Nutritional properties of dietary fats

Dietary fat is human second most important energy-producing macronutrient. It also contains fatty acids and vitamins essential for growth, development and maintenance of good health.

It has been reported that a lean man of 70kg is made up of water (60%), protein (17%), fat (12 kg or 17%) and a balance (6%) which includes glycogen and bone.

Dietary fat is an important caloric source for human metabolism and the major substrate that keeps human alive during most of each day.

It is widely available and efficient source of energy at 9 cal/g compared with only 4 for carbohydrate and protein and can be turn onto energy with only minimal metabolic modification. 

The average daily intake of fat in a western diet ranges between 50 to 100 g and provides between 35% and 40% of total energy.

For daily intake of 2000 kcals, 67 g or fat corresponds to 30 per cent of total energy. Level of 35 per cent and 40 per cent of total energy correspond to daily fat intakes of 78g and 89 g respectively.

Dietary fat consists mainly of triacylglycerol (TAG), which forms the principal component of visible oils and fats, and minor quantities of phospholipids and cholesterol esters.

Dietary fats are derived from both plant and animal sources and are classified as ‘visible’ or ‘invisible’ types, fats that are used as such at the table or for cooking (vegetable oils, vanaspati, butter and ghee) are termed ‘visible’ fats.

Fats that are present as an integral component of different foods are referred to as ‘invisible’ fat.

The physical properties of dietary fat, such as their hardness at room temperature (melting point) and subsequent metabolic properties once in the body, are determined by the number of double bonds in their constituent fatty acid, (degree of saturation or unsaturation) and length of the fatty acid carbon chain.
Nutritional properties of dietary fats