A low-sodium diet is recommended primarily because excess sodium raises blood pressure, and high blood pressure is the leading modifiable risk factor for heart disease and stroke. The World Health Organization recommends adults consume less than 2,000 mg of sodium per day, which works out to about one teaspoon of table salt. Most people eat well above that threshold, and the consequences show up across multiple organs over time.
How Sodium Raises Blood Pressure
Sodium controls where water goes in your body. When sodium levels rise in your bloodstream, water follows it there, increasing the total volume of fluid your blood vessels have to contain. More fluid in the same space means more pressure on arterial walls. Your body compounds this effect through hormonal responses: it ramps up a system that causes blood vessels to constrict and kidneys to hold onto even more sodium and water. The result is a self-reinforcing cycle of rising pressure.
A 2023 crossover trial published in JAMA showed just how directly sodium intake drives blood pressure. When 213 participants spent one week on a low-sodium diet, their median systolic blood pressure dropped to 119 mm Hg, compared to 126 mm Hg on a high-sodium diet. That 8-point average reduction happened in nearly 75% of participants, regardless of whether they already had hypertension. The effect was measurable after just seven days.
Heart Disease and Stroke Prevention
The blood pressure connection matters because it translates into dramatically different rates of cardiovascular events over time. Finland’s nationwide effort to cut sodium consumption by one-third led to a 75% to 80% reduction in both stroke and ischemic heart disease deaths. England saw similar results on a smaller scale: between 2003 and 2011, a population-level reduction of 1.9 grams of daily sodium was linked to a 42% drop in stroke deaths and a 40% drop in coronary heart disease deaths. Blood pressure in adults not taking blood pressure medications fell by 2.7/1.1 mm Hg during the same period.
These aren’t small effects. For context, a sustained drop of even 5 mm Hg in systolic blood pressure across a population significantly shifts the number of people who develop heart failure, have strokes, or die from cardiovascular causes. Sodium reduction is one of the simplest ways to achieve that shift.
Protecting Your Kidneys
High sodium intake puts particular strain on the kidneys. People with chronic kidney disease tend to be “salt sensitive,” meaning their blood pressure rises more steeply in response to sodium. But the damage goes beyond blood pressure alone. Excess salt increases the filtration pressure inside the kidney’s tiny filtering units and drives up the amount of protein that leaks into urine, a key marker of kidney damage. Together, these changes create conditions that accelerate kidney disease progression. For anyone with early or established kidney problems, sodium restriction is one of the most important dietary interventions available.
Stomach Cancer Risk
A less well-known reason for limiting sodium is its link to stomach cancer. A meta-analysis of 38 case-control studies, covering more than 37,000 people, found that high salt intake was associated with a 55% increased risk of gastric cancer compared to low salt intake. The mechanism appears to be twofold: salt directly irritates and damages the stomach lining, promoting cancerous changes, and it also encourages colonization by H. pylori, the bacterium most strongly linked to stomach cancer. Salt-preserved and heavily processed foods carry the highest risk.
Where the Sodium Actually Comes From
Most dietary sodium doesn’t come from the salt shaker. It’s embedded in packaged and prepared foods, often in amounts that are hard to guess without reading labels. A study of major U.S. packaged food brands found that some of the highest-sodium categories per serving include:
- Canned meat dishes: about 1,046 mg per serving
- Meat mixed dishes: 966 mg
- Poultry mixed dishes: 830 mg
- Pasta mixed dishes: 805 mg
- Pizza: 765 mg
- Macaroni and cheese: 759 mg
- Soups: 700 mg
- Sandwiches: 615 mg
- Frankfurters and sausages: 557 mg
- Cold cuts and cured meats: 497 mg
A single serving of canned meat or soup can deliver half your entire daily sodium budget. And many people eat two or three label servings in one sitting, which doubles or triples those numbers. Even foods that don’t taste salty, like bread (216 mg per serving), ready-to-eat cereal (172 mg), and salad dressing (304 mg), contribute significantly because you eat them repeatedly throughout the day.
How to Reduce Sodium Practically
The most effective strategy is cooking more meals from whole ingredients, where you control what goes in. Fresh vegetables, fruits, unprocessed meats, dried beans, and whole grains are all naturally low in sodium. When buying packaged foods, compare labels within the same category. Sodium content varies widely between brands: the difference between a lower-sodium soup and a standard one can be 300 to 400 mg per serving.
Canned goods are consistently among the highest-sodium products on shelves. Rinsing canned beans or vegetables under water removes a meaningful portion of the added salt. Choosing “no salt added” versions, when available, cuts sodium even further. Condiments also add up quickly. Soy sauce, hot sauce, ketchup, and salad dressings all contribute more sodium per day than most people realize, simply because they’re used at nearly every meal.
Your taste buds do adjust. Foods that seem bland during the first week or two of cutting back will start tasting normal, and heavily salted foods you used to enjoy may begin tasting unpleasantly salty. Using herbs, spices, citrus juice, and vinegar fills in the flavor gap while your palate recalibrates.
When Very Low Sodium Becomes a Concern
While most people benefit from eating less sodium, going extremely low carries its own risks for certain groups. People taking high-dose diuretics (water pills) need careful monitoring if they also restrict salt significantly, because the combination can deplete fluid and electrolytes to dangerous levels. For the general population following standard guidelines of under 2,000 mg per day, the risk of consuming too little sodium is very small. The far more common problem is consuming two to three times the recommended amount without realizing it.