Fat Facts - saturated fats versus unsaturated fats: have we got it all wrong
- By:Craig Burton
Fats and oils are simply essential to optimal health. They are important building blocks for the cells of your body, a source of energy and they provide a variety of hormones.
The respected medical journal ‘The Lancet’ (v339, 3/21/93) comments that low-fat diets are associated with increased rates of depression, psychological problems, fatigue, violence and suicide (3).
So why all the bad publicity? Let’s take a brief look at the history of dietary fats and heart disease.
Before 1920 Coronary Heart Disease (CHD) was rare in America, but by the mid fifties it was the leading cause of death among Americans (this corresponds with most Western countries). So what had changed?
In 1953 American doctor Ancel Keys believed that high-fat food was the culprit. He set out to prove this by comparing death rates from CHD and the amount of fats eaten in certain countries to suggest a positive correlation. However it seems Dr. Keys was very selective as to which countries he chose. Out of the possible 22 countries with available data he chose only 6 that supported his hypothesis, which ultimately painted a very different picture.
Dr. Uffe Ravnskov in his book ‘The cholesterol myths’- exposing the fallacy that saturated fat and cholesterol cause heart disease’ shows Dr. Keys selected graph with only 6 countries and as a comparison the complete picture with all 22 countries that shows no correlation at all.
However Dr. Keys proved to be very persuasive at the time and so the ‘diet/heart’ hypothesis was born. How, with such a dramatic flaw, could this hypothesis recommending a reduction in saturated fats and cholesterol have further continued and gathered strength one may ask? Proponents of the ‘diet/heart’ hypothesis point the finger at the beneficiaries. The main beneficiaries of the research that found fault with competing traditional foods were the vegetable oil and food processing industries, who consequently then began promoting and funding further research designed to support the ‘diet/heart’ hypothesis.
Out of the ‘diet/heart’ hypothesis came several large-scale, long-term, human intervention studies to be set up in many parts of the world. These involved thousands of subjects and hundreds of doctors and scientists costing billions of dollars to prove that a fatty diet caused heart disease.
The most influential and respected investigation of heart disease was carried out by the Harvard University Medical School and called the Framingham Heart Study. This study was influential in determining our current dietary fat recommendations – such as reduce saturated fats and cholesterol – and involved measuring cholesterol and saturated fat intake with subsequent blood cholesterol levels. However after 22 years, the researchers concluded:
“There is, in short, no suggestion of any relation between diet and the subsequent development of CHD in the study group” (1). So why are we still being told this you may ask? Good question!
Nathan Pritikin is cited for being instrumental in the low-fat diet movement. His weight-loss programs proved to be very successful at first. One component included reducing fat. However he also advocated eliminating sugar, white flour and all processed foods and replacing them with fresh, whole foods and a strenuous exercise program, which obviously makes it difficult to single out any one factor. Unfortunately the low fat and fat free diets proved to be very difficult to maintain and over a length of time, as many clients suffered from low energy, depression and weight gain (2).
The World Health Organisation’s European Coronary Prevention Study published in 1983 again proved no correlation between fats and heart disease. The study reduced saturated fats to only 8% of the calorie intake daily, yet in the UK section those subjects who ate more saturated fat died later (1).
So what is the real culprit? Here are some ‘interesting’ facts:
Between 1910 and 1970: animal fat consumption decreased from 83% to 62%
Butter consumption decreased from 18 pounds to 4 pounds per year
Margarine, shortening and refined oils consumption increased 400%
The fatty acids found in arterial clogs are mostly unsaturated (74%) of which 41% are polyunsaturated (Lancet 1994, 344:1195) (3)
Today, CHD causes at least 40% of all US deaths
Let us now have a closer look at fats for a better understanding of their differences. Fatty Acids are classified in the following ways:
Saturated Oils
All carbon bonds are occupied by a hydrogen atom. They are highly stable, solid at room temperature, and normally do not go rancid, even when heated. E.g. coconut oil, butter and lard.
Monosaturated Oils
One double bond in the form of two carbon atoms, double-bonded to each other, and therefore lack two hydrogen atoms. They tend to be liquid at room temperature and like saturated fat are relatively stable, not going rancid easily and therefore can be used in cooking. E.g. olive, almond and peanut oil as well as avocados.