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The Straight Dope



What are the supposed healthful benefits of sea salt? Does it have any minerals that standard table salt doesn't? Could current sea salt contain human-induced toxins of one sort or another, due to pollution, that salt formed millennia ago wouldn't? --Kerinsky, via e-mail

The main thing sea salt has going for it is happy vibes. Salt mines have long been proverbial sites of drudgery. In contrast, you rarely hear anyone gripe about having to get back to the beach.

The alleged health benefits of sea salt, ranging from improving digestion to imparting "harmonious energy," are credited to minerals and trace elements that are refined out of table salt. Since the underground salt deposits that produce most table salt are the result of evaporating seawater or salty lakes, you'd think the chemistry would be pretty much the same, and mostly it is. Both rock salt (i.e., from mines) and sea salt contain, besides sodium chloride, such chemicals as calcium, potassium, and magnesium sulfates. However, when a large body of water evaporates, the chemicals in it precipitate out in stages--calcium compounds get deposited first, then sodium, and finally magnesium and potassium. Because of this, a rock salt deposit is often a more homogenous mass of sodium chloride than what you get by drying out seawater commercially. Since rock salt destined for human consumption is typically processed to remove grit and other impurities, by the time it reaches the shaker table salt is nearly pure sodium chloride.

Sea salt generally is far from pure--the impurities are its big selling point and frequently an identifying mark, such as the tiny bits of clay that give gray sea salt its color, or the iron-rich red volcanic clay added to Hawaiian sea salt after drying. Although fans tout sea salt's trace elements, the major constituents are the aforesaid calcium, potassium, etc. The importance of minerals in the diet can't be dismissed; after all, the iodine commonly added to table salt helps prevent thyroid conditions. But there's little (actually, from what I can tell, no) research demonstrating that consuming sea salt is helpful in ways that consuming the ordinary kind isn't. Conceivably a benefit will someday be shown; for example, a few studies claim mineral-rich Dead Sea water--when bathed in, not drunk--is useful in treating psoriasis.

Meanwhile, as with all health fads, be careful that in your quest for self-improvement you don't make things worse. You're right in supposing that sea salt can be contaminated--industrial water pollution, in fact, has led some French sea-salt works to shut down. Sea salt also usually contains less iodine than you find in iodized table salt. Goiter has largely disappeared in the developed world; why help bring it back?

Why does salt enhance the ├čavor of almost all food? --Rol Klingberg, via e-mail

Surely you remember that salt is one of the four (by some counts, five) basic taste sensations. (Quick, what's the fifth? Answer: umami, the taste associated with glutamic acid; found naturally in various savory foods, it's the basis of the flavor enhancer monosodium glutamate.) Besides banging harder on the body's salt gong, adding NaCl to some foods can increase the volatility of certain chemical compounds, meaning the molecules are more easily releasedto the air, and of course aroma is an important part of the taste experience. Finally, studies have shown the sodiumin salt can suppress bitter tastes.

The real question isn't why your body encourages you to consume salt, an essential nutrient, but rather why it responds in such a big way to sweet, sour, bitter, and umami. Sure, sweet means sugar, the body's chief fuel, and without sour, there'd be no point to lemonade. But bitter mainly helps us recognize hydrogen cyanide (OK, beer too), and the chief purpose of umami, or anyway MSG, seems to be propping up the Chinese restaurant business. Meanwhile, where's the taste receptor to encourage kids to eat their vegetables?

I've always been told to salt the water before boiling pasta. My mother says it's to add flavor, the Food Network says the iodine in salt locks in flavor, others say it raises the water's boiling point. I've also heard salting water keeps vitamins locked inside vegetables. When should one salt the water before boiling something, and why? --David, via e-mail

I doubt iodine affects the taste of food much. When UNICEF was trying to boost iodized salt in developing countries, local food producers resisted, fearing it would make their wares look or taste funny. So UNICEF researchers did tests to see if volunteers could tell if food had been prepared with iodized salt. Answer: no. Salt does raise water's boiling point, but you'd need a full ounce per quart to raise it one degree Fahrenheit. I can find no evidence that any reasonable amount of salt will impact vitamin retention. So listen to mom: the only practical reason to add salt is for flavor.

Art accompanying story in printed newspaper (not available in this archive): illustration by Slug Signorino.

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