Sodium

Electrolyte · salt

What does Sodium do in your body?

Essential for fluid balance and nerve signals — but most people eat far more than they need, mostly from packaged and restaurant food.

The main positive ion outside cells. Controls fluid volume and, with potassium, creates the electrical gradient nerves and muscles use.

Blood and fluid between cells, nerves, muscles. Kidneys set the balance.

About 70% of sodium in US diets comes from packaged and restaurant foods: bread, cured meats, pizza, soups, sandwiches. Table salt is ~40% sodium.

Adequate Intake: 1,500 mg. Chronic Disease Risk Reduction intake: reduce if above 2,300 mg/day.

Rare from diet; low blood sodium usually results from illness, medications or drinking excessive water.

Higher intakes raise blood pressure on average, increasing heart disease and stroke risk.

Higher potassium intake blunts some of sodium's effect on blood pressure.

Reducing sodium lowers blood pressure (strong trial evidence). Exact effects at very low intakes are debated.

Adults should reduce sodium intake if it's above 2,300 mg per day. Evidence: regulatory. Known: Chronic Disease Risk Reduction intake set by the National Academies based on blood pressure and cardiovascular evidence. Unknown: Optimal lower bound is debated. Source: National Academies of Sciences, Engineering, and Medicine, Dietary Reference Intakes for Sodium and Potassium (2019).
Most sodium in the US diet comes from packaged and restaurant foods, not the salt shaker. Evidence: strong. Known: Dietary surveys estimate about 70%. Unknown: Varies by person and country. Source: US FDA, Sodium in Your Diet (Current revision).

General education only, not medical advice. Drafted Oct 2026 · pending qualified expert review.