Editing Fat (section)

==={{anchor|Trans fat}}"Cis fat" vs. "trans fat"===
{{main|Trans fat}}
In nature, unsaturated fatty acids generally have double bonds in [[cis–trans isomerism|''cis'' configuration]] (with the adjacent C–C bonds on the same side) as opposed to ''trans''.<ref name="mart2007" /> Nevertheless, [[Trans fat|''trans'' fatty acids]] (TFAs) occur in small amounts in meat and milk of [[ruminant]]s (such as cattle and sheep),<ref name="kuhnt2011" /><ref>{{cite book|first1=Fred August |last1=Kummerow |first2=Jean M. |last2=Kummerow|title=Cholesterol Won't Kill You, But Trans Fat Could|publisher=Trafford|year=2008|isbn=978-1-4251-3808-0}}</ref> typically 2–5% of total fat.<ref name="tfca2006" /> Natural TFAs, which include [[conjugated linoleic acid]] (CLA) and [[vaccenic acid]], originate in the [[rumen]] of these animals. CLA has two double bonds, one in the ''cis'' configuration and one in ''trans'', which makes it simultaneously a ''cis''- and a ''trans''-fatty acid.<ref name="mejo0000" />

{| class="wikitable"
|+ Trans fat contents in various natural and traditionally processed foods, in g per 100 g<ref name="tarr2006" />
|-
! Food type
! Trans fat content
|-
| butter
|2 to 7 g
|-
| whole milk
|0.07 to 0.1 g
|-
| animal fat
| 0 to 5 g<ref name="tfca2006" />
|-
|ground beef
|1 g
|}
The processing of fats by hydrogenation can convert some unsaturated fats into trans fat]]s.  The presence of trans fats in various processed foods has received much attention. 
[[File:Margaryn 022.jpg | thumb | upright=1.3 | [[Margarine]], a common product that can contain trans fats]]

[[File:Crisco Cookbook 1912.jpg | thumb | Cover of original [[Crisco]] cookbook, 1912. Crisco was made by hydrogenating cottonseed oil. The formula was revised in the 2000s and now has only a small amount of trans fat.]]