The 140 Milligrams Per Serving Maximum: How the FDA Defines a 'Low Sodium' Food

A food product can only carry a "low sodium" label in the United States if it contains 140 milligrams of sodium or less per standard serving. The Food and Drug Administration enforces this exact ceiling under Title 21 of the Code of Federal Regulations, ensuring the phrase means the same thing on a can of soup as it does on a box of crackers.[1][2]

When you pick up a packaged food, that 140-milligram limit represents exactly 6.08 percent of the FDA's Daily Value (DV) of 2,300 milligrams for adults. By capping the claim at this specific number, federal regulators ensure that eating a standard portion of a "low sodium" food barely dents a person's daily allowance, leaving room for the rest of the day's meals.[3]

The rule relies on a standardized metric called the Reference Amount Customarily Consumed, or RACC. Manufacturers cannot simply shrink their serving size to an unrealistic 10 grams to sneak under the 140-milligram wire and print a health claim on the box.[1]

If the RACC for a particular snack—say, potato chips—is 30 grams, the product must meet the 140-milligram threshold within that specific 30-gram window. This standardizes the math for shoppers, anchoring the claim to how much a person actually eats in one sitting.[1][3]

The regulatory framework creates a strict hierarchy of sodium claims that dictate exactly what can be printed on the packaging. While "low sodium" sits at 140 milligrams, a product labeled "very low sodium" must contain 35 milligrams or less per RACC.[1][4]

To claim a food is entirely "sodium free" or "salt free," the serving must contain less than 5 milligrams of sodium. This tiered system allows consumers managing hypertension to calibrate their grocery carts with precision.[2][5]

The most misunderstood label in the grocery aisle is "reduced sodium." Unlike the absolute 140-milligram ceiling of "low sodium," a "reduced" claim is entirely relative to the manufacturer's standard product.[3][5]

A "reduced sodium" product must simply contain 25 percent less sodium than its regular counterpart. If a standard soy sauce contains 920 milligrams of sodium per tablespoon, a "reduced sodium" version might still pack 690 milligrams—nearly five times the "low sodium" threshold, yet legally compliant with the "reduced" definition.[5][6]

"Light in sodium" requires a 50 percent reduction compared to the standard reference food. These relative claims often trick well-meaning shoppers into buying highly salted foods, assuming the label implies a low absolute amount of sodium.[4][6]

The FDA's strict definitions serve a broader public health initiative. In October 2021, the agency issued voluntary guidance to the food industry, aiming to cut average American sodium intake from 3,400 milligrams a day down to 3,000 milligrams over a two-and-a-half-year period.[7]

"This is a critical step in addressing the epidemic of diet-related chronic diseases," the FDA noted in its 2021 announcement, targeting the packaged and restaurant foods that account for more than 70 percent of the sodium consumed in the United States.[7]

The 140-milligram rule shifts slightly for products classified as "meals" or "main dishes," such as frozen dinners. Because these items replace an entire meal rather than a single component, the FDA requires them to contain 140 milligrams or less per 100 grams of the product.[1][2]

This prevents a 400-gram frozen lasagna from claiming to be "low sodium" simply because it meets a per-serving threshold that was designed for a handful of pretzels. The per-100-gram rule scales the sodium limit to the volume of the meal.[1]

For foods with naturally small serving sizes—specifically those where the RACC is 30 grams or less, or 2 tablespoons or less—the 140-milligram limit applies to a 50-gram equivalent of the food.[2][4]

This 50-gram rule stops highly concentrated salty items, like certain condiments, pickles, or cured meats, from earning a "low sodium" badge just because their standard serving size is tiny. It forces the manufacturer to prove the food is low in sodium by weight, not just by portion.[4]

The distinction between these labels dictates how food scientists reformulate products in the test kitchen. Replacing sodium chloride often requires adding potassium chloride or yeast extracts to maintain the savory profile and microbial stability consumers expect.

As manufacturers work toward the FDA's broader reduction goals, the 140-milligram ceiling remains the gold standard for heart-healthy marketing. It provides a fixed, mathematical guarantee in an aisle otherwise dominated by subjective branding, allowing shoppers to trust the math on the front of the box.[3][7]