A new study to be published this month in the American Journal of Clinical Nutrition found “no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD [heart attacks and stroke]”. The authors did a meta-analysis of 21 prospective studies which followed a total of 347,747 people for 5 to 23 years. The result found no increased risk with increased dietary consumption of saturated fat, regardless of age or sex.
The belief that saturated fats caused heart disease originated with a paper by Dr. Ancel Keys in 1953. Keys noticed a correlation of heart disease mortality and fat intake and concluded a cause-effect relationship. Since then this belief has become ingrained in western medical and nutritional thought, although research since then has repeatedly failed to prove the link. While many studies show a relationship between modern western diet and heart disease, there are other factors to consider besides saturated fats.
The “Mediterranean diet” with its emphasis on fresh fruit, vegetables, fish and olive oil, has been shown to reduce risk of heart disease and stroke. But besides a reduction of saturated fat, this diet is also low in processed foods which contain trans fats and refined carbs like sugar and white flour.
There are three main fatty acids in saturated fat – stearic acid, palmitic acid and lauric acid. Stearic acid is converted in your liver into oleic acid which is the main monounsaturated fatty acid (75%) in olive oil, and has no effect on your cholesterol levels. Both palmitic and lauric acids raise total cholesterol, but raise the HDL (good) more than the LDL (bad) blood lipids, so has a net beneficial effect. Besides providing a source of energy, these fatty acids are needed to build cell membranes and hormones (including cholesterol) and have other useful functions in the body. So in moderation, saturated fats can actually be good for you.
Trans fats, however are another story. These are artificially saturated fats found in hard margarines, shortening, and many processed foods. They are similar to natural saturated fats chemically but different structurally, so do not work the same in our bodies. Trans fats are known to raise LDL and lower HDL lipids so will have a detrimental effect on heart health. Studies that do not differentiate between natural and trans saturated fats give all saturated fats a bad reputation.
Old beliefs die hard. I predict it will take many years and a few more studies like this before we get past the abhorrence of saturated fat and can give it the place, however small, it deserves in a healthy diet.
This article is intended for educational purposes only; for medical advice consult your licensed health practitioner.
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