiovascular disease is the number one cause of death in the world
  • Excess sodium intake raises blood pressure
  • High blood pressure is one of the major contributors to the development of cardiovascular disease

Research just published modelling populations across 187 countries attributed more than 1.6 million cardiovascular-related deaths per year to sodium consumption above the World Health Organization’s recommendation of a maximum of 2.0 g per day.

The details of the study

The researchers collected and analysed existing data from 205 surveys of sodium intake in countries representing nearly three-quarters of the world’s adult population, in combination with other global nutrition data, to calculate sodium intakes worldwide by country, age, and sex.

The researchers found the average level of global sodium consumption in 2010 to be 3.95 g per day, nearly double the 2.0 g recommended by the World Health Organization. All regions of the world were above recommended levels, with regional averages ranging from 2.2 g per day in sub-Saharan Africa to 5.5 g per day in Central Asia.

The proportion of deaths from heart attacks and strokes attributable to sodium ranged quite a bit. In Canada, the United States, Australia and New Zealand, about 10% of cardiovascular deaths were linked to high salt intake. But in a wide band stretching from Eastern Europe all the way across into Central Asia and East Asia, the percentage of cardiovascular deaths attributed to sodium consumption jumped up to 20 to 25%. This happens to be the Old Silk Road, where people traveled vast distances on trade missions and needed salt to preserve their food. This tradition of eating salt-preserved foods has survived to our days.

The researchers found that reduced sodium intake lowered blood pressure in all adults, with the largest effects identified among older individuals, blacks, and those with pre-existing high blood pressure. They stated that because the study focused on cardiovascular deaths, the findings may not reflect the full health impact of sodium intake, which is also linked to higher risk of nonfatal cardiovascular diseases, kidney disease and stomach cancer, the second most-deadly cancer worldwide.

So that’s settled then, is it? Doom and gloom, since limiting salt consumption is difficult given that 80% of a person’s daily salt intake comes from the foods they eat, rather than the salt shaker.

Not so fast!

On the contrary, another recent study suggests that many dietary guidelines for sodium intake are unrealistic, and that the low recommended level of sodium could be associated with a higher risk of cardiac disease and mortality.

Although it has long been the view that eating too much salt will raise your blood pressure, a comprehensive global study now says that too little salt in your diet also can harm your heart health. There appears to be a “sweet spot” for daily sodium intake between 3 and 6 g (equal to 7.5 to 15 g of salt) associated with a lower risk of death and heart disease than either more or less.

The study included more than 100,000 adults from the general populations of 17 countries, providing a broad sample of people that varied greatly in socioeconomic, geographic and demographic makeup. The study found that those who consumed more than 6 g of sodium daily had higher blood pressures than those who consumed less sodium. Within this group, blood pressure increased with higher sodium intakes. The effect of dietary sodium intake on blood pressure was less dramatic for those in the medium (3 to 6 g) range of sodium intake and none for those in the low range of sodium intake (less than 3 g). However, sodium intake of less than 3 g per day was tied to a 27 percent increased risk of death and heart disease, according to their findings.

The study thus provided evidence that both high and low levels of sodium intake may be associated with an increased risk of death and cardiovascular disease and that healthy people probably can eat about twice the amount of salt compared to what is currently recommended — or about as much as most people consume anyway. Since only one in 20 people in the world currently eat what is recommended, it’s not a very practical recommendation.

The good news

Potassium in bananas can counter effects of sodium (Photo: Branko Collin)

Potassium in bananas can counter effects of sodium (Photo: Branko Collin)

But there is more. Before you start to worry too much about a futile effort of counting your exact intake of sodium think potassium. The study provided new evidence about the association of sodium and potassium intake with blood pressure, death and major cardiovascular events. It showed that consuming larger amounts of potassium counterbalanced the adverse effect of high sodium excretion on blood pressure. Potassium is a nutrient found in fruits, vegetables and beans. Rather than focusing on sodium, maybe it is better to focus on eating an overall healthy diet and pursuing healthy lifestyle changes.

It is probably safe to say that if you don’t already have high blood pressure and you’re not over 60 or eating way too much salt, salt won’t have much impact on your blood pressure.

But this is controversial news that could potentially undercut current public health messages about salt. It will take some further time before scientists can agree on the way forward.

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