Onion Salt: What It Is, How Much Sodium It Carries, and How to Use It

Shake on onion salt and you’re mostly adding salt. It’s salt blended with dried onion, and it seasons a dish the way salt does, with a toasty onion flavor on top. McCormick’s version carries 440 mg of sodium per ¼ teaspoon,¹ about three-quarters of the sodium in the same measure of Morton’s iodized table salt.² It works best standing in for some of a dish’s plain salt. You can’t swap it one for one with onion powder, and you can’t add more onion without adding more salt.

At a glance

What’s in it

McCormick’s label lists salt, onion, sodium silicoaluminate (to keep it free-flowing) and extractives of onion. It doesn’t say how much of each. Plain onion powder has very little sodium, 73 mg per 100 g in USDA’s data, so nearly all the sodium in onion salt comes from the salt.³¹

The onion part is dehydrated onion. Oregon State University’s horticulture department notes that white onions are the type most often grown for dehydration, and that varieties bred for drying can reach 23% soluble solids or more.⁵ We found no published account of how any commercial onion salt is made.

Flavor and the compounds behind it

Fresh onion’s flavor comes from compounds called thiosulfinates. The compound that makes your eyes water is made by a separate enzyme, lachrymatory-factor synthase.⁶ We didn’t find a study of how drying and grinding change those compounds in onion powder or onion salt.

McCormick describes its onion salt as savory and toasty. It tastes of salt first, then cooked onion, without the sharpness of raw onion. And like any flavored salt, you can’t add more onion without adding more salt.

Origin and history

Onion is only known in cultivation, and Kew places its origin in Central Asia. Popular stories about onions in Egyptian carvings, in the Roman army’s baggage and on early colonial ships, plus a claim that onion salt was first sold in the early 1900s as a breath-friendly seasoning, couldn’t be traced to a source we could open, so we’ve left them out.

How onion salt is used

As the salt in a dish. Onion salt works best standing in for some of the plain salt. McCormick suggests it for soups, stews and burgers. It’s also common in barbecue dry rubs, salad dressings and dips, and sprinkled on roasted vegetables, fries or popcorn.

In place of fresh onion. NDSU Extension lists 1⅓ teaspoons of onion salt as a stand-in for one small onion, alongside 1 teaspoon of onion powder or 1 to 2 tablespoons of minced dried onion.⁴ Onion salt brings salt that fresh onion doesn’t, so cut the recipe’s salt when you use it, and add salt back when you go the other way.

Instead of onion powder. You can’t swap them one for one. Onion powder adds onion with almost no sodium; onion salt adds both. See onion salt vs. onion powder.

Buying and quality

Read the ingredient list. A plain onion salt lists salt and onion, plus maybe an anticaking agent and onion extractives. Seasoned salts and onion-flavored blends with sugar, garlic or other spices are different products. Replace a jar once it stops smelling clearly of onion.

Storage

We didn’t find a shelf-life figure for onion salt from a regulator or standards body. Store it like any ground seasoning: closed, dry and away from heat.

Safety and health

Sodium. By McCormick’s label, one teaspoon of onion salt carries about 1,760 mg of sodium (4 × 440 mg).¹ The FDA’s Daily Value for sodium is less than 2,300 mg a day,⁷ and the World Health Organization recommends adults stay below 2,000 mg a day, naming raised blood pressure as the main health effect of eating too much.⁸ Table salt is about 40% sodium,⁹ so no blend of salt and onion can be “at least 50 percent sodium,” a figure you’ll sometimes see. It can only be less than 40%.

Health claims. Onion salt sometimes gets pitched as a low-calorie seasoning that helps with weight loss or heart health, or as a source of fiber and minerals. We found no evidence for any of that at the amounts you’d use, and its sodium makes the heart-health claim backwards. We’re not making any health claim for onion salt.

Substitutes and comparisons

• Onion salt substitutes
• Onion salt vs. onion powder
• Onion powder, onion powder substitutes and onion powder vs. fresh onion
• Other flavored salts: garlic salt, celery salt, seasoned salt
• Table salt and too much salt