Contrary to the prevailing belief, this is the crucial take-home message: to be healthy, you must ensure that you take in sufficient water and salt in your diet.
So, the word on the street and in nearly every physician's office is that salt is bad. A remarkably incorrect statement about one of the most essential substances in the human body, and as it happens, every biological system on the planet.
Please don't misunderstand me; too much salt can be harmful, and in marine environments where salt levels are very high, plants and animals have mechanisms to deal with the high levels. But we all need salt in our diet because we are a container of saline, salt plus water, in which every cell is immersed.
Tip #1 - As we cannot manufacture either salt or water, we need to consume both in our diet.
How does it work? In slightly simplified numbers, the body is a container filled with 10 litres of water and 10 grams of salt, a ratio of one to one, one litre of water to one gram of salt. This is the concentration or salinity of body water. Chemical and electrical processes require this concentration to work correctly. In practical terms, this means that if you lose salt, you must lose the equivalent amount of water. If the body loses one gram of salt, it can only have 9 litres of water in it! How do you lose salt, primarily in sweat, urine and faeces? In normal circumstances, the vast majority is lost in sweat. The more you sweat, the more salt you lose. The body can acclimate to exercise and hotter climates producing a lower salt content sweat, but let's deal with most of us.
Most people know that you will become dehydrated if you don't drink enough water. That's true, on a typical day you need about one to two litres. If you exercise and sweat, you lose both water and salt, often in large quantities.
In the era of low salt, people shy away from adding salt to their diet, so they become low in total body salt (and water).
Tip #2 - Maintain one-to-one ratio
Here lies a problem, the body must maintain the one-to-one ratio, so any water above the amount of salt is turned into urine.
Let's look at an example. You exercise for two hours and lose half a gram of salt in your sweat and one litre of water- your sweat has less salt in it than body water. Your body now contains nine and a half grams of salt (so it can only hold nine and a half litres of water to maintain the ratio of 1:1) and nine litres of water. You drink three bottles of plain water for a total of one and a half litres. You think you have done the correct thing. Soon you pass some urine, it is pale yellow or even clear, which means you know that you are hydrated. Wrong!
If you measured that urine output, you might be surprised to find that it is one litre. Your body needs ten litres. You lost one litre exercising, so why would you urinate out a litre rather than a half litre? The answer is that if you only have nine and a half grams of salt left after the loss from exercise, you can only have nine and a half litres of water. You drank one and a half litres, so your body will dump one litre and hold onto only a half litre. At the end of the process, you are still half a litre short.
This can happen quickly, as in the example above, or slowly over many days if you restrict your salt and fail to replace the salt you lose in sweat, urine and faeces. The net result is a slow decrease in your body's salt and water content, which is bad. Most people feel fatigued and off-colour. A common presentation in my office. It is easily fixed by adding salt back into the diet.
There is evidence that salt restriction seems to be linked to decreased levels of both calcium and magnesium in the body, both critical minerals.
Less salt = increased sugar consumption
Worse, as we now all drink purified water, we have compounded the problem. First, everyone is advised to drink a lot of water, so many people do so, and probably too much. The result, they pass a lot of urine and in that urine is salt! So by drinking too much pure water, you actually wash more salt out of the body.
And if that is not enough, there is evidence that salt restriction seems to be linked to decreased levels of both calcium and magnesium in the body, both critical minerals for the normal functioning of the body. In the case of magnesium, most people are already deficient! Low-salt diets also seem to increase sugar consumption.
All in all, another crazy medical fallacy imposed upon people.
The reason and the solution to follow in part two next week!