In her book Nourishing Traditions, Sally Fallon, brought together the scientific evidence on fat fundamentals.   The following article summarizes her key findings on the truths about fats and oils.

Fats from animal and vegetable sources provide a concentrated source of energy, serve as building blocks for cell membranes, hormones and hormone like substances, and slow down nutrient absorption so that we can go longer without feeling hungry.  Dietary fats also act as carriers for important fat-soluble vitamins (i.e. A, D, E and K) and are needed for the conversion of carotene in yellow and orange vegetable and fruits to vitamin A, which is important for mineral absorption and for a host of other metabolic processes.

At the turn of the century, mots of the fatty acids in the diet were either saturated or monounsaturated, primarily ingested from butter, lard, tallow, coconut oil, and small amounts of olive oil.  Today most of the fats in our diet are polyunsaturated vegetable oils derived from soy, corn, grape, safflower and canola.

Modern diets contain as much as 30% of calories from polyunsaturated oils, but scientific research indicates that this amount is far too high.  The best evidence indicates that our intake of polyunsaturated fat should not be greater than 4% of the caloric total (1.5% omega-3 and 2.5% omega-6 fatty acids).  The rest of our dietary fat should be derived from monounsaturated and saturated fats (<10%). Consumption in this range is found in native populations in temperate and tropical climates.

Excess consumption of polyunsaturated oils has been shown to contribute to a large number of diseases including cancer, heart disease, immune system dysfunction, liver damage, digestive disorders, depressed learning ability, impaired growth and weight gain and diseases of the reproductive organs and lungs.

One reason polyunsaturated oils cause so many health problems is that they tend to become oxidized or rancid when subjected to heat, oxygen and moisture in cooking and processing.  Rancid oils contain free radicals which are extremely reactive chemical compounds.  Free radicals have been characterized as ‘marauders’ in the body because they attack cell membranes, red blood cells, protein, lipids and the DNA.  The damage caused by free radicals accelerates aging and the development of chronic illnesses, including cancer.

Olive oil is perhaps the most trusted vegetable oil that has been consumed for thousand of years with largely beneficial effect.  However, the quality of olive oil varies widely and the oil of choice should be an unrefined, extra-virgin, and cloudy and yellow gold in color.  The high percentage of oleic acid makes olive oil ideal for salads and for cooking at moderate heat.  Cold pressed sesame oil can occasionally be used for frying because it contains unique antioxidants that are not destroyed by heat.  When high temperatures are involved (above 320F), ghee (clarified butter) or coconut oil are the most stable fats and can be safely used in small amounts by individuals with normal and low cholesterol levels.

If you want to know more about fats and oils, please explore the articles available from the Weston A. Price Foundation