Night-time toilet trips are a fact of life for many of us, especially as we get older. More than half of people in their 50s have to get up once or more a night to relieve themselves.  This can lead to irritability and poor daytime functioning, having quite an impact on quality of life.

Japanese researchers have found that reducing or stopping night-time toilet trips (known as “nocturia”) may be as simple as lowering your salt intake.

When 223 volunteers cut their salt by 25 per cent, from 10.7g to 8g a day, their average night time toilet expeditions fell from an average of 2.3 trips to 1.4 times.  In contrast, when 98 subjects increased their intake from  9.9 to 11g they found that their need to urinate increased from 2.3 times/night to 2.7 times/night.

What causes nocturia?

Nocturia has several causes, such as hormonal changes as we age, and in men, the enlarging prostate gland causing pressure.  However, even then, reducing salt intake may help.

Your body can only get rid of excess salt through the urine, so a high consumption leads to greater urine production.  Eating salt also makes us thirsty, so it tends to go along with greater fluid intake.  In addition, the body becomes less efficient at dealing with salt as we get older, which can mean salt accumulates in the body and leads to fluctuations in urine production, especially at night.

Professor Marcus Drake of Bristol University, the Working Group Lead for the EAU Guidelines Office Initiative on Nocturia, said: “Research generally focuses on reducing the amount of water a patient drinks, and the salt intake is generally not considered.  Here we have a useful study showing how we need to consider all influences to get the best chance of improving the symptom”.

How much is too much?

Adults in the UK are recommended to eat no more than 6g of salt a day, equal to 2.4g of sodium.  Children should eat less – only 2g of salt for ages one to three, rising to 5g for seven to 10-year-olds.  After age 11, children can have up to 6g.

Most adults eat at least 8g a day.  This raises blood pressure, strains the heart and vascular system, the kidneys and the brain, and can increase the risk of stroke, heart attack, and dementia.  Reducing our consumption to 6g could prevent 14,000 deaths a year, saving the NHS around £3 billion, experts have calculated.

Reducing your intake

The problem is that much of our daily salt intake is “hidden” in everyday foods, such as bread, cereal, condiments, cheese, frozen meals, and canned or pickled foods.  It’s also difficult to work out how much salt is in your food, as many labels only list the “sodium” content per 100g.  High salt content is considered to be more than 1.5g salt (or 0.6g sodium) per 100g.

To calculate salt intake for a portion of food, multiply the “sodium per 100g” figure by 2.5,  and then divide by 100.  Measure how much your portion size weighs in grams, and multiply by this number to give you the salt content for your serving.

Try food swaps to reduce your salt intake.  Look for “low-sodium” bread, or make your own, salt-free.  Swap salty snacks such as crisps for unsalted nuts, popcorn or breadsticks.  Rinse canned foods such as vegetables and pulses before use.  Make fresh soup rather than using tinned, and go for fresh meat and fish rather than processed (such as sausages and fish-fingers).

So when it comes to salt, go low – your heart and your head will thank you!


Salt – the Facts: NHS Choices

Consensus Action on Salt and Health