When I was in the army cadets we used to go to week long camps in windswept and unloved parts of the country so that we could be driven by four tonne Bedford lorry to the nearest wilderness to spend each day marching from point to point and hone our mapwork skills. One of the ‘tips’ given to us by NCOs (in fact school kids a couple of years older) was that eating salt was a good way to prevent cramp, and I think that there is a germ of truth in there unless I’m just not particularly prone to cramp. There was one occasion, though, when we were coerced into eating quite a lot of salt, poured into our hands from the blue plastic compo ration salt cellar, and then made to “down in one”. It took just a short period of time for me to become overwhelmed with tsunamis of nausea, and in just a few minutes a small collection of kids in green were festooned around the camp, bent at the middle and dry retching as much as is possible to dry retch. Obviously, it was not fatal.
I came to think of this recently when I had cause, as you do, try and find information on the microbiological quality of table salt. I was surprised I could find nothing considering that salt is poured on to food and so is essentially ‘ready to eat’. To me this is a data gap, especially when you consider the contamination that is prone to occur with salt’s non-identical twin, pepper. EU rules say that it is not normally necessary to test table salt for Listeria monocytogenes.
What my research did turn up was that eating salt can be fatal. Wikipedia states that the mean fatal does is 3g per kg body weight, so for me (and to my shame) I’d need to eat 330 g of salt. That is quite a lot and you’d hope that my previously-proven retch-response would kick in and save me. However, people have managed to kill themselves with salt. How could this be? Ofran et al. (2004) provide a case report of a woman suffering from depression who consumed salt as part of an ‘exorcism’, apparently drinking saline containing a total of1 kg salt. The same paper also cites another 16 cases where 95% of cases were women and all had psychiatric problems. In children problems can occur as part of accident (mistaking salt for sugar), abuse or when used as an emetic.
Beyond this lurks the dangers of social media challenges, an example being given in this article from the Daily mirror:
People egg each other on to eat handfuls of salt without spitting it out.
An interesting review has been published on fatalities arising from acute salt toxicity, which was prompted by the existence of social media salt-eating challenges (Campbell and Train, 2017). Worryingly it is reported that in some cases less than 25g of sodium (about 63g salt) was consumed. In one case of a child 7g of sodium (about 17.5g salt) was the estimated dose. This is obviously of concern as it seems quite conceivable for small amounts to be eaten deliberately or by mistake that could lead to mortality. In some cases the reports seem implausible, such as 6g being a fatal dose for an adult and the authors acknowledge that the doses are only estimates based on incomplete information.
Ingesting large amounts of sodium may result on non-fatal but serious outcomes, such as the case of a person drinking a litre of soy sauce to cleanse their colon of toxins, which resulted in permanent brain damage. The amount of salt consumed was 200g.
Should there be warning labels on high salt foods?
Campbell, N.R.C. and Train , E.J.(2017) A systematic review of fatalities related to acute ingestion of salt. A need for warning labels? Nutrients, 9:648.
Ofran, Y., Lavi, D., Opher, D., Weiss, T.A. and Elinav, E. (2004) Fatal voluntary salt intake resulting in the highest ever documented sodium plasma level in adults (255 mmol L): a disorder linked to female gender and psychiatric disorders. Journal of Internal Medicine, 256: 525–528