Dextrose is added to table salt to keep the iodine from breaking down. If you’ve ever checked the ingredients on a container of iodized salt and wondered why sugar is listed alongside sodium chloride, the answer is simple: dextrose acts as a stabilizer that prevents the added iodine from escaping into the air.
How Dextrose Protects Iodine
Most table salt is iodized, meaning potassium iodide has been mixed in to help prevent iodine deficiency. The problem is that potassium iodide is chemically unstable in salt. Without protection, it oxidizes and converts into iodine gas, which evaporates right out of the container. Over weeks and months on a shelf, iodized salt without a stabilizer would gradually lose the very nutrient it was designed to deliver.
Dextrose is a simple sugar (the same molecule as glucose) that acts as a reducing agent. It essentially absorbs the oxidizing reactions that would otherwise turn potassium iodide into volatile iodine gas. Some salt producers use other stabilizers like sodium thiosulfate or increase the alkalinity of the salt with sodium bicarbonate, but dextrose is the most common choice in the United States because it’s cheap, food-safe, and effective in tiny amounts.
How Much Dextrose Is Actually in Your Salt
The amount is vanishingly small. According to Don Mercer, a food scientist at the University of Guelph, only about 0.04% of iodized salt is dextrose. That’s four one-hundredths of a percent. In a typical quarter-teaspoon serving of salt (roughly 1.5 grams), you’re getting about 0.0006 grams of sugar. It contributes zero calories, zero sweetness, and has no effect on blood sugar. You’d never taste it or notice it nutritionally. It’s listed on the label purely because food regulations require every added ingredient to appear, regardless of quantity.
Why Dextrose Instead of Regular Sugar
Dextrose is glucose in its pure crystalline form. It dissolves easily, blends uniformly into fine salt crystals, and performs its stabilizing role without clumping or altering the texture of the salt. Table sugar (sucrose) is a larger molecule that doesn’t function as well as a reducing agent in this context. Dextrose is also widely available as a food-grade additive, making it a practical choice for salt manufacturers operating at industrial scale.
Does Non-Iodized Salt Contain Dextrose
Generally, no. If you pick up a box of non-iodized salt, kosher salt, or sea salt, the ingredient list is typically just sodium chloride, sometimes with an anti-caking agent. The dextrose is there specifically because of the iodine. No iodine means no need for a stabilizer to protect it. So if the presence of dextrose bothers you for any reason, non-iodized salt avoids it entirely, though you’d be giving up a convenient source of dietary iodine in the process.
Anti-Caking Agents Are a Separate Additive
While you’re reading that ingredient label, you might also notice calcium silicate or silicon dioxide listed. These are anti-caking agents that keep salt from clumping in humid conditions, and they serve a completely different purpose from dextrose. Anti-caking agents are about texture and pourability. Dextrose is about chemistry, specifically keeping iodine locked in its useful form so it’s still there when you sprinkle salt on your food months after it was packaged.