Nocturia and Sodium-Potassium Balance
Table salt (sodium chloride) has gotten a lot of bad press in recent years, due to the discovery that high sodium intake is associated with cardio-vascular disease. The average person consumes far more sodium than necessary, an estimated 10 times the needed amount. But everybody is not an “average” person. If a person drinks a lot of fluids, avoids added salt in the diet even though blood pressure is normal, and also consumes a lot of fruits and vegetables (which are high in potassium), then a sodium-potassium imbalance could result. Some authors have criticized indiscriminate salt restriction even concerning cardio-vascular health (1). I will describe my own experience with salt restriction, and the disappearance of my nocturia (waking up during the night to urinate) after reintroduction of salt in my diet. Note that I'm not offering medical advice. You should always consult your doctor about your specific condition before you attempt to diagnose or treat any health problem. My personal experience may not be safe or applicable to other people.
For many years I've known that my blood pressure is normal, but like many health-conscious (and perhaps superficial) people I stopped adding any salt to my diet and avoided bread, salty prepared foods, and packaged snacks. I have also suffered from nocturia (2) for the past few years as I have aged, and never suspected any relation to salt restriction. Nocturia is usually defined as waking several times during the night to urinate, but here I'm defining the term more broadly as at least one disturbance of sleep per night due to urgent need to urinate, so long as the symptom is chronic.
In the past I attempted to limit fluid intake at the last meal, with little effect. For years I have also used sodium bicarbonate powder (baking soda) to wash fresh fruit and vegetables, which may modify serum pH, with no apparent effect. However, when I discovered the delicious taste of sun-dried black olives, I tried to approximate that delicacy by drying fresh black olives under sea salt (mostly sodium chloride). Before consuming the salt-dried olives at my last meal of the day I rinsed them under running water to remove the excess salt. Traces of salt remained, evidenced by the salty taste, and at the same time my nocturia disappeared.
Nocturia is fairly common in senior citizens. I used to wake up at least once during the night to urinate, and even during the day I was urinating with urgency. A doctor I consulted said that wasn't bad (I'm 65), compared to some seniors who wake up twice or more during the night to urinate. However, once I began eating salt-dried olives with my last meal of the day, I slept straight through without waking up, and even in the morning I didn't suffer any sense of urgency to urinate. I had no symptoms of hyponatremia before, so to test whether it was the salt or something else in the olives that had the beneficial effect, I began adding some sea salt to anything I ate at my last meal of the day. There were no other changes to my diet, and no medicines or supplements were taken. I'm a non-smoker who exercises every day, and I have no other health problems. It has now been about 90 days, and the nocturia has not returned. I haven't experienced any side-effects, and my normal blood pressure is unchanged (124/79). Fasting plasma sodium: 142.0mmol/L (normal range 136-145mmol/L). Potassium: 4.6mmol/L (normal 3.5-5.1mmol/L).
The theoretical basis for this observation is solid, since sodium is a known anti-diuretic. The average person doesn't consume a diet rich in fruits and vegetables (i.e. a potassium-rich diet), so my nocturia was an apparent result of a sodium-potassium imbalance. The kidney attempts to compensate for excess potassium by expelling more water. There are other possible causes of sodium depletion that may be treated by i.v. normal saline solution (3). But since cardio-vascular disease is a life-threatening condition, hypernatremia (excess sodium) is considered a more serious danger than excess potassium. Diuretic drugs that make you urinate are life-savers if your blood pressure is high. But if a person's blood pressure is normal, and the potassium intake is high, then moderate use of table salt or sea salt may be conducive to sodium-potassium balance and a possible treatment for nocturia.
This hypothesis is based on informal observations in my personal experience, so it should be tested by laboratory measurements of electrolyte levels before and after introduction of moderate salt consumption, and statistical analysis in a significant number of experimental subjects and controls, to determine if any improvement in nocturia is actually associated with improved sodium-potassium balance, and under what conditions salt consumption could be modified. My little discovery, if validated by more formal research, was purely accidental and hence I can't claim any credit for it.
References
- To Protect Your Heart, Your Sodium to Potassium Ratio Is More Important Than Your Overall Salt Intake. https://articles.mercola.com/sites/articles/archive/2014/08/25/sodium-potassium-ratio.aspx
- Nocturia Frequency, Bother, and Quality of Life: How Often Is Too Often? A Population-Based Study in Finland. http://www.europeanurology.com/article/S0302-2838(09)00341-8/abstract
- Sodium Disorders in the Elderly. J Natl Med Assoc. 2005 Feb; 97(2): 217–224. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2568789/pdf/jnma00183-0087.pdf