“Dietary fat, whether saturated or not, is not a cause of obesity, diabetes, or any other chronic disease of civilization.” Gary Taubes, author, Why We Get Fat
Since 1961, when the American Heart Association first endorsed board member Ancel Keys’ anti-fat diet, there has been a “War on Saturated Fat” that continues to this day. Newspapers, magazines, bloggers, college textbooks, and the major media – in unison – classify saturated fat as ‘bad’ – lumping natural saturated fat with not-found-in-nature industrial trans fatty acids.
Unfortunately, most of what has been written and said about saturated fat is incomplete, misleading, and just plain wrong.
The Basics (if a bit technical) Facts About Fats
Fats and oils (lipids) are a group of compounds insoluble in water. (Water and oil don’t mix.) Fats and oils are made of molecules called triglycerides (TG), formed when three fatty acids (or fats) attach to glycerol. Like cholesterol, glycerol is a high molecular weight alcohol that holds the three fatty acids together. (The fats, technically, are esterified to glycerol.)
There are no animal fats
Fats are universal. Microorganisms, plants and animals share lipids, including the lipoproteins (LDL, HDL) that transport lipids in our blood. As an example, saturated stearic acid (18:0) is the same fat whether found in bacteria, beef, chocolate, or human milk. (The same is true of glycerol.) Your body can’t tell the difference between saturated stearic acid in your chocolate bar and the saturated stearic acid in roast beef – they are identical.
Fats are chains of carbon connected by electron-sharing chemical bonds
Fatty acids are formed from carbon (C), hydrogen (H) and oxygen (O). Carbon will form into a fatty acid chain (C-C-C-C). A saturated fat is a chain of carbons in which the connecting chemical bonds share one set of electrons, resulting in: Single, stable chemical bonds (C-C-C-C).
So a saturated fat is a straight chain of carbons with single stable chemical bonds and the carbons are saturated with hydrogen – creating chemical stability. Non-reactive saturated fats were traditionally used for higher heat cooking.
Below is a simplified diagram of 4 carbon saturated butyric acid:
H H H H
C – C – C – C
H H H H
Unsaturation (double bonds) introduces chemical instability
Unsaturated fats have one or more double bonds (C=C) and missing hydrogen (H) – which introduces chemical instability. The more double bonds a fat contains, the more reactive it is to heat, light and oxygen. As an example, monounsaturated oleic acid – dominant in olive oil and pork fat (lard), has one double bond and is relatively stable (1 or mono unsaturated) – safe for medium-heat cooking.
Unsaturation: There is missing hydrogen (H) at the site of the double bond (C=C). This is a segment of an unsaturated fat with hydrogen missing at the double bond:
H H H H
C – C = C – C
Polyunsaturated linoleic acid – dominant in soybean and canola oil – has two (2) double bonds and is very unstable – more missing hydrogen – rendering the fat highly reactive to light, heat, and oxygen. As a result, polyunsaturated fat – called ‘good’ fat by the so called experts in health and nutrition – should not be used in cooking. Polyunsaturated fats generate unwanted free radicals (lipid peroxides) that raise havoc in your body.
Naming of fats
In lipid biochemistry, fats have names (like stearic acid) as well as a numerical shorthand designation (like 18:0). Common to cocoa butter and beef tallow, saturated stearic acid is 18:0. The number before the colon is the length of the carbon chain; the figure after denotes the number (#) of double bonds. Saturated fat, with no missing hydrogen, has zero (0) reactive double bonds.
- Relatively stable monounsaturated oleic acid is 18:1 – 18 carbons and one double bond.
- Very unstable polyunsaturated linoleic acid is 18:2 – 18 carbons and two double bonds.
As you may note, fats can be defined by chain length as well as degree of saturation. Common saturated fats come in 8 different chain lengths beginning with short chain butyric acid (4:0) – found only in the milk fat and butter of ruminant animals. Ignored by the establishment – why talk about a good saturate – short chain butyric acid helps maintain and restore the integrity of the gut lining while also reducing inflammation.
Because the gut uses butyric acid as an energy source, butyric acid has been shown to benefit those with gut disorders like ulcerative colitis and Crohn’s disease. And what cows eat matters – a lot! Grain feeding reduces more than vitamin A and cancer-fighting conjugated linoleic acid (CLA). According to http://eatwild.com, feeding grain to dairy cows “reduced the contribution of butyric acid to milk fat on average from 4.5 to 3.9 grams per 100 grams of milk fat.”
Take Away Lesson:
If you drink milk, fat is the most valuable component. In 1910, skim milk was only fed to pigs (who turned the milk sugar into lard found in most kitchens in America). Use full fat milk – preferably raw – from cows on pasture. Milk fat is the most complex fat on earth containing 12 different fatty acids including 8 different saturated fats with 8 different chain lengths.
Yes, lipid metabolism is very complex, and sweeping one-size-fits-all Anti-Saturated Fat statements lack scientific foundation. Chain length – never mentioned in the Dietary Guidelines or by the American Heart Association matters. According to our lipid biochemist Dr. Michael Gurr:
- “Suggestions that saturated fatty acids differed in their cholesterol-raising capacities was already apparent in the 1950s and certainly in the 1960s.
- Dietary saturated fat/plasma cholesterol relationships have been grossly oversimplified.
- Old simplistic statements such as saturated fats raise plasma cholesterol need to be reappraised.”