Roles of fat in human body

Body fat stores are the major energy stores of the body and are important determinants of survival in starvation or undernutrition.

Human body require stores of energy and mechanisms to accumulate and release these stores in the short and long term. Fat, here taken to be triacylglyceride, is quantitatively the most important form of stored energy and is found in adipose tissue (AT).

Adipose tissue makes up a significant part of human bodies. Adipose tissue can also be found surrounding organs such as the liver, pancreas, kidneys and the heart, to some degree. It is also found in muscles and other areas of the body including part of the orbital cavities.

In chemistry, fat is a compound formed from chemicals called fatty acids. Fats are greasy, solid materials found in animal tissues and in some plants.

For most part, human did not require fat sources in their diets because the body can synthesize most of the fatty acids it needs from other constituents, including carbohydrate and protein.

Essential fat is that in bone marrow, heart, lungs, liver, kidneys, intestines, muscles and lipid-rich tissue of the central nervous system with roles other than energy storage.

Saturated and monounsaturated fatty acids are synthesized in the body for energetic, physiological, and structural functions, and they are present in many foods. The brain needs saturated fats, polyunsaturated fat, cholesterol, and a number of other fats.

Fats are also a component of cell membranes, vitamin D and sex hormones. Men have a central pattern of deposition, mainly on the trunk and abdomen. In women deposition is, characteristically, on the buttocks and thighs.

Some types of fats give cell membranes flexibility and help regulate the transfer of nutrients into and out of cells. While others serve as precursors to vitamin D and sex hormones, such as estrogen and testosterone.
Roles of fat in human body

Brief view of edible fats

Edible fats are complex mixture of triglycerides and small amounts of other substances. Triglycerides are esters of glycerol and three fatty acid molecules. Fatty acids may contain different numbers of carbon atoms and may have different degrees and unsaturation and branching. Triglycerides are also called triacylglycerols.

Edible fats occur naturally or are derived through processing and storage of fats.

The natural fats are naturally made up mostly of mixed triglycerides with only trace amounts of mono- and diglycerides and little or no free fatty acids.  The exact composition of natural fats can’t be pinpointed, because they are dependent on factors such as growing conditions, plant/animal breeding, and processing.

Butter

In contrast, processed fats may contain up to 20% of mono- and diglycerides.  Successful production of processed fats products relies on the manipulation of the fat blend to produce suitable physical properties and prevent undesirable changes during and after processing.

The other substances associated with natural fats include the flowing:
*Phospholipids
*Sterols
*Fat-soluble vitamins
*Pigments
*Hydrocarbon
*Oxidation products
*Trace Minerals
*Water
Brief view of edible fats

What are the functions of oils and fats?

Fats and oils consist of a mixture of glycerol esters of fatty acid, called triglycerides, in concentrations peculiar to each fat or oil source.

Oils and fats are concentrated sources of energy. In addition, to supply energy, oils and fats have several functions in the body:

*They carry fat-soluble vitamins (A, D, E and K) into the body and help in the absorption of these vitamins.
*Vegetable oils are a source of essential fatty acid linoleic acid and monounsaturated fatty acid.
*The subcutaneous layer of fat helps us to conserve body heat.
*Fats act as cushion and protect vital organs of the body.

In addition to their nutritional functions, oils and fats have other uses which derive principally from their distinct physical properties. They contribute to the tenderness, flavor, colour and texture of food products.
What are the functions of oils and fats?

What are the different types of fat in food?

Fats and oil can undergo detrimental flavor changes as a result of two major types of deterioration, oxidation at the double bonds in unsaturated fatty acids and hydrolysis at the ester linkage.

High intakes of fat are linked to health problems and can lead to obesity (overweight). Fats are concentrated sources of energy and many fats contain vitamins A and D which are important for good health. Fats in the body include those consumed in the diet and those produced from carbohydrates and proteins.

There are four main types of fat are saturates, monounsaturates, polyunsaturates and transfats.

Saturated fat
Fats that contain no double bonds are referred to as saturated fats. Saturated fat may raise blood cholesterol levels which may cause heart disease. It is necessary for proper bone development and for the prevention of osteoporosis.

Saturated fats also support the immune system and help keep the human healthy.

Saturated fats are found in meat products such as pies and sausages, dairy produce and cakes and biscuits’ made from hydrogenated vegetable oil or butter.

Monounsaturates
Fats containing some double bonds are known as unsaturated fats – those with one double bond are mono-unsaturated. Monounsaturates are not associated with heart disease and are found in olive oil and rape seed oil.

Polyunsaturates
Fats with two or more double bonds are polyunsaturated. The more double-bonds in a fat, the more fluid it is, and it is this fluidity found in highly unsaturated fatty acids and that is so crucial in brain structure and function. Polyunsaturates lower blood cholesterol levels and are found in sunflower oil and soya oil.

Transfats
Transfats found in pastries, some margarine, fried foods and many snack and convenience foods.
What are the different types of fat in food?

Definition and summary of fats

Fat has been loosely and interchangeably described as lipids. The descriptions were attempts to distinguish fat from other nutrients based on it solubility in nonpolar solvent.

Currently, fat refers to triglycerides in the United States but total lipids in the European Community.

Fats are comprised of fatty acids bound, in bundles of three, to glycerol. There are three major types of fats or fatty acid:
*Saturated
*Monounsaturated
*Polyunsaturated

Saturated fats are solid at room temperature and have no room for any additional hydrogen atoms. It is primarily found in animal foods.

Mono and polyunsaturated fats, which remain liquid at room temperature, have room for additional hydrogen atoms.

Fats contains mixtures of all three types of fatty acids; the balance of the mix determines whether the fat is generally saturated (hard) or polyunsaturated (soft).

Fats are insoluble in water and require special treatment for digestion and transport. In digestion, bile acids act as detergents to solubilize fats to aids digestion.

In transport, the fatty material is surrounded by a coat of protein plus phospholipid. The full particle is a lipoprotein.

The liver can convert carbohydrate to fat, which is exported from the liver as a lipoprotein.

Fats are an important energy source in human nutrition. Besides the high energy content, many fats and oils contain fatty acids that are essential to health and cannot be synthesized by the human body.

Certain polyunsaturated fatty acids are nutritionally essentially because:
1. They are the precursors of the vitality important regulators of metabolism, the prostaglandins
2. The body cannot make them from either carbohydrate or existing dietary fatty acids.

The fat content of foods can range from very low to very high in both vegetable and animal products. Fats are sometimes divided into visible and invisible fats.

In the United States, about 60 percent of total fat and oil consumed consists of invisible fats – that is, those contained in dairy products – eggs, meat, poultry, fish, fruits, vegetables and grain. The visible fats, including lard, butter, margarine, shortening and cooking oils, account for 40 percent of total fat intake.
Definition and summary of fats

Fats in foods

Fats constitute one of the three major classes of food products. The other two are proteins and carbohydrates. Fats are glyceryl esters of fatty acids.

Fats, as do carbohydrates, contain the elements carbon, oxygen, and hydrogen, but the proportion of oxygen in fats is less, and it can be said that fats are fuel foods of a more concentrated type than are the carbohydrates.

Dietary fats are a concentrated source of energy. Fats supply about 9 kcal/g, as compared with about 4 kcal/g from proteins and carbohydrates. An additional advantage of fat form viewpoint of energy availability is that it stores well in large amounts in adipose tissues.

Thus fat, considered to be a reserve form of fuel for the body, is an important source of calories.

Among functions of fats:
*Heat transfer – pan frying, deep frying
*Shortening power – biscuits, pastries, cakes, cookies
*Emulsions – Mayonnaise, salad dressings. Sauces, gravies, puddings, cream soups
*Varying melting points – candies
*Plasticity – confection, icings, pastries, other baked goods
*Flavor/mouthfeel – flavor
*Texture – creaminess, flakiness, tenderness

Paradoxically, this is not advantageous in affluent societies where the problem is not the availability of food for energy, but rather the health hazard of obesity.

The majority of added fats in the diet are invisible. They are the hidden fats of fried foods and baked goods, sauces and mixed dishes, and dips and spreads. Other invisible fats include the fats the marbling of meat and the fat ground into lunch meats and hamburger.

Fats may occur in foods as materials that are solid at room temperatures or as oils that are liquid at room temperatures. This physical property depends mainly on the fatty acids that they contain.

Solid fats contain comparatively small amounts of fatty acids with two or more groups of adjacent carbons that are not fully saturated with hydrogen.
Fats in foods

Fats in Human Diet

Most fats are derived from animals or vegetable food sources. All of its share a common feature in that they are made of carbon and hydrogen with a molecule of oxygen. Normally dietary fats have a negative reputation since their link to heart disease and cancer.

In some cases their negative reputation is justified, although the role of dietary fat in health and disease is very complicated.

Certain fats have required for proper growth and maintenance of health, while their absence can cause specific deficiency disease.

Too much certain kind of fats can increase the risk of chronic and serious diseases. The person who chooses a diet too high in saturated fats or trans fat invites heart and artery disease, the number one killer of adults in United States and Canada.

Obesity carries serious risks to health, and the high energy density of fatty foods makes it easy for people to exceed their energy needs and so gain unneeded weight.

High-fat diets are indirectly related to type 2 diabetes mellitus and hypertension. Both disorders may stress the circulatory system; a high dietary fat intake may further limit the functioning of circulatory system through the potential development of atherosclerosis.

The most important lipids in the food supply are triglycerides and cholesterol, which are chemically unrelated substances except for the fact that they do not dissolve in water.

Triglycerides are the lipids commonly known as fat, oil, grease, shortening, lard, tallow, suet, ghee, and a variety of other names.

Many triglycerides eaten in foods are transported to the fat depots – muscles, breasts, the insulating fat layer under the skin and others – where they are stored by the body’s fat cell for later use.

When a person’s body starts to run out of available fuel from food it begins to retrieve this stored fat to use for energy.

Cholesterol is another dietary lipid but it is found only in animal products - cholesterol does not exists in the plant kingdom.

Cholesterol is made in the body in adequate amounts and is therefore not considered an essential nutrient. Liver manufacturers cholesterol, manages their release into the bloodstream and collects them back form the blood stream.

Unlike triglycerides, cholesterol provides no energy but it is critical structure component of every cell in the body.

Dietary cholesterol has been studied primarily with respect to intestinal cancer. Although the data inconsistent, most points to a possible relationship between dietary cholesterols and colon tumor development.
Fats in Human Diet