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Triglycerides (fats) and fatty acids

Triglycerides are fats, compounds (esters) made of glycerol and various fatty acids. Depending on the type of fatty acids within a triglyceride we categorize fats into: saturated and unsaturated (mono-, poly- and trans). Saturated, as well as trans fats have well-ordered structures that allow dense packing. On the other hand, unsaturated fats have kinks in their structures that prevent compact arrangements. In addition to causing differences in the physical appearance of fats (at room temperature saturated and trans fats are most commonly solid, while mono and poly saturated fats are liquids), the structure of fatty acids determines their physiological effects. For example, while saturated and trans fats increase the amount of LDL - “bad” cholesterol that contributes to cardiovascular disease risk - mono and poly- saturated fats increase HDL - “good” cholesterol that helps remove bad cholesterol from the body. Furthermore, characteristics and function of cell membrane depend on the structure of the fatty acids that are part of it. For the right balance of cell membrane’s rigidity and fluidity, which allows for optimal cell functioning, we need both saturated and unsaturated fatty acids. The former provide order and rigidity, the latter disorder and fluidity. It is thus important not to completely exclude saturated fats from your diet, but to reduce their intake in case you are overindulging (meat and dairy are particularly rich in saturated fats). On the other hand, trans fats have only harmful effects on our health and should thus be eliminated from our diet. Trans fats are commonly found in industrially prepared foods: cakes and cake frostings, deep-fried foods, potato and tortilla chips, microwavable popcorn and vegetable shortening. Small amounts of trans fat are found naturally in meat and dairy, but since they are present in very small amounts they do not represent a health risk. In 2015 the US 

Food and Drug Administration (FDA) ruled that partially hydrogenated oils (the primary source of trans fats) are not safe to consume, and gave food manufacturers three years to remove them from their food products. While waiting for the “no trans fat “ law to fully come into effect, make the habit of checking nutritional labels to ensure that you are not consuming products that contain them. Keep in mind that a food product with up to 0.5 g of trans fat is allowed to claim 0g of trans fat on its food label. It is thus best to look for the presence of partially hydrogenated oils (PHO) in the ingredient list. If PHO are present, the product certainly contains trans fats, even though they might not be listed on the label.


Following a meal, calories that are not immediately needed – regardless of whether they are in the form of carbohydrates, proteins or fats - are all converted to triglycerides and stored in fat (adipose) tissue. Between meals, the stored triglycerides are taken out of the fat tissue to the sites where energy is needed. Because of this busy traffic in and out of the fat tissue, triglycerides can normally be found circulating in the blood. Although this is still debated, high levels of triglycerides in the blood indicate an increased risk of cardiovascular disease. 

Last updated: March 24, 2017

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