Should I Take Salt During a Marathon?
The body needs fluids and electrolytes when running long distances. The most important of these is sodium, or salt, which is the main electrolyte lost in sweat that helps the body’s cells keep the right balance of fluid. During long, sweaty endeavors like a marathon, runners often need to take in sodium to stay hydrated, along with fluids.
How Much Salt Is Lost While Running?
The amount of sodium lost in sweat varies greatly for each person, and so do the recommendations on how much sodium to take in during a marathon. Heavy, salty sweaters need more than those who do not sweat as much. Temperature during training and racing also plays a role, as runners need more sodium in warmer, more humid conditions.
Only a lab test can show exactly how much salt is lost in your sweat. However, you are likely a salty sweater if:
- You have white streaks on your clothing after a run
- You get little crystals or grit on your skin after your sweat dries, and/or
- Your sweat stings your eyes
Best Ways to Replace Salt Lost During Runs and Races
Most sports nutrition products—including gels; chews; salt pills; and electrolyte drinks, powders, and tablets—have their sodium content listed on their nutrient facts panel. A standard energy gel may contain about 20–100 mg of sodium, depending on the brand. (For context, a quarter teaspoon of regular table salt has 500–600 mg sodium.) Heavy sweaters may need 700 mg or more of sodium for every liter of fluid consumed during a marathon, while lighter sweaters may only need around 300–500 mg for every liter of fluid.
The key is trial and error during training, especially in the warmer months. For example, if you’re a salty, heavy sweater and you drink about half a liter (16 ounces) of fluid per hour when running, try 350 mg of sodium in your preferred form (gel, chew, etc.) and take note of how you feel during and after your runs. From there, adjust the amount of sodium you take in with your fluids so you’re feeling your best. Electrolyte tablets are helpful if you’re not able to consume enough sodium from your nutrition and fluids alone.
Consuming a salty pre-run meal two to three hours before a long run or race can also help offset some lost sodium once you start running. Examples could be a salted bagel with peanut butter, oatmeal made with a hefty sprinkle of sea salt, or even salted pretzels paired with an electrolyte drink. Similarly, consuming a salty meal after your run or race can also help replace sodium lost during your activity.
Salt and Hydration: Keeping a Healthy Balance
It’s important to keep in mind that drinking too much water without taking in enough sodium during long runs can be dangerous. It can cause hyponatremia, which happens when there is not enough sodium in your blood because you’ve taken in too much water. Signs of hyponatremia include headache, nausea, trouble with balance, confusion, and in rare cases, seizures or coma. Getting enough electrolytes, especially sodium helps your body use fluids the right way and keeps you well hydrated.
Nailing down proper sodium intake can seem daunting, especially for newer runners. It’s always helpful to work with a registered dietitian for guidance.
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