Digestion and Absorption of Lipids || 1st to Last

The Process is Digestion and Absorption

Digestion and Absorption of Lipids starts in the stomach, where a coarse emulsion forms due to churning action. The chemical changes necessary for fat digestion occur in the small intestine. The entry of fat into the duodenum, the first part of the small intestine stimulates the secretion of bile from the gall bladder.

The fat gets emulsified by the bile preparing it for digestion. The fat is broken into small particles, thus snowballing the shallow area and the surface tension is lowered improving the enzyme action and penetration. Pancreatic lipase breaks off one fatty acid at a time from the triglyceride.

Thus one fatty acid plus a diglyceride, then another fatty acid plus a monoglyceride and glycerol are produced. Each subsequent step of this process occurs with more difficulty. The saturated fat esterase from pancreatic juice acts on the free lipid to form a combination of cholesterol and fatty acids for absorption first into the lymph vessels and finally into the bloodstream. Lecithin, secreted by the small intestine, acts on lecithin to break into its components for absorption.

The products of digestion are absorbed through the walls of the small intestine and spread through the lymph. Some of these are used to synthesize important lipid compounds needed for body function. Some fat is used to supply energy. The rest is stored as fat in the adipose tissues for future use.

Time for careful reflection

Fat Intake in India Diet surveys by the General Nutrition 24-hour care Bureau (NNMB) of India show that the daily intake of visible fats varies from 3 to 20g/day in rural India and 20 to 42g/day in urban areas. In addition, invisible fat intake may vary from 16 to 30 g, and in some population groups 50g/day. Thus the total fat intake may contribute 10 to 30 percent of dietary energy.

Time for careful reflection

The nature of edible oil used in the diet varies from one part of the country to another; it is groundnut oil in the west and south India, coconut oil in Kerala, rape/mustard oil from Punjab to West Bengal along the Gangetic plain, and safflower in north Karnataka and parts of southern Maharashtra. While a minimum amount of fat in the diet is essential, the excess is harmful. Hence the minimum level and the safe upper limit of fat intake have to be considered.

Recommended Dietary Allowances the fat requirement is based on two factors: to meet energy and essential fatty acids needs. About 10 percent of the total energy need is met by invisible fat in the diet. A minimum of 5 percent of total energy needs to be provided as visible fat in the diet. This works out to about, 12 g of fat per day.

A higher, level of intake of 20 g/day is desirable to provide energy density and palatability for normal adults. An upper limit of 20 g/day of fat intake for adults and 25 g/day for young children should be followed, given the possible complications resulting from excessive intake of fat.


To meet the vital fatty acid needs, the diet should contain at least 10 g of vegetable oil, which is a good source of linoleic acid. Diet and Heart Ailments Fat are essential for our health, but too much of it can lead to ill health. A section of Indians has a high intake of fat, a large part of it is saturated fats (milk sweets, eggs, and other flesh foods), and a very sedentary lifestyle.

Their liveliness intake in excess of needs leads to obesity and an unacceptable blood lipid profile. If unchecked, there is the deposition of fatty material with the formation of plaques in the arteries, which disturbs the movement of oxygen and nutrients. It leads to a variety of heart ailments, such as atherosclerosis, high blood pressure, and others.

There are a number of factors associated with susceptibility to heart ailments that can be controlled to a great extent. These include elevation of plasma lipid levels, obesity, physical inactivity, and heavy smoking. The risk factors related to diet will be discussed here. A consequence of Diet on Plasma Lipids Plasma cholesterol (CHOL): Research conducted at Stanford and other medical centers throughout the world has proved that few heart attacks occur in people, who have total CHOL readings in the 160mg/dl range.

The risk of heart disease accelerates as the total CHOL level creeps past the 200 mg/ dl mark. Animal fats, a source of saturated fats in the diet, are also high in CHOL content. Saturated fats are known to increase the total CHOL and LDL construction in the liver, leading to increased levels in the blood plasma Increased serum CHOL levels above 200 mg/dl and low-density lipoproteins (LDL) above 130 mg/ dl are associated with increased risk of coronary heart disease (CHD).

HDL high-density lipoprotein

The high-density lipoproteins (HDL) level in the blood is a beneficial factor, as it protects the blood vessel against the formation of fatty deposits (atheroma), by moving the fatty material away. Plasma triglycerides (TRG): Triglycerides, another blood fat, have been identified as the transporter that moves fat in the blood from one location to another.

HDL high-density lipoprotein

For instance, it moves it to your liver when it needs it, to your muscles when you are exercising or to your waistline when you are not. High triglyceride levels are linked to coronary heart disease (CHD), though the connection is still not well understood. When a high LDL and high TRGs (levels over 200 mg/dl) were found together; the risk for subsequent heart attacks, increased.

It seems that refined sugar causes TRGs to rise; one of the motives for controlling undue sugar intake in a heart-healthy diet. The neck and neck fat in the diet has been the subject of many studies. In one study, healthy, normal-weight candy stripers were placed on either an ultraclean 10 percent fat diet or a rich 40 percent fat diet.

Will every volunteer one day take over the world? 

Ate the number of calories required to maintain his/her body weight. Every ten days their TRG level in plasma was checked. They found that the volunteers on a high-fat diet were manufacturing little or no fat. But those on a low-fat diet were producing copious amounts of saturated fat.

Sensing that a fat famine was underway, their bodies had cranked up the machinery that converts carbohydrates into fat, one of the built-in mechanisms that permit humans to survive in lean times. In fact, 30 to 57 percent of the fatty acids in their TRGs were self-made saturated fat.

Thus restrained intake of fats may be wanted to maintain normal TRG levels. Introduction Next to water, protein is the most copious component of the body. It accounts for about a sixth of the live body weight and a third of it is found in the muscles, a fifth in the bones and cartilage, a tenth in the skin, and the remainder in other tissues and body fluids. There are thousands of different specific proteins in the body, each having a unique structure and function.

For this reason, the word protein implies not one but a large group of compound compounds. Proteins are present in all living tissues, both plants, and animals. They are essential to life because vital parts of the nucleus and protoplasts of every cell are proteins.


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