Sodium

botanicalsodium atom

What is it

Sodium is an essential electrolyte that, along with chloride, regulates fluid balance, blood pressure, nerve impulses, and muscle contractions. It is the primary cation of the extracellular fluid and is consumed mainly as sodium chloride (table salt).

How it works

Sodium is rapidly absorbed in the small intestine and circulates in blood and extracellular fluid. Its movement across cell membranes through Na+/K+ ATPase and various co-transporters drives nerve impulses, glucose absorption, amino acid transport, and the gradient required for cells to maintain their volume and excitability. The kidneys are the primary regulator of body sodium content, adjusting excretion to match intake under the control of hormones like aldosterone, antidiuretic hormone, and atrial natriuretic peptide. Sodium also plays a key role in maintaining blood pressure through its effect on plasma volume. While sodium is essential, most adults consume far more than they need, primarily from processed foods, restaurant meals, and condiments. Chronically high intake contributes to hypertension in salt-sensitive individuals.

Evidence for 4 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Hyponatremia (low blood sodium)

Grade A

Strong evidence

Sodium replacement (orally or IV depending on severity) is the standard treatment for symptomatic hyponatremia, which can cause confusion, seizures, and death. Rate of correction must be careful to avoid central pontine myelinolysis.

Adrenal insufficiency (Addison's disease)

Grade A

Strong evidence

Patients with Addison's disease often crave salt and benefit from liberal sodium intake to compensate for impaired aldosterone-mediated retention. Combined with hormone replacement, this stabilizes blood pressure and electrolytes.

Endurance exercise (sweat replacement)

Grade B

Good evidence

Sodium replacement during prolonged exercise (greater than 2 hours) helps prevent hyponatremia from excessive water intake and supports performance in hot, humid conditions. Sports drinks typically contain 200-700 mg/L.

Orthostatic hypotension / POTS

Grade B

Good evidence

Increased salt and fluid intake (often 6-10 g/day of salt with 2-3 L of fluid) is part of standard management for low blood pressure on standing and POTS, when supervised by a clinician.

3 commercial forms

Sodium chloride (table salt)

Essentially 100% absorbed; standard dietary form.

Universal source of dietary sodium. Iodized versions also provide iodine.

Sodium bicarbonate (baking soda)

Well-absorbed; also acts as a buffer.

Used for some sports performance protocols and acute medical situations (acidosis). Provides sodium plus alkalinizing effect.

Sodium citrate

Well-absorbed; alkalinizing.

Used in some electrolyte products and to alkalinize urine for certain medical purposes.

Dosage

The Adequate Intake (AI) for adults is 1,500 mg/day, with a Chronic Disease Risk Reduction (CDRR) intake of 2,300 mg/day above which intake should be reduced. Average U.S. intake is approximately 3,400 mg/day. There is no UL but the CDRR serves as a practical upper guideline. Endurance athletes losing large amounts of sweat may need more, particularly in hot conditions.

When and how to take it

Sodium is consumed naturally throughout the day with food. For athletes, sodium-containing fluids or electrolytes are typically consumed before, during, and after prolonged exercise (over 60-90 minutes), especially in heat. For most people, no special timing is needed since dietary sodium is plentiful. People on low-sodium diets can spread intake evenly across meals to maintain stable electrolyte balance.

Food sources

Food	Amount	%DV
Table salt (1/4 tsp)	575 mg	—
Bread (1 slice)	100-250 mg	—
Cheese, processed (1 oz)	350 mg	—
Deli ham (2 oz)	600 mg	—
Canned soup (1 cup)	700-900 mg	—
Pickle (1 spear)	400 mg	—
Soy sauce (1 tbsp)	900 mg	—
Pizza (1 slice)	600-800 mg	—

Safety

Most adults consume too much sodium, which contributes to hypertension, stroke, and cardiovascular disease risk in many people. Acutely, very high doses can cause hypernatremia, dehydration, and confusion. Conversely, very low sodium (hyponatremia) from excessive water intake, certain medications, or endurance events can be dangerous and cause seizures or death. The therapeutic window is wide but both extremes are harmful.

Who should be cautious

People with hypertension, heart failure, kidney disease, or liver disease are generally advised to limit sodium. Pregnant women with preeclampsia may need to monitor intake. Endurance athletes in hot conditions may benefit from higher intake to replace sweat losses. Older adults are at higher risk of hyponatremia and should avoid extreme restriction without medical guidance.

Interactions

Diuretics, ACE inhibitors, ARBs, and certain antidepressants can affect sodium levels. NSAIDs may cause sodium retention. Lithium clearance is highly dependent on sodium status and changes in salt intake can alter lithium levels dangerously. Corticosteroids cause sodium retention. Athletes using salt tablets should be aware of interactions with medications affecting renal function.

Frequently asked questions

How much sodium is too much?⌄

The Chronic Disease Risk Reduction intake is 2,300 mg/day. Average U.S. intake is about 3,400 mg. Cutting back from very high intake (especially from processed foods and restaurants) is generally beneficial.

Do I need a sodium supplement?⌄

Almost certainly not, unless you are an endurance athlete in hot conditions, have a medical condition causing low sodium, or are advised by a clinician. The Western diet provides ample sodium.

Are pink salt and sea salt healthier?⌄

Specialty salts contain similar sodium content per gram to table salt. Trace minerals are present in tiny amounts that do not meaningfully affect nutrition. The main practical difference is texture and flavor, not health impact.

Should I take salt tablets for exercise?⌄

For long endurance events in hot weather, sodium replacement is important to prevent hyponatremia and cramps. For typical workouts under 60-90 minutes, a normal post-exercise meal usually suffices.

Does low-sodium always equal heart-healthy?⌄

For people with hypertension or salt sensitivity, reducing sodium often helps. For others, very low sodium intake may not provide additional benefit and could be harmful in some contexts. Individual response varies.

References

NIH Office of Dietary Supplements - Sodium — NIH ODS link
Sodium - Wikidata — Wikidata link

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Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you're pregnant, breastfeeding, on medications, or managing a chronic condition.