Functional use of vitamin E in human body

Vitamin E is the collective term given to a group of fat-soluble compounds first discovered in 1922 by Evans and Bishop.

Vitamin E consists of two families of compounds, the tocopherols and tocotrienols, characterized by a 6-chromanol ring and an isoprenoid side chain. The members of each family are designated alpha((α)-, beta(β)-, gamma(γ)-, or delta(δ)- according to the position of methyl groups attached to the chroman nucleus.

Vitamin E functions as a chain-breaking antioxidant that prevents the propagation of free radical reactions. It is primarily located in the cell and organelle membranes where it can exert its maximum protective effect, even when its concentration ratio may be only one molecule for every 2,000 phospholipid molecules. It acts as the first line of defense against lipid peroxidation, protecting the cell membranes from free radical attack.

It has been found that alpha-tocopherol mainly inhibits the production of new free radicals, while gamma-tocopherol traps and neutralises the existing free radicals. Oxidation has been linked to numerous possible conditions/diseases including: cancer, ageing, arthritis and cataracts.

The vitamin is a peroxyl radical scavenger and especially protects polyunsaturated fatty acids (PUFAs) within membrane phospholipids and in plasma lipoproteins.

Vitamin E increases the orderliness of the membrane lipid packaging, thus allowing for a tighter packing of the membrane and, in turn, greater stability to the cell. In 2011, study showed that vitamin E is necessary for maintaining proper skeletal muscle homeostasis and that the supplementation of cultured myocytes with α -tocopherol promotes plasma membrane repair.

α-tocopherol appears unique in regulating phosphorylation cascades. Such a role may be important in heart disease where cell adhesion, proliferation, and oxidant production may all be modified through vitamin E-sensitive pathways.
Functional use of vitamin E in human body

The importance of vitamin K

In 1929, Henrik Dam of Denmark discovered vitamin K. Vitamin K is a fat soluble vitamin has been implicated in both cardiovascular and bone health.

Vitamin K is needed for the production of prothrombin which is necessary for blood clotting. The blood clotting process involves the participation of a number of vitamin K dependent plasma proteins. They include factors II (prothrombin), XII (pro-convertin), IX (Christmas factor) and X (Stewart factor) and proteins C, S, Z and M.

It is also essential for bone formation and repair; it is necessary for the synthesis of osteocalcin, the protein in bone tissue on which calcium crystallizes. Consequently, it may help prevent osteoporosis.

The importance of the availability of sufficient vitamin K for the rate of carboxylation became evident when it was shown that osteocalcin circulating in the blood of normal volunteers only reach full carboxylation when vitamin K supplements were given.

Vitamin k plays important role in the intestine and aids in converting glucose into glycogen for storage in the liver, promoting healthy liver function.

It may increase resistance to infection in children and help prevent cancers that target the inner linings of the organs. It aids in promoting longevity.
The importance of vitamin K

What are the roles of vitamin A in human body?

Vitamin A refers to all isoprenoid compounds from animal products with the biological activity of all-trans-retinol. Vitamin A activity depends on the presence of one, non-hydroxylated beta-ionone ring in the provitamin A structure.

There are three active forms of vitamin A in the body known as retinoids – retinol (an alcohol), retinal (an aldehyde), and retinoic acid (an acid). Carotenoid (plant pigments) can also be converted to vitamin A by the liver.

Vitamin A (retinol) functions in reproduction, growth, the maintenance of skin and mucous membranes and the visual process.

Epithelial cells (those cells present in the lining of body cavities and in the skin and glands) require vitamin A.

Vitamin A is normally transported in the blood linked to a specific protein, retinol binding protein (RBP). Specific proteins on cell surfaces and within cells are also involved with intracellular transport of the vitamin.

The role of vitamin A in maintenance of eye health and the visual cycle is quite well understood. Retinoic acid is required for normal differentiation of the cornea, conjunctival membranes and photoreceptor rod and cone cells of the retina.

Vitamin A is fat soluble and is primarily stored in the liver, where RBP is synthesized. In a well nourished person, vitamin A stores are generally sufficient to last many months on a vitamins A-deficient diet before signs of deficiency appear.
What are the roles of vitamin A in human body?

Human body composition

Human body is composed of various tissues and numerous body cavities filled with body fluid.

Around 1850s, Justus von Liebig found that the human body contains many substances present in food and that body fluids contain more sodium and less potassium than tissues.

The average human body contains about 20 % of fat, 15% protein, much smaller amounts of carbohydrate (perhaps I %) and large amounts of water.

Although fat is found primarily in adipose tissue, intracellular triglyceride pools are also observed in liver, skeletal muscle and other organs, particularly in pathological conditions such as hepatic steatosis and various forms of lipidosis.

Human body also contains substantial amounts of the “major minerals,” from calcium and phosphorus down to sulfur and magnesium as well as trace quantities of most elements.

The water content of the human body is never higher than at birth – about 70% of a term newborn infant’s weight may be water.

By adulthood, body water content is generally 56 to 64%. As the water content of the extracellular fluid is by and large controlled hormonally, the greatest influence upon tissue water content remains the ration of skeletal muscle to adipose tissue.

The human diet reflects this compositional need, and consists of large quantities of water containing, proteinaceous, fatty, and carbohydrate foods, as well as others rich in the minerals.
Human body composition 

Fat composition in human body

The variables of body composition were measured through the following methods: bioelectrical impedance analysis (BIA), near-infrared interactance (NIR), slaughter cutaneous skinfold equations (SKI) and body mass index (BMI).

Body composition generally refers to the absolute amount of fat and nonfat tissue within the body as well as the ratio of fat to total body mass (TBM).

Typically, body composition is assessed to determine the percentage of body fat and of lean body mass (LBM) or fat free mass (FFM).

Although FFM and LBM are often used interchangeably, LBM includes not only all nonfat portions of the human body, but also essential fat deposits, whereas FFM is the total mass of all tissues within the body excluding all fat.

Fat mass (FM) is the total mass (or kilograms) of all fat within the body. Body fat is made-up of about 10% water and 90% adipose tissue.

Essential fat is found associated with the bone marrow, the central nervous system and internal organs. Without fat in these areas, the body cannot function properly.

The essential body fat percentage or minimum level of body fat comparable with health in men is approximately 3-5% and in women is approximately 12-14%.

Many factor such as age, gender, stature heredity, and pregnancy influence body composition.

Young individual tend to have higher resting metabolic rates, are more active, and as a result are lean.
Fat composition in human body

Distribution of calcium in human body

Calcium is the element with the symbol Ca and atomic number 20. It has atomic mass of 40.078 amu.

This mineral is the most abundant electrolyte in the human body, and in healthy adults, accounts for about 2% or 1,300 g, of body weight.

The skeleton is an important reservoir of calcium, serving both a maintain plasma calcium concentrations and to make optimal use of ingested calcium.

Approximately 99% of total body calcium is stored in skeleton and teeth, with many functions and serves also as a structural element in bone.

The rest of the calcium in the body has other important uses, such ‘neurotransmitter release’, muscle contraction and ‘exocystosis’ (a durable process by which a cell directs the contents of secretory vesicles out of the cell membrane).

In the plasma there is also a protein bound calcium fraction, which is present at concentration of 3.2 mg/100 ml (0.8 mmol/l).

About 50% calcium in plasma is ionized and 10% is complexed with citrate phosphate, bicarbonate and lactase.

From birth to approximately 20 years of age, when skeleton reaches its full size and density, calcium content increases by some 40 fold.

Numerous end organs participate in the regulation of calcium. The gastrointestinal tract and kidney, along with bone, are major regulators of calcium balance.

Calcium receptors in the liver may monitor the calcium concentration in plasma, sending signals to the brain and affecting other peripheral sites in the body.
Distribution of calcium in human body

The digestion of fat in human body

While a small amount of fat splitting may take place in the stomach, most of the digestion of food fat is carried on in the intestine through the action of intestinal and pancreatic enzyme and of bile.

In human body fat occurs mainly as neutral fat in the form of triglycerides of oleic, palmitic and stearic acid. In addition to neutral fats, fats include phospholipids, cholesterol and its ester. Neutral fats are triglycerides i.e, glycerol combined with three molecules of fatty acids.

The first step of fat digestion begins in the stomach. Lingual lipase secreted from the serous glands of the tongue, and gastric lipase, secreted from the chief cells of the gastric mucosa, digest approximately one third of the dietary triglycerides.

Main digestion of fats is carried out by pancreatic lipase at optimum pH 8 and temperature of 40° C.

Bile salts are helpful and break up the fat droplets, which are emulsified. This emulsification results in increase of the fat surface on which pancreatic lipase can act.

The main path of fat digestion progresses from triglycerides to 1,2-diglycerides, to 2-monoglycerides and finally to free fatty acids and glycerol, perhaps after isomerization to the 1-monoglyceride.

During digestion, exchange of free fatty acids with glyceride fatty acids occurs.

Fats are involved in brain development, inflammatory processes, atherosclerosis, carcinogenesis, aging and cell renewal.
The digestion of fat in human body