Types of dietary fats include polyunsaturated, monounsaturated and saturated fats. While saturated fats are quite heart-unhealthy and contribute to high cholesterol and cardiovascular disease, both polyunsaturated and monounsaturated fats are much healthier. Sometimes colloquially referred to as simply "poly fats" and "mono fats," both are important in a healthy diet.
Structure of Fat
Fats consist of four major parts -- a glycerol backbone and three fatty acids. Glycerol is similar to alcohol, and fatty acids are chains of carbon and hydrogen with two oxygen atoms attached to one end. If only single chemical bonds exist between carbon atoms in the fatty acids, a fat is saturated. The word "unsaturated" with regard to fat means there are double bonds in the carbon chain of the fat molecule, explain Drs. Reginald Garrett and Charles Grisham in their book "Biochemistry."
Polyunsaturated Fats
Polyunsaturated fats have more than one double bond between carbon atoms in their fatty acid tails. They're very heart-healthy fats, because they don't tend to increase blood cholesterol and risk of cardiovascular disease. The American Heart Association notes that some studies suggest that polyunsaturated fats can actually lower your LDL, or bad cholesterol, when you include them in your diet regularly. Good sources of polyunsaturated fats include vegetable oils such as soybean oil, as well as the oils in many nuts and seeds, according to MayoClinic.com.
Monounsaturated Fats
Monounsaturated fats have only one double bond in each of the fatty acid carbon tails. The major physical difference between the two types of fat is that monounsaturated fats typically have higher melting points than polyunsaturated fats, meaning they're more likely to be solid at cooler temperatures. Like polyunsaturated fats, monounsaturated fats don't increase bad cholesterol and may actually lower it. As such, they benefit heart health. Good sources of monounsaturated fat in the diet include olive oil and certain nut and seed oils, notes MayoClinic.com.
Eating Fats
A 1995 study published by Dr. C. Gardner and colleagues in the journal "Atherosclerosis, Thrombosis and Vascular Biology" found essentially no difference in the heart-healthy effects of polyunsaturated fats and monounsaturated fats. Daily consumption of both types is recommended. Fats serve important metabolic roles -- they support the immune system, maintain cellular function and provide energy -- but it's best to fill your fat needs with heart-healthy varieties rather than with the much less healthy saturated fats.
References
- "Biochemistry"; Reginald Garrett, Ph.D. and Charles Grisham, Ph.D.; 2007
- American Heart Association: Know Your Fats
- MayoClinic.com: Dietary Fats
- "Atherosclerosis, Thrombosis and Vascular Biology"; Monounsaturated Versus Polyunsaturated Dietary Fat and Serum Lipids: A Meta-Analysis; C. Gardner et al.; November 1995
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