Niacin (nicotinic acid)-One of the B complex vitamins. Niacin functions as a component of the coenzymes, NAD (nicotinamide adenine dinucleotide) and NADP (nicotinamide adenine dinucleotide phosphate). Niacin [but not nicotinamide, also called niacinamide] also functions as a vasodilator and in reducing plasma cholesterol. You may have experienced the vasodilation first hand, if you've ever taken niacin supplements on an empty stomach, shortly after, developing flushing of the skin, and a sensation of heat.

 

Good sources of niacin are unrefined grains, cereals, meats, liver, and milk. Niacin can also be synthesized from the amino acid tryptophan (see proteins). Niacin synthesis from tryptophan, however, is inefficient, since a large proportion of the amino acid is required for the production of but a small amount of niacin.

 

Daily requirements for niacin are measured in niacin equivalents (NE). The NE takes in consideration the amount of dietary tryptophan as a niacin source, since niacin can be synthesized from tryptophan. One NE is defined as 1 mg of niacin or 60 mg of tryptophan (the body uses 60 mg of tryptophan to manufacture 1 mg of niacin). The adult requires about 13 NE per 1000 kcal from the diet.

 

Deficiency of niacin results in the condition known as Pellagra (Italian, meaning "rough skin"). Pellagra is characterized by dermatitis, inflammation of mucous membranes, diarrhoea (diarrhea), and psychic disturbances. The dermatitis occurs on the portions of skin exposed to light or trauma. Mental symptoms include depression, irritability, confusion, anxiety, delusions, and hallucinations. Always remember the 3 D's: dermatitis, diarrhoea, and dementia (and the fourth D, if untreated: death).

 

In chronic large doses, depressed liver function and peptic ulcer activation. With IV administration, anaphylactic reactions (rarely) and hypotension (because of nicotinic acid's vasodilator affect). Many people will develop flushing, and heat sensation after taking a normal dose, on its own. This again, is due to the vasodilator properties of nicotinic acid.

Pantothenic acid-Pantothenic acid is one of the B complex vitamins, and is composed of a dihydroxydimthylbutyric acid linked to a molecule of Beta-alanine. Pantothenic acid functions as a component of Coenzyme A. Coenzyme A is responsible for carrying acyl compounds as thiol esters. There are many types of coenzyme A structures. Fatty acyl CoA, succinyl CoA, and acetyl CoA are but some of the possible coenzyme A structures.

Pantothenic acid is also a component of the enzyme, fatty acid synthase.

 

Pantothenic acid is found in many foods, especially, liver, eggs and yeast.

 

The estimated RDA for pantothenic acid is 4-7 mg/day.

 

Pantothenic acid deficiency in humans has not been fully elucidated yet. It may exist in conjunction with other vitamin deficiencies, being masked by their symptoms.

phytonadione-A form of vitamin K, known as vitamin K₁. It can be obtained from plants and can be used as an intramuscular vitamin K source in the clinical setting, for emergency treatment of haemorrhage. Phytonadione can be converted in the body to the active form of vitamin K. Since vitamin K is fat-soluble, it needs bile for intestinal absorption.

Note: Menadione and its derivatives are known as vitamin K₃. Although menadione is fat- soluble, menadione bisulfite sodium (a derivative) is water-soluble and therefore, doesn't require bile for intestinal absorption

phytonadione-A form of vitamin K, known as vitamin K₁. It can be obtained from plants and can be used as an intramuscular vitamin K source in the clinical setting, for emergency treatment of haemorrhage. Phytonadione can be converted in the body to the active form of vitamin K. Since vitamin K is fat-soluble, it needs bile for intestinal absorption.

Note: Menadione and its derivatives are known as vitamin K₃. Although menadione is fat- soluble, menadione bisulfite sodium (a derivative) is water-soluble and therefore, doesn't require bile for intestinal absorption

Folic acid-A water-soluble vitamin of the B complex. Folic acid is composed of pteroic acid bonded to L-glutamic acid (pteroylglutamic acid) or other derivatives. Folic acid is required for haematopoiesis (blood cell production). Upon absorption, folic acid is reduced to dihydrofolic acid and then to tetrahydrofolic acid. Derivatives act as coenzyme carriers in various metabolic reactions.

 

Good sources of folic acid are liver, green vegetables, and yeast.

 

The recommended intake of folic acid is 100 micrograms/day. Since folic acid has role in nucleic acid synthesis, more is needed during periods of increased tissue growth, such as pregnancy (800 micrograms), and breast feeding (500 micrograms).

 

Insufficient amounts of folic acid are characterized by growth retardation and megaloblastic anaemia. Folic acid metabolism has a close relation with vitamin B₁₂.

Para-aminobenzoic acid (PABA)-An acid required by many organisms to synthesize folic acid. Although it is not required as an essential human nutrient, PABA is included as part of the B complex. PABA can absorb ultraviolet (light beyond the visible light spectrum) light and can be used in the form of aminobenzoic acid, as a sunscreen for skin protection.

Inositol-A cyclic sugar alcohol (fully hydroxylated derivative of cyclohexane). Inositol occurs naturally in different stereoisomers, especially the myo-isomer. Used alone, the term inositol usually denotes this isomer (form).

Myo-inositol-The myo-isomer of inositol. This isomer occurs in many plant and animal tissues and microorganisms, and is usually phosphorylated and a component of phosphatidylinositols. Myo-inositol is part of the B complex vitamins. Myo-inositol is a component of several substances in the human. 1,4,5-triphosphate (InsP₃, IP₃), is a messenger generated from the splitting of phosphatidylinositol 4,5-bishphosphate in calcium-mediated hormone responses. InsP₃ causes the release of calcium from specialized intracellular organelles.

Dietary inositol also serves as a precursor for the intracellular synthesis of glucoronic acid. Glucuronic acid is a required portion of glycosaminoglycans, which are water attracting substances in connective tissues. Glucuronic acid is also necessary for detoxification reactions of insoluble compounds such as bilirubin and some steroids.

 

Good sources of myo-inositol can be obtained from vegetables, citrus fruits, cereal grains, organs and other meats.

choline-A water-soluble chemical derivable from many animals, some vegetables, and produced synthetically. Choline is considered one of the B-complex vitamins. It is a component of lecithin and prevents fatty deposit in the liver.

The acetic acid ester of choline is called acetylcholine which is essential in synaptic transmission of nerve signals.

ascorbic acid-Alternate name for vitamin C. This is a water-soluble vitamin found in many types of fruits and vegetables. Ascorbic acid is needed for optimal function of several enzymes. Ascorbic acid is best known for its assistance to a variety of hydroxylation processes of collagen. Ascorbic acid also aids the absorption of Iron (Fe) by reducing it to the ferrous state in the stomach. This means that it changes the electrical charge of the iron atom, so it is easily absorbed.

10 milligrams (mg) per day will prevent scurvy, which is caused by a deficiency of ascorbic acid. Although 10 mg is thought to prevent scurvy, this is not entirely true, considering signs of scurvy are initially diagnosed on a macroscopic (what we can see with the naked eye) scale. Since the signs and symptoms of scurvy are listlessness, anorexia, cachexia, gingivitis, loosened teeth (you can wiggle them), halitosis (unpleasant breath), bleeding from gums, nose, hair follicles, bladder, joints and other places, to wait until your health gets to this point? Of course, full blown scurvy is seen in economically deprived parts of the world. But it still exists in the western world, and many of the microscopic changes to your health, as well as other signs and symptoms go undetected. It's better to be safe and increase the daily dose of vitamin C. RDA's have changed over time and are in the range of 60 mg per day. You can safely take much higher doses (500-1000mg) per day. Keep in mind that ascorbic acid is a water soluble vitamin, and your body will only use what it needs. The unused portion is excreted from the body. So higher doses will not harm you.

toxicity of ascorbic acid-Acute toxicity has not been observed with ascorbic acid, because most of the vitamin is excreted. However, a small portion is oxidized to dehydroascorbic acid and metabolised to oxalate. Calcium salts of oxalate are one of the components of kidney stones. Therefore, chronic large doses of ascorbic acid should be avoided, especially in those with a family history, or tendency to form kidney stones.

Doses of 1-4grams (1000-4000mg) of ascorbic acid per day seem to reduce both the severity and duration of colds to a degree. This is probably because of several reasons. High doses of ascorbic acid have an antihistamine-like effect, relieving nasal congestion, runny nose and some of the other symptoms of the cold or flu. Ascorbic acid also helps in the general healing process of any microscopic damage caused by the inflammatory reactions from the cold or flu virus. Collagen, a connective and supporting tissue in the body, plays an important role. Collagen is made up of roughly 10% hydroxyproline (an amino acid), Proline (an amino acid), must be hydroxylated in the formation of quality collagen. A reducing agent like ascorbic acid is needed for hydroxylation of proline to occur. If ascorbic acid is lacking, substandard collagen is produced. Ascorbic acid not only helps in tissue repair during bouts with colds and flues, in everyday collagen production. Therefore, it is essential for tissue repair of all types, including maintainence from daily wear and tear, wound repair, and other processes.

Did you know that the Australian billygoat plum, Terminalia ferdiandiana, contains the highest natural source of vitamin C? It contains more than 100 times the amount found in oranges !

Menaquinone-A form of vitamin K, known as vitamin K₂. This is the form of vitamin K which is obtained from intestinal bacteria.

Other forms of vitamin K

-phytonadione or vitamin K₁

-Menadione or vitamin K₃

B complex-An umbrella term denoting the group of water- soluble substances which include:

Thiamine (vitamin B₁)

Riboflavin (vitamin B₂)

Niacin (nicotinic acid)

Niacinamide (nicotinamide)

Vitamin B₆ group

Biotin

Pantothenic acid

Folic acid

Choline

Vitamin B₁₂

Inositol

Biotin-A water-soluble substance, considered to be part of the B complex vitamins. Biotin is chemically, what we call a dicyclic monocarboxylic acid. Biotin is an essential cofactor for several enzymes (eg., carboxylases), and helps in the metabolism of fatty acids and amino acids.

 

Biotin can be obtained from most foods, especially liver, egg yolk, and milk.

 

Approximately 200 micrograms per day of biotin are sufficient. Since most foods contain biotin, normal UK and US diets are sufficient in supplient the necessary amounts.

 

Biotin deficiencies are rare because most foods contain this vitamin. In addition the bacterial gut flora synthesize small amounts, which are absorbed through the intestines. A cause for a biotin deficiency would be starvation. If this were the case, most other vitamins would be deficient as well. Another possible mechanism in developing a biotin deficiency would be to consume large amounts of egg whites. Raw egg whites contain a avidin, a glycoprotein that binds biotin and prevents intestinal absorption. It would take nearly two dozen egg whites per day to achieve this result. Therfore, an egg white on occasion is not harmful. This is something to consider, as there is an in vogue practice of eating raw egg whites as a protein source. This is something that is popular in gyms, where the participant consumes many raw egg whites per day in pursuit of large amounts of protein for increased muscle mass. One must also consider that raw egg whites do not come without their potential risks. The risk of illness through consumption of an infected egg can does exist and many consumers of raw eggs have contracted Salmonella. It is safer to cook the egg white, because much of the protein is still available, and the avidin is denatured if thoroughly cooked.

Biotin deficiency is characterized by dermatitis, glossitis anorexia, nausea and alopecia. This is reversible once biotin levels return to normal.

carotene-One of four similar pigments, found in plants and having colours ranging from violet to yellow. Each of the four carotenes is preceded by a Greek letter (alpha, beta, gamma, or delta) and merely indicates the slight difference in structure. Carotenes are found in many dark green, leafy and yellow vegetables such as carrots, sweet potatoes, squash, and turnips. Carotenes are also found in yellow fruits such as oranges peaches, apricots, cantaloupes, etc.). They are fat-soluble, and can be split into 2 molecules of retinal by enzymes in the intestinal wall and the liver. In humans, B-carotene is the major provitamin (precursor) of vitamin A. B-carotene is not absorbed as well as retinol, but is in greater availability in the diet.

Beta-carotene can be used as a provitamin (precursor) of vitamin A since it can be split into 2 molecules of retinal. Oral Beta-carotene preparations have also been used to reduce the severity of photosensitivity in patients with certain types of porphyria. Beta-carotene has also been used as a method of artificial tanning.

carotene-One of four similar pigments, found in plants and having colours ranging from violet to yellow. Each of the four carotenes is preceded by a Greek letter (alpha, beta, gamma, or delta) and merely indicates the slight difference in structure. Carotenes are found in many dark green, leafy and yellow vegetables such as carrots, sweet potatoes, squash, and turnips. Carotenes are also found in yellow fruits such as oranges peaches, apricots, cantaloupes, etc.). They are fat-soluble, and can be split into 2 molecules of retinal by enzymes in the intestinal wall and the liver. In humans, B-carotene is the major provitamin (precursor) of vitamin A. B-carotene is not absorbed as well as retinol, but is in greater availability in the diet.

Beta-carotene can be used as a provitamin (precursor) of vitamin A since it can be split into 2 molecules of retinal. Oral Beta-carotene preparations have also been used to reduce the severity of photosensitivity in patients with certain types of porphyria. Beta-carotene has also been used as a method of artificial tanning.

Vitamin D-A group of fat-soluble compounds resembing steroids.

 

Vitamin D can come from the diet, or from endogenous production in the body. Ergocalciferol (vitamin D₂ is obtained from plants. Cholecalciferol (vitamin D₃ is obtained from animal tissues. These two derivatives of vitamin D are sources of preformed vitamin D activity.

Endogenous vitamin D is derived from intermediates in cholesterol synthesis. 7-dehydrocholesterol is an intermediate in the synthesis of cholesterol and is converted to cholecalciferol in the dermis and epidermis when exposed to sunlight. Preformed vitamin D is only required in the diet if a person cannot be exposed to sunlight for any reason.

Vitamins D₂ and D₃ are not active. They must be converted to the active form inside the body. Vitamin D₃ is hydroxylated at the 25-position by a hydroxylase present in the liver. The result is 25-hydroxycholecalciferol (25-OH-D₃ and is the major plasma form and storage form of vitamin D.

25-OH-D₃ is hydroxylated again, this time at the 1- position by 25-hydroxycholecalciferol 1-hydroxyolase, an enzyme found in the kidney. After hydroxylation, the result is 1,25-dihydroxycholecalciferol (1,25-diOH-D₃). 1,25-diOH-D₃ is the most useful form of vitamin D and its synthesis is strictly monitored by the concentrations of serum phosphate and calcium.

Activity of the renal enzyme 25-Hydroxycholecalciferol 1-hydroxylase is directly increased by low serum phosphate and/or indirectly by low serum calcium. Low level of serum calcium and phosphate stimulate the release of parathyroid hormone (PTH). In summary, low levels of calcium stimulate the production of 1,25-diOH-D₃. Why do low levels of calcium and phosphate cause a rise in active vitamin D? The answer is quite simple if we look at the function of vitamin D. The active form of vitamin D (1,25-diOH-D₃) is to maintain normal serum levels of calcium. 1,25-diOH-D₃ achieves this by stimulating the intestine to increase the uptake in calcium, stimulating the bone to release calcium from its supply (resorption), and by lowering the loss of calcium through the kidney.

 

Sources of vitamin D include eggs, liver, butter, fatty fish and milk (only if fortified with vitamin D).

 

5 micrograms/day of cholecalciferol or 200 IU/day of vitamin D is recommended for adults.

 

Vitamin deficiency causes bone demineralization. Calcium and phosphates are is regarded as minerals. Therefore, removal of this mineral from the bone is referred to as demineralization. Demineralization of the bone is known as rickets in children and osteomalacia in adults. In rickets, continued formation of collagen (the protein framework of bone) occurs, but bone mineralization (for compression strength, like a sidewalk or walkway) is incomplete. This is because calcium is not absorbed properly without vitamin D, therefore, the child becomes calcium deficient. The result in the child is soft, pliable bones. These bones can bend over time due to compressional forces, such as when walking. This bending of the femur, tibia and fibula can result in the child developing "bowed" legs. In the adult, osteomalacia increases the risk of bone fractures.

 

Vitamin D, being fat-soluble, is stored in the body in appreciable amounts and is slowly metabolized. Chronic excessive doses can cause anorexia, nausea, vomiting, thirst and stupor. Excess vitamin D administration also causes hypercalcaemia (higher than normal calcium in the blood). This can lead to calcium deposit in the organs, and blood vessels.

Vitamin E-This is a collective term of eight naturally occuring tocopherols. Alpha-tocopherol has the highest activity of the eight.

Vitamin E functions primarily as an antioxidant. This antioxidant activity helps us in preventing the nonenzymatic oxidation of polyunsaturated fatty acids from oxygen and free radicals.

Vegetable oils are good sources of vitamin E. Eggs and liver provide moderate amounts of the vitamin.

 

The RDA for alpha-tocopherol is 10mg for males and 8 mg for females. With an increase in polyunsaturated fats in the diet, the requirement for vitamin E increases.

 

In adults vitamin E deficiency is associated with defective lipid absorption and transport, and abnormal cellular membranes. Premature infants have the highest susceptibility to complications of vitamin E deficiency.

 

Chronic excessive amount of alpha-tocopherol can cause gastrointestinal distress, fatigue, rashes and increases in serum cholesterol. IV injection to premature infants can cause pulmonary deterioration, kidney and liver failure, and many other problems. This may not be due to the alpha-tocopherol, but rather from the effects of the polysorbate in the preparation.

menadione-A synthetic and fat-soluble provitamin. Menadione can be converted in the body to the active form of vitamin K. Menadione is also known as vitamin K₃ and menaphthone.

Vitamin D-A group of fat-soluble compounds resembing steroids.

 

Vitamin D can come from the diet, or from endogenous production in the body. Ergocalciferol (vitamin D₂ is obtained from plants. Cholecalciferol (vitamin D₃ is obtained from animal tissues. These two derivatives of vitamin D are sources of preformed vitamin D activity.

Endogenous vitamin D is derived from intermediates in cholesterol synthesis. 7-dehydrocholesterol is an intermediate in the synthesis of cholesterol and is converted to cholecalciferol in the dermis and epidermis when exposed to sunlight. Preformed vitamin D is only required in the diet if a person cannot be exposed to sunlight for any reason.

Vitamins D₂ and D₃ are not active. They must be converted to the active form inside the body. Vitamin D₃ is hydroxylated at the 25-position by a hydroxylase present in the liver. The result is 25-hydroxycholecalciferol (25-OH-D₃ and is the major plasma form and storage form of vitamin D.

25-OH-D₃ is hydroxylated again, this time at the 1- position by 25-hydroxycholecalciferol 1-hydroxyolase, an enzyme found in the kidney. After hydroxylation, the result is 1,25-dihydroxycholecalciferol (1,25-diOH-D₃). 1,25-diOH-D₃ is the most useful form of vitamin D and its synthesis is strictly monitored by the concentrations of serum phosphate and calcium.

Activity of the renal enzyme 25-Hydroxycholecalciferol 1-hydroxylase is directly increased by low serum phosphate and/or indirectly by low serum calcium. Low level of serum calcium and phosphate stimulate the release of parathyroid hormone (PTH). In summary, low levels of calcium stimulate the production of 1,25-diOH-D₃. Why do low levels of calcium and phosphate cause a rise in active vitamin D? The answer is quite simple if we look at the function of vitamin D. The active form of vitamin D (1,25-diOH-D₃) is to maintain normal serum levels of calcium. 1,25-diOH-D₃ achieves this by stimulating the intestine to increase the uptake in calcium, stimulating the bone to release calcium from its supply (resorption), and by lowering the loss of calcium through the kidney.

 

Sources of vitamin D include eggs, liver, butter, fatty fish and milk (only if fortified with vitamin D).

 

5 micrograms/day of cholecalciferol or 200 IU/day of vitamin D is recommended for adults.

 

Vitamin deficiency causes bone demineralization. Calcium and phosphates are is regarded as minerals. Therefore, removal of this mineral from the bone is referred to as demineralization. Demineralization of the bone is known as rickets in children and osteomalacia in adults. In rickets, continued formation of collagen (the protein framework of bone) occurs, but bone mineralization (for compression strength, like a sidewalk or walkway) is incomplete. This is because calcium is not absorbed properly without vitamin D, therefore, the child becomes calcium deficient. The result in the child is soft, pliable bones. These bones can bend over time due to compressional forces, such as when walking. This bending of the femur, tibia and fibula can result in the child developing "bowed" legs. In the adult, osteomalacia increases the risk of bone fractures.