Optimal Sodium Intake Per Day (for Bodybuilders, Runners, and More)

Metals are a group of minerals that cannot be produced by the body. Sodium, being an inorganic element, is an essential component in human nutrition.

In light of this fact, excessive or very low intake of sodium can have adverse effects on the body.

Therefore, attention should be paid to this element. Most reviews on sports nutrition tend to praise the macronutrients protein, carbohydrates and fat without paying much attention to sodium⁽¹⁾.

The loss of body fluids during sport or exercise is largely due to sweating.

Therefore, it’s important to replace sodium loss in sweat when:

• The duration of exercise > than 2 hrs
• When exercising in a hot climate
• During intense sodium loss in sweat (e.g., >3-4g sodium)⁽²⁾

What is sodium and why is it important?

Sodium chloride (common salt) is an anionic compound with an extracellular fluid concentration adjusted to about 135–145 mmol/L.  

It is the main cation (a positively charged ion) in extracellular fluid with an array of benefits for both the general and athletic population, such as contributing to the release of digestive secretions and controlling the absorption of certain nutrients (i.e., amino acids, glucose, galactose and water).

It also ensures sufficient blood volume, blood pressure and, ultimately organ perfusion⁽³⁾.

In addition to its importance in terms of regulating water and fluid balance, it is vital for the stimulation of muscle and nerve cells and is also involved in the control of acid-base balance.

Sodium is also an electrolyte, putting it in the same group as potassium, magnesium, calcium, and phosphate.

Electrolytes create electrically charged ions when dissolved in the body’s fluids and a big job for sodium and potassium is maintaining the right balance of fluids inside and outside of your cells. In other words, they help make sure your cells don’t shrivel like raisins or blow up like balloons.

Electrolytes also maintain the proper pH of your blood, but an important thing to note is that when we perspire, sweat takes electrolytes with it on its way out of your pores.

How much you lose can vary, but generally speaking you can lose between half a liter to four liters of sweat per hour during a workout and a liter of sweat has roughly 900 milligrams of sodium, 200 milligrams of potassium, 15 milligrams of calcium and 13 milligrams of magnesium.

In short, you lose way more sodium when you sweat than any other electrolyte.

That’s why athletes who sweat a lot should focus on replenishing sodium more than the other electrolytes, particularly since if you’re eating plenty of fruits, vegetables, and whole foods, you probably don’t need to worry about supplementing the other ones (i.e., potassium magnesium, calcium).

Muscle and Nerve Function

Both muscles and nerves require electrical currents to function properly. Muscle and nerve cells generate these electrical currents by controlling the flow of electrically charged molecules, including sodium.

For muscle cells, these electrical currents stimulate contraction of the muscle.

Before a muscle contraction occurs, sodium rushes into your nerve cells, triggering the transmission of a small electrical signal.

When your muscles sense this signal, your muscle fibers shorten and contract. Of course, this means sodium is a crucial electrolyte for muscle effort during resistance training.  (See figure below to see the step for muscle contraction.)

Fig: Contraction of a Muscle Fiber.  A cross-bridge forms between actin and the myosin heads triggering contraction. As long as Ca2+ ions remain in the sarcoplasm to bind to troponin, and as long as ATP is available, the muscle fiber will continue to shorten.

Nerves, on the other hand, need electrical activity to communicate with other nerves.

Cells use molecular pumps to keep sodium levels outside the cell high. When an electrical current is needed, cells can allow the positively charged sodium ions into the cell, generating a positive electrical current.

What’s the Recommended Sodium Intake Per day for Athletes?

The consensus among people is that you shouldn’t consume too much sodium in your diet.  Too much is supposed to cause high blood pressure and increase your risk of heart disease.

The real question is what constitutes “too much”?

• Dietary guidelines for Americans, 2015-2020, recommend that Americans aged 2 and older reduce sodium intake to less than 2,300 mg/day (2.3g/day). 

• The guidelines also recommend that people 51 and older, African Americans, or people with high blood pressure, diabetes, or kidney disease, should further reduce sodium intake to 1,500 mg/day (1.5g/day). 

It’s very difficult to reduce sodium levels to this level give how ubiquitous sodium is in the foods we eat.

A recent meta-analysis investigated the impact of different levels of sodium on cardiovascular morbidity and mortality⁽⁴⁾. 

Participants in these studies were organized into sodium exposure groups:

• Low (mean intake less than 2,645 mg sodium)
• Usual
• High (mean intake more than 4,945 mg sodium)
• Researchers examined the following outcomes:
• All-cause mortality
• Cardiovascular disease outcome
• Stroke outcome
• Heart disease outcome
• Combined outcome for cardiovascular disease, stroke, and heart disease

Results of this meta-analysis found that the risk of all-cause mortality and cardiovascular disease events were decreased when usual sodium intake was compared to low sodium intake by 9-10%.  

Risk of all-cause mortality and cardiovascular disease events were also decreased when usual sodium intake was compared to high sodium intake, and risk was 12-16% higher with high intake.

After narrowing their analysis to adjust for multiple confounders (i.e., sex, age, body mass index, smoking, alcohol, diabetes, cardiovascular disease, blood pressure, hypertension, etc.) usual sodium intake decreased risk for all-cause mortality by 14% compared to low sodium intake.

There was no impact when usual sodium intake was compared to high sodium intake.

Essentially, results are consistent with the previously hypothesized U-shaped relation between sodium intake and health outcomes which essentially shows that too low of intake is not good, just as too high of an intake.

The positive news of this meta-analysis is the range of healthy sodium intakes that are much more practically obtainable (2,645mg to 4,945mg) or basically 2.6 to 5g per day.

It seems that only when sodium intake exceeds approximately 5,000mg per day daily does there appear to be an adverse effect on health.

In the same manger, when sodium intake drops too low (<2,645mg) it may also have an adverse effect on health. This data questions the general dietary recommendations that sodium should be reduced below 2,300mg in healthy people.

So why is there so much emphasis on reducing sodium intake?

The focus on reducing sodium has been based primarily on the assumed blood pressure effect.  However, this effect is proportional to the baseline blood pressure, for example, individuals with higher pressures will get a greater drop in blood pressure from a reduction in sodium intake compared to someone with a lower blood pressure.

This essentially means the impact of salt intake on blood pressure has been overestimated.

There is also evidence indicating that other variables affecting cardiovascular health (e.g., hormones and lipids) may get worse when people drastically reduce sodium, which would negate any small benefit from a reduction in blood pressure⁽⁵⁾.

Overall, these findings lend to support to people who have questioned the scientific basis for sodium reduction. Therefore, not only does sodium reduction make little sense given the results of this paper, but it is also not very practical.

Benefits of sodium on physical performance

Some research studies that have been dedicated to determining the benefits of salt intake on endurance performance⁽⁶⁾.

Most of them report improved physical performance, an attenuated decrease in serum sodium concentration and enlarged plasma volume during endurance activities.

Maintaining fluid balance is crucial for athletes because those electrical charges help to activate muscle tissue and neurons.

Randomized controlled trials on triathletes supplementing with salt-laced water finished a medium-distance race 26 minutes faster than a control group⁽⁷⁾ and a more recent study of endurance runners found that “maximal performance was enhanced significantly” by supplementing with sodium⁽⁸⁾.

Sodium helps to maintain serum electrolyte concentrations resulting in a balance of intravascular osmotic pressure and plasma volume.

It increases the thirst stimulus and reduces the amount of urine produced, effects that ultimately reduce physical fatigue and medical problems associated with these homeostatic imbalances in endurance sports⁽⁹⁾.

Summary

Sodium is an element that should not be missing from people’s diets. It’s crucial in maintaining fluid balance which is vital for optimal athletic performance.

It also important in creating electrical charges that help activate muscle tissue and neurons. The ideal amount of sodium intake in the largest range of the population appeared to be in the range of (2,645mg to 4,945mg per day.

It’s also important to individual understand your sodium and fluid requirements. Attention should first be paid to the individual amount of fluids consumed and then to the amount of sodium consumed.

If you're looking to replenish nutrients lost during intense bouts of exercise quickly, add HYPERADE to your shaker cup and drink it throughout your training session.

HYPERADE quickly replenishes muscle glycogen and electrolytes that are depleted from intense bursts of energy.

References:
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3.    Stolarz-Skrzypek, K., et al., Sodium and potassium and the pathogenesis of hypertension. Curr Hypertens Rep, 2013. 15(2): p. 122-30.
4.    Graudal, N., et al., Compared with usual sodium intake, low- and excessive-sodium diets are associated with increased mortality: a meta-analysis. Am J Hypertens, 2014. 27(9): p. 1129-37.
5.    Graudal, N.A., A.M. Galloe, and P. Garred, Effects of sodium restriction on blood pressure, renin, aldosterone, catecholamines, cholesterols, and triglyceride: a meta-analysis. JAMA, 1998. 279(17): p. 1383-91.
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8.    Freis, T., et al., Effect of sodium bicarbonate on prolonged running performance: A randomized, double-blind, cross-over study. PLoS One, 2017. 12(8): p. e0182158.
9.    Speedy, D.B., et al., Oral salt supplementation during ultradistance exercise. Clin J Sport Med, 2002. 12(5): p. 279-84.