How to avoid hyponatremia in your outdoor activities

Yes, the title of this article is a little odd and goes against the nutritional messages that we hear frequently! To eat salty? Do not drink too much water? And what is hyponatremia?

This article is complementary to the article on hydration that I wrote a short time ago and in which I had already mentioned the importance of mineral salts during an effort. Today we will see this in more detail and focus on the role of sodium.

This is not a topic much discussed for hiking, but it is for sports like running or triathlon for example. Still, it’s worth looking into the problem for some hikes.

This article is the result of research that I did that complemented what I already knew about it. I tried to make a relatively simple article and popularized without going too much into the physiological details.

The goal here is to make you aware of hyponatremia (I explain later what it is) and to question the need for sodium intake for certain hikes.

Why worry about sodium?

When hiking (as in any sports effort), our body not only loses water (mainly through perspiration) but also mineral salts.

You have probably already noticed that sweat has a salty taste or even that it leaves white marks on clothes. This is a proof that by sweating we are losing salts. Some of these salts contain sodium – which seems to play a very important role during an effort (perhaps more than other mineral salts).

During an effort, it is normal to replace the lost water by drinking, so why not fill in the sodium losses? After all, it seems logical enough!

I remember hearing about it the first time when I was little. At the time, I was playing football, and I had a glass of salt water before leaving for a game. I heard it was good. I did not know why, but I drank that glass. I still remember it – and I’ve never done it again since. I do not know if it was because of the dosage (probably very heavy) but I have a pretty horrible memory. In addition, I did not notice a difference in performance. But, that did not stop me from reoffending with a glass of sugar water a few times later. 😉Experiencing is always a good way to learn!

Studies have shown that sodium loss (and non-replacement) may have a direct effect on hyponatremia. Do not worry, I’ll explain right away what it is.

Hyponatremia and how to avoid it

Natremia is the concentration of sodium in the blood plasma. Hyponatremia is therefore a too low concentration of sodium in the blood plasma (below 136 mmol / L).

Symptoms and consequences

The symptoms are quite variable and not very characteristic. It can be headaches, dizziness, water disgust, fatigue, nausea, etc. But it is something to take seriously because it can lead to death in severe cases.

What is it and how can it be avoided?

There are several causes of hyponatremia, but here we will focus on hyponatremia caused by stress (some anti-inflammatory drugs for example increase the risk). There are two main theories:

  • Hyponatremia is thought to be due to loss of sodium (not replaced) during exercise that would decrease the sodium concentration.
  • Hyponatremia is thought to be due to excessive water consumption during exercise that “dilutes” sodium.

In doing some extensive research, I realized that the role of sodium in hydration is not as clear as I thought. Not all publications go in the same direction, the subject is extremely complex and researchers do not seem to have reached a consensus yet.

And it is especially to answer the question “how to avoid it” that many researchers do not agree.

Let’s start with the point on which everyone is pretty much in agreement: Too much water during an effort can lead to hyponatremia – some even talk about hyperhydration. After a race, some athletes finish even heavier than before the start because of too much water consumption.

On the other hand, what is the subject of this article is the link between sodium intake during exercise and the risk of hyponatremia. Some studies show that sodium intake limits or avoids the risk of hyponatremia for athletes. Others say that these sodium intakes during exercise have no effect on the serum sodium. These discrepancies are due to physiological mechanisms that are difficult to understand.

What to conclude?

To avoid hyponatremia, do not drink too much. The problem, as we saw in the article “Do you hydrate properly during your hikes?” Is that you have to drink enough to avoid dehydration and that you can not trust the feeling of thirst. It is therefore quite difficult to drink enough but not too much.

Cases of hyponatremia are not extremely common in hiking (at least less common than dehydration), but it can happen. So think about this before limiting your water consumption.

According to some publications, sodium intake during exercise does not reduce the risk of hyponatremia. On the other hand, in the various studies and publications, I did not see any discouraging a sodium intake (moderate) during the effort – except for the people at risk (arterial hypertension or others).

My opinion

When in doubt, I prefer to try to compensate for the loss of sodium, consuming more during significant efforts. My point of view (surely very basic) is also that we must replace what is lost to return to balance.

After, maybe in 10 years, we will realize that all the sodium intake during the effort was a stupidity or just a marketing move for some drinks!

Of course, I would not recommend sodium for all walks. Let’s see now in which cases it may be interesting to ask the question.

Warning : What I say in this article is quite general and must be seen on a case by case basis. Supplements and sodium intakes are not recommended for everyone, such as people with high blood pressure. If in doubt, talk to your doctor.

When should you be concerned about the risk of hyponatremia?

It seems that some people are more prone to hyponatremia resulting from an effort than others – without the reasons being really explained yet. It seems that the habit of exertion also plays a role – the loss of sodium in perspiration being diminished with training and habit. But, as we have seen, the link between sodium loss and hyponatremia is still discussed.

Although it is surely possible to suffer from hyponatremia without effort, by simply drinking too much water (probably by doing it on purpose), hyponatremia is especially associated with intense and long efforts . This is why most studies have been done on triathletes or long distance runners and long trials.

So, if you’re not doing extremely intense day hikes, you probably do not need to worry about your sodium intake for an effort like this. Do not drink 3 gallons of water during the day.

For multi-day hikes, very sporty hikes or in hot weather, I think it’s worth trying to compensate for the loss of sodium. Especially, for multi-day hikes, the food we carry is different from the one we eat every day and sometimes much lower in sodium.

How to replace sodium lost during exercise?

The simplest and most practical way to compensate for your sodium losses is by eating or drinking (I do not recommend intravenous ;-)).

The goal is not to sprinkle salt on all your food or to eat potato chips all day, but to choose foods that are high in sodium (and as long as you do other minerals).

As for good hydration, it is not enough to consume more sodium only during the effort. It is also important to consume before to prepare well and after the effort to recover – especially between two consecutive days of hiking.

As always, “not enough” is not good, but “too much” is not good either. Be careful not to consume too much sodium – which will dehydrate you. This is why salt pellets are absolutely not recommended. The amount of sodium ingested at one time is too much. Plus, salt pellets are not absorbed easily and can cause digestive problems – not great for having a good time.

The ideal, and what is recommended for runners and endurance athletes is to have a sodium intake in the water they consume. Sports and energy drinks still contain sodium for this reason.

If you do not want to add salt to your water (which I totally understand ;-)) or consume energy drinks, you can simply consume more sodium in your diet. Of course, it is a less regular intake than in drinks, but it is surely enough to hike.

What sodium intake?

As we have seen previously, not all studies agree on the importance of sodium intake in limiting the risk of hyponatremia.

So, with regard to the amount of sodium to be consumed during the effort, the studies diverge even more. Especially that it depends on each person as well as conditions.

To give you a reference, the WHO (World Health Organization) recommends about 0.17 oz of sodium per day per person (contained in the food and beverages we eat). This is an average daily figure that does not necessarily take into account sports efforts. It should be known that these are recommendations and that many people are currently above these recommendations.

Caution : Do not confuse salt with sodium afterwards. Table salt contains about 40% sodium. 1 oz of salt therefore contains about 0.39 oz of sodium (and about 0.59 oz of chlorine).

Sodium intake in drinks

Some recommendations range from 400 mg sodium per liter of water (1g of table salt) to 700 mg per liter of water . This is quite close to the concentration found in isotonic beverages, which typically contain about 500 to 700 mg of sodium per liter.

Other studies claim that this intake is too low and that it can lead to hyponatremia – even if, according to them, with less luck than drinking still water. They recommend an intake closer to the sodium concentration of sweat (about 1g / L).

Others prefer to reason in terms of mg of sodium per hour and I have seen figures ranging from 700 mg to 1 g of sodium per hour of effort. These figures were given for running and triathlon so are probably too high for hiking – which is usually a less intense effort.

Some publications advise athletes (triathlon and running) to increase their sodium intake by 10 to 20 grams per day for a long race. For hiking, I think we would rather be around 5 grams for a day of hiking given the intensity of the effort.

Sodium intake in food

If you are like me and do not like too much salt water or energy drinks, you can increase your sodium intake through food. But how do you know how much sodium to consume?

One way to do the math is to calculate the number of liters of water you consume in a day and consume that number in grams of extra sodium per day. It is a very rough calculation but can serve as a basis. For example, if I drink about 5 liters of water in a day of hiking, I consume 5 g more sodium each day.

To calculate the amount of sodium you consume, you can use food packaging charts. Most display sodium content per 100g per serving.

Otherwise, here is a table that lists the sodium concentrations of different foods :


This article is a bit technical, but I hope that it has allowed you to discover what hyponatremia is and to present to you the results of studies done to date on this topic.

You probably understand my point of view, which is to have an extra salt intake during a long effort, although not all studies show that sodium intake reduces the risk of hyponatremia. But, I have not found any studies showing that a moderate intake of sodium during exercise can have a detrimental effect.

It’s up to you to make up your mind and choose to have an extra sodium intake or not depending on your hikes and your health.

I am curious to know what you think. Is sodium something you thought about before? And will this article change something for you and your hikes? Tell me all this in the comments.

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