WHO’s new salt guideline: Why replacing sodium with potassium salt may prevent hypertension, heart attacks

What are K-salts?

Normal table salt contains sodium chloride. The K-salts or potassium-based substitutes replace the sodium chloride with potassium chloride. These salts have double benefits — they may help in bringing down sodium consumption while increasing potassium consumption. There is evidence to suggest that increasing potassium consumption, even in isolation, can significantly reduce blood pressure. Potassium intake mainly happens from foods such as beans, peas, nuts, vegetables such as spinach and cabbage, and fruits such as bananas and papaya.

What does the guideline say?

First, it reiterates cutting down sodium intake to less than 2 grams per day, which is equivalent to about 5 grams of salt. Second, it recommends doing away with table salt as it continues to be one of the best ways of cutting down sodium intake. The third and newest guideline asks users to partially replace table salt with potassium.

The new recommendation, however, does not apply to women, children, or people living with kidney impairments. There wasn’t enough data to suggest the use of potassium-based salts in these groups.

What is the evidence that WHO looked at to formulate the guideline?

Experts looked at 26 randomised control trials from across the world, including one from India, totalling almost 35,000 participants. The follow-up period ranged from nearly two months to five years.

Switching the table salt on average reduced the systolic pressure by 4.76 mmHg and diastolic blood pressure by 2.43 mmHg.

It also reduced the risk of non-fatal strokes by 10 per cent and cardiovascular deaths by 23 per cent.
Using these salt substitutes also resulted the level of potassium in blood increasing by 0.12 mmol/L

However, the WHO did not “strongly” recommend the switch to the salt substitutes. This is because some of the evidence showed that despite using the substitutes, sodium intake in the participants remained high, suggesting that lowering the blood pressure may be because of the potassium intake alone. The evidence to suggest reduction in cardiovascular events and stroke deaths was also not very strong.

While most of the studies replaced sodium in table salt with potassium in proportions varying from 19 per cent to 50 per cent, some of the studies also replaced it with potassium in combination with magnesium and calcium.

Why is the guideline important?

It is extremely important for India, considering the significant burden of hypertension, heart attacks and strokes, even in younger age groups. Nearly 35.5 per cent of the country’s population — or 315 million people — are estimated to be living with hypertension in India, according to the INDIAB study. Cardiovascular diseases accounted for 28.1 per cent of the total deaths in India in 2016, according to an analysis of the Global Burden of Disease study.

What are the challenges?

High sodium foods build taste addiction and thirst, leading to increased sales of mineral water and colas. Sodium salts are also good at absorbing and retaining moisture, so they can increase the weight of products at no extra cost. Additionally, sodium-based salts increase shelf-life of foods. This is the reason the switch may be difficult in pre-packaged foods.