Humans need a certain amount of fat in their diets to help maintain immune function, serve as a source of energy, and provide building blocks for biological molecules. There are many different kinds of fat, however, and some are healthier than others. Fish oils, for instance, contain lots of unsaturated fat, which is typically much healthier than saturated fat.
Fat Chemistry
Nutritional fats consist of large molecules called triacylglycerides, explain Drs. Reginald Garrett and Charles Grisham in their book "Biochemistry." Triacylglycerides are made up of three molecules called fatty acids, which consist of long chains of carbon and hydrogen, with two oxygen atoms at one end. The three fatty acid molecules are bound to an alcohol-like molecule called glycerol, made up of carbon, hydrogen and oxygen. Depending upon the types of bonds in the fatty acids, triacylglycerides can be saturated, unsaturated or trans fats.
Types of Fatty Acids
If a fatty acid has no carbon-carbon double bonds in it, explain Drs. Mary Campbell and Shawn Farrell in their book "Biochemistry," the fatty acid is considered saturated. A triacylglyceride made up of saturated fatty acids is a saturated fat. These fats have long, stick-like shapes that make them pack into solids easily. Consequently, saturated fats are malleable solids at room temperature. Unsaturated fats have carbon-carbon double bonds in their fatty acids, giving them kinked shapes. They therefore form oils rather than solids, and are liquid at room temperature.
Fat Sources
Dietary sources of saturated fat include most animal fats and tropical plant fats, like coconut oil. Dietary sources of unsaturated fat include liquid plant oils, like corn oil or soybean oil. Cold water fish are also sources of unsaturated fat, because the cold temperatures at which the fish live force them to store unsaturated fats so that their body fat stays malleable, even at near-freezing temperatures, note Drs. Campbell and Farrell.
Fat Health
Taking in saturated fats in the diet leads to negative health effects, including higher cholesterol levels. This is because the body cells can make LDL, or bad cholesterol, from saturated fat. Cells don't make LDL out of unsaturated fat, so fish oil and other sources of unsaturated fat provide needed dietary fat, without the negative health ramifications of saturated fat intake.
Expert Insight
While all unsaturated fat sources are healthier than saturated fat sources, compared to other sources of unsaturated fat, fish oils have special benefits. Cold water fish oils, like salmon and tuna fats, contain a specific subclass of unsaturated fats called omega-3 fats, explain Drs. Garrett and Grisham. The body uses omega-3 fats to reduce inflammation and enhance brain function, and eating cold water fish can help provide a good source of essential omega-3 fatty acids.
References
- "Biochemistry;" Reginald Garrett, Ph.D. and Charles Grisham, Ph.D.; 2007
- "Biochemistry;" Mary Campbell, Ph.D. and Shawn Farrell, Ph.D.; 2005
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