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Can we put the demonization of saturated fat to rest?

In March 2010, the prestigious American Journal of Clinical Nutrition published an article (1) which explained an analysis of pooled data from 21 epidemiological studies encompassing 347,474 individuals.  The authors concluded, “there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD (coronary heart disease) or CVD (cardiovascular disease). “  Finally maybe we are beginning to see the light!  Natural saturated fat is a necessary and healthy part of everyone’s diet.  It does not clog arteries.

Heart attacks were unknown prior to 1912, when the first report of this unusual phenomenon appeared in the Journal of the American Medical Association (2).  Doctors at that time had never seen one.  Why then?  Suspiciously, Crisco had come on the market in 1911.  In 1907 candle-maker William Procter and soap-maker James Gamble needed a use for cheap cottonseed oil, a waste product of the cotton mills they owned, and developed the process of hydrogenation, which turned the liquid oil into a solid resembling lard. Since candles were rapidly being replaced by electric lighting, they needed a new product and Crisco (crystallized cottonseed oil) was born (3).  It was heavily advertised to the unsuspecting public as a healthier and cheaper alternative to lard.  The partial hydrogenation of cottonseed oil produced an abundance of trans fatty acids.  Oleomargarine, made by the same process but using corn and soy oils, had been invented in France in 1869 and began being manufactured in the 1870s. This inexpensive butter substitute became popular, particularly during the 2 world wars, when butter was scarce or rationed.  Numbers of heart attacks increased steadily. Deaths from heart disease peaked in the 1960s and have since declined, due mainly to better medical intervention, and a steep decrease in smoking (4), although they are still the number one cause of death in the US.

Meanwhile, in the late 1960s a government committee, with far less than universal consensus, decided that eating saturated fat and cholesterol led to cardiovascular disease (heart attacks, strokes, and clogged arteries).  Fat, particularly saturated fat, has been demonized ever since.  Trans fat was added later, when the overwhelming evidence for its adverse health effects could no longer be suppressed by the big food companies.  But isn’t it strange that humankind has been eating natural fats from animals, olives, nuts and coconut for hundreds of thousands of years and heart attacks have only become a problem in the last 100 years?  And we are encouraged to give up natural fats like butter, lard and beef fat in favor of modern, industrially processed, often trans fat laden vegetable oils?  What an egregious experiment in human health.

Besides trans fatty acids, what makes vegetable oils so problematic?  All fats and oils are made up of mixtures of fatty acids.  The solid fats have a higher proportion of saturated fatty acids.  Notice that saturated fatty acids are more abundant in tropical plants and warm-blooded animals.  They make up much of the structure of cell membranes, which must remain semi rigid to function correctly.  Seed oils (soy, corn, safflower, canola) come from temperate zone plants.  These contain mainly omega-6 fatty acids.  Cold water fish contain mainly omega-3 fatty acids.  Their cell membranes must remain permeable at cold water temperatures.  Humans need to consume both of these unsaturated fatty acids, ideally in equal amounts, but we need them in very small quantities.  They are both prone to oxidation and herein lies the danger.  Oxygen, the very substance that is so necessary for life, has a dark side.  It is very chemically reactive with the equally reactive double bonds in unsaturated fatty acids and it is this oxidation that damages our cells, including those in our blood vessel walls.  Saturated fats have no reactive double bonds so they do not oxidize.

Most clinical or epidemiological studies comparing people consuming vegetable oils in place of butter or lard claim that they see less heart disease when people switch from the more saturated fats to the polyunsaturated oils.  However, the vast majority of these studies are confounded by testing too many factors at the same time and then singling out saturated fat consumption to blame for heart disease.  The few studies e. g. (5)(6) (7) that specifically tested the substitution of vegetable oils for animal fats found either no difference in heart disease or worse outcomes in the vegetable oil group.

Why are butter, eggs cream, whole milk, beef, pork and chicken fat still getting a bad rap?  Again, follow the money.  The vegetable oil industry is huge and highly profitable.  A myriad of processed foods can be made with cheap vegetable oil, sugar and white flour and sold at a huge markup.  We like the taste of deep fried foods.  Heating polyunsaturated oils to high temperatures speeds up oxidation and with it cell damage (ours).  As we persist in consuming these oils more of us succumb to obesity, diabetes, heart disease, cancer, you name it.  They are not the only cause but certainly a contributing factor.  And the drug and medical industries profit as we become sicker and sicker.  As usual we can conclude that eating real, whole, minimally processed food, cooked at home (most of the time), with generous quantities of natural fats will keep us in the best health.

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