Trace

[carlos]

When a food says it has a trace amount of a nutrient - what is that in real terms? Is threshold after which it stops being trace and begins to be measured? Cheers

[Buenchico]

A 'trace amount' is officially defined as 'detectable but not quantifiable'. In practice, that probably means that to quantify the amount would require a greater number of decimal places than is used to quantify the other ingredients.

For instance, I've just grabbed the first can which came to hand in my kitchen cupboard. (Morrison's Bettabuy New Potatoes). 'Typical values per 100g' are quoted to the nearest 0.1g. (So, for example, protein is shown as 1.5g and carbohydrate is 15.1g).

Saturated fat is shown as 'trace'. I take this to mean that, when rounded to 1 decimal place, the figure will be 0.0g (i.e. it's less than 0.05g). Obviously, anyone seeing '0.0g' is likely to read this as 'zero' which (because there's a detectable quantity, however small) isn't strictly true. Therefore 'trace' is used to indicate that there's a small amount present but, within the accuracy of the scale being used, it can't be meaningfully quantified.

Chris