Sea salt and regular table salt are chemically the same substance: sodium chloride. By weight, both contain 40% sodium. The differences between them come down to how they’re made, what else ends up in them, and how they feel in your hand and on your tongue.
Same Chemical, Different Source
Table salt is mined from underground salt deposits, then heavily processed to strip out impurities and minerals. Sea salt is made by evaporating ocean water or saltwater lake water, with minimal processing afterward. Both end up as sodium chloride crystals, but they take very different paths to get there.
That processing gap is where the real differences emerge. Table salt gets ground into fine, uniform grains and mixed with anti-caking agents like calcium silicate or calcium stearate to keep it flowing freely from the shaker. Most table salt in the U.S. and Canada is also fortified with iodine, a nutrient your thyroid needs to function properly. Sea salt, by contrast, typically skips all of that. It keeps its irregular crystal shapes and retains small amounts of minerals from the water it came from.
The Trace Mineral Question
Sea salt does contain trace amounts of magnesium, potassium, calcium, zinc, and iron. These are the minerals that give varieties like Celtic gray salt their color. But “trace” is doing a lot of work in that sentence. The quantities are so small that they make no meaningful nutritional difference. You would need to eat dangerous amounts of salt to get a useful dose of magnesium or potassium from it. If you’re looking for those minerals, leafy greens, nuts, and bananas are vastly more efficient sources.
Sodium Content Per Teaspoon
Here’s where things get slightly tricky. A teaspoon of fine table salt contains about 2,330 mg of sodium. A teaspoon of fine sea salt contains roughly 2,120 mg, and coarse kosher salt comes in around 1,920 mg. That might look like sea salt is lower in sodium, but it’s not. The crystals are just shaped differently. Coarser, flakier crystals don’t pack together as tightly in a measuring spoon, so you physically fit less salt into the same volume. Gram for gram, the sodium is identical.
The American Heart Association is direct on this point: sea salt and kosher salt are not low-sodium alternatives to table salt. They affect blood pressure the same way because they deliver the same sodium to your body.
Iodine: A Meaningful Difference
One practical difference worth paying attention to is iodine. Iodized table salt in Canada, for example, is required to contain 76 micrograms of iodine per gram. Testing of sea salt brands found that nearly all of them contained less than 2 micrograms per gram, unless they were specifically labeled as iodized. That’s a roughly 40-fold difference.
If you’ve switched entirely to sea salt for cooking and finishing, you’ve likely cut your main dietary source of iodine. This matters most for people who don’t eat much seafood, dairy, or eggs, since those are the other common sources. Iodine deficiency can lead to thyroid problems, so it’s worth checking whether your diet covers that gap.
Why They Taste Different
Many cooks swear sea salt tastes better, and there’s a physical explanation for that. The shape and texture of salt crystals change how fast they dissolve on your tongue, which changes how intense the saltiness feels. Research published in the journal Food Research International found that non-cubic and irregularly shaped crystals, like those in flaky sea salt or Maldon salt, dissolve up to 3.8 times faster than compact cubes. That rapid burst of dissolution made people perceive up to 17% more saltiness, and they hit peak flavor 40% sooner.
This is why chefs often use flaky sea salt as a finishing salt, sprinkled on food right before serving. The large, crunchy crystals deliver a sharp hit of flavor on the surface of your tongue. Fine table salt, dissolved evenly into a soup or dough, does the same job of seasoning the whole dish. They’re tools for different moments in cooking, not better or worse versions of the same product.
Microplastics in Sea Salt
Because sea salt comes from ocean water, it picks up whatever is in that water. A 2018 study in the journal Environmental Science & Technology tested 39 salt brands from six continents and found microplastics in the vast majority of sea salt samples. The range was wide: from zero to over 1,600 particles per kilogram, with one Indonesian brand reaching over 13,000 particles per kilogram. Rock salt (the mined kind used to make table salt) contained far fewer, averaging 38 particles per kilogram.
Asian-produced sea salts had notably higher concentrations, averaging over 1,000 particles per kilogram compared to about 39 per kilogram in brands from other continents. The most common plastics found were polyethylene, polypropylene, and PET, the same materials used in packaging and bottles. The long-term health effects of ingesting microplastics at these levels are still being studied, but it’s a factor that simply doesn’t apply to mined table salt in the same way.
Which One Should You Use
For your health, it genuinely doesn’t matter. The sodium is the same, the calorie count is the same (zero), and the trace minerals in sea salt are nutritionally irrelevant. Your blood pressure won’t know the difference. The only health-relevant choice is how much salt you use total, not which kind.
For your cooking, the choice is more interesting. Fine table salt is cheap, consistent, and dissolves quickly into batters, doughs, and liquids. It’s the workhorse. Sea salt, especially flaky varieties, adds texture and a burst of flavor when you sprinkle it on a finished dish. Many home cooks keep both: table salt for the pot, sea salt for the plate. If you do rely mainly on sea salt, just make sure you’re getting iodine from somewhere else in your diet.