Introduction to Dietary Fats

Note: This article is more about technical basics than advice.  Read if you want to understand more about the underlying science.

One of the most confusing aspects of modern nutrition is fat.  The recommendations seem to be more liquid than the ocean, so trying to figure out what to do is exhausting and sometimes nearly impossible.  Walk into a store and you will see hundreds of items advertising themselves as “Fat-Free”, “Reduced Fat”, “Low Fat”, and “Fat removed”.  Looking at these it would be easy to assume that fats are dangerous and we must be incredibly careful with their consumption.  However, as with most things in life, the truth is more complicated than that.    Fats are one of the basic nutrients required for survival.  Fats are critically important to the maintenance of the myelin sheaths on nerves.  It is also critically important for certain vitamins as they are fat soluble, without enough fat certain vitamins cannot be processed (Mayo Clinic Staff).  Without fats there is an immediate decline in human health.  Knowing how important these fats are the movement towards a low fat diet seems a little perplexing.  However low fat advocates believe that because fat is high in calories it is easy for it to contribute to weight gain, and because excess weight causes significant health problems it is therefore important to limit fat (Mayo Clinic Staff).  In this first article in this series I am going to discuss some general classifications for fats.

In order to truly understand the current state of dietary recommendations it is first important to understand the different types of fat and what a fat is.  We are actually discussing fatty acids, and these are long hydrocarbon chains.  The two main types of fat consumed are saturated fat and unsaturated fat.

Saturated fats are fats with only single bonds, where they are saturated with the maximum number of hydrogens.

(This is a monounsaturated fat)

Monounsaturated fats are fats with a single double bond, meaning they have fewer hydrogens.  Polyunsaturated fats have multiple double bonds and therefore fewer hydrogens.

Partial hydrogenation results in trans fats an isomer of unsaturated fats (American Dietetic Association 1599).  (An isomer is a compound that has the same chemical formula but a different arrangement of the molecules).

It is difficult to consider fats as a large group, because each of these fats has a different effect on human health.  So when looking at dietary recommendations, it is important to look at how they treat each fat, and in turn how much of each type of fat you consume.  The current position of the American Dietetic Association (ADA) and Dietitians of Canada (DC) that dietary fat for the adult population should provide 20% to 35% of energy and emphasize a reduction in saturated fatty acids and trans-fatty acids and an increase in n-3 polyunsaturated fatty acids” (American Dietetic Association 1599).  This closely mirrors the Mayo Clinic recommendation of trying to reduce your consumption of saturated fat and trans fat and replace it with polyunsaturated fats (Mayo Clinic Staff).  The general recommendation seems to be to limit fats to at most a third of your calories and to reduce the “bad fats” of saturated and trans fat as far as possible.  However, it is important for us to not just consider the recommendations, but the science that the recommendations are based on.   That is what will be covered over the next several posts.  An in depth dive into the different fats and what the science suggests about how much should be consumed.

References

American Dietetic Association. “Position of the American Dietetic Association and Dietitians of Canada: Dietary Fatty Acids.” Journal of the American Dietetic Association 107.12 (2007): 1599-1611. Web.

Mayo Clinic Staff. Dietary Fats: Know Which Types to Choose. 7 August 2014. Mayo Clinic. Web. Second April 2015.