Sodium – Health or Hazard for Runners?

By Beth Mansfield, Sport Dietitian and Exercise Physiologist

Moderate to intense physical activities done for prolonged periods of time can lead to high sweat rates and an increased risk for dehydration and significant mineral losses, particularly sodium. Losing too much sodium can dilute the concentration of electrolyte minerals in the blood, effectively impairing our ability to regulate our internal temperature, maintain an optimal fluid balance, and ensure peak athletic performance.

Electrolyte containing drinks (e.g. sport drinks with sodium) and foods (e.g. salted pretzels) stimulate thirst, thereby encouraging a greater voluntary intake of fluid while optimizing sodium levels lost through sweat. This is important for very young athletes and older, masters athletes as their thirst mechanisms tend to be suboptimal. Foods and fluids containing sodium also help with recovery as the sodium has been shown to stimulate the process of post workout rehydration. Sodium, in appropriate concentrations, appears to enhance the rate of fluid absorption from the small intestine into the blood stream, especially when glucose is in the gut at the same time. So a sport drink effectively addresses fluid, sodium and glucose needs for effective maintenance of hydration and sodium balance during exercise.

BUT…does this mean that those of us that are involved in this type of training need to top up sodium intakes with electrolyte sport drinks and more liberal use of the salt shaker? Use the following checklist to evaluate your current salt intake:

Do you…
•Shake salt on your food only AFTER you have tasted it?
•Eat fresh/frozen vegetables and use canned vegetables rarely?
•Eat processed meats less than once every 2 weeks?
•Skip salt in cooking?
•Season foods mainly with herbs and spices?
•Check sodium content of foods & buy those with less or labeled “no added salt”?

If you said NO to three or more of the questions, then you are likely getting more salt than you need in your daily diet. Even if sodium intakes are on the low side, the body adapts by minimizing sodium losses in both sweat and urine, making deficiencies unlikely.

Some people over 50 years of age are sodium sensitive and experience high blood pressure with excess sodium (salt) intake. This might also be a sign that you should follow the DASH diet (dietary approaches to stop hypertension also known as high blood pressure). The DASH diet, which emphasizes fruits, vegetables and low-fat dairy products, and includes grains, nuts, poultry and fish, is not only good for reducing blood pressure, it is also a pattern of eating for peak sport performance!

For more nutrition information from Beth Mansfield, and a list of upcoming sport nutrition workshops, check out Beth’s website at

Beth Mansfield is a Sport Dietitian and Exercise Physiologist at Peak Performance in Ottawa.