Introduction

Getting up once at night to urinate is considered normal, but if you have to get up numerous times, this can impact your sleep pattern. Nocturia is defined as the need for individuals to wake up often during the night to urinate. It is one of the most common and troublesome urinary symptoms and leads to inconvenience and sleep deprivation. 

Approximately one in three adults over 30 get up at least twice each night, and around 50% of adults over 65 get up at least once per night to use the bathroom. Studies report that individuals with nocturia who wake up three or more times per night have a significantly higher mortality rate compared to the general population. This condition impacts overall health and daytime functioning due to sleep loss, increases the risk of falls and injury at night, reduces quality of life, and lowers productivity. Nocturia can also affect the health of partners due to disrupted sleep. In the US, financially, nocturia costs an estimated $62.5 billion annually due to loss of productivity and sick leave from preventable falls, fractures, and associated injuries. Despite its impact and frequency, nocturia is often under-reported, poorly managed, and inadequately treated, with many patients mistaking it as a normal part of ageing. This misconception can delay effective treatment by 1 to 2 years from the onset of symptoms to physician-directed management.¹ 

Nocturia has many potential causes, including the amount and type of fluid intake (alcohol, coffee, water, etc), high sodium intake, any medications taken (like diuretics), comorbid medical conditions (like obesity, diabetes and hypertension), and urinary tract symptoms. This article focuses on the impact of fluid intake and diet on nocturia.¹

Fluid intake and nocturia

Fluid intake volume is correlated with urine volume. Drinking large amounts of fluids can cause nocturia, even if there are no other health issues. This increase in fluid intake could be due to several reasons: personal choice, psychological factors, or medical conditions like diabetes.¹ 

Managing the type and amount of fluid intake is crucial in addressing nocturia. While this approach may not entirely resolve the issue, it serves as a reasonable initial step towards symptom management. The following recommendations have been made to manage nocturia with respect to fluid intake:¹

1. Caffeine, found in many foods and beverages, is excreted through urine, increasing diuresis (stimulates the bladder and increases urine production). High caffeine intake can worsen nocturia. A study found that drinking over three cups of tea daily increases nighttime urination. Alcohol can have similar effects, disrupting sleep patterns and contributing to increased nocturia symptoms. A reduction in the consumption of caffeine and alcohol in the late afternoon and evening has been recommended 
2. It is suggested that fluid consumption be minimised between dinner and bedtime. Specifically, one should avoid drinking any liquids within two hours of going to bed. This practice helps reduce the volume of urine produced during sleep hours
3. One should aim to limit the total daily fluid intake to 2 litres. However, it is important to maintain hydration throughout the day, focusing on morning and early afternoon intake.
4. Certain foods, such as those high in salt or sugar, can increase thirst and fluid intake. One should consider adjusting the diet to support one's fluid management goals
5. Sudden changes in fluid intake can be challenging to maintain. Implementing these strategies gradually allows your body to adjust and increase the likelihood of long-term adherence

While these fluid management techniques may not completely cure nocturia, they can significantly help prevent symptoms from worsening and may lead to noticeable improvements. In addition to fluid management, other lifestyle modifications and medical interventions may also be needed; by thoughtfully managing what, when, and how much one drinks, individuals can take a significant step towards better-managing nocturia and improving overall sleep quality and quality of life.

Diet and nocturia

The impact of diet is often overlooked in treating nocturia. The focus usually lies on lifestyle adjustments and medications, while it is forgotten that food and nutrients also affect urine production. The body makes urine to:²

1. Keep fluid levels balanced
2. Manage electrolytes
3. Control acid-base balance
4. Remove waste products

What one eats and drinks directly affects these processes because the diet provides fluids, electrolytes (like sodium and potassium), and substances that affect water balance (such as urea and glucose). These dietary components can increase urine production and may lead to excessive urination at night and/or throughout the day. The effects of some food components are summarised below:

1. Sodium intake - Sodium intake varies widely based on cultural, socioeconomic, and geographical factors and individual eating habits. The primary source of sodium in the diet is processed foods. Consuming too much sodium can lead to increased thirst and fluid intake, which can worsen nocturia. Reducing sodium intake is a common recommendation to manage nocturia. Studies show that people who cut their salt intake from 10.7 grams to 8.0 grams per day experienced a significant reduction in nighttime urination. Conversely, those who increased their salt intake from 9.6 grams to 11 grams per day saw an increase in nocturia symptoms² 
2. Fruits and vegetables - Fruits and vegetables are rich in essential nutrients like vitamins, minerals, and fibre. A high intake of fruits and vegetables (more than 350 grams per 1,000 calories per day) significantly reduces urinary frequency, urgency, and nocturia compared to moderate intake (250-350 grams per 1,000 calories per day). Eating a lot of dark leafy vegetables (more than 50 grams per 1,000 calories per day) also significantly reduces symptoms compared to moderate intake (25-50 grams per 1,000 calories per day)²
3. Protein intake - Urea, a small organic molecule produced in the liver, is the main nitrogenous waste product resulting from the breakdown of dietary proteins. Though urea is a primary component of urine, relatively less attention has been given to urea. In a typical Western diet, which includes about 80 grams of protein daily, healthy adults typically excrete around 400 mmol of urea, 140 mmol of sodium daily, and other solutes. This means that the amount of urea excreted daily is significantly higher than that of sodium. Urinary urea excretion is linked to the amount of protein consumed in the diet. While a small portion of urea can be excreted through sweat, the majority is filtered by the kidneys and eliminated through urine. A high-protein diet is associated with increased urinary urea excretion and sodium excretion. High-protein diets, especially those including processed meats, dairy, or cereal products, often contain excess sodium. The excretion of these excess amounts of urea and sodium can lead to increased urine production. Reducing protein intake in the evening has been recommended as an effective lifestyle change to manage nocturia³
4. Melatonin and sleep - The relationship between food and nocturia may indirectly be related to melatonin. Melatonin is a hormone that regulates the sleep cycle, and disruptions in its release can lead to sleep disorders. Individuals with nocturia have been found to have lower serum melatonin levels compared to those without nocturia. Supplementing with melatonin has been used to improve sleep quality and reduce nocturia symptoms. Diet plays an important role in the body's natural production of melatonin. Certain nutrients are needed for melatonin synthesis. These include tryptophan, vitamin B, magnesium, zinc, and polyunsaturated fatty acids. Foods rich in these nutrients can boost melatonin levels. Examples of such foods are rice, barley, tomatoes, cranberries, strawberries, walnuts, olive oil, unprocessed cow's milk, eggs, and fish, all of which are excellent sources of melatonin. Studies have also shown that caffeine and alcohol impact melatonin levels. Caffeine has been shown to have both stimulatory and inhibitory effects on melatonin, while alcohol consumption has been shown to reduce night-time serum melatonin concentration. Hence, maintaining a diet rich in specific nutrients can help the body's melatonin production and alleviate nocturia² 

Summary

Nocturia is a condition in which an individual needs to wake up more than once each night to urinate. It significantly impacts the quality of life, sleep patterns, and overall health of affected individuals, especially among older adults. This condition is often misunderstood as a normal part of ageing, leading to higher mortality rates, increased risk of falls and injuries, and substantial healthcare costs. Effective management is frequently delayed due to under-reporting and misconceptions about its seriousness.

Managing nocturia involves paying attention to the food intake, fluid intake and melatonin production. Limiting caffeine intake, especially in the late afternoon and evening, can also help reduce night-time visits to the bathroom. Reducing sodium intake can lessen symptoms, while a high intake of fruits and vegetables can improve bladder function. High protein and processed foods intake contributes to increased urea and sodium excretion in the urine, suggesting that reducing evening protein consumption can be beneficial. Furthermore, a nutrient-rich diet can improve sleep quality and alleviate nocturia by supporting the body's natural melatonin production. Foods rich in tryptophan, vitamin B, magnesium, zinc, and polyunsaturated fatty acids, such as rice, tomatoes, walnuts, and fish, can boost melatonin levels. Avoiding substances that disrupt melatonin, like caffeine and alcohol, enhances melatonin levels. By making these dietary adjustments, one can better manage nocturia and improve the overall quality of life. These lifestyle changes also contribute to better overall health, enhanced daytime functioning, and an improved quality of life. While nocturia may not be entirely curable through these methods alone, they provide a strong foundation for more effective management and symptom reduction.