FitLife writes in 10 amazing benefits of pink himalayan salt:

Commercial refined salt is not only stripped of all its minerals, besides sodium and chloride, but is also chemically cleaned, bleached and heated at unnecessary high temperatures.

In addition, it is treated with anti-caking agents which prevent salt from mixing with water in the salt container. These agents also prevent dissolving within our system leading to build up and then deposit in organs and tissue, causing severe health problems.

Is it true that table salt contains those anti-caking agents that have a biological effect?

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    There are no citations and this would be a huge scandal if it turned out to be true, so I suspect this is in the realm of an old wives' tale. – PointlessSpike Apr 11 '16 at 14:20
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    I would think that if the salt didn't dissolve, it wouldn't end up in many organs or tissue, and would instead be eliminated as solid waste. But I might not be understanding their claim (or the biology). Here's another version of the claim from 2007, with very similar wording, plus a more explicit claim of causing hyperthyroidism. – Dan Getz Apr 11 '16 at 14:39
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    Anti-caking agents make salt flow better. But they clearly don't stop salt added in cooking from dissolving fully and that they would stop a similar process in your stomach sounds rather far-fetched. Plus much commercial salt contains iodide by government mandate to compensate for low iodide content in some areas which clearly avoids known health problems. – matt_black Apr 11 '16 at 16:05
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    This can be easily tested by placing a bit of salt on your tongue, as you watch in a mirror to see if it dissolves. Or putting some in water. As for the idea that salt is "stripped of all its minerals", we can re-word that to state that it is refined to remove impurities. – jamesqf Apr 11 '16 at 18:14
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    The site isn't even consistent internally: himalayan salt is good because it contains other minerals like iodide but table salt is bad because they have to add iodide. Worse, "natural" impurities are good but "artificial" additives are bad. Natural salt is good because you use less due to the "different" crystal structure being less dense. It's bollocks, total unmitigated bollocks. – matt_black Apr 11 '16 at 20:52

Short answer: Yes, commercial table salt contains anti-caking agents; No, these do not prevent salt from dissolving in your body. Anti-caking agents are added to prevent the salt crystals from sticking together due to air humidity. They achieve this by reacting with water before the salt can. Without them you would have a hard time getting finely ground salt out of a salt shaker.

There are different agents in use. Sodium aluminosilicate seems to be the most common agent in the USA, while in Europe sodium and potassium ferrocyanide are used. They should be mentioned in the list of ingredients of any commercial salt you buy. None of these prevent salt from dissolving in liquid water, as you can easily demonstrate by adding a spoon of salt to a glas of water and stirring. The solubility of sodium chloride in water is about 360 g / liter at room temperature. I could not find any reputable sources claiming that this is changed by the addition of anti-caking agents. Sodium aluminosilicate is probably insoluble, depending on its exact composition (which can vary quite a bit), but that will only result in a suspension of the insoluble particles in your liquid.

Edit: The question whether these substances have a "biological effect" is different from the headline question. Since everything you interact with will have some kind of effect, it makes more sense to limit the answer to the question of toxicity. All anti-caking agents have to be and have been approved by the appropriate agencies (FDA in the US, EFSA in Europe).

Ferrocyanide is a highly stable complex that does not react in the body and is excreted via feces and urine. Its use as an anti-caking agent is limited to table salt in the EU. 1 At very high concentrations it can lead to kidney damage due to crystal formation in the kidneys. It has not been observed to have carcinogenic or teratogenic properties. 2 The LD50 of potassium ferrocyanide (oral, rat) is given as 3600 mg/kg, which is higher than that of pure sodium chloride (table salt) which is 3000 mg/kg. Since the highest allowed concentration of ferrocyanides in table salt is 20 mg /kg, it can be considered impossible to ingest a toxic dose of this agent. Criticisms against these anti-caking agents are usually based on possible environmental effects, but as such are not part of the question.

Sodium aluminosilicate is actually not a clearly defined compound, but includes several amorphous materials, zeolites and naturally occurring minerals. 3 It is generally insoluble in water and is excreted from the body via urine and feces. The peer reviewed literature shows no negative impact on health or environment. 4 (Toxnet entry, contains links to the peer reviewed literature) The LD50 data for this material is a bit inconsistent, giving values from >5000 to > 27000 mg/g (oral, rat). The highest danger comes from inhalation of the dust, but even here toxicity starts at 140 mg/m3 over 4 hours of exposure. 5

Since the other claims made in the quote were not part of the question, I will just provide a link to a blogpost where most of them are discussed.

  • At the moment the answer doesn't discuss the effects of Sodium aluminosilicate or potassium ferrocyanide in humans. Do you think there's no peer reviewed research investigating that issue? If so please be explicit about it. – Christian Apr 12 '16 at 12:56
  • It is true that I focused on the headline question regarding changes in solubility in the human body. The anti-caking agents have been approved for use in foods by the relevant authorities (FDA in the USA), therefore the toxicology has to be known. I will edit the answer and add some data tomorrow. – DocM Apr 12 '16 at 20:14
  • Having used salt lacking in anti-caking agents in humid weather I can definitely state that it's a royal pain to use in a shaker. – Loren Pechtel Apr 13 '16 at 0:39
  • "It is generally insoluble in water and is excreted from the body via urine and feces." Do you have a reference for this? I would not expect to find many insolubles in urine. – Oddthinking Apr 13 '16 at 14:22
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    @oddthinking Yes, surprised me as well, but then I'm a chemist, not a toxicologist. Quote [2] mentions this "The compound is excreted via urine through glomerular filtration." I also found this observation confirmed in other sources, e.g. inchem.org/documents/jecfa/jecmono/v05je02.htm ("Rats dosed orally with 200 g/kg potassium ferrocyanide excreted about 47 per cent. unchanged in the feces and three per cent.") – DocM Apr 13 '16 at 16:15

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