This week the World Health Organization (WHO) released new guidelines recommending people switch the regular salt they use at home for substitutes containing less sodium.

But what exactly are these salt alternatives? And why is the WHO recommending this? Let’s take a look.

A new solution to an old problem

Advice to eat less salt (sodium chloride) is not new. It has been part of international and Australian guidelines for decades. This is because evidence clearly shows the sodium in salt can harm our health when we eat too much of it.

Excess sodium increases the risk of high blood pressure, which affects millions of Australians (around one in three adults). High blood pressure (hypertension) in turn increases the risk of heart disease, stroke and kidney disease, among other conditions.

The WHO estimates 1.9 million deaths globally each year can be attributed to eating too much salt.

The WHO recommends consuming no more than 2g of sodium daily. However people eat on average more than double this, around 4.3g a day.

In 2013, WHO member states committed to reducing population sodium intake by 30% by 2025. But cutting salt intake has proved very hard. Most countries, including Australia, will not meet the WHO’s goal for reducing sodium intake by 2025. The WHO has since set the same target for 2030.

The difficulty is that eating less salt means accepting a less salty taste. It also requires changes to established ways of preparing food. This has proved too much to ask of people making food at home, and too much for the food industry.

Enter potassium-enriched salt

The main lower-sodium salt substitute is called potassium-enriched salt. This is salt where some of the sodium chloride has been replaced with potassium chloride.

Potassium is an essential mineral, playing a key role in all the body’s functions. The high potassium content of fresh fruit and vegetables is one of the main reasons they’re so good for you. While people are eating more sodium than they should, many don’t get enough potassium.

The WHO recommends a daily potassium intake of 3.5g, but on the whole, people in most countries consume significantly less than this.

Potassium-enriched salt benefits our health by cutting the amount of sodium we consume, and increasing the amount of potassium in our diets. Both help to lower blood pressure.

Switching regular salt for potassium-enriched salt has been shown to reduce the risk of heart disease, stroke and premature death in large trials around the world.

Modelling studies have projected that population-wide switches to potassium-enriched salt use would prevent hundreds of thousands of deaths from cardiovascular disease (such as heart attack and stroke) each year in China and India alone.

The key advantage of switching rather than cutting salt intake is that potassium-enriched salt can be used as a direct one-for-one swap for regular salt. It looks the same, works for seasoning and in recipes, and most people don’t notice any important difference in taste.

In the largest trial of potassium-enriched salt to date, more than 90% of people were still using the product after five years.

Making the switch: some challenges

If fully implemented, this could be one of the most consequential pieces of advice the WHO has ever provided.

Millions of strokes and heart attacks could be prevented worldwide each year with a simple switch to the way we prepare foods. But there are some obstacles to overcome before we get to this point.

First, it will be important to balance the benefits and the risks. For example, people with advanced kidney disease don’t handle potassium well and so these products are not suitable for them. This is only a small proportion of the population, but we need to ensure potassium-enriched salt products are labelled with appropriate warnings.

A key challenge will be making potassium-enriched salt more affordable and accessible. Potassium chloride is more expensive to produce than sodium chloride, and at present, potassium-enriched salt is mostly sold as a niche health product at a premium price.

If you’re looking for it, salt substitutes may also be called low-sodium salt, potassium salt, heart salt, mineral salt, or sodium-reduced salt.

A review published in 2021 found low sodium salts were marketed in only 47 countries, mostly high-income ones. Prices ranged from the same as regular salt to almost 15 times higher.

An expanded supply chain that produces much more food-grade potassium chloride will be needed to enable wider availability of the product. And we’ll need to see potassium-enriched salt on the shelves next to regular salt so it’s easy for people to find.

In countries like Australia, about 80% of the salt we eat comes from processed foods. The WHO guideline falls short by not explicitly prioritising a switch for the salt used in food manufacturing.

Stakeholders working with government to encourage food industry uptake will be essential for maximising the health benefits.

Xiaoyue (Luna) Xu, Scientia Lecturer, School of Population Health, UNSW Sydney and Bruce Neal, Executive Director, George Institute Australia, George Institute for Global Health

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Water is essential for daily functioning and health, and we can only survive a few days without it. Yet we constantly lose water through sweat, urination and even evaporation when we breathe.

This is why we have evolved a way to regulate and maintain water in our bodies. Like other animals, our survival relies on a strong biological drive that tells us to find and drink water to balance fluid loss.

This is thirst – a sensation of dryness in the mouth signalling we need to have a drink. This basic physiological mechanism is controlled mainly by part of the brain’s “control centre”, called the hypothalamus. The hypothalamus receives signals from various regions of the body and in return, releases hormones that act as a messenger to signal the thirst sensation.

What is dehydration?

Staying hydrated (having enough water in our bodies) is important for several reasons, including:

• regulating body temperature through sweat and respiration
• lubricating joints and eyes
• preventing infections
• digesting and absorbing nutrients
• flushing out waste (via the kidneys)
• preventing constipation
• brain function (including memory and concentration)
• mood and energy levels
• physical performance and recovery from exercise
• skin health.

Dehydration occurs when our body doesn’t have enough water. Even slight drops in fluid levels have noticeable consequences, such as headaches, feeling dizzy, lethargy and struggling to concentrate.

Chronic dehydration can pose more serious health risks, including urinary tract infections, constipation and kidney stones.

What does the evidence say?

Despite thirst being one of the most basic biological drivers for good hydration, science suggests our feelings of thirst and subsequent fluid intake don’t always correlate with hydration levels.

For example, a recent study explored the impact of thirst on fluid intake and hydration status. Participants attended a lab in the morning and then later in the afternoon to provide markers of hydration status (such as urine, blood samples and body weight). The relationship between levels of thirst in the morning and afternoon hydration status was negligible.

Further, thirst may be driven by environmental factors, such as access to water. For example, one study looked at whether ample access to water in a lab influenced how much people drank and how hydrated they were. The link between how thirsty they felt and how hydrated they were was weak, suggesting the availability of water influenced their fluid intake more than thirst.

Exercise can also change our thirst mechanism, though studies are limited at this stage.

Interestingly, research shows women experience thirst more strongly than men, regardless of hydration status. To understand gender differences in thirst, researchers infused men and women with fluids and then measured their thirst and how hydrated they were. They found women generally reported thirst at a lower level of fluid loss. Women have also been found to respond more to feeling thirsty by drinking more water.

Other ways to tell if you need to drink some water

While acknowledging some people will need to drink more or less, for many people, eight cups (or two litres) a day is a good amount of water to aim for.

But beyond thirst, there are many other ways to tell whether you might need to drink more water.

1. urine colour: pale yellow urine typically indicates good hydration, while darker, concentrated urine suggests dehydration

2. frequency of going to the toilet: urinating regularly (around four to six times a day) indicates good hydration. Infrequent urination can signal dehydration

3. skin turgor test: gently pinching the skin (for example, on the back of the hand) and observing how quickly the skin returns to its normal position can help assess hydration. Slow return may indicate dehydration

4. mouth and lips: a dry mouth or cracked lips can be early signs of dehydration

5. headaches and fatigue: frequent headaches, dizziness, or unexplained fatigue can be signs of inadequate hydration

6. sweating: in physically active people, monitoring how much they sweat during activity can help estimate fluid loss and hydration needs. Higher levels of sweat may predispose a person to dehydration if they are unable to replace the fluid lost through water intake

These indicators, used together, provide a more comprehensive picture of hydration without solely depending on the sensation of thirst.

Of course, if you do feel thirsty, it’s still a good idea to drink some water.

Lauren Ball, Professor of Community Health and Wellbeing, The University of Queensland and Kiara Too, PhD candidate, School of Human Movement and Nutrition Sciences, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.