“Low sodium” has two distinct meanings depending on context: on a food label, it means 140 mg or less per serving. In a blood test, it means your sodium level has dropped below 135 mmol/L. Both definitions matter, and understanding the difference helps you make sense of dietary advice, food packaging, and lab results.
Low Sodium on Food Labels
The FDA regulates exactly what food manufacturers can print on packaging. A product labeled “low sodium” must contain 140 mg or less of sodium per serving. For meal products like frozen dinners, the threshold is 140 mg or less per 100 grams of the product. This isn’t a suggestion or marketing term. It’s a legally enforced standard.
Below that, you’ll find two stricter tiers. “Very low sodium” means 35 mg or less per serving, and “sodium free” means less than 5 mg per serving. These labels are useful shortcuts when you’re scanning shelves, but the most reliable tool is the Nutrition Facts panel on the back. A quick rule of thumb: 5% Daily Value or less per serving counts as low, while 20% or more counts as high.
You’ll also see comparative claims like “reduced sodium” or “light in sodium.” These don’t tell you the absolute amount. They only mean the product has less sodium than the original version, which could still be quite high. A reduced-sodium soy sauce, for example, can still pack over 500 mg per tablespoon. Always check the actual milligrams.
How Much Sodium You Should Eat Per Day
The American Heart Association recommends no more than 2,300 mg of sodium per day, with an ideal target of 1,500 mg for most adults. The World Health Organization sets a similar ceiling at 2,000 mg per day, equivalent to just under a teaspoon of table salt. Most people in Western countries consume far more than either target, often 3,400 mg or higher.
For people managing specific health conditions, the targets get tighter. The National Kidney Foundation recommends less than 2,400 mg per day for most adults with chronic kidney disease and high blood pressure, noting that further reduction to around 1,200 mg per day may lower blood pressure even more but is harder to sustain. For heart failure, guidelines from major cardiology organizations generally suggest between 2,000 and 3,000 mg per day, with some recommending below 2,000 mg for severe cases. The most recent U.S. heart failure guidelines from 2022 stop short of a specific number, instead advising patients to avoid excessive sodium intake.
These numbers can feel abstract until you start reading labels. A single slice of deli turkey can contain 400 to 500 mg. A can of soup often has 800 to 1,000 mg. A restaurant entrée can easily exceed your entire daily target in one sitting. The sodium adds up fast in processed and prepared foods, which is why most reduction strategies focus there rather than on the salt shaker at the table.
Low Sodium in Your Blood
A healthy blood sodium level falls between 135 and 145 mmol/L. When it drops below 135, the condition is called hyponatremia. This is a completely different issue from dietary sodium and refers to the concentration of sodium dissolved in your blood.
Mild hyponatremia may not cause obvious symptoms. As levels fall further, you might notice nausea, headaches, confusion, fatigue, or muscle cramps. Severe drops can lead to seizures, loss of consciousness, and in rare cases, can be life-threatening. The condition isn’t always caused by eating too little salt. More commonly, it results from the body retaining too much water, which dilutes the sodium that’s already there. Certain medications (especially some types of antidepressants and diuretics), kidney problems, heart failure, and hormonal imbalances can all shift the balance.
Endurance athletes sometimes develop hyponatremia by drinking large volumes of water without replacing electrolytes during prolonged exercise. This is sometimes called “water intoxication” and is one reason sports drinks exist.
Choosing Lower-Sodium Foods in Practice
The biggest sources of dietary sodium aren’t the foods most people suspect. Bread, pizza, sandwiches, cold cuts, canned soups, and condiments contribute far more sodium to the average diet than anything you’d salt at home. Shifting toward fresh, whole foods is the single most effective strategy for lowering intake.
When shopping for packaged foods, compare similar products side by side. Sodium content varies dramatically between brands of the same item. One brand of canned tomatoes might have 300 mg per serving while another has 15 mg. Frozen vegetables without sauce are almost always very low in sodium. Fresh or frozen meat and poultry without added solutions are naturally low as well.
Cooking at home gives you the most control. Herbs, spices, citrus juice, and vinegar can replace much of the flavor that salt provides. Most people who gradually reduce sodium find their taste adjusts within a few weeks, and previously normal-tasting foods start to taste noticeably salty.
When a Low-Sodium Diet Can Backfire
For the vast majority of people, reducing sodium is a good idea. But there are exceptions. Some kidney conditions cause the body to waste sodium through urine rather than retain it. In these cases, restricting salt can actually cause dangerous volume depletion. People with certain adrenal gland disorders or those who lose large amounts of sweat regularly may also need more sodium than standard guidelines suggest.
Very aggressive sodium restriction, below 1,000 mg per day, is difficult to maintain and hasn’t been shown to provide additional cardiovascular benefit for most people. Some research suggests it may even be counterproductive in certain heart failure patients. The sweet spot for most adults sits between 1,500 and 2,300 mg per day, adjusted based on individual health conditions and how your body handles fluid and electrolytes.