As the founder of Precision Hydration, people often ask me if it’s possible to overdose on salt by consuming too many electrolyte drinks. And although it’s theoretically possible, it’s highly unlikely to happen from just drinking a sports drink.
Maintaining blood sodium levels between about 135 and 145mmol/l is a major homeostatic priority for your body, so when a lot of salt is dumped into your blood stream in one go, fluid is shunted from other areas into the plasma in an attempt to dilute it. The technical term for this high blood-sodium level is hypernatremia, which is the polar opposite of hyponatremia, a far more common and widely talked about topic.
Severe hypernatremia from acute sodium ingestion usually only occurs when salt is consumed in very large quantities without water, or when it’s taken in a solution that’s significantly saltier than blood. Even the most sodium-rich sports drinks contain only a fraction of the sodium you’d need to ingest to severely overdose on salt and, crucially, they contain sodium at a much lower concentration than that of blood. So even though they do introduce more sodium into your blood stream, there’s plenty of water going in too, which ensures the relative concentration doesn’t rise too much.
If you take in slightly more fluid and sodium than you need, your kidneys will pass most of the excess in your urine. If, however, you significantly overdo it over a longer period, there’s a chance that your body will retain some additional extra cellular fluid to keep a balance. That can be a good thing, pre-exercise, as it gives your body an extra reservoir of fluid and sodium to lose through sweating before performance-hampering dehydration sets in.
On the other hand, if this fluid retention becomes chronic it can cause bloating, weight gain and mild swelling. If you see any of these symptoms, you’ve probably gone overboard on your sodium intake. In which case, it’s best to reduce your intake and drink plain water until the symptoms subside.
So, can you give yourself hypernatremia by drinking a sports drink? In short, no. But that doesn’t mean that electrolyte drinks should be consumed recklessly. They’re designed to be used when your fluid and sodium levels are going to be significantly challenged (before, during and after strenuous exercise). Your aim should be to prevent sodium overload happening in the first place by understanding your personal sweat levels and rate of sodium loss. As such, it’s a good idea to get a sweat test to find out what and how much you need to drink during training and any of your targeted events.