Salt and pee

I have long wondered why my husband pees so much more than I do. We both drink about the same amount of liquid a day, yet he pees a lot and I don’t.  At the same time, he craves and eats more salt than I do, but doesn’t drink more to compensate for the added salt. New research may shed some light on this conundrum.

Remember that your body knocks itself out to maintain a constant sodium level. Sodium is an important nutrient: it maintains normal blood pressure, supports the work of nerves and muscles, and regulates your body's fluid balance. If you eat too much, your body excretes it.

The new research was performed over a number of years on cosmonauts in captivity. Scientists kept track of their salt and liquid intake as well as their urine output. As would be expected, when the crew ate more salt, the amount of sodium in their blood remained constant because they excreted more salt and their urine volume increased. But the scientists were surprised to discover that, when they ate more salt, instead of drinking more, the crew members were drinking less! So where was all this excreted water coming from? It turns out that the water was coming from a breakdown of fat and muscle in their bodies, a result of in increased production of glucocorticoid hormones, which influence both metabolism and immune function. Because this breakdown process requires energy, the crew members were not only hungrier the more salt they ate, but they also lost weight! (Don’t eat excess salt to lose weight, because glucocorticoid hormones don’t do you any good under these circumstances.)

 As to the relationship between salt and thirst, it turns out that we get thirsty because salt-detecting neurons in the mouth stimulate an urge to drink. This kind of “thirst” may have nothing to do with the body’s actual need for water.

As one of the scientists said, “The work suggests that we really do not understand the effect of sodium chloride on the body.” I appreciate the candor.

I must confess that I’m not sure how this new research solves the mystery of why my husband pees more than I do. He probably just has better-functioning kidneys.

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