Daily Fluid Intake Recommendations and How It Effects the Pelvic Floor

Jim is a 75-year-old male who has been experiencing an increase in nighttime urination (nocturia) and difficulty with bowel movements over the past few years. His doctor recently sent him to pelvic physical therapy where the PT began discussing daily fluid intake. Jim tries to drink 2 glasses of water per day but much prefers a couple of sodas to quench his thirst. Despite not feeling thirsty, he is surprised to hear that he needs to increase his fluid intake, particularly water, and change the timing of his drinking to help address his concerns.  

Water makes up 75% of our body weight as an infant and 55% of our body weight as an elderly person. Our body maintains a state of balance, or homeostasis, by either keeping an increase in water when we are dehydrated or excreting (peeing out) more fluid when we are well hydrated.1  

Our body, in simple terms, is like a saltwater pool. If we don’t have enough water in the pool than it becomes too salty. This is what essentially what happens when we are dehydrated and is why we will feel thirsty and seek out fluid. Now, if it rains and too much water gets into the pool, it decreases the saltiness and some of the water must be removed to keep the pool at an optimal level. 

The kidneys help to cycle through the fluid in our body and determine what fluid and molecules need to be excreted and what fluid and molecules need to be kept in the body. They can functional more efficiently when provided with an adequate water supply. If water is lacking in the body, the kidneys must work harder to cycle through and preserve water in the body, which increases energy used. The same is true when we consume excessive amounts of salt or toxins that our body has to work in overtime to get rid of.1  

So, the question is, how much fluid should I be consuming in a given day? Unfortunately, there is no one size fits all answer since hydration has many variables, including age, activity level, and climate; however, there are general guidelines. According to the Institute of Medicine’s Dietary Reference Intakes Macronutrients Report from 2002 and World Health Organization, the adequate intake for females ages 19 and over is 2700 ml/day and males 19 and over is 3700 ml/day.1-2  

It is estimated that 22% of water comes from our food intake in the United States and even higher in some European countries where they have a higher consumption of fruits and vegetables. Food has varied water content and some food is a better source of hydration than others. If water counts as 100%, certain fruits and vegetables like cantaloupe, strawberries, watermelon, lettuce, celery, spinach, pickles, and cooked squash have 90-99% water content. Yogurt, apples, oranges, carrots, cooked broccoli, pears, and pineapple have 80-89% water content. Bananas, avocados, cottage cheese, ricotta cheese, and shrimp have 70-79%.1 

It is no secret that those  60 years and older typically have a fluid intake that is lower than other age groups. In fact, fluid intake over three non-consecutive days at home showed that 88% of elderly people have inadequate fluid intake (below 1500 ml/day). The U.S Agency for Healthcare Research and Quality lists dehydration as one of the 20 most common diagnoses with more than 300,000 hospital admissions involving older people, and it has been found that 50% of older people hospitalized for acute and chronic dehydration died within one year of admission.2 

In the older population, appropriate fluid intake can reduce the risk of falls, fractures, pressure ulcers, constipation, urinary infections, kidney stones, coronary events and pneumonia. Adequate fluid intake can assist with increased cognitive abilities, such as preventing confusion and delirium. The European Society for Clinical Nutrition and Metabolism recommends that older males drink 2.0 L/day (2000 ml/day) and females 1.6 L/day (1600 ml/day).2   

Much like older adults, males and females below 65 years old can experience a myriad of symptoms when not adequately hydrated. Low levels of dehydration can lead to reduced endurance, increased fatigue, altered ability for the body to regulate temperature, reduced motivation, reduced concentration, reduced short-term memory, and increased perceived effort or exertion. It is especially important to remain hydrated during exercise, particularly exercise in hot environments. Exercising in hot conditions without adequate fluid intake can increase the likelihood of hyperthermia, reduce the heart’s ability to pump blood out to your body (cardiac output), decrease blood pressure, decrease blood flow to your muscles, and elevate cortisol (stress) hormone.1 Water loss through sweat is essential to cool ourselves during exercise or in hot environments. Sweating can result in 0.3L/hour of water loss in sedentary conditions to 2 L/ hour in high activity heat, which means water intake can range from 2.5-3 liters per day in adults under normal conditions and up to 6 liters per day in high heat or activity. Physical performance has found to be affected in as little as 2% of sweat loss in athletes.1 

Rehydration can reduce these deficits and reduce stress of the system. It has been found that fluid intake based on thirst is not sufficient to offset fluid loss during exercise. Therefore, you should be drinking before you are thirsty! It is important to supplement water with minerals, such as salt, when sweating to increase water retention in the body which equates to increased hydration.1 

Now we know that staying hydrated is important, especially when being active. But how does fluid intake type and timing effect my pelvic floor? 

Women with fecal incontinence have been found to consume less water and more carbonated beverages than women without. Eight ounces or more of carbonated beverages is associated with increased symptoms of straining to defecate. Some women with fecal incontinence have noted improvement with increased water intake.3 

Low water intake has been associated with bowel symptoms in women with urinary incontinence and a contributing factor to constipation in older women.3 

Nocturia (nighttime urination) can be reduced by modifying type of fluid intake and timing of fluid intake. This includes reducing fluid intake 2 hours before sleep, especially caffeine and alcohol, emptying the bladder before bed, reducing dietary salt intake (this reduces excessive water retention in the body), and reducing overhydration.4  

Overactive bladder (OAB) occurs when there is increased urinary frequency, urinary urgency, and urinating at night with or without urinary urge incontinence. Unfortunately, many people with OAB restrict their fluid intake in hopes that it will reduce their frequency of restroom visits. However, a study of 91 women with OAB used urge suppression techniques and modified fluid consumption. Modified fluid consumption meant researchers had women continue to consume an adequate amount of daily fluid but with the majority (two-thirds) of the fluid consumed between morning and lunch. Day time urinary frequency of greater than 20 times was reduced 36.3% to 22%, nocturia of four times or more was reduced from 29.7% to 9.9%, urinary urgency had a statistically significant improvement, and 51.6% of women felt that they were "very much better or much better" after 3 months of treatment.5 

In summary, based on the recommendations from the National Academy of Medicine, if approximately 20% of our fluid intake occurs from food than men should consume 2,960 ml or approximately 100 ounces of non-food fluid per day and women should consume 2,160 ml or approximately 73 ounces per day.1 The average plastic water bottle is 16.9 ounces meaning that women should be consuming about 4.3 water bottles per day and men should consume approximately 6 water bottles per day. Ideally, the majority of fluid intake should be water as compared to carbonated beverages, and we should be consuming fluids prior to feeling thirsty. Staying hydrated can help with physical performance during exercise, increase alertness, and improve short term memory. If you are having difficulty with consuming enough fluids, add foods that are high in water content, keep a reusable bottle filled near you, use a straw if you are more inclined to sip, and set a timer on your phone as a reminder. Ideally, you want to sip water throughout the day with the majority of your fluid intake occurring in the first half of the day and limiting intake about 2 hours before bed.  

Whether you are experiencing fecal or urinary incontinence, fecal or urinary urgency and frequency, or another pelvic floor condition, your physical therapist should be assessing and addressing your fluid intake to ensure adequate hydration for optimal healing! 

Written by Jordan Schmidt, PT, DPT 

References 

1. Popkin, B. M., D'Anci, K. E., & Rosenberg, I. H. (2010). Water, hydration, and health. Nutrition reviews, 68(8), 439–458. https://doi.org/10.1111/j.1753-4887.2010.00304.x- pubmed  

1. Masot, O., Miranda, J., Santamaría, A., Paraiso Pueyo, E., Pascual, A., & Botigué, T. (2020). Fluid Intake Recommendation Considering the Physiological Adaptations of Adults Over 65 Years: A Critical Review. Nutrients, 12(11), - DeepDyve 

1. Halani, P., Harvie, H., Arya, L., & Andy, U. (2020). Is Fluid Intake Associated With Fecal Incontinence in Women?. Female Pelvic Medicine & Reconstructive Surgery, 26(2), 137-140. – DeepDyve 

1. Oelke, M., De Wachter, S., Drake, M. J., Giannantoni, A., Kirby, M., Orme, S., Rees, J., van Kerrebroeck, P., & Everaert, K. (2017). A practical approach to the management of nocturia. International journal of clinical practice, 71(11), e13027. https://doi.org/10.1111/ijcp.13027 - pubmed; reduce fluid intake before bed 

1. Pal, M., Chowdhury, R. R., & Bandyopadhyay, S. (2021). Urge suppression and modified fluid consumption in the management of female overactive bladder symptoms. Urology annals, 13(3), 263–267. https://doi.org/10.4103/UA.UA_52_20