The properties of triglycerides (TGs) are determined by the proportion and chemical structure of the constituent fatty acids (FAs).
- Shorter and more unsaturated fatty acids characterize fats that are soft or liquid at room temperature.
- Solid fats such as beef fat contain large amounts of long chain fatty acids.
- The number and position on the double bonds as well as the position of the fatty acids on the glycerol molecule also influence the properties of TGs.
- Energy: TGs have a high energy density. In adipose tissue, i.e. body fat, TGs are the major storage form of energy for the body.
- Insulation: TGs in the subcutaneous layer of fat provide insulation, which preserves body heat and helps regulate body temperature.
- Transport: TGs are essential for the transport of fat-soluble metabolites in the blood.
- Absorption: TGs are essential for the absorption of fat-soluble vitamins.
- Satiety: Fat in food delays gastric emptying and thus aids satiety after a meal.
- Palatability: Fat adds to the palatability of food by improving flavour development, taste and texture.
TGs are the storage form of fatty acids in the body. In the case of excess energy intake, TGs are synthesized from fat and carbohydrate metabolism. Excess protein can also be converted into fat. Fatty acids are delivered to adipose cells via a protein carrier or as TGs in lipoproteins which are then re-synthesized into TGs for storage. The glycerol for re-synthesis comes from glucose, which enters the adipose cell with the help of insulin.
Triglycerides and disease:
- Data associating high levels of plasma TGs with Cardio Vascular Disease (CVD) is conflicting. It appears to be the combination of high TGs levels, with low levels of High Density Lipoprotein (HDL)-cholesterol that increases the risk of CVD. It is important to note that HDL-cholesterol is protective against CVD, thus low levels are not desirable.
- Raised plasma TG levels may also be associated with diabetes and obesity.