Fats contained in the foods we eat are broadly classified into three groups: saturated, mono-unsaturated and polyunsaturated. Mono-unsaturated fats are widely considered by nutrition experts to be “good fats” and healthy to eat as part of a balanced diet. These fats are found in foods like macadamias, avocados and olives. Polyunsaturated and saturated fats have been the subject of a confusing lack of consensus amongst nutritionists as to whether they are good or bad for us. The most recent and more comprehensive research has found that saturated fats are generally a healthier choice and polyunsaturated fats more harmful to health.
The term ‘saturated fat’ comes from the hydrogen saturation of the fat molecule. Saturated fats are triglycerides which contain only saturated fatty acid radicals and are fully ‘saturated’ with hydrogen atoms – they have no double bonds, so their chemical structure has no more room for extra hydrogen atoms (they cannot be ‘hydrogenated’).
All fats have a carboxyl group “tail” (in red in the diagram to the left) at one end and a “spine” of carbon atoms with hydrogen atom “arms” attached to those carbon atoms and a single hydrogen “head” attached to the carbon furthest away from the carboxyl group.
Saturated fats have a stronger molecular structure which makes them much more stable at higher temperatures (such as frying or baking at around 200 degrees Celsius/392 degrees Fahrenheit) than their unsaturated counterparts. They are less prone to oxidisation whereas unsaturated vegetable oils degrade into trans fats fairly readily under heat. Polyunsaturated fats are the least stable and most prone to unhealthy oxidisation.
Saturated fats have received a lot of bad press over the last 50 years regarding their relationship to heart disease, however, a recently published meta-analysis with data from over 348,000 subjects found no statistically significant relationship between saturated fat intake and cardiovascular disease. It appears that other factors may need to be taken into consideration to explain the previously perceived link, such as carbohydrate intake or the ratio of saturated fat to other fats. Studies have found that the saturated fat in dairy products does not appear to increase the risk of heart disease and populations of traditional Polynesian/Pacific Island dwelling people who obtain up to 2/3 of their entire caloric intake from coconut oil have practically no heart disease at all.
Dairy products, meat and fish, coconut oil, soy oil and cottonseed oil are some of the main examples of foods containing significant amounts of saturated fat.
Different foods have different amounts of the four main types of fatty acids that make up saturated fats: myristic acid, lauric acid, palmitic acid and stearic acid and the balance between these fatty acids determines what properties the fat will have. Lauric acid, for instance, has antimicrobial properties and increases the amount of good HDL cholesterol in the blood. Another fatty acid called butyric acid is found in butter, cream and cheeses as well as fermented foods like kombucha tea and kefir. Studies in rodents have found that supplementing a high fat diet with butyric acid prevents the weight gain and other metabolic problems that the control group suffered, in particular improving insulin sensitivity, increasing energy expenditure and reducing food intake. Other results included a drop in triglycerides and cholesterol levels as well as fasting insulin levels. Other studies have found that it has anti-inflammatory and anti-cancer properties and that butyrate intake is associated with a lower risk of heart attack and progression of atherosclerosis.
As you can see from these examples, saturated fats can form an important part of a balanced, healthy diet. They need not be demonised unnecessarily.
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Ruzin A, Novick RP (May 2000). “Equivalence of Lauric Acid and Glycerol Monolaurate as Inhibitors of Signal Transduction in Staphylococcus aureus” J Bacteriol 182 (9): 2668–2671.
Siri-Tarino PW, Sun Q, Hu FB, Krauss RM (March 2010). “Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease”. The American Journal of Clinical Nutrition 91 (3): 535–46. doi:10.3945/ajcn.2009.27725
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Nutrition Data: Foods High in Butyric Acid: http://nutritiondata.self.com/foods-000017000000000000000-w.html