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Is sea salt more healthy than table salt?

Promoted as having health benefits, sea salts lack a vital ingredient.

Sea salt, produced through evaporation of ocean or salt-lake water, usually undergoes little processing. Hence, it typically contains a variety of trace minerals, such as magnesium and calcium, and elements that give it the colour and flavour that make it popular with foodies.

In contrast, table salt is often mined from underground deposits and undergoes more processing as it’s transformed into a white powder that flows freely, thanks to anti-clumping additives.

But in New Zealand, Cerebos’ table salt is made from salt obtained from Marlborough’s Lake Grassmere. The salt water is collected and evaporated by the sun and wind via a series of salt beds and drying processes. The resulting product is then milled or crushed into varying crystal sizes from rock crystal to fine table salt.

Read more: The latest research on salt's link to heart, cancer and brain diseases

Table salt typically has fewer minerals and elements, with the exception of iodine, which New Zealand manufacturers must add because our soils and therefore national diet are deficient in that element.

More recently, an array of sea salts have emerged on shop shelves promoted as containing “higher levels of calcium, magnesium and other minerals” than standard table salt and having “beneficial effects” on the body. It sounds great, although rather vague. So, what’s the truth?

New Zealand’s Dominion Salt provides a full nutritional analysis of its sea-salt products, revealing its Flaky Sea Salt has about the same levels of calcium and iron as iodised table salt, whereas its Natural Sea Salt product has much higher levels of both. The Natural Sea Salt also has much more magnesium than the Flaky Sea Salt and iodised table salt. Importantly, though, both products have only a fraction of the iodine content of iodised table salt. “That’s because the amount of iodine in sea water itself is too low to bring it up to that level,” says Sheila Skeaff, professor of human nutrition at the University of Otago.

Expensive Himalayan salt, popular for its pink colour and supposed health properties, lacks meaningful amounts of iodine.

With sea-salt products, says Skeaff, “If it doesn’t say it’s iodised, it won’t contain the recommended range of iodine.”

There’s no evidence to suggest that sea salt is nutritionally superior. In fact, its lack of iodine is a distinct disadvantage. And its minute amounts of trace minerals are far more easily obtained in other nutrient-dense foods such as nuts.

Enjoy sea salt on occasion for its flavour, but, ultimately, your health is better served in New Zealand by choosing iodised table or rock salt to optimise your iodine levels.

This article was first published in the January 18, 2020 issue of the New Zealand Listener.

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