Surprising details about salt

water2We recently published a blog abut the health impact of high salt intake. We told you that the body relies on sodium from salt for a variety of functions, including blood pressure and the transmission of nerve impulses. And that it is important that the sodium level in blood is carefully maintained.

But there is more.

The conventional wisdom has long been that if you eat a lot of salt you will become thirsty and drink water, diluting your blood enough to maintain the proper concentration of sodium. Ultimately, you will get rid of the excess salt and water through urine. One way of increasing urine production is to increase blood pressure – the negative health impact of too much salt in the diet.

Sounds simple enough, but some of this may be very wrong.

Surprising findings

Two new studies have put part of this simple theory on its head. In long-term studies of simulated space travel the participants were given a well controlled diet with either 6, 9 or 12 g of salt per day. Eating more salt actually made the participants less thirsty, but somehow hungrier despite the amount of food being exactly the same.

Instead of drinking more, the participants were drinking less when getting more salt. But still increased urine production to get rid of the excess sodium. So where was the excreted fluid coming from? Well, the only explanation available would be that the fluid had been generated from existing body constituents.

How bizarre!

To get to the bottom of the findings the scientists repeated the experiments on mice and found that they burned more calories when they got more salt in the diet. Since they had unlimited access to food – in contrast to the humans above – they ate 25% more just to maintain their weight.

The animals were getting water – but not by drinking it. Instead an increased level of glucocorticoid hormones helped break down fat and muscle in their own bodies. This freed up water for the body to use. However, this process requires energy, thus the mice ate more food.

We already know that a starving body can burn its own fat and muscle for survival. That something similar happens on a salty diet was a surprise. But this is what camels do to create water from the fat in their humps when travelling through deserts with no water.

No, it’s no dieting solution

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So could this be a new weight loss fad? To eat more salty foods as salt seems to be involved in weight loss. In contrast to the previous opinion that a high-salt diet encourages a greater intake of fluids, which increases weight.

No, the advice is not to increase salt intake for three reasons:

  • Firstly, more salt in the diet will make you hungrier and you will eat more unless you have a very strong resolve. This would defeat the purpose of the dieting.
  • Secondly, the resulting high glucocorticoid levels are known to cause osteoporosis, muscle loss, diabetes and other metabolic problems.
  • And finally, the increased blood pressure due to the high salt intake can cause heart disease and premature death.

So it is a no brainer to still reduce salt intake. But at least now you know more about what happens when you eat too much salt.