Pure curiosity, and the title is pretty much my question. I’ve noticed that nutritional labels (USA) say something like 0g of trans fat, 10g of saturated fat (50% daily value)… but then it lists the total fat as 20g and only 26% of the daily value. 50% obviously doesn’t equal 26% and 10g doesn’t equal 20g so it must mean there are way more types of fat out there than trans and saturated?
If there are other fats, why do labels not provide a breakdown of the others? Why are saturated fats special enough to be listed?
Thanks!
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So fats, chemically, are long chains of carbon and hydrogen. Aside from the ends, each carbon is bonded to two other carbons and two hydrogens.
Saturated fats have two hydrogens attached to every carbon (which, aside from the two ends, is the most hydrogens that the carbon in the chain can have). They make long, straight chains that stack very nicely together and are solid at biological temperatures.
Unsaturated fats are missing some number of hydrogens (always in multiples of two) and those carbons instead have a double bond. “Trans” refers to the position of the remaining hydrogen on the doubly bonded carbons. If both remaining hydrogens are on the same side, it is “cis”, if they are on opposite sides, they are trans. Unsaturated fats will sometimes be labelled as “mono” (having one double bond) or “poly” (having many double bonds).
Because trans fats are only one subcategory of unsaturated fats, your sum will always be less than total fat. You’d need cis and trans unsaturated plus saturated to get to total fat.
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