Hyponatremia is one of the greatest risks you face on any outdoor adventure. Whether it’s a day hike through a nearby park or a multi-week thru hike in another country, understanding how to prevent and treat hyponatremia is a critical skill every outdoor enthusiast should have.
Proper nutrition and hydration are two of the biggest prevention tools, but balance is key. Many members of the OutdoorFoodLab team have direct experience with hyponatremia, so trust us when we say that reading this article won’t just make your future adventures more enjoyable—it could save your life.
Hyponatremia Causes & Symptoms
In the U.S. alone, hyponatremia causes $2.6 billion in healthcare spending every year. At its worst, it can lead to osmotic demyelination syndrome, which often results in major neurological impairment or death.
Fortunately, the causes of hyponatremia are easily avoidable if you understand how your body functions.
You’ve probably heard of electrolytes. While most people know that sodium is an electrolyte, others include calcium, chloride, magnesium, phosphorus, and potassium. All of these electrolytes aid your body’s core functions in different ways. According to Hammer Nutrition:
“Electrolytes are analogous to the motor oil in your car—they don’t make the engine run, but they’re absolutely necessary to keep everything running smoothly. Proper functioning of the digestive, nervous, cardiac, and muscular systems depends on adequate electrolyte levels.”
Hyponatremia occurs when the electrolyte levels in your blood—specifically sodium—fall below a certain threshold. Normally, your blood sodium level should exceed 135 milliequivalents per liter. If these levels fall below that threshold, hyponatremia symptoms begin.
Like the quote above, you can think of this as having too little oil in your car engine. This can cause severe symptoms, including:
Importantly, having low electrolytes levels in your blood can occur for two reasons:
- You didn’t consume enough sodium to replenish your electrolyte balance
- You drank too much water, diluting your sodium levels
The second case is critical to understand. On long and strenuous hikes, especially when faced with fatigue, cramps, and hardship, many hikers ingest more water to combat these conditions. After all, we were always taught that proper and regular hydration is crucial. Yet without balancing this water intake with electrolytes, your sodium balance will become imbalanced rather quickly.
It’s also important to note that many medications and unrelated conditions can impact your blood’s sodium levels. For example, Addison’s disease, heart and liver conditions, and certain medications are all known to interfere with the body’s sodium concentration. It’s important to talk with your doctor about how these will impact your necessary electrolyte and water consumption.
How to Prevent & Treat Hyponatremia
According to the Mayo Clinic, the most popular way to treat hyponatremia is to “address the underlying cause.” This simply means correcting your body’s sodium balance by cutting back on fluids and ingesting more sodium.
In the field, treatment options are usually limited, so preparation is key. Salt tablets are a popular option, but they aren’t without risk.
First, they typically only supply two electrolytes: sodium and chloride. While this can be enough to treat hyponatremia, it’s important to keep in mind that they are not meant for broad-spectrum electrolyte replenishment. Second, because they consist heavily of sodium, they can quickly oversupply your body with a single molecule, posing risks to your biological functions that regular sodium levels.
These issues are why prevention is always the best method. This can be done in two ways:
- Consume enough electrolytes during your meals. For health reasons, many people have reduced their sodium intake. While this can provide plenty of benefits, it’s often a poor choice during periods of intense, prolonged exercise. When looking at popular outdoor meals, many outdoors people are surprised at the sodium content. For example, the highly-rated Backpacker’s Pantry Pad Thai has 68% of your daily sodium needs in a single package! But as we’ll see, this elevated salt intake can be highly necessary.
- Augment your water breaks with electrolyte-rich snacks. Get in the practice of eating salty snacks, like energy bars, salted nuts, or Gu Energy Gels whenever your stop for water breaks. It doesn’t take much, but this practice can make sure your sodium balances stay in check.
How Much Sodium Do You Need to Prevent Hyponatremia?
The average American consumes roughly 3400 mg of sodium per day, greatly outstripping the upper limits of most respectable health organizations. Recommended daily allowances vary, but generally range from 1,500mg to 2,300mg. Note that 2,000mg is roughly one teaspoon of salt.
- United States Department of Agriculture: 2,300 mg
- American Heart Association: 1,500 mg
- Academy of Nutrition and Dietetics: 1,500 to 2,300 mg
- American Diabetes Association: 1,500 to 2,300 mg
But those figures are for daily life. How should these numbers change when you’re sweating constantly from continuous exercise, like during a thru hike?
A study in the National Institutes of Health evaluated soccer players and sedentary students to determine exactly how much electrolytes you’re losing through sweat. These figures can help you figure out how much to consume to offset these losses.
According to the study:
“The authors analyzed 208 sweat samples to determine losses of iodine, sodium, potassium, and calcium in sweat. The mean losses in sweat following a 1-hour game were…1,896mg [of sodium].”
So for every hour of activity, sodium losses amounted to about 1,900mg, or nearly 2 grams. That’s just as much as a sedentary person should consume throughout an entire day!
A good shorthand method for estimating your sodium loss through sweat by equating 1 gram of sodium per 1 liter of water consumed. So if you’re drinking 1 liter of water per hour, you’ll need to balance that with 1 gram of sodium intake.
Making it Easy to Plan Your Sodium Intake & Prevent Hyponatremia
In each review, the team at OutdoorFoodLab has made it easy to see how much sodium you’ll be ingesting, with easy-to-read nutritional labels and tables sorting every important ingredient and molecule. While retailers and manufacturers only show you sodium levels per serving, we clearly indicate the sodium levels per package, taking the guesswork out of meal planning.
Plus, we rank and review every meal on critical factors like taste, ease of preparation, and weight. Check out our full library of reviews here. As always, these reviews are completely independent and unbiased. We never accept payment for a review.