Sodium, Fluid Retention, and Edema
Sodium is the body's primary extracellular electrolyte. When you consume more sodium than your kidneys can promptly excrete, osmotic pressure rises and your body retains extra water to dilute it — producing swelling (edema) in the face, hands, and ankles, along with elevated blood pressure. The WHO recommends staying below 2,000 mg of sodium per day (about 5 g of table salt).
The average American consumes around 3,400 mg daily — well above the limit. About 70% comes from processed and restaurant food rather than the salt shaker. Drinking more water and eating potassium-rich foods (bananas, avocados, leafy greens) helps the kidneys excrete sodium more efficiently.
Frequently Asked Questions
In most healthy people, the kidneys can clear excess sodium within 1–2 days of returning to a low-sodium diet and drinking adequate water. Drinking extra water helps dilute blood sodium and speeds up renal excretion. Persistent edema unrelated to diet should be evaluated by a doctor.
Yes, but the amount is modest compared to urinary excretion. Sweat contains roughly 500–1,500 mg of sodium per liter. During intense exercise in heat, sweat losses can be meaningful and may actually increase sodium needs rather than reduce them. Replenishing both fluids and electrolytes is important after heavy sweating.