Monday, July 6, 2009

Assaulting the salt

It has been about a decade or more since i last heard about the evils of salt. I don't know why the wellness revolution has not discussed salt. I wonder if salt is no longer seen as the evil or it is common knowledge that it is bad for you.

We don't use salt in cooking and only occasionally add it to a meal. Salt is ubiquitous in processed food so we are not going to lack any.

I found a 1990 article a very interesting study. It looked at salt consumption in a factory cafeteria which served 2400 meals a day. They varied the size of the holes in the top of the salt shakers. The standard size was 2.9 mm in diameter, and the new holes were either 2, 3 or 4mm in diameter. After 10 days after a size change they looked at salt consumption. For those who are not aware about how different a small diameter change can make here is an example. We run a 20mmm diameter back bone for our cold water, with 15mm diameter feeds. The 20mm pipe carries twice as much water as a 15mm pipe, because the area of the 20mm pipe is about twice that of the 15mm pipe. Hence a small change in diameter has a large impact on area.

They changed the size of the salt shaker lids then waited 10 days before measuring the salt usage. Therefore this gives the cafeteria clients time to change their shaking length from feedback as to how the food tasted.

They found that as the hole size increased so did the consumption of salt. The result is shown in the figure below. It is quite a dramatic increase, doubling the salt intake by making the hole size 4mm instead of 2mm. Therefore we can conclude from the data that the workers were doses their meals out of habit, not from taste of the food. Because they are not adjusting their shaking to the amount of salt being produced.

It got me thinking - maybe with sugar and fat we can lower intake by reducing the "hole" size. For instance using a smaller spoon to get a teaspoon of sugar.... more ideas will hopefully come as I mull this over.

Reference: Farleight, Shepherd and Wharf The effect of manipulation of salt pot hole size on table salt use. Food Quaility and Preference vol 2 1990

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