Triglycerides and Fatty Acids

steak-fats
The white fatty tissue you see when you cut into a steak is composed of triglycerides.

triglyceride
The fat that hangs on our arms, looks like jelly on our thighs, and can make your stomach look like a spare tire, is composed of triglycerides. It make up our body fat and the fat we see and eat in our foods. About 95 percent of the lipids* in our diet, derived from both plant and animal, are triglycerides.

Triglycerides are composed of individual fat molecules known as fatty acids. It takes three fatty acid molecules to make a single triglyceride molecule. Fatty acids are linked together by a single glycerol molecule. The glycerol molecule acts as a backbone, for the triglyceride.

There are dozens of different types of fatty acids. Scientists have grouped theses into three general categories: saturated, monounsaturated, and polyunsaturated. Each category contains several members.

Each of the fatty acids, regardless of whether it is saturated or not, affects the body differently and exerts different influences on health. Therefore, one saturated fat may have adverse health effects, while another may promote better health. The same applies for monounsaturated and polyunsaturated fats.

olive oil.jpg

Olive oil has been hailed as one of the “good” fats because those who eat it in place of other oils have less heart disease. Olive oil is composed primarily of a monounsaturated fatty acid called oleic acid. However, not all monounsaturated fats are healthy. Another monounsaturated fatty acid, known as erucic acid, is extremely toxic to the heart, more so than perhaps any other fatty acid known (Belitz and Grosch, 1999). The difference between the two, chemically is very slight. Likewise, some polyunsaturated fatty acids can also cause problems. On the other hand, the saturated fatty acids that  are found in coconut oil have no harmful effects and actually promote better health. So we cannot say one oil is “bad” because it is saturated while another is “good” because it is monounsaturated or polyunsaturated. It all depends on the type of fatty acid and not simply on its degree of saturation.

No dietary oil is purely saturated or unsaturated. All natural fats and oils consist of a mixture of the three classes of fatty acids. To say an oil is saturated or monounsaturated is over simplifying it. Olive oil is often called “monounsaturated” because it is predominantly monounsaturated, but like all vegetable oils, it also contains some polyunsaturated and saturated fat as well.

FAT PERCENT OF SATURATED FATS PERCENT OF MONOUNSATURATED FATS

PERCENT OF POLYUNSATURATED FATS

Canola oil 6 62 32
Safflower oil 10 13 77
Sunflower oil 11 20 69
Corn oil 13 25 62
Soybean oil 15 24 61
Olive oil 14 77 9
Chicken fat 31 47 22
Lard 41 47 22
Beef fat 52 44 4
Palm oil 51 39 10
Butter 66 30 4
Coconut oil 92 6 2

Animal fats are generally the highest in saturated fat. Vegetable oils contain saturated fat as well as monounsaturated and polyunsaturated fat. Most vegetable oils are high in polyunsaturated fats, the exception being palm and coconut oils, which are very high in saturated fat. Coconut oil contains as much as 92 percent saturated fat—more than any other fat, including beef fat and lard.

There are many factors that contributed to the healthfulness of each type of fat—its saturation, the size of the carbon chain, and its susceptibility to peroxidation and free-radical generation.

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