VITAMINS in KALE
Vitamins are organic compounds which either in their pre-cursor forms or in their active forms the body cannot synthesize for itself and yet are essential for the human body in one way or another, and where insufficient quantities in the diet or complete lack of it will cause some disease, ailment or even death. Vitamins are obtained from the diet.
The amounts of Vitamin B7 (
Biotin) and Vitamin B12 (CyanoCobalamin, HydroxyCobalamin and MethylCobalamin), if any, have yet to be determined, but may be low.
The Vitamins do not include what are also the essential minerals for humans, such as compounds of elements from the periodic table, or even some elemental elements. This list is divided into four and is not to imply that Kale contains all these human essential minerals, nor even many, but it will invariably contain some, particularly from the last list of four.
The entries of elements with a '(??)' against them means that these elements are only considered to be possibly essential, but have not been confirmed as such.
Essential metals, but only in trace amounts, they are highly toxic in any larger amounts:
Iron (in several differing
Haemoglobin which is in red blood cells to capture oxygen).
Molybdenum (as cofactors in many enzymes e.g. Sulfite Oxidase)
Manganese (a cofactor in enzymes, in enzymes in mitochrondria to detoxify superoxide radicals; in Xanthine Oxidase, Aldehyde Oxidase and Sulfite Oxidase) [Also essential in plants to assimilate CO2 during photosynthesis, in nodules of
Fabaceae to fix nitrogen]
Zinc (in several enzymes, in DNA-binding and RNA-binding 'zinc fingers' to help regulate genes, also found in semen)
Vanadium (??) Vanadium has a specialised role as cofactors in other organisms (also found in
Fly Agaric mushrooms as the complex Amavadin) and are also probably involved some way in mammals (including humans) too.
Vanadium is toxic and is implicated in Manic Depression: those who have MD also have elevated levels of vanadium in their hair, which decreases to normal levels when they are cured of Manic Depression. Vanadium (and Molybdenum and Tungsten) replaces insulin in the body, which may be good for diabetics if it were not for the fact that it also kills beta cells which will not help diabetics at all! But Vanadium also blocks dozens of enzymes in the body which include ribonucleases, mutases, kinases and synthases, which has both positive and negative consequences, such as damage to DNA, blocking of protein synthesis, as well as the blocking lipid oxidation which is considered a primary step in the development of cardiovascular disease. These effects are probably due to the fact that Vanadates mimic Phosphates, and can put spanners in the works of any of the large variety of moieties in mammals with phosphates in them, such as DNA and a plethora of others.
Chromium (inclusion in essential metals is contentious) (involved in sugar and lipid metabolism by interacting with insulin, method unknown)
Cobalt (in the 4 forms of Vitamin B12 of which Cobalamin is one such). Greater amounts are toxic
Nickel (??). In the enzymes urease and hydrogenase belonging to gut bacteria nickel is an essential component. In several animals such as goats, pigs and sheep nickel deficiency resulted in reduced thyroid hormone concentrations. In humans it is possible that nickel may be a cofactor or a structural component in metalloenzymes involved in gene expression, hydrolysis and redox reactions. Nickel is toxic and some people are allergic to metals containing nickel when that is constantly in contact with the skin (e.g. a metal watch-back).
Copper (an important electron donor in various biological reactions; without copper iron will not function correctly in the human body in many redox enzymes such as Cytochrome C Oxidase which is within mitochondria)
Strontium (??). Strontium is involved in the use of calcium within the human body, promoting bone uptake of calcium but greater dietary amounts result in rickets.
Essential non-metallic elements, but again, only in trace amounts, higher amounts are toxic:
Selenium (as the 21st amino acid
SelenoCysteine essential to the activity of many anti-oxidant enzymes, e.g. Glutathione peroxidases).
Selenomethionine, is a naturally occurring amino acid where the sulfur atom in Methionine is replaced by one of selenium and is the primary dietary source of selenium.
Lithium (??). Nutritional studies in mammals suggest Lithium is an important trace element for health, but it is not proven for humans. Lithium is toxic, but in smaller amounts is used to treat bipolar disorder.
Boron (??). Boron is present in all plants as a required mineral; boron deficiency in plants results in large crop loses in the World. Boron deficiency in humans is said to result in arthritis and osteoporosis. Non-toxic to humans.
Silicon. Silica rich plants include the toxic
Horsetails, Alfalfa, Beetroot and other beets, Brown Rice,
Oats and Stinging Nettle but many other plants contain it for structural integrity. It is also present in beer (probably from the barley grains used to make malt)
Iodine (in Thyroid hormones
Thyroxine and TriIodoThyronine which regulate metabolic rate and prevent goitre)
The human body also requires much larger amounts of:
Sodium (an electrolyte involved in electrical nerve impulse transmission in nerves, with Potassium coregulates ATP)
Potassium (an electrolyte for electrical signalling in nerves and helps regulate heart-beat, with Sodium coregulates ATP)
Magnesium (for processing ATP, in bones and muscles and is essential in >300 metabolic reactions)
Calcium (in bones as mineral
Apatite, involved in protein regulation and muscle contraction, supports building and function of blood cells)
Phosphorus (in ATP which provides energy for every cell, in mineral
Apatite which is in bones and teeth, in DNA)
Sulfur (in two amino acids, Cysteine & Methionine)
Chlorine (to produce
Hydrochloric Acid in stomach for digesting foods).
Chlorine was a WWI poison gas which is toxic to inhale.
And far larger quantities of:
Carbon (present universally in all organic compounds, amino-acids, proteins, enzymes, DNA, the lot)
Oxygen Required for respiration to oxygenate haemoglobin which contains several iron-containing haem moieties. A component of all carbohydrates and hundreds of organic molecules essential for life in the human body (and most other life-forms)
Nitrogen (in the 20 (21) amino acids contained in proteins and DNA)
Hydrogen (present almost universally in many compounds, proteins, enzymes, DNA, the lot)
The body obtains these elements as various compounds containing them; only rarely as the free element. But no matter how much the body requires them, and may die or suffer serious disease without them, no essential minerals are classed as Vitamins.
[The external links above are to one of your Authors other websites, this one being on Chemistry, Astrophysics, the Periodic Table and the Segre chart of Isotopes, the full site of which is Info for Isotopes]
Kale is a particularly rich source of Vitamins, especially of Vitamin K where a 100g portion on the dinner plate contains 670% of the 705µg daily (United States) recommended amount for adults. It also contains a generous portion of Vitamin C (145% of US daily recommended daily amount of 120mg).
In the UK the NHS recommends daily amounts which are linearly dependent upon body weight, and thus try to be more accurate. The NHS recommended amounts for Vitamin K are 1µg per kg of body weight; but for Vitamin C the NHS does not consider body mass and just gives a recommended daily amount of 40mg, which is three times lower than the USA recommended amount (but perhaps Americans have an average body mass higher than those in the UK?). Vitamin C has a low toxicity. Exceeding 1000mg of Vitamin C per day can cause minor problems, so there is no hard and fast rule for Vitamin C. Some individuals, such as Linus Pauling, took excessive amounts of Vitamin C intravenously (like 12,000mg per day) in the belief they will live to be 120 on Vitamin C's known anti-oxidant properties, said to include anti-cancer. Linus Pauling died at age 93 due to prostrate cancer. The generally accepted LD50 for Vitamin C which will kill 50% of a large group taking it is about 12mg per kg for rats. No one has done any experiments with humans to find their Vitamin C LD50, but they are definitely in the danger zone exceeding 3000mg Vitamin C per day. It should be noted that the USA's FDA have not approved high-dose Vitamin C for treatment of cancer or for any other disease.
Vitamins were slowly discovered over a period between about 1910 to 1950 in the last century when biochemistry was in its infancy and identification of compounds was not as refined as it is today. The Vitamins are labelled by the word 'Vitamin' followed by a letter of the alphabet (and in some cases a number as well to differentiate the many different forms that a Vitamin which acts similarly can take). Many labelled Vitamins exist in several molecular forms. Some forms are in-active forms which only become the molecule really responsible for the beneficial effects after biochemical alteration within the body. The active forms of the Vitamins (the forms used by the biochemical mechanisms within the body to perform the essential function which the body itself cannot perform) are usually unstable and do not persist long within the body - but rather they are synthesized within the body from 'provitamins' much nearer to where they are required. Thus, the vitamins in the food we eat are not usually the active form of the vitamin, but rather their precursors, the provitamins. But you will not see them labelled in health shops (or on cereal packet labels) under 'provitamins' but rather under 'vitamins'. The active form of the vitamin can usually be synthesized within the body from several slightly differing provitamins, which explains why, in some cases, there are a profusion of provitamins all with slightly differing structural formulae.
There are several forms which
Vitamin A can take, all fat soluble, and together amount to a daily requirement of about 900µg/day. A deficit of it results in Night Blindness at first, and total blindness in severe cases, also to rough skin.
Retinol is the main form of Vitamin A, but other forms include
Retinal (the active form),
Retinoic Acid (which is inactive) and five carotenoid provitamin A's, namely
α-Carotene, the main one β-Carotene,
β-CryptoXanthin), Lutein and Zeathanthin. Within the human body these provitamins are converted, first into Retinal and then into the active form of Vitamin A, Retinol. Carnivores such as cats lack a key enzyme necessary to convert any carotenoids into Retinol. Retinol is a yellow coloured fat-soluble compound. Retinol itself is unstable, and is instead usually available as an ester such as
Retinyl Acetate or
Retinyl Palmate for use medicinally or as supplements; these also convert to Retinol within the human body.
Retinol is converted within the human body into Retinal (the aldehyde of Retinol), Retinal being the active form of Vitamin A. Within the eye Retinal combines with the protein opsin to form
Visual Purple, which is the light-absorbing molecule necessary for both night-vision (scotopic vision) mediated by the rods and for colour vision (photopic vision) mediated by several different cones. [See Colour Vision]
It can be seen that two Retinal moieties (minus the -OH) are contained in one molecule of β-Carotene, thus β-Carotene is twice as effective at supplying Retinal than is β-Cryptoxanthin which contains only one moiety of Retinal. Kale also contain the carotenoids Zeaxanthin and Lutein, which both contain two hydroxyl moieties, on each one each ring which when relocated elsewhere can also produce Retinal, two units in the case of Zeaxanthin but only one in the case of Lutein where one of the rings has a double-bond in the wrong place.
Lutein and Zeaxanthin are isomers, but not stereoisomers: the only difference between the two being the position of the double bond on the left hand ring. All except β-Carotene have an -OH on the ring(s), Zeaxanthin and Lutein have one on each ring. β-Cryptoxanthin (aka Xanthophyll) has the double-bond on each ring in positions differing from the other 3 shown here as well as the dimethyl on differing places. β-Carotene is orange, whilst Lutein, Zeaxanthin and β-Cryptoxanthin (aka Xanthophyll) are yellow. All are tetraterpenoids constructed from
Isoprene units and all have antioxidant properties. Being yellow in colour, both Lutein and Zeaxanthin absorb the more energetic blue light from reaching the retina, and thus helps reduce the risk of light-induced oxidative damage to the retina which could otherwise lead to age-related macular degeneration (AMD).
All four carotenoids above, β-Carotene, Zeaxanthin, Lutein and β-Cryptoxanthin are provitamins of Vitamin A and can be converted into the active form of Vitamin A (Retinal) by the enzyme βCarotene-15,15'-dioxygenase within the eye, although the last two only yield half the amount as the first two. β-Carotene is the most important source because that occurs at higher concentrations in foods which contain Vitamin A.
α-Carotene is the second most common form of Vitamin A but with a double bond in the wrong place on one of the rings; that too can only yield one molecule of Retinal per molecule of α-Carotene rather than the two with β-Carotene.
γ-Carotene, δ-Carotene, ε-Carotene and ζ-Carotene also exist, the first two possessing a break in one of their rings.
Thiamine is water soluble and is also known as Vitamin B1 of which about 1.2mg/day are required. Thiamine contains an atom of sulfur, an aminopyrimidine ring linked to a thiazole ring. Both rings contain a heterocyclic nitrogen atom, one ring contains two. It is a Zwitterion, with a positive charge on one of the nitrogen atoms. Thiamine is a co-enzyme in the breakdown of sugars and amino acids. It occurs in low concentrations in a wide variety of foods but kale, pork, beef, chicken, eggs, yeast, Oatmeal, Flax, Annual Sunflower seeds, brown rice, Asparagus,
cauliflower, Potatos, oranges and whole-grain cereals have much greater quantities. Of the cereals, most is contained within the outer layers which are usually removed in refined grains. Whereas white flour contains but 0.06mg/100g, whole-wheat flour contains 55mg/100g. There is no data for an upper daily limit of Thiamine, but about 0.9mg to 1.4mg / day are required. Deficiency results in Beriberi, Wernicke-Korsakoff syndrome affecting the brain, and can lead to metabolic coma and death. Thiamine deficiency can also occur in alcoholics.
Vitamin B2, aka Riboflavin
(→UV→) which is water soluble and also known as
Vitamin B2, E101 (as a permitted yellow colouring) and the abbreviation RBF. It is essential to mammals and plays a key role in energy metabolism of fats, ketones, carbohydrates and proteins. About 1.3mg/day are required. It is a dietary requirement used in coenzymatic reactions involving flavoproteins, which includes those involving the activation of other vitamins. Riboflavin is based upon Pteridine and is one of the
Flavins. In solution is both coloured yellow and fluoresces yellow-green under ultraviolet light. In solid form it is more orange in colour. Its name derives from the reduced
Ribose sugar it contains,
Ribitol (the long dangling chain in the structural diagram) and flavus, meaning 'yellow' in Latin.
Riboflavin occurs in the free form within the retina of the eye. It is also found in Legumes,Asparagus, Green Peas,
Spinach, Mushrooms, milk, eggs, cheese and in whole grains.
Deficiency of Vitamin B2 results in anaemia, but one in which the blood cells are of the normal size and the haemoglobin content is also normal (this differs from the anaemia caused by deficiency of
Folic Acid (
Vitamin B9) or of CyanoCobalamin (Vitamin B12) where blood cells are enlarged and haemoglobin content lower).
Folate molecules consist of Pteridine bonded to
para-AminoBenzoate which in turn is bonded to
Glutamate. The pteridines are synthesized in the plants cytosol; the
para-AminoBenzoic Acid in the chloroplast and the glutamate is found elsewhere...
Nicotinic Acid, is part of the Vitamin B complex. It is a water-soluble vitamin occurring in various plant and animal tissues. Nicotinic acid is converted into Nicotinamide by the human digestive system. Nicotinamide (aka
Niacinamide) has a substituted carboxamide group in place of the carboxyl group.
Both Niacin and Nicotinamide are referred to as Vitamin B3 for they are equivalent from the point of view of effectiveness as Vitamin B3, of which about 16mg/day are required. Deficiency of Vitamin B3 results in a disfiguring skin disease to any parts of the skin exposed to sunlight with accompanying skin lesions called Pellagra as does possibly an intake of too much
Leucine (which mammals cannot synthesize themselves but is available in the diet from plants) an α-amino acid involved in the biosynthesis of proteins. The two do not behave identically with the body, however, Niacin is toxic to the liver but Nicotinamide (despite its conversion to Niacin in the body) is not toxic. The body can withstand overdoses of Nicotinamide but not of Niacin. Nicotinamide can be an effective oral treatment for Actinic Keratoses, pre-cancerous reddish scaly patches of skin regularly exposed to too much UV from the Sun, and which is common on top of balding mens heads. A deficiency of Vitamin B3, like an oversupply of Leucine, causes Pellagra. Pellagra is common in those populations (usually in South America) whose staple diet is of Maize, which is deficient in both Tryptophan and Niacin unless subjected to a process known as Nixtamalization where the Maize (or other grain) is both soaked and cooked in an alkaline solution, usually limewater, and then hulled and washed before consumption. The unpalatable alkaline waste now containing organic compounds such as starch can be used to make Amate, a kind of bark paper. Nixtomalization is an ancient Mesoamerican process dating from about 1200-1500 BC and apparently developed by the Aztecs and Mayan civilizations. With modifications the process is still in use today to make tortillas, tortilla chips, tamales, hominy and many other foods.
Until recently Choline was not considered as a vitamin in humans because an endogenous synthesis pathway exists, but when Methionine (a substance which acts similarly to Choline in the human body) is not available in sufficient quantities then Choline deficiency can result. It is still not technically considered a Vitamin because the body can synthesize it, but not at a sufficient rate to meet bodily demands, and dietary input is usually required. Choline belongs to the Vitamin B complex and is sometimes called called
Vitamin Bp. Choline is a ubiquitous compound in cell membranes, both plant and mammal, and is available in many common foods. The major product the body synthesizes from Choline is
AcetylCholine, one of the main neurotransmitters, (although over 100 and counting have now been found in the brain including Dopamine,
serotonin, Tyramine, Tryptamine,
glycine, Nitric Oxide,
hydrogen sulfide etc).
Vitamin B5, aka
Pantothenic Acid is water soluble and a dietary requirement of about 5mg/day are required. A deficit results in paraesthesia, a tickling, prickling and numbness of the skin commonly known as 'pins and needles', but without the common cause of pressure on a limb or diabetes. It is an
Aminopropanoic Acid, being the amide between
Pantoic Acid. Hypoglycaemia is also a result of deficiency. Vitamin B5 is found in almost every food, but with high amounts in egg yolks, liver and dried mushrooms and is normally found as the provitamin B5,
Pantothenol and as the calcium salt of that
Calcium Pantothenate, both of which are more stable forms. Somewhat contradictory, it is only the dextrorotatory stereoisomer (D-form) which is effective; the laevorotatory stereoisomer (L-form) being antagonistic! [Most optical isomers which function in the human body are of the L-form]. There is no known toxic limit of Vitamin B5. Pantothenic Acid synthesizes coenzyme A (aka CoA) which is important in the metabolism of pyruvate. Coenzyme A requires Cysteine,
Pantothenate and ATP in order to be synthesized in the human body. It is also involved in nerve impulse transduction and both enzyme activation and deactivation, performing major roles in all forms of life.
Pyridoxine are all water soluble and all act as
Vitamin B6 aka
Pyridoxal Phosphate of which a total of between 1.3 - 1.7mg/day are required by the human body. All these compounds are based upon a
pyridine ring with various side-groups. Vitamin B6 is involved in the metabolism of nutrients within cells, the expression of genes and in the synthesis of neurotransmitters, histamine and haemoglobin, so one can imagine all sorts of problems a lack may cause. The classic symptoms of Vitamin B6 deficiency are numerous: seborrhoea, soreness of tongue, inflammation of both corners of the mouth, conjunctivitis (pink-eye), inflammation of the skin, sleepiness, confusion and neuropathy, but Vitamin B6 deficiency is unlikely to occur alone, it is often associated with deficiencies in other B vitamins. Deficiency is rare because it is widely available in differing foods, although cooking can reduce the amount by up to 50%. It is found in Potato,
Chickpeas, Pork, Turkey and Beef amongst many others.
Vitamin B7 aka Biotin is an unusual vitamin containing an atom of
Sulfur as well as two of nitrogen, the first is heterocyclic within a 5-membered ring - a
Thiophene, the second heterocyclic within another 5-membered ring - an
Imidazoline (aka Ureido ring), and both rings are fused together. For good measure the moiety has a short Valeric Acid chain attached to the
Thiophene ring. To top it all, as well as being an acid, it is a ketone (the =Oxygen on the Imidazole ring). Quite an achievement for such a small molecule.
Biotin is water-soluble and works synergistically with other B-group vitamins, Coenzyme Q as well as with Carnitine. Biotin is a coenzyme for carboxylase enzymes (hence its former name Coenzyme R) and is essential to the synthesis of Amino Acids, Fatty Acids, and the amino acids
Valine and for the metabolism of Carbohydrates. Deficiency is rare because it occurs in many foods such as whole wheat,
Soybeans, Eggs and
Mushrooms and is also synthesized internally by intestinal bacteria. However, alcohol inhibits its absorption within the gut.
Raw egg whites contain the protein called
Avidin which can bind 4 molecules of Biotin completely disabling it. Folk consuming a lot of raw egg yolk can suffer Biotin deficiency. Mild Biotin deficiency can result in neurological and psychological symptoms such as depression, hallucination, lethargy, numbness and pins and needles of the extremities and seborrhoeic dermatitis whilst more severe deficiencies will result in loss of hair, brittle fingernails, conjunctivitis.
Biotin does not appear to be toxic in excess.
The so-called Vitamin B8 (
Adenylic Acid) was once thought to be a vitamin, but is not now considered so because the body can synthesize it itself from
glucose! However, many so-called 'health shops' persistently promote this as Vitamin B8.
Other Vitamins can also by synthesized within the human body, such as Vitamin B3 (Niacin) and Vitamin B7 (
Biotin), but not in sufficient amounts, so these are still called Vitamins.
Inositol, being CycloHexaneHexol, is just a hexane ring with six -OH groups attached to each of the 6 carbon atoms. It can form 9 possible stereoisomers, but myo-Inositol, with 4 cis-OH and only 2 trans-OH is the one most commonly found in foods - this being the most stable arrangement (the least energetic arrangement of -OH moieties, because of the way the molecule folds itself into the 'chair' arrangement whereby the -OH moieties are as far apart from each other as is possible). Inositol is a sugar alcohol, with a sweetness judged to be half that of sucrose. Inositol should not be confused with Inulin, another sugar synthesized by only some plants. Inositol occurs in many fruits especially oranges.
However, the hexaphosphate of inositol is found in plants and called
Phytic Acid (aka Inositol Hexa-kis-Phosphate, or IP6) and occurs together with Phytic Acid salts called
phytates, neither of which are digestible because humans lack the enzyme phytase, indeed, it is often said to be an 'anti-nutrient' because it interferes with the absorption of essential minerals such as Calcium, Magnesium, Iron and Zinc in the diet (see below about sequestration) potentially leading to mineral deficiencies if grains are your main diet. But ruminants do possess phytase and are able to digest Phytic Acid. Phytic Acid is not claimed to be a vitamin even by health shops. Phytic Acid occurs in grains and cereals especially in bran and in legumes. It is the principle storage reservoir for phosphate in plants. Catabolism of Phytol results in the release of a number of the phosphate moieties in Phytic Acid, to result in lower Inositol Polyphosphates, such as Inositol penta-Phosphate (IP5), Inositol tetra-Phosphate (IP4) and Inositol tri-Phosphate (IP3), etc as the plant uses the phosphate from this reservoir. Sprouting grains make especial use of the phosphate store in Phytates. Phytic Acid is also ubiquitous in the cells of mammals but is not obtained from the diet but rather produced in the kidneys by alteration of glucose to inositol which is then phosphated. Phytic Acid is a cofactor in DNA repair mechanisms (DNA contains a lot of phosphate moieties).
Variants of Phytates can sequester Uranium Nickel and other heavy metals and it can be used in soil and land remediation.
The hexanitrate of Inositol is used in many modern explosives and in solid propellants in rockets.
Vitamin B9 (aka
Vitamin M and
Vitamin Bc) is represented by both
Folinic Acid and
Folic Acid, with forms other than Folic Acid resulting in a higher 70% greater requirement above the 400µ-g/day. Folic Acid is sometimes called PteroylMonoGlutamic Acid, or Vitamin B10. The compounds are water-soluble and based upon a Pteridine ring which contains 4 endocyclic nitrogen atoms with a long side-group containing various moieties including a benzene ring. The normal requirement is 400µg/day but mothers may need extra supplements during pregnancy. Vitamin B9 is used within cells to synthesize both RNA and DNA and to prevent changes to DNA thereby preventing potentially cancerous DNA changes. It is also used in cell division to create new cells. Deficiency results in impaired ability to execute these functions, especially cell division, DNA replication and DNA repair. Folate is used to make both red and white blood cells, so deficiency will result in anaemia and reduced ability to fend off disease, as well as glossitis, diarrhoea, depression and confusion. Pregnant women require more folate than usual to prevent neural tube defects and brain defects in the developing fetus. Because it is water-soluble overdose is unlikely to cause much problem.
Folinic Acid differs from Folic Acid in that the pyridine moiety of Folic Acid has changed into something else, losing two of its 4 double bonds, the hydrogen atoms on the 2 lowest nitrogen atoms in the fused ring, and the addition of a CHO group on the second ring. It is a vitamer for Folic Acid and exhibiting the same level of Vitamin B9 activity. The salts of Folinic Acid are used adjuvant in cancer chemotherapy.
Salicylic Acid used to be thought to be a vitamin but it has since been found not to meet the two criteria for inclusion: That it should be essential for life and that it should not be synthesized by the body itself. The latter statement is sometimes qualified by 'should not be synthesized by the body in sufficient quantities' which sneaks some compounds into the exclusive club...
Vitamin B12 is an essential substance within the body and is required to make red blood cells. Deficiency of the vitamin causes pernicious anaemia, a debilitating illness.
The central cobalt complex is asymmetric (being the tetra-pyrrole ring called a
corrin ring - shown in purple). [The corrin ring is similar to the
porphyrin ring found in
cytochromes]. The single central cobalt atom has 6 bonds, 3 of which are coordinate bonds and holds a positive charge. Bonded to the cobalt atom is a diMethylBenzimidazole moiety (shown in blue) which bonds to a Ribose glycoside (in red) which in turn bonds to a phosphate (in green) which bonds to a propylamide which is bonded to back to the corrin ring (shown in purple). The corrin ring is adorned by two sorts of amides (4 of ethylamide and 2 of propylamide, shown in black).
The lone Cobalt atom in the very centre of this is co-ordinately bonded to 5 nitrogen atoms plus a radical, R, which in the case of the naturally occurring form of Vitamin 12, HydroxyCobalamin, is, you guessed, an -OH, hydroxy moiety. HydroxyCobalamin is produced by bacteria and also occurs in fish, shellfish, meat, liver, poultry, milk and eggs (but the bioavailability in eggs is low at only 9% whereas in fish, poultry and meat it is 40-60%). Vitamin B12 is rare in plants and vegetarians are at risk of deficiency. Within the human body after consumption it is converted into several vitamers of Vitamin B12. MethylCobalamin, where R=CH3, (which is also produced by some bacteria) and R=CN (CyanoCobalamin) or R=Adp (AdenosylCobalamin) all behave as Vitamin B12, albeit with slightly differing properties. Of these Cobalamins, only CyanoCobalamin does not occur naturally in the body.
MethylCobalamin is also necessary in the human body for the synthesis of Methionine from
HomoCysteine, an amino acid. Methionine is important in the methylation of genes which helps inhibit cancer, prolongs life, and is essential for human development.
MethylCobalamin can also bio-methylate some heavy metals by the catalytic powers of the coordinately-bonding cobalt atom it contains. Heavy metals such as Mercury to produce the highly toxic MethylMercury Hg+CH3 which is produced in the sea and other aquatic systems such as rivers, streams, ponds, wetlands, soils and sediments by the action of MethylCobalamin on a source of metallic mercury, such as volcanoes, weathering of mercury-containing rocks and from human sources such as broken thermometers and disposed mercury-containing products.
HydroxyCobalamin (in large amounts and administered also with
Sodium Thiosulfate) can be used to treat cyanide poisoning, where the Hydroxy moiety has a great affinity for any cyanide radical (CN) and can snatch it from the Haemoglobin where it is preventing that from taking up oxygen in the lungs and swaps the -OH moiety on HydroxyCobalamin for the -CN moiety on Haemoglobin, becoming CyanoCobalamin in the process. The cyanide is safely sequestered away and the human can oxygenate his blood once more, rather than dying of asphyxiation.
Vitamin B12 deficiency is potentially severe and can lead to irreversible damage to the brain and central nervous system. Symptoms include anaemia, peripheral neuropathy, forgetfulness, fatigue, depression, and even mania and psychosis. It is more likely to occur in the elderly because absorption of Vitamin B12 by the gut decreases with age.
Vitamin C aka Ascorbic Acid, which contains a
furanone ring and is a
lactone. Vitamin C is not one specific molecule, but instead refers to a number of vitamers that have Vitamin C activity, L-Ascorbic Acid being only one. Others involved are some of the salts of L-Ascorbic Acid. To work well, these are usually converted to the most active form of the vitamer, Dehydro-Ascorbic Acid within the body.
Vitamin C is required by the body in order to build collagen and as a cofactor for the enzymes Prolyl hydroxylase and Lysyl hydroxylase. A shortage of Vitamin C leads to a condition called Scurvy, which will eventually result in a low red-blood cell count. Death can result if deprivation of sufficient Vitamin C is prolonged. It is now rare but can occurs more commonly in alcoholics and those with mental disorders, unusual eating habits or from dialysis. It used to be common in long-distance seafarers due to a lack of fresh citrus fruit, which contains high amounts of it. Vitamin C also occurs in blackcurrants, strawberries and kiwifruit, less so in vegetables such as
Spinach and Kale. Cooking gradually destroys Vitamin C, the higher the baking temperature the more so, although the water within the vegetables will tend to limit their internal temperature to little more than 100C (until they are desiccated).
There are 5 differing Vitamin D's, Vitamin D1 to Vitamin D5. However not one of these is actually the active hormone responsible for Vitamin D effects, for that role belongs to Calcitrol (shown as the last item in the Vitamin D section).
Deficiency of Vitamin D (which is obtained from both food and from exposure of the skin to the Sun) can cause osteomalacia (in children it is called rickets) and softening of bones due to reduced bone mineralization.
Vitamin D overdose from sun exposure is not possible because there are in-built mechanisms in the body to prevent this (but these mechanisms will not prevent sunburn!). That due to supplementary high doses of Vitamin D can lead to toxicity, but that is rare. Symptoms of overdose are anorexia, nausea, vomiting, polyurea (excessive urination), polydipsia (excessive thirst), muscle weakness, insomnia, nervousness, pruritis (itchy skin) and ultimately kidney failure!
Vitamin D is a prohormone rather than a vitamin in the strictest sense. When consumed the body metabolises it into a number of differing substances which act hormonally. There are over 200 hormonal effects of Vitamin D acting within the body.
Vitamin D1 is a mixture of two compounds,
ErgoCalciferol, the latter is also assigned as Vitamin D2. This must be due to historical happenstance when separating or identifying compounds was not nearly so easy as it is now. Apart from Lumisterol (which is a steroid), all the vitamin D chemical compounds are
seco-steroids, which are steroids where one of the rings has been broken (and in the case of those shown here under Vitamin D, it is the second ring up from the bottom which has been broken). Ergosterol is a stereoisomer of Lumisterol (directly above). Ergocalciferol is formed from Ergosterol by the breaking open of the second ring from the bottom of Ergosterol and the one shift moving of two electrons on the resulting bridge that is created between the two ring systems. The breaking of the ring is initiated by ultraviolet photons in sunlight.
Vitamin D2 is
ErgoCalciferol which is also a one-half member of Vitamin D1 (see above). ErgoCalciferol is synthesized from Ergosterol.
The main forms of Vitamin D are Vitamin D2 (Ergocalciferol) and Vitamin D3 (Cholecalciferol). Both are equally effective as manufactured Vitamin D supplements, taken orally.
Ergosterol is contained within the skin of a person. When ultraviolet light strikes ergosterol in the skin, Ergosterol is transformed into Vitamin D3, Cholecalciferol. The skin is where most Vitamin D is synthesized. There are feedback mechanisms preventing the production of too much Vitamin D in the skin and thus preventing humans from overdosing on sunlight-produced Vitamin D2. But this limiting mechanism does nothing to prevent someone from overdosing on ingested Vitamin D3 (Cholecalciferol) supplements.
Both Vitamin D2 (Ergocalciferol) and Vitamin D3
Cholecalceferol are found in some mushrooms, where it is produced by the action of UV light on the Ergosterol within them. Vitamin D2 (Ergocalciferol) is also found in plants such as Alfalfa and in some Lichens, such as
Vitamin D3 is
Cholecalceferol which is synthesized from
7-DehydroCholesterol within the skin when that is exposed to sunlight, specifically UV-B radiation.
However, Cholecalciferol itself is actually inactive until it is converted to its active form,
Calcitrol (shown below as the last item under the Vitamin D banner). However, Cholechalciferol itself is very sensitive to UV radiation in sunlight and which itself is claimed to get converted into so-called 'sura-sterols' (your Author has been unable to find out what 'sura-sterols are!) which are then themselves converted (irreversibly) into Ergosterol (shown above under the Vitamin D2 heading).
Vitamin D4 is
22-DihydroErgocalciferol, which is schematically like Vitamin D2 but with a single bond replacing the double-bond in the upper side chain. Vitamin D4 is also found in food but it is an ineffective form of Vitamin D.
Vitamin D5 is
SitoCalciferol which is synthesized from
7-dehydroSitosterol. SitoCalciferol is a synthetically produced form of Vitamin D, and is an analogue of Vitamin D3, Cholecalciferol, (the only difference being an additional ethyl group on the upper side-chain). Vitamin D5 is the safest form of Vitamin D to take as supplements (out of the over 1500 variants of Vitamin D which scientists produced artificially and tested) and is less toxic in overdose than Vitamin D3. Two other artificially manufactured forms of Vitamin D are Vitamin D6 and Vitamin D7, but Vitamin D5 is the least toxic of all, and has undergone several tests to test its efficacy for both the prevention and treatment of cancer.
It has been shown epidemilogically that those people who had either an ample source of Vitamin D in their diet or who had high levels of sunlight-generated Vitamin D levels in their skin were less likely to develop cancer. So Vitamin D5 is now being considered as one of the possible treatments for cancer, especially colon cancer. Vitamin D3 had previously been trialled but the toxicity of Vitamin D3 at the elevated levels necessary for cancer treatment ruled it out.
For treating vitamin D deficiency, supplements of either D2 and/or D3 are available, although D3 is more effective. It is only when high doses are required to treat cancer and other diseases where Vitamin D5 may be required instead.
All the previous Vitamin D's are not actually the active form,
Calcitriol is the real active form to which all these other Vitamin D's are converted, given the chance. It has 3 hydroxy groups, the one at the bottom left belonging to Cholecalciferol from which it is derived.
1,25-DiHydroxyCholecalciferol (aka Calcitrol) is the hormonally active metabolite which increases blood calcium ion (Ca2+) levels which has numerous effects such as helping the absorption of calcium from the intestinal tract, increasing liver re-absorption of calcium to prevent calcium loss in urine and releasing calcium from bone. If the dietary intake of Vutamin D is too high then the bones can be weakened, which is also what happens when there is insufficient Vitamin D in the diet. Thus the intake of Vitamin D is a balancing act.
These compounds all have an aliphatic side-chain attached to a
Chromane (aka BenzoDihydroPyran) moiety (the fused ring on the left) with a hydroxyl side-group, making that a
Vitamin E occurs in 8 differing forms, four each of the
Tocotrienols. The difference between the
Tocopherols and the
Tocotrienols are that the Tocotrienols have three double-bonds on the aliphatic side-chain, hence the 'trien'. The only difference between the α-, β-, γ- and δ- forms being the number of methyl groups and their position on the benzene ring (which is at the far left). With their long aliphatic chain all these 8 forms are fat soluble. The 4 tocopherols each have an E-number designation, E306, E307, E308 and E309 α- to δ- forms respectfully. The Tocopherols are the most studied, but there is growing interest in the properties of Tocotrienyls.
All 8 shown here are depicted with 3 methyl groups each on the aliphatic side chain, but they can have a variable number of methyl groups, so in theory dozens of stereoisometric forms of each could exist, especially if each stereocentre is taken into account. However, only a certain few stereoisomers are actually synthesized by plants. But of those, all exhibit Vitamin E activity except a certain few (those few with 2S chirality at the end of the aliphatic side-chain).
Vitamin E is found in Maize, Asparagus,
Coconut and in the oils made from Annual Sunflower,
Peanut, Poppy Seeds.
Vitamin E deficiency causes neurological and neuromuscular problems as well as anaemia due to oxidative damage to red blood cells. Vitamin E is an anti-oxidant. The synthetic esters of these Tocotrienyls and Tocopherols (where the -OH moiety is replaced by, for instance, acetate, CH3OOH-) are more stable and easier to use in Vitamin E supplements. The daily requirement is about 15mg. Higher amounts of Vitamin E increase the risk of internal bleeding.
Vitamin K's comprise both
Vitamin K1) and the
Vitamin MK-4 and
Vitamin MK-7 which are sub-types of
Vitamin K2. Phylloquinone is a
NaphthoQuinone with a long
aliphatic side-chain, the first of which is an isoprene unit (with a double bond) whilst the other 3 units are of
Vitamin K are fat-soluble minerals coming in 2 types, K1, PhylloQuinone and K2 the MenaQuinones, MKn, where n represents the number of Isoprene units are concatenated in the side-chain. Vitamin K is essential to the synthesis of certain proteins, for the binding of calcium in bones and teeth, and for coagulating blood when it is leaking out of the body. A shortfall of Vitamin K results in weaker bones and uncontrolled bleeding, both internal and external (in the case of a puncture wound). Bacteria in the gut can convert Vitamin K1 to Vitamin K2, and can also add extra isoprene units to produce MenaQuinones MK-7 through to MK-11.
PhytoNadione) is synthesized within plants especially. It is directly involved in the process of photosynthesis, functioning as an electron acceptor and forming part of the electron transport chain of Photosystem I. Naturally the highest concentrations are to be found in the green parts of plants, especially the leaves.
MenaQuinones are all subtypes of Vitamin K2, which has a semi-conjugated chain of
isoprene units where the number of isoprene units is between 1 and n, where n can be any (reasonable) number. Shown are the more abundant MenaQuinone MK4 and MenaQuinone MK7 (possessing 4 and 7 Isoprene units).
There exist also 3 synthetic forms of Vitamin K, Vitamin K3 (aka Menadione, which exhibits some toxicity) and non-toxic forms Vitamin K4 and K5.
Recommended intake of Vitamin K (in any form) for adults is between 90-120µg/day. For patients on Warfarin (used as blood anti-coagulant) Vitamin K will interfere with the action of Warfarin making the drug less effective, but Warfarin is often prescribed with known amounts of Vitamin K (and the Warfarin dose increased accordingly) so that dietary intake of Vitamin K has less effect on the anti-coagulating effect of Vitamin K.
Of the edible plants, Vitamin K is contained mainly within the green parts of Asparagus, Broccoli,
Turnip Greens. Absorption of Vitamin K is often greater when cooked in oils or butter because Vitamin K is fat-soluble.
Deficiency is not usual in average diets, but alcohol-induced liver damage can impair uptake, and lead to deficiency in alcoholics. Those on Salicylates, Barbiturates or Cefamandole can also suffer Vitamin K deficiency. It is not known to be toxic in higher doses, although some people are allergic to supplementary intake of Vitamin K.
The above is mostly about the modus-operandi and function of Vitamins in Mammals. But there does not seem to be as much coverage findable on what function all these vitamins perform within the plants in which they are found. One thing is (almost) certain: they are not there for altruistic reasons; they must all also perform some (vital?) function for the plant(s). But with the plants being very different from each other in numerous ways, that function may vary between plants. And not all plants contain as many different vitamins as does Kale, their concentration may be much lower, or include other human vitamins. The reader is encouraged to follow the links shown for any information on the purpose of human vitamins within plants themselves. Some are hormones within plants (such as the non-vitamin B11 (Salicylic Acid).