Hydrogenated & Trans Fats 3:

Dangerous Deception


A continuation of Trans Fats Introduction, this article discusses three types of hydrogenated fats: 

  1. Partially-hydrogenated fats (Trans fats), such as margarine and Crisco, which have been making negative headlines of late, and for good reason;

  2. Fully hydrogenated, trans-fat-free fats, such as the “new” Crisco, which could be even worse than trans fats, especially for glucose and fat metabolism.

  3. Interesterified (IE) fats, such as some trans-fat free fats that chemically combine a saturated fat such as palm oil (or fully hydrogenated vegetable oil) and a liquid vegetable fat such as soybean or safflower oil to achieve the desired consistency.  These, too, might be even worse than trans fats.

When Is a Fat Not a Fat?

The FDA defines a fat as a triglyceride, presumably because this is the form of stored fat in all animals and plants. And we know a triglyceride as a glycerol backbone with three fatty acid chains attached.  But, what about the mono and diglycerides?  Why aren’t they included, when they also contain fatty acids and a glycerol backbone?

Why do we care?  Because it affects food labeling.  Because the caloric content of foods is based on the calories per gram of each nutrient.  Fats, as triglycerides, provide 9 calories per gram, because the fatty acids in the triglycerides provide 9 calories per gram.  Thus, mono and diglycerides, also provide 9 calories per gram.

Yet when fat content is reported on food labels, only the fats from triglycerides are counted.  And when trans fats are reported, only those trans fatty acids from triglycerides are included.

This subtle rule allows food manufacturers to mislead the buyer.  It allows them to use trans fats in food and yet declare their food as trans-fat-free.  How do they do this?  They can use mono and diglycerides instead of triglycerides as emulsifiers and shortening in prepared foods like ice cream, cottage cheese, crackers, breads, lo-fat salad dressings, etc..  These mono and diglycerides are made industrially, not extracted from plants or animals.  And because they are made by man, the chance of them containing trans fatty acids is very high.  And yet they are not defined as fats. 4

It is best to avoid foods that have mono and/or diglycerides on the label.

Fully Hydrogenated Vegetable Oil

Since the early discovery of trans fats, science has discovered it can fully saturate the poly-unsaturated fatty acids by carefully controlling the reaction conditions (heat and pressure).  Indeed, this is just what Smuckers is now doing to create “trans-fat-free” Crisco.

Because fully saturated vegetable oil is too hard and stiff for most uses, manufacturers randomly incorporate stearic acid (produced by the hydrogenation process) into the triglycerides of natural soybean oil, to achieve a similar consistency as margarine. 7  This process, known as “interesterification” (IE), merely creates another unnatural fat. 

Healthcastle.com, “Your Trusted Source for Nutritional Information,” states: “Fully hydrogenated oil does not contain trans fatty acids. Instead, it contains more saturated fat (primarily stearic acid). Stearic acid is immediately converted into oleic acid (a type of mono-unsaturated fatty acid) in our body and that's why stearic acid does not raise LDL cholesterol (the bad cholseterol).” 6

I find this interesting, and scary.  ‘Hydrogenated oils,’ in theory, are fully saturated. However, I would still be suspect of any fat labeled as ‘hydrogenated’ because it is difficult for any chemical reaction to happen 100%.  Thus, there could still be some unsaturated trans fatty acids present.  This doesn’t worry the manufacturers, because the amount of trans fats is below the 5% cutoff point for required labeling as trans fat.  Also, how are we to know that there is not some other, yet unknown harmful difference, between these chemically altered fats and the naturally occurring saturated version?

Stearic acid is a common saturated fat in foods, especially meats, providing 2-4% of daily energy.  It is an 18-carbon saturated chain, and indeed would result from a complete saturation of 18-carbon linoleic and linolenic acids, the two essential omega-3 fats present in vegetable oils.  And stearic acid has indeed been observed to have a neutral effect on cholesterol and lipoprotiens. 7  But, what’s the point of saturating poly-unsaturated fatty acids to stearic acid, when stearic acid is readily obtained from natural dietary sources?  The point is, that big business stands to gain if consumers buy industrially-converted vegetable fats instead of the naturally occurring saturated fats falsely labeled as “artery-clogging.”

Toxic Fats Study

We’ve all heard by now that trans fats are bad for us.  Now manufacturers are beginning to replace these known toxins with other chemically altered vegetable fats, in the hope that we will continue to prefer these industrial products to natural, whole counterparts (butter, coconut oil, palm oil).

This new study 7 compared the impact of three types of vegetable fats on human fat and sugar metabolism.  These three types of fats are all currently available on our grocers shelves:

  1. 1.natural saturated fats (e.g., palm oil shortening)

  2. 2.trans, partially-hydrogenated fats (e.g., Crisco shortening & margarines)

  3. 3.TFF: trans-free, hydrogenated & interesterified fats (e.g., “New Crisco,” & trans-free margarines)

Study results reflect undesirable changes in fat and sugar metabolism when subjects consumed the chemcially-altered fats (trans and TFF), compared with when they consumed the natural saturated fat: 

  1. Trans- and TFF fats caused undesirable changes in a lipid profile (LDL and triglycerides went up, HDL went down) compared with the natural fat.

  2. TFF fat was slightly less bad than trans fats with respect to fat metabolism.

  3. TFF fat was definitely worse for sugar metabolism than the toxic trans fats! 7

The researchers attribute the problems seen with TFF fats to the interesterification (IE) process, which allows fatty acids to combine randomly to the three positions on the glycerol backbone to make a triglyceride.  When a fatty acid is in a position the body’s enzymes cannot recognize, the substance is toxic, altering metabolic processes in ways harmful to health.

For more detail about this study, refer to my article Chemically Altered Fats:  A New Study

See also Mercola's website for more on interesterified fats: http://articles.mercola.com/sites/articles/archive/2009/03/05/Interesterified-Fat--Is-it-Worse-Than-Trans-Fat.aspx


If our 100-year deadly experiment with trans fats has proven anything, it is that in biological systems, geometry is everything; just as the pieces of jig-saw puzzles will only connect in specific places, so it is with biochemical molecules.  Natural fatty acids have a specific geometry governed by the position and number of double bonds in the chain: natural unsaturated fats have bends and kinks, while trans fats are rigid and linear.  Natural triglycerides are formed by enzymatic action on glycerol and fatty acids, which ensures that the fatty acids are connected at the appropriate position on the glycerol backbone for metabolic processes; TFF triglycerides have fatty acids linked in the wrong position, making them toxic.


  1. 1.www.newstarget.com/011444.html

  2. 2.www.umm.edu/features/transfats.html

  3. 3.en.wikipedia.org/wiki/Trans_fat

  4. 4.www.dldewey.com/hydroil.htm

  5. 5.www.mayoclinic.com/health/trans-fat/CL00032

  6. 6.www.healthcastle.com/trans.shtml

  7. 7.www.nutritionandmetabolism.com/content/4/1/3

  8. 8.www.bantransfats.com/diabetes.html by Mary Enig

return to Diet Menu  or Health Essays Menu

  1. Introduction

  2. When is a Fat Not a Fat?

  3. Fully Hydrogenated Vegetable Oil

  4. Toxic Fats Study

  5. Conclusion

by Catherine M. Haug,  January 2007 (moved from Hydrogenated Fats Article)