Salt intake linked to night-time toilet trips

salt and toilet trips

Reducing salt intake could help reduce the need to use the toilet in the night, according to new research from Japan.

Researchers from Nagasaki University have found that reducing the amount of salt in the diet could help significantly reduce excessive night-time toilet trips – a condition called nocturia which affects over half of people aged over 50.

Reduction in salt                                    

The research involved tracking 321 people over the course of three months. Of these, 223 volunteers reduced their salt intake by 25% – from an average of 10.7g a day to 8g a day; and the other 98 volunteers increased their salt intake from 9.9g to 11g.

Those who reduced their salt intake found that the average number of times they needed to use the toilet during the night fell from an average of 2.3 trips a night to 1.4 trips. In contrast, those who increased their salt intake found their need to use the toilet rose from 2.3 times a night to 2.7 times.

The volunteers who reduced their salt intake, and therefore their need to urinate in the night, also said their quality of life improved.

This new research was presented at the European Association of Urology Congress in London.


Nocturia is the frequent need to urinate during the night. It mainly affects those over 50 years old and incidence tends to increase with age. It can be caused by hormonal changes, prostate problems, bladder problems, sleep-related problems or other medical conditions such as heart problems or diabetes.  

As we age, the body becomes less efficient at dealing with salt, and can result in an accumulation of salt and uneven urine production, particularly at night.

The condition can cause severely disrupted sleep and can affect people’s quality of life.

Salt intake

The NHS recommends that adults consume a maximum of 6g of salt a day.

The reason for the findings of this latest research are to do with how salt is disposed from the body. It can only be removed when dissolved, so the more salt that is eaten, the more urine is produced. Eating salty food also increases thirst, and therefore more liquid is consumed.

Quality of life

The lead researcher of the study, Dr Matsuo Tomohiro, said: “This is the first study to measure how salt intake affects the frequency of going to the bathroom.

“Night-time urination is a real problem for many people, especially as they get older. This work holds out the possibility that a simply dietary modification might significantly improve the quality of life for many people.”


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