Low Sodium vs Reduced Sodium vs No Salt Added: What Labels Mean
The federal definitions behind sodium claims, from sodium free to light in sodium, and why reduced sodium or unsalted foods can still be high in sodium.
Sodium claims are some of the most common words on the front of a package, and some of the most misread. "Reduced sodium" sounds like "low sodium," and "no salt added" sounds like "salt free," but each one has its own legal definition. Here is what the federal rule, 21 CFR 101.61, actually requires, along with the FDA's plain-language guide to the same terms.
The claims at a glance
| Claim on the package | What it means |
|---|---|
| Sodium free, salt free | Less than 5 mg of sodium per serving |
| Very low sodium | 35 mg or less per serving |
| Low sodium | 140 mg or less per serving |
| Reduced sodium, less sodium | At least 25% less sodium than the regular product |
| Light in sodium, lightly salted | At least 50% less sodium than the regular product |
| No salt added, unsalted | No salt added during processing; not necessarily sodium free |
The first three are absolute claims: the food must be under a fixed number. "Reduced" and "light" are relative claims: they only compare the product with another version of itself. That difference is where most confusion comes from.
The fine print behind "low" and "very low"
The regulation measures sodium against the reference amount customarily consumed, the standard amount used to set serving sizes. For foods with small reference amounts, 30 grams or 2 tablespoons or less, the limit must also be met per 50 grams of food. For meals and main dishes, the limits are set per 100 grams instead.
The rule also covers foods that are naturally low in sodium. If a food qualifies without any special processing, the label has to make clear the claim applies to all foods of its type, not just that brand. The regulation's own example is "fresh spinach, a low sodium food."
Why "reduced sodium" can still be high
A relative claim says nothing about the final amount. Here is a worked example using a soup that starts at 800 mg of sodium per serving:
| Version | Rule | Maximum sodium per serving |
|---|---|---|
| Regular | 800 mg | |
| Reduced sodium | At least 25% less | 600 mg |
| Light in sodium | At least 50% less | 400 mg |
| Low sodium, for comparison | 140 mg or less | 140 mg |
Even the "light" version in this example carries nearly three times the sodium allowed for a "low sodium" claim. The claim is accurate, but only relative to the original.
The regulation adds two protections for shoppers:
- A "reduced sodium" label must identify the reference food and the percentage difference near the claim, and give the actual numbers, for example "Sodium content has been lowered from 300 to 150 mg per serving."
- A product cannot make a "reduced sodium" claim if the regular version already meets the "low sodium" definition.
So when you see "reduced sodium," look next to the claim or near the Nutrition Facts panel for the before-and-after figures.
Salt is not the same as sodium
The regulation states plainly that "salt" is not synonymous with "sodium." Salt is sodium chloride, and the FDA explains that sodium is a mineral found in salt, not the same thing. The FDA also lists other sodium sources used in food, such as monosodium glutamate (MSG), sodium bicarbonate (baking soda), sodium nitrite, and sodium benzoate. These add to the sodium figure on the Nutrition Facts label too.
That is why salt-based claims have their own rules:
- "Salt free" may only be used if the food also meets the sodium free definition.
- "Unsalted," "without added salt," and "no salt added" may only be used if no salt is added during processing and the food it replaces is normally processed with salt.
- If such a food is not sodium free, the label must carry a statement such as "not a sodium free food" or "not for control of sodium in the diet" next to the Nutrition Facts.
The FDA's guide sums it up: no-salt-added products may not be salt or sodium free unless stated.
What "sodium free" allows
To be labeled sodium free, a food must have less than 5 mg per serving and, in general, contain no ingredient that is sodium chloride or is generally understood to contain sodium. If it does include one, the ingredient must be marked with an asterisk pointing to a note such as "adds a trivial amount of sodium."
Why claims are only part of the picture
The FDA notes that over 70% of dietary sodium comes from packaged and prepared foods, not from salt added during cooking or at the table. It also warns that taste is a poor guide: foods like cereals and pastries can contain sodium without tasting salty, and foods eaten several times a day, like bread, can add up even when one serving is modest.
A front-of-package claim tells you how a product compares or whether it clears a threshold. The Nutrition Facts panel tells you the actual milligrams, which is the number to compare across brands.
Key takeaways
- Sodium free means under 5 mg, very low means 35 mg or less, and low means 140 mg or less per serving.
- Reduced sodium means at least 25% less than the regular product, and light means at least 50% less, not a low amount.
- Reduced-sodium labels must show the reference food and the before-and-after numbers.
- Salt and sodium are different; "no salt added" foods can still contain sodium and must say so if not sodium free.
- The FDA says over 70% of sodium in the diet comes from packaged and prepared foods.
This article explains how to read labels and is not medical or dietary advice. Talk to a doctor or registered dietitian about how much sodium is right for you, especially if you have high blood pressure, heart disease, or kidney disease.