LIPIDS IN DIET

LIPIDS IN DIET

Lipids are mostly consumed in the form of neutral fats, which are also known as triglycerides. Triglycerides are made up of glycerol nucleus and free fatty acids. Triglycerides form the major constituent in foods of animal origin and much less in foods of plant origin. Apart from triglycerides, usual diet also contains small quantities of cholesterol and cholesterol esters.

Dietary fats are classified into two types:

1. Saturated fats

2. Unsaturated fats.

SATURATED FATS

Saturated fats are the fats which contain triglycerides formed from only saturated fatty acids. The fatty acids having maximum amount of hydrogen ions without any double bonds between carbon atoms are called saturated fatty acids.

UNSATURATED FATS

Fats containing unsaturated fatty acids are known as unsaturated fats. Unsaturated fatty acids are fatty acids formed by dehydrogenation of saturated fatty acids.

Unsaturated fats are classified into three types:

1. Monounsaturated fats

2. Polyunsaturated fats

3. Trans fats.

1. Monounsaturated Fats

Unsaturated fats which contain one double bond between the carbon atoms are called monounsaturated

fats.

2. Polyunsaturated Fats

Unsaturated fats with more than one double bond between the carbon atoms are called polyunsaturated

fats. Polyunsaturated fats belong to the family of essential fatty acids (fatty acids required in diet).

Polyunsaturated fats are of two types:

1. Omega-3 fats or omega3 fatty acids having double bond in the third space from the end of the carbon chain

2. Omega-6 fats or omega6 fatty acids having double bond in the sixth space from the end of the carbon

chain. Both omega-3 and omega-6 fatty acids are beneficial to the body. However, consuming too much of omega6 fatty acids results in hazards than benefits. So, the diet containing 3 : 1 ratio of omega-6 to omega-3 fatty acids is often recommended by experts.

3. Trans Fats

Trans fats or trans fatty acids are unsaturated fatty acids, with molecules containing trans (across or opposite side) double bonds between carbon atoms.

DIGESTION OF LIPIDS

Lipids are digested by lipolytic enzymes.

 IN THE MOUTH

Saliva contains lingual lipase. This enzyme is secreted by lingual glands of mouth and swallowed along with saliva. So, the lipid digestion does not commence in the mouth.

IN THE STOMACH

Gastric lipase or tributyrase is the lipolytic enzyme present in gastric juice.

IN THE INTESTINE

Almost all the lipids are digested in the small intestine because of the availability of bile salts, pancreatic

lipolytic enzymes and intestinal lipase.

Role of Bile Salts

Bile salts play an important role in the digestion of lipids

Lipolytic Enzymes in Pancreatic Juice

Pancreatic lipase is the most important enzyme for the digestion of fats. Other lipolytic enzymes of pancreatic juice are cholesterol ester hydrolase, phospholipase A and phospholipase B.

Lipolytic Enzyme in Succus Entericus

Intestinal lipase is the only lipolytic enzyme present in succus entericus .

FINAL PRODUCTS OF FAT DIGESTION

Fatty acids, cholesterol and monoglycerides are the final products of lipid digestion.

 

Post a Comment

0 Comments