I’m a runner and have heard recommendations for an electrolyte drink called LMNT. One serving has 1,000 milligrams of sodium. On their website, they talk about how the FDA guidelines are too low and boast about their studies showing we need more sodium based on medical data from various cultures. Curious about their claims. Is there any reliable science on this?
I didn’t write this question, but I could have. So I asked the person who I rely on for this information to weigh in. Thanks to Meghann Featherstun for the answer! —Emily
This is a great question and something that confuses a lot of us. I am a sports dietitian and 2:49 marathon runner who works with runners to fuel daily life and running performance through my business, Featherstone Nutrition.
The National Institutes of Health creates dietary reference intakes (DRIs), which help guide our nutrition choices. They present evidence that consuming 2,300 milligrams of sodium a day for adults represents the safest amount to reduce chronic disease risk. Yet they also state that an adequate intake (AI), aka the amount of sodium we need to survive, for most adults is only 1,500 mg a day.
However, as runners, we have higher sodium needs than sedentary adults, and consuming the above amounts of sodium may not be optimal for us. When we sweat, we lose water and electrolytes such as calcium, magnesium, potassium, and sodium. Sodium is lost in the largest amounts; the average runner loses 900 mg of sodium per liter of sweat. It is not uncommon for runners to lose one to two liters of sweat per hour in the heat or on a treadmill. If you go on a two-hour-long run, that means somewhere between 1,800 and 3,600 mg of sodium lost. That’s a lot — and it needs to be replaced.
It is important to replace the sodium lost via sweat in our daily diet to stay adequately hydrated and support overall health and running performance. Therefore, as a runner, you may need an additional 1,000 to 2,000 or more mg of sodium above the recommended DRI. If we do not increase our sodium intake as runners, side effects can include headaches, dizziness, fatigue, nausea, diarrhea, and muscle cramps.
The takeaway here is that our sodium needs are highly individualized based on our activity level, sweat rate, sweat composition, and overall health status and concerns.
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