Pantothenic Acid Metabolic Roles

Pantothenic acid, a water-soluble vitamin, plays a crucial role in various physiological processes essential for human health. It is indispensable for normal growth, nerve development, and maintaining healthy skin. Serving as a component of enzyme systems, particularly in acetylation processes, pantothenic acid is intricately linked with riboflavin in human nutrition.

At the core of its metabolic significance lies its role in coenzyme A (CoA) synthesis. CoA, a vital cofactor, is pivotal for the formation of acetyl CoA, which acts as a central hub in numerous metabolic pathways, including both energy generation and biosynthesis.

Notably, CoA is indispensable for ATP production from carbohydrate, protein, and fat metabolism, underscoring pantothenic acid's importance in energy homeostasis.

Moreover, pantothenic acid serves as the prosthetic group for acyl carrier protein, a key constituent of the fatty acid synthase complex involved in fatty acid synthesis. Studies have demonstrated that even mild pantothenate deficiency in animal models leads to elevated serum and free fatty acid levels, highlighting its regulatory role in lipid metabolism.

Furthermore, emerging evidence suggests a potential role of pantothenic acid in enhancing wound healing and resilience to physical stressors. This underscores its broader implications beyond basic metabolic functions, extending to tissue repair and adaptation mechanisms.

In conclusion, pantothenic acid's multifaceted roles in metabolism, including its involvement in CoA synthesis and fatty acid metabolism, underscore its significance for overall health and well-being, with potential implications for wound healing and stress resilience.
Pantothenic Acid Metabolic Roles

Physiological Importance of riboflavin

Riboflavin, also called vitamin B-2, is one of several essential vitamins required as part of a balanced diet, as well as one of eight B-family vitamins.

Vitamin B2 is a water-soluble vitamin, so it dissolves in water. All vitamins are either water soluble or fat soluble.

Riboflavin is important for body growth. It helps in red blood cell production. It also aids in the release of energy from proteins.

Riboflavin is essential to the formation of two major coenzymes, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). Vitamin B-2 helps human body break down the three macronutrients -- protein, carbohydrate, and fat. Riboflavin, in the form of FAD, helps body break down fats and carbohydrates into fuel by contributing to the electron transport chain, a series of chemical reactions that give off usable energy for body cells.

Without an adequate amount of riboflavin, macronutrients like carbohydrates, fats, and proteins cannot be digested and maintain the body. With a healthy digestive system, the body can absorb most of the nutrients from the diet, so it is important to get most of the riboflavin from dietary sources.

Riboflavin also helps convert tryptophan to niacin, which activates vitamin B6. The conversion of vitamin B6 to the coenzyme pyridoxal 5'-phosphate requires FMN. Vitamin B-6 (pyridoxine) is important for normal brain development and for keeping the nervous system and immune system healthy.

Riboflavin (as FAD or FMN) is required for the metabolism of iron. It also plays an essential role in folate and related one-carbon metabolism, where FAD is required as a cofactor for methylenetetrahydrofolate reductase (MTHFR), a key folate-metabolizing enzyme.

Riboflavin also serves an antioxidant function due to its ability to activate antioxidant enzymes. Antioxidants protect body cells from damage caused by harmful chemicals called reactive oxygen species, or ROS.
Physiological Importance of riboflavin

Functions of niacin in human body

Niacin (also known as vitamin B3) is the generic name for nicotinic acid (pyridine-3-carboxylic acid), nicotinamide (niacinamide or pyridine-3-carboxamide), and related derivatives, such as nicotinamide riboside.

Niacin is required for cell respiration and helps in the release of energy and metabolism of carbohydrates, fats and proteins, proper circulation, maintenance of healthy skin, functioning of the nervous system and normal secretion of bile and stomach fluids. Niacin is important for the development and function of the cells.

A sufficient intake of vitamin B3 (niacin) is important as it helps the body to
• convert food into glucose, used to produce energy
• produce macromolecules, including fatty acids and cholesterol
• DNA repair and stress responses.

Niacin is found in multivitamin/multimineral supplements. It is also available in B-complex dietary supplements and supplements containing only niacin. The two main forms of niacin in dietary supplements are nicotinic acid and nicotinamide.
Functions of niacin in human body

Vitamin B Complex: Vitamin B5

Vitamin B5, also called pantothenic acid, belongs to the group of water-soluble B vitamins. Pure pantothenic acid is a viscous, yellow oil. It is stable at neutral pH, but is readily destroyed by acid, alkali, and heat.

Calcium pantothenate, a white, odorless, crystalline substance, is the form of pantothenic acid usually found in commercial vitamin supplements due to its greater stability than the pure acid. Pantothenic acid is an essential nutrient that is naturally present in some foods, added to others, and available as a dietary supplement.

It was largely the efforts of research groups associated with R.J. Williams, C.A. Elvehjem, and T.H. Jukes that resulted in the identification of pantothenic acid as an essential dietary factor. Its name originates from the Greek word "pantos", meaning everywhere, as it can be found throughout all living cells.

Vitamin B5 (pantothenic acid): Symptoms of deficiency are fatigue, chronic stress, and depression. Vitamin B5 is needed for hormone formation and the uptake of amino acids and the brain chemical acetylcholine, which combine to prevent certain types of depression.

The chemical structure of pantothenic acid consists of pantoic acid and β -alanine bound in amide linkage.

The main function of this water-soluble B vitamin is in the synthesis of coenzyme A (CoA) and acyl carrier protein. CoA is essential for fatty acid synthesis and degradation, transfer of acetyl and acyl groups, and a multitude of other anabolic and catabolic processes.

CoA is essential to numerous metabolic pathways that sustain life:
• Synthesis of pantothenic acid cofactors (CoA, 4’-phosphopantetheine)
• Cofactor and co-substrate function (CoA, 4’-phosphopantetheinylation)
• Acyl-carrier protein
• 10-formyltetrahydrofolate dehydrogenase
• α-aminoadipate semialdehyde synthase

Pantothenic acid is naturally present in almost all foods. It is also added to some foods, including some breakfast cereals and beverages (such as energy drinks). Foods that are considered to be exceptionally good dietary sources of pantothenic acid include peanut butter (5-8 mg/100 g), liver (5-7 mg/100 g), kidney (4-6 mg/100 g), peanuts (2-3 mg/100 g), almonds (2-3 mg/100 g), wheat bran (2-3 mg/100 g), cheese (1.5 mg/100 g), and lobster (1.5 mg/100 g).

Pantothenic acid in dietary supplements is often in the form of calcium pantothenate or pantethine.

Refining, freezing, canning and cooking food causes losses of pantothenic acid, so a modern processed food diet would be expected to have lower amounts of vitamin B5 than a whole foods diet.

About 85% of dietary pantothenic acid is in the form of CoA or phosphopantetheine. These forms are converted to pantothenic acid by digestive enzymes (nucleosidases, peptidases, and phosphorylases) in the intestinal lumen and intestinal cells. Pantothenic acid is absorbed in the intestine and delivered directly into the bloodstream by active transport.
Vitamin B Complex: Vitamin B5

Properties and functions of vitamin A

Vitamin A is an essential micronutrient for humans, meaning that it cannot be biosynthesized in the body and thus must be obtained from dietary sources.

The vitamin exists in three major forms: retinal (the aldehyde isoform), retinol (the alcohol isoform), and retinoic acid (RA), which is the irreversibly oxidized form of retinol.

Retinol empirical formula: C20H30O with molecular weight of 286.45

Retinol is soluble in fats and oils and practically insoluble in water and glycerol. Vitamin A esters are readily soluble in fats, oils, ether, acetone and chloroform. They are soluble in alcohol but insoluble in water.

Dietary vitamin A is absorbed in the small intestine in the form of retinol and transported in blood attached to retinol-binding protein (RBP). Inside the cells, retinol is oxidized into its main biologically active derivatives, first retinaldehyde (retinal), which plays a role in vision, and then retinoic acid (RA), which regulates the expression of multiple target genes.

Among other functions of vitamin A:
* Vitamin A appears to facilitate the mobilization of iron from storage sites to the developing red blood cell for incorporation into hemoglobin, the oxygen carrier in red blood cells.

*Together with the protein opsin, the 11-cis isomer of retinol forms the light -sensitive visual pigment rhodopsin located in the rod of the retina. Rod cells with rhodopsin can detect very small amounts of light, making them important for night vision.

*Animal studies shown that vitamin A is required for normal growth and development. Retinol and retinoic acid (RA) are essential for embryonic development. During fetal development, RA functions in limb development and formation of the heart, eyes, and ears.

*Another major function of vitamin A is its role in cell differentiation.

*Vitamin A often called the antireflective vitamin, is protection against infections. The skin and mucosal cells (cells that line the airways, digestive tract, and urinary tract) function as a barrier and form the body's first line of defense against infection. Retinol and its metabolites are required to maintain the integrity and function of these cells.
Properties and functions of vitamin A

Vitamin B12: Structure and functions

Vitamin B12, also called cobalamin, is an indispensable molecule with a very complex structure and an intricate pathway of absorption and cellular trafficking that requires molecular escort proteins in body fluids and intracellular chaperones.

The vitamin is a cobalt-containing coordination compound generated by intestinal microbes, and a natural water-soluble vitamin of the B-complex family that must combine with Intrinsic Factor for absorption by the intestine.

Cobalamins cannot be synthesized by higher organisms and must be supplied with the diet. In humans, the lack of dietary cobalamin, or malfunctioning of absorption or of the enzymatic catalysis may provoke neurological disorders, in addition to pernicious anaemia.

However, a highly modulated absorption ability and transport through body fluids prevents any possible shortage even after many years of no intake.

Cobalamin is an organometallic factor composed of a tetrapyrrolic corrinic ring with a cobalt atom coordinated to four equatorial nitrogen atoms.

Vitamin B12 in food is bound to protein and is released in the stomach by the acid environment and by proteolysis of binders by pepsin. The released vitamin B12 initially binds to R-binders, which are dietary proteins that have affinity for vitamin B12.

Cobalamin is necessary for hematopoiesis, neural metabolism, DNA and RNA production, and carbohydrate, fat, and protein metabolism. B12 improves iron functions in the metabolic cycle and assists folic acid in choline synthesis.

B12 metabolism is interconnected with that of folic acid. Vitamin B12 deficiency causes pernicious anemia, megaloblastic anemia, and neurologic lesions.
Vitamin B12: Structure and functions

Forms of Vitamin K

Vitamin K actually comes in three different forms:
First, there’s vitamin K1, or phylloquinone. Phylloquinone is ubiquitously distributed in plants, green leafy, vegetables oils, and algae and is the main source of vitamin K in the human body. This group of lipophilic vitamins, mostly required for blood coagulation, also plays important roles in bone metabolism, calcification and vascular health.

Next, there’s Vitamin K2, also called menaquinone. This the form friendly bacteria in the intestines make. Vitamin K2 helps the body turn on biological switches that activate three critical preteens: osteocalcin, calcitonin, and matrix G1a. Osteocalcin, calcitonin, and matrix G1a are calcium-binding proteins that are essential in guiding into the bone.

The September 2003 International Journal of Oncology revealed that treating lung cancer patients with vitamin K2 slowed the growth of cancer cells. Among food sources of vitamin K2 are green vegetables, parsley, cilantro, watercress, culinary herbs and green drinks”.

The last form would be called vitamin K3. This is the artificial form, also called menadione. All vitamin K ends up in liver, where it’s used to make some of the substance that make blood clot.
Forms of Vitamin K

Vitamin D for normal bone

Vitamin D comes from two sources in humans; it could either be synthesized in form of vitamin D3 (cholecalciferol) under the influence of solar UV-B radiation in the epidermis, or be absorbed from the diet or from supplements and food additives, which in some countries may contain vitamin D2 (ergocalciferol).

This vitamin is necessary for normal tooth and bone formation. Vitamin D contributes to bone health by regulating calcium absorption. Vitamin D is crucial for maximizing gut absorption of calcium via vitamin D dependent Ca receptors. It is estimated that adequate vitamin D status increases Ca absorption to 30–40% of intake compared with only 10–15% absorption without adequate vitamin D.

Adequate vitamin D is necessary for absorption of calcium. Vitamin D is made in the skin after exposure to sunlight. Estimates include 5-16 minutes of sun exposure 3 times a week on the face, hands, and arms will meet vitamin D needs.

The recommended adequate intake (AI) of vitamin D for children and adults up to 50 years is 200 IU, whereas the recommended AI for adults 51–70 years and 71+ years is 400 IU and 600 IU, respectively.
Vitamin D for normal bone

Vitamins: Functions and applications in food processing

Modern food processing preserve food quality, controls food spoilage and disease-causing microorganisms, preserve desirable sensory qualities such as flavor, odor, texture, and appearance, preserve nutrients content, and in many case enhances the nutrient value as well.

Vitamins are organic compounds that are necessary in very small amounts for the maintenance of life. Most vitamins can be synthesize by the body and must be supplied by the diet. Vitamin functions in biochemical reactions within all living cells, and are necessary for metabolism.

Moreover, vitamins play an important role as functional additives in food processing. The chemical properties of certain vitamins provide significant functional benefits in processed foods.

The technical used for vitamins and their various application are as below.

• Antioxidants
• Colorants
• Inhibitions of can corrosion
• Protection of taste, flavor and clarity
• Prevention of black spot prevention
• Prevention of nitrosamine formation
• Flour dough improvement
• Maintenance of color in meat package in controlled atmosphere.

Vitamins: Functions and applications in food processing

Vitamins applications in food processing

The technical used for vitamins and their various applications are as below:
Antioxidants
With increasing awareness concerning the importance of antioxidants in health maintenance, particularly vitamin E, their retention through food processing and storage has been assuming an increasing importance. The antioxidant vitamins C and E frequently are utilized to prevent undesirable color changes and to retard the development of rancid flavor.

Colorants
Riboflavin (vitamin B2: provides a greenish lemon-yellow color) and beta-carotene (pro-vitamin A: provides an orange color) are utilized as natural coloring substances.

Inhibitions of can corrosion
Among functions of ascorbic acid are inhibition of can corrosion in canned soft drinks.

Protection of taste, flavor and clarity
 Other functions of ascorbic acid are protection of flavor and color of wine, prevention of black spot formation in shrimp, stabilization of cured meat color and dough improvement in baked goods.

Other applications of vitamins including:
Prevention of black spot prevention 
Prevention of nitrosamine formation 
Flour dough improvement 
Maintenance of color in meat package in controlled atmosphere
Vitamins applications in food processing

Vitamin B complex

The group of vitamin known as the B complex helps the body to produce energy from food by aiding the conversion of carbohydrate to glucose - the body’s main fuel. The B complex are all water soluble, and they are generally needed in small amounts.

It is called the B complex, since it is composed of several types of vitamin Bs, each responsible for specific functions in the human body.

Thiamin (B1), riboflavin (B2), nicotinic acid or niacin (B3), vitamin B6, biotin and pantothenic acid (B5) are examples of vitamin B. This B complex also includes amino-benzoic acid and inositol.

The presence of B complex vitamins on the body is vital to the metabolism of both fats and proteins. They are also essential for a well-functioning liver and gastrointestinal tract, the nervous system, and for maintaining healthy skin, hair and eyes.

The B-complex vitamins are important components of the stress response in that deficiency of vitamin B1, B5 and B6 can lead to anxiety reactions, depression, insomnia, and cardiovascular weakness, while B2 and niacin deficiencies have been known to cause stomach irritability and muscle weakness.

Three of the B vitamins are especially important: folate, B6 and B12.
*Folate is extremely important for general health
*Vitamin B6 is important for heart and also needed for the manufacture of serotonin, an important chemical in the brain that helps prevent depression.
*Vitamin B12 has many functions, including keeping the brain, heart, arteries, and nervous system healthy.
Vitamin B complex

Properties of vitamin K

Vitamin K comprises derivatives of 1,4-naphthiquinone. Naturally occurring forms are equipped with structures possessing the unsaturated isoprenoid side chain linked to naphthoquinones at crabon-3.

Vitamin K also fat soluble. It is essential for the synthesis of prothrombin a compound involved in the clotting of blood.

Vitamin K is mostly needed to help to stop bleeding, but it has some other jobs as well.

It is a cofactor specific to the formation of –carboxyglutamyl residues from specific glutamate residues in certain proteins.

The most important is the crucial role vitamin K, plays building bones. Vitamin K is needed to help hold onto the calcium in bones and make sure it’s getting to the right place.

It actually comes in three different forms: First, there’s vitamin K1, or phylloquinone. This is the form of vitamin K found in plant foods.

Vitamin K1 is quite stable to oxidation and most food processing and food preparation procedures. It is unstable to light and alkaline conditions.

Next, there’s Vitamin K2, also called menaquinone. This the form friendly bacteria in the intestines make. 

The last form would be called vitamin K3. It is also called menadione. Menadione is the only formed isolated from Staphylococcus aureus and also chemically synthesized. It is a synthetic compound that can be converted into K2 in the gastrointestinal tract.

All  vitamin K ends up in liver, where it’s used to make some of the substance that make blood clot.
Properties of vitamin K

Lipoic acid

When researchers in the 1950s isolated a sulfur-containing fatty acid, they thought at first they found a new vitamin.

The new substance, which they called lipoic acid, turned out to be essential for helping mitochondria – turn glucose into energy.

Lipoic acid is a vitamin-like chemical called an antioxidant. Lipoic acid is a naturally occurring compound present in most kinds of pro and eukaryotic cells. In human diet, lipoic aid is present in several food products such as meat - in particular, liver and heart.

Lipoic acid is not considered a vitamin because there are indications that its biosynthesis occurs from fatty acids. Lipoic acid, also sometimes called alpha-lipoic acid or thioctic acid is needed to help body cells turn glucose into energy and to recycle glutathione.

Lipoic acid supplement can also give human body extra free-radical protection. This could help prevent a lot of health problems, including atherosclerosis and cataracts.

It can function as an antioxidant and has been proposed that lipoic acid may have value in the prevention or treatment of other chronic diseases associated with oxidative stress.

It has been established that lipoic acid protects from lipid peroxidation and increases the activity of antioxidant enzymes – catalase and superoxide dismutase - in peripheral nerves.
Lipoic acid 

Metabolism of vitamin K

There are two principal forms of vitamin K: vitamin K1 (phylloquinone) is found in plant foods and vitamin K2 (menaquinone) is derived from animal and bacterial sources.

Vitamin K1, K2 and K3 (menadione) are essential nutrients associated with blood clotting and bone metabolism.

Vitamin K1 is fat soluble and requires bile salts for absorption in the upper gastrointestinal tract.

Vitamin K seems to play an indispensible role in the formation of normal amounts of prothrombin by the liver.

Prothrombin, in turn is a constituent of the blood essential to normal blood clotting. Deficiency in prothrombin results in an appreciable prolongation of the clotting time of the blood.

Vitamin K acts a factor in the final synthesis of proteins with modified amino acid residue.

This modified glutamic acid residue is found in the blood and along vessel walls, along with platelet-derived phospholipid, where it binds and facilitates the action of calcium, and is an integral part of the clotting process.

Many drugs impair vitamin K metabolism. Broad spectrum antibiotics destroy the colonic bacteria that produce vitamin K and can increase risk of deficiency.

Drugs which impair fat absorption aloes can reduce absorption of vitamin K.
Metabolism of vitamin K

Antioxidant vitamins

The antioxidant vitamins are E and C, as well as beta carotene, a plant form of vitamin A.  The antioxidant function of these vitamins could at least in part, enhance immunity by maintaining the functional and structural integrity of important immune cells.

Oxidation is a process that naturally occurs in the body and natural consequences of it are the radical particles that have since been dubbed as ‘free radicals’. Acting at the molecular level, these antioxidants inactivate a particle of free radicals, which in humans are most commonly ‘activated’ oxygen molecules.

Free radicals can damage basic genetic material, cell walls and other cell structures and eventually this damage can become irreparable and lead to disease.

Some of the basic food groups that prove to be rich sources of antioxidant vitamin are the following:
*Breads, cereals, pasta and starchy vegetables
*Fruits and vegetables
*Fat-free milk and low-fat dairy products
*Lean meat, fish and poultry

A frequent health recommendation to reduce the risk for development chronic disease is to continue at least five servings of fruits and vegetables. A steady supply of antioxidant vitamin should enhance the body’s natural defense mechanism and improve the quality and length of life.

A large body of epidemiologic evidence now supports the role of antioxidant vitamin including ascorbate, alpha-tocopherol and beat-carotene as protective agents against atherosclerotic cardiovascular disease.

A high intake of antioxidant vitamins seems to be protective many kinds of cancer, including oral, esophageal, and reproductive.
Antioxidant vitamins

Vitamin A required for vision

Vitamin A is fat soluble vitamin formed in the body from precursors, yellow pigments of plants (alpha, beta and gamma carotene).

Vitamin A is required for vision. Epithelial cells (those cells present in the lining) of body cavities and in the skin and glands) require vitamin A.

The form of vitamin A required in vision is 11-cis-retinal. On the retina, the initiating event of vision occurs when a photon of light excites a molecule so 11-cis-retinal that is covalently bound to the protein opsin. 

Vitamin A seems to be essential for maintenance of the integrity of the rods because on prolonged depletion of the vitamin the outer segments of the rods lose their opsin resulting in their eventual disintegration.

A shortage of vitamin A results in inadequate formation of rhodopsin, the pigment mediating low- intensity.
Vitamin A required for vision

Functions of Vitamin D

Vitamin D can be considered either a vitamin or a hormone. The active from of vitamin D is like a hormone because it is made in one part of the body and regulates activities in other parts.

Vitamin D is essential for the absorption of calcium and phosphorus from the digestive tract and deposition in the bones.

By promoting calcium absorption, vitamin D helps to form and maintain strong bones. When the dietary calcium is not sufficient to satisfy the body’s requirement, then vitamin D mobilizes calcium stores from the skeleton.

It acts in the concert with two others hormones: parathyroid hormone (PTH) from the parathyroid glands and calcitonin from the thyroid glands.

It is also important for regulating cell differentiation and growth. It modulates the transcription of cell cycle proteins, which decrease cell proliferation and increase cell differentiation of a number of specialized cells of the body – osteoclastic precursors, enterocytes, keratinocytes.

It may suggested that vitamin D protective against colorectal cancer.

Vitamin D also has a role in modulating immune defense mechanisms. The receptor is found in significant concentrations in the T-lymphocyte. It has been suggested that by providing vitamin D to infants may prevent the development of type 1 diabetes.

Vitamin D is formed from a substance present in our skin, called 7-dehydrocholestrol when exposed to sunlight. This substance will be converted to cholecalciferol which then enters the bloodstream and travels to the liver.

It is a fat-soluble steroid hormone precursor that contributes to the maintenance of normal levels of calcium and phosphorus in the bloodstream, which in turn needed for the normal mineralization of bone, muscle contraction, nerve conduction and general cellular functions in all cells of the body.
Functions of Vitamin D

The roles of Vitamin D

Vitamin D can be considered either a vitamin or a hormone. Vitamin D is essential for the absorption of calcium and phosphorus from the digestive tract and deposition in the bones.

By promoting calcium absorption, vitamin D helps to form and maintain strong bones.

25(OH)D is the active form of vitamin D which its primary role is to maintain blood calcium and phosphorus levels within a normal range.

It acts in the concert with two others hormones: parathyroid hormone (PTH) from the parathyroid glands and calcitonin from the thyroid glands.

It is also important for regulating cell differentiation and growth. It may also protective against colorectal cancer.

Vitamin D is formed from a substance present in our skin, called 7-dehydrocholestrol. This substance will be converted to cholecalciferol which then enters the bloodstream and travels to the liver.

It is a fat-soluble steroid hormone precursor that contributes to the maintenance of normal levels of calcium and phosphorus in the bloodstream.

The infant needs to be exposed to sunlight to permit the synthesis of vitamin D from the precursor in the skin.

Sensible sun exposure can provide an adequate amount of vitamin D which is stored in body fat during the winter, when vitamin D cannot be produced.

Since milk, human as well as cow’s, is not a good source of vitamin D, a small supplement is required for both breast-fed and bottle-fed infants.

Fish liver oil preparations are normally used as supplements for the supply of vitamins A and D.

Food sources of vitamin D come in natural and fortified forms. Fortified forms are included in milk, cereals, and some margarines.

Natural sources include fish oils, salmon, sardines, herring, egg yolks and liver.
The roles of Vitamin D

Fat Soluble and Water Soluble Vitamins

Fat Soluble and Water Soluble Vitamins
Vitamins can be defined as essential organic micronutrients that are involved in fundamental functions of the body, such as growth, maintenance of health and metabolism. Because of these substances must be supplied wholly or partially by the diet. Although the clinician should be able to recognize the syndrome caused by a lack of the vitamin in the case of a deficiency, it is more relevant in this country of abundant and varied food supply for the nutrition professional to think in terms of what a specific vitamin does rather than what disease it [prevents. Unfortunately, at the present time it is often impossible to relate directly the function of the vitamin to its deficiency syndrome.

Vitamins for the most part are not related chemically and differ in their physiologic roles. The broad classifications of water soluble vitamins and fat soluble vitamins are made because of certain properties common to each group. For instance, absorption and transport of fat soluble vitamins are closely associated with the absorption and transport of lipids; optimal absorption requires the presence of bile slats, these vitamins can also be stored in body lipids, although the amounts stored varies widely among the four fat soluble vitamins.

The water soluble vitamins are handled quite differently by the body. Their absorption requires no formation of micelles and with the exception of cyanocobalamin (vitamin B12), they cannot be retained by the body for long periods. Any storage occurring, results from their binding to enzymes and transport proteins. Water soluble vitamins are excreted in the urine wherever plasma levels exceed renal thresholds.
Fat Soluble and Water Soluble Vitamins

Vitamins in General

Vitamins in General
20th century marks the most exciting era in the history of nutrition science. It was during this time that the discovery of vitamins or “accessory growth factors,” began. Researchers found that for life and growth animals required something more than a chemically defined diet consisting of purified carbohydrate, protein, and aft, the essential mineral, and water.

The first of these dietary essentials discovered was and antiberiberi substance isolated from rice polishing by Funk, a Polish biochemist. Because the substance was an amine and necessary for life, Funk gave it the name vitamine. Very shortly thereafter McCollum and Davis extracted a factor from butter fat that they called fat soluble A to distinguish it from the water soluble antiberiberi substance. These two essential factors became known as vitamine A and vitamine B. As each additional vitamin was discovered, it was assigned a letter; the e on vitamine was dropped to give the general name vitamin because only a few of the essential substances were found to be amines.

As the chemical structure of the vitamin became known through its isolation and synthesis; it was given a chemical name. When the chemical name was assigned, it was assumed that the name applied to one substance with one specific activity. Now it is evident that a vitamin may have a variety of functions and that vitamin activity may be found in several closely related compounds known as vitamers. An excellent example of this is vitamin A, which has several seemly unrelated functions and encompasses not only retinol but also retinal and retinoic acid.
Vitamins in General