There are tell-tale signs that you might be overdoing your sodium consumption and the key to finding the 'sweet spot' with your sodium intake is understanding your body's own needs. 

Is it possible to overdose on sodium?

Naturally, this question is often posed to us when athletes first learn that our strongest drinks (PH 1000 and PH 1500) contain about 2 and 3 times more sodium than a regular sports drink, making them amongst the strongest electrolyte replacement drinks on the market.

And of course the short answer is ‘Yes’, it’s theoretically possible to OD on sodium (as it is with nearly all nutrients).

However, overdoing it to the extent that it’s dangerous or detrimental just through drinking a sports drink really is highly unlikely. That's as long as if you apply some basic common sense and you take the time to understand your body and figure out what it needs.

The man who overdosed on soy sauce

I read an interesting post headlined ‘Soy Sauce Overdose Sends Man Into Coma’ and it reminded me to write this post about something we get asked about a lot - i.e. is it possible for athletes to dangerously overdose on sodium using electrolyte drinks?

The man in question reputedly drank about 1.14 litres (1 quart) of the condiment in a very short space of time ‘as a dare’. I can’t help imagining a group of blokes stood around him chanting ‘Down it, Down it, Down it!’. He consumed about 165g of salt in the process, that’s 28 times the recommended daily allowance here in the UK. As the salt referred to in this calculation is table salt - NaCl - he would have taken in around 66g of sodium (salt is about 40% sodium 60% chloride) in just over 1 litre of fluid!

Image credit: Stocksnap (copyright free)

To put this INSANE figure into context; in the same amount of seawater he’d ‘only’ have consumed 14g of sodium (from 35g of NaCl), and to achieve the same strength solution using our products he’d have had to have added 88 tablets (or sachets) of our 1500mg/l strength mix to just over 1 litre of water. It really was a ridiculous dose to consume all in one go and unsurprisingly, it very nearly killed him…

The massive influx of sodium into his bloodstream caused the rapid onset of a condition called acute Hypernatremia. The term literally means high blood sodium levels and is said to occur when the sodium concentration rises rapidly to above 145mmol/l. It’s the polar opposite of hyponatremia - a much more common and widely talked about topic in sports science and one we’ve written about before).

The hypernatremic episode was so dramatic it sent him into seizures, spasms and a coma. He was extremely lucky to get quick and effective treatment from a nearby hospital. They quickly flushed his system out with glucose laden fluids and, as a result, he survived what would otherwise have been a fatal salt overdose. In the end he walked out of the hospital a few days later with few lingering ill effects.

Summary: It is theoretically possible to overdose on all nutrients, including sodium, but it's extremely unlikely as long as you implement common sense and listen to your body's needs (and don't drink 1.14 litres of soy sauce in one sitting!).

What is hypernatremia?

Severe acute hypernatremia effects how fluid shifts between the different compartments of your body. Maintaining blood sodium levels between about 135 and 145mmol/l is a major homeostatic priority for the body, so when a shed load of salt is dumped into the blood stream in one go, fluid is desperately shunted from other areas into the plasma to try to dilute it down. This can literally suck water from the inside of cells (including brain cells, nerves and other delicate structures), causing them to be irreversibly damaged.

This damage leads to malfunctioning in the cells, which in turn manifests itself as confusion, seizures, muscle spasms, coma and even death if it's severe and widespread enough. It’s a really nasty scenario indeed.

Severe hypernatremia due to acute sodium ingestion can only normally occur in the body when salt is either consumed in very large quantities without water, or when it’s taken in a solution that is significantly saltier than blood.

Documented occurrences of this happening are extremely rare in adults; our soy sauce quaffing friend being one example and this case of a ship wrecked sailor being another. And this is because people just don’t tend to voluntarily ingest large amounts of salt or super salty liquids as it's rather unpalatable and goes against all our natural instincts to do so.

Image credit: Da Cuoi via Pexels (copyright free)

Sodium content in blood and isotonic sports drinks

Anyway, as you can see from the table below, even the most sodium-rich sports drinks (including our strongest 1500mg/l drink mixes) contain only a fraction of the amount of sodium that soy sauce or sea water does. And the crucial point here is that they contain sodium at a much lower concentration than that of blood, so when you drink them they contribute more water to your body than sodium (in relative terms).

This ultimately means that sports drinks are unable to cause acute hypernatremia on their own as, even though they do result in more sodium being introduced to the blood stream, there's plenty of water going in with it to ensure the relative concentration does not rise too much. In fact (according to this excellent overview of the whole topic) there have been no documented fatalities from exercise-associated hypernatremia to date.

Summary: Hypernatremia is defined as high blood sodium levels (i.e. when the sodium concentration rises rapidly to above 145mmol/l). To put this into context, PH 1500's sodium concentration is ~65mmol/l whereas soy sauce's concentration is ~2,870mmol/l. 

When to use a strong sodium-based sports drink

That said, just because they won’t give you severe, acute hypernatremia (and kill you off), it doesn’t mean that strong electrolyte drinks like our PH 1500s are meant to be consumed recklessly on a day-to-day basis. The reason that we have such strong products in our range is that there are very specific uses for them...

  1. For ‘pre-loading’ the body shortly before long, hot or very intense exercise, when sweat losses are going to be very high and/or when the ability to drink during the activity will be limited. More on that in the blog we wrote about how to START events hydrated
  2. For drinking during exercise by athletes who are known to have very high sweat and sodium losses, to help them maintain performance during prolonged workouts and races.
  3. For promoting faster post-exercise rehydration than is possible with water alone, at times when dehydration has occurred and fast recovery is desirable. Again, we've written specifically about hydration for recovery before.

In other words, they’re designed to be used before, during or after times when your fluid and sodium levels are going to be significantly challenged (i.e. mainly around strenuous, prolonged and sweaty exercise) and not whilst you’re just sat on the sofa watching Downton Abbey, or playing FIFA on the Xbox.

When they're used when they're actually needed, extra strong electrolyte drinks can work spectacularly well for athletes who have higher than average sweat and sodium losses because they replace a hell of a lot more sodium than traditional isotonic sports drinks do (most normal sports drinks only contain 400-500mg per litre but the range of sweat sodium loss we see in individuals we sweat test is anywhere between 200mg/l and 2000mg/l).

Often this means those with higher sodium losses and a history of premature fatigue, low blood pressure, cramping or generally ‘fading out’ in longer/hotter events find our PH 1500s to be something of a game changer when they’re used in that context.

How kidneys balance your fluid and sodium

The good news is that your body has a few tricks up its sleeve to maintain homeostasis in the face of a pretty broad range of inputs and outputs when it comes to fluid and sodium balance (even if chucking a whole litre of soy sauce down the hatch in one go pushes it a bit too far!).

In the short term, if you take in a bit of extra fluid and sodium, one of the first things your kidneys do is excrete most of the excess in urine. The kidneys are highly sensitive to the total amount of salt and fluid in the body and can dial up and down the amount of fluid you pee out and the concentration of sodium in that pee quite dramatically. This is primarily how things are kept balanced in the face of a bit of excess intake.

Image credit: Robina Weermeijer via Unsplash (copyright free)

If you significantly overdo your sodium intake over a prolonged period of time there's a good chance that as well as trying to pee out excess fluid and sodium, your body might be forced to hold onto some additional extra cellular fluid (ECF) to keep everything balanced in terms of it’s overall sodium content.

For athletes, expanded ECF volume is something of a double edged sword; on the one hand if it occurs in the blood acutely pre-exercise, it can be a good thing as it gives your body an extra reservoir of fluid and sodium to ‘lose’ through sweating before a level of performance hampering dehydration sets in. After all, that's what we’re aiming for when we pre-load with extra sodium and fluid pre-competition, as has been described in a good few research articles like this one.

Summary: A stronger sodium-based electrolyte drink is useful for preloading before long, hot or very intense exercise. It's also useful for athletes who are heavy or very salty sweaters, and it can be a useful recovery aid after intense exercise and when swift rehydration is desirable. 

The kidneys help to maintain homeostasis by controlling how much you pee and the concentration of your pee. 

The signs of sodium overconsumption (and how to avoid them)

On the other hand, if this fluid retention becomes more chronic and permeates out of the vascular system into the ECF around the body’s tissues, it can cause puffiness, bloating, weight gain and mild swelling (edema) of some of your body parts (often showing up in ankles and fingers) and that's clearly not so good!

This can happen over a period of a few hours if intake is aggressive enough and urine output can’t keep up. Or it may happen over days/weeks with lower but consistent levels of overconsumption. Athletes taking in a chronic excess of sodium might also often feel thirsty (and start to dislike the taste of anything salty) as the body begins to crave plain water to dilute the salt that is building up in the blood and it’s tissues.

What this ultimately means is that if you're taking in quite a lot of sodium (in the form of strong sports drinks, other sodium supplements like capsules, salty foods or a combination) and you're starting to get symptoms like bloating, puffiness under the skin and in your joints, strong sensations of thirst and a dislike of salty tastes, it’s highly likely to be because you’ve actually gone overboard on the salt intake.

If this happens, it’s best to reduce any supplementation (or eating any salty food) and to drink plain water to thirst whilst giving your body some time to sort itself out. The likelihood is that before long your kidneys will start to produce more urine to get rid of the excess fluid and sodium as things will start to get back to a more healthy equilibrium.

Understand your own sweat and sodium losses

Of course, the actual aim is to prevent sodium overload happening in the first place. The best way to do this is to understand your own personal levels of sweat and sodium loss in more detail. You can do this through a bit of organised trial and error through your daily fluid and sodium intake in different conditions during training and by using our free Fuel & Hydration Planner (or by taking a Sweat Test if you’re really serious and want to find out exactly how much sodium you lose per litre of sweat).

Ultimately, you’re aiming to find a ‘sweet spot’ of sodium replacement that meets your individual needs based on how much sweating you’re doing and how much sodium you lose in your sweat. When you get this right you’re more likely to feel good and be able to perform at your best because your body will have a much easier time maintaining homeostasis.

In our experience, the individual needs for fluid and sodium intake vary massively. That's why our range has different strengths, from 250mg up to 1500mg of sodium per litre, and so don’t be afraid to get out there and experiment to figure out what works best for you.

Do just remember the moral of this tale though, if you’re thinking of using soy sauce as your primary salt replacement product it will probably need watering down a bit first...

Summary: Tell-tale signs of chronic overconsumption of sodium are puffiness, bloating, weight gain, crave plain water. To avoid this, use some trial and error in training to find your 'sweet spot' for sodium replacement during exercise. 

Further Reading