Most vitamins are produced by plants and micro-organisms, but they may be concentrated in some animal tissues
A vitamin is a substance that is needed by the body, and which cannot be synthesised in necessary amounts, so it must be provided in the diet. It is therefore defined in the context of certain animal groups.
The same substances may be produced in adequate amounts in other animal groups, or in plants, but they are not termed vitamins in this context.
Vitamins perform a variety of functions in the body, mostly to do with transfer of energy. They can act as
Role in body
- coenzyme in breakdown of glucose and amino acids (releasing energy)
- involved in biosynthesis of the neurotransmitter acetylcholine and gamma-aminobutyric acid (GABA)
Deficiency causes
Beri-beri
symptoms include severe lethargy & fatigue, + complications affecting cardiovascular, nervous, muscular, and gastrointestinal systems
Amount required
mg/day
[RDA]
1.4
Good sources
Yeast, cereal grains e.g. rice [but removed when processed into white rice], beans, nuts, and meat, esp. pork
Role in body
Precursor to
FAD and
FMN (involved in a number of biochemical transformations to do with energy, as well as
other B group vitamins).
Also acts as an
antioxidant
Deficiency causes
Inflammation of the lips, lining of mouth and tongue, mouth ulcers, cracks at the corners of the mouth, and a sore throat or more general dry and scaling skin, fluid in the mucous membranes. Eyes may also be itchy/watery/bloodshot, and sensitive to bright light.
Amount required
mg/day
[RDA]
0.3-1.3
Good sources
Milk and dairy products, Lean meats, Eggs, Green leafy vegetables, Legumes, Nuts, Yeast
Flours and cereals are often
fortified with riboflavin.
Riboflavin is destroyed as a result of exposure to light.
Role in body
Precursor to
NAD and
NADP - hydrogen and electron acceptors in respiration and photosynthesis.
Niacin is involved in the production of various steroid hormones in the adrenal glands. It is also thought to help improve (blood) circulation and reduce atherosclerosis.
It has been found that in higher doses, niacin (but not nicotinamide) blocks the breakdown of fats and increases the level of high-density lipoprotein (HDL) or "good" cholesterol and lowers low-density lipoprotein (LDL) in blood.
Deficiency causes
Pellagra
cracked, scaly skin, dementia, and diarrhea
Amount required
mg/day
[RDA]
14-18
Good sources
Yeast and yeast products, most meats, many fruits and vegetables
Maize : (sweet)corn may prove to be deficient in niacin unless
cooked in alkaline solution
In the liver, niacin can also be synthesized from tryptophan, an essential amino acid. This conversion requires riboflavin (vitamin B2), pyridoxine (vitamin B6) and iron.
Role in body
Precursor to Coenzyme A which transfers smaller molecules in the process of respiration and in other processes
Many other possible functions have been suggested.
Deficiency causes
Symptoms very rare but perhaps seen in extreme malnourishment (victims of famine and maltreated prisoners of war):
extreme tiredness due to reduced energy metabolism, neurological conditions e.g numbness due to reduced acetylcholine synthesis, perhaps increased sensitivity to insulin because receptors are not deactivated by acylation.
Amount required
mg/day
[RDA]
6
Good sources
Pantothenic means everywhere, and this is found in nearly every food, especially whole-grain cereals, vegetables (legumes), fruit, eggs and meat
Role in body
Precursor to pyridoxal 5'-phosphate (PLP), which acts as coenzyme in the synthesis of amino acids and neurotransmitters, and other reactions
Deficiency causes
Muscle weakness, nervous problems (irritability, depression, difficulty concentrating, and short-term memory loss)
Amount required
mg/day
[RDA]
5-25
Good sources
Meat, fish, dairy products, vegetables, cereals - especially wheat germ and whole-grain flour, and nuts.
Vitamin
+ link to 3-D model
B7
Biotin
(also sometimes known as
vitamin H)
Role in body
Essential cofactor of enzymes involved in carboxylation reactions, e.g. pyruvate carboxylase and acetyl-CoA carboxylase, which catalyze key reactions in gluconeogenesis, fatty acid metabolism, and amino acid catabolism.
Deficiency causes
Main cause of deficiency: Raw egg white contains a protein avidin which absorbs biotin, making it unavailable. Cooking deactivates it, and does not damage biotin.
In various food sources, biotin is bound to a protein which must be broken down before it can be absorbed.
Symptoms of biotin deficiency: Hair loss , conjunctivitis, facial and other rash, various neurological symptoms.
Amount required
mg/day
[RDA]
(uncertain)
Good sources
Liver, green leafy vegetables, egg yolk.
Intestinal bacteria produce enough biotin for most people.
Role in body
- Involved in synthesis and repair of DNA, important in cell division, hence:
- necessary for the formation of healthy red blood cells - in conjunction with vitamin B12 (and iron)
- helps reduce the risk of central nervous system defects such as spina bifida in unborn babies
Deficiency causes
Macrocytic or megaloblastic anemia
Neural tube defects in developing embryos
plus other possible disorders, including cancer.
Amount required
mg/day
[RDA]
0.2
(double this in pregnancy)
Good sources
Many leafy vegetables: broccoli, brussels sprouts, spinach, and also legumes: peas, beans, lentils, chickpeas. In many countries different cereal products e.g. bread, flour, pasta and breakfast cereals are fortified with it.
It is also available from animal sources: liver, kidney, egg yolk, and yeast and associated products.
Role in body
Necessary for the formation of healthy red blood cells - in conjunction with vitamin B9 (and iron)
also involved on fatty acid synthesis and energy metabolism
Deficiency causes
Brain and nervous system damage: fatigue, depression, and poor memory.
Megaloblastic anemia
Vitamin B12 deficiency can be caused by the metabolic disorder pernicious anemia, which is an autoimmune disease which attacks certain cells of the stomach so that gastric intrinsic factor is not produced. This is necessary for the absorption of vitamin B12 in the small intestine; in its absence B12 in not absorbed from food that has been eaten.
Amount required
mg/day
[RDA]
0.002 - 0.003
(2-3µg )
Good sources
Meat, especially liver, eggs, milk products, shellfish
Not produced in plant sources
Role in body
Needed for the
formation of collagen in connective tissue and for healthy teeth, gums and blood vessels;
also as an
antioxidant
Deficiency causes
Scurvy
Gingivitis (inflammation of the gums) and bleeding gums; rough, dry, scaly skin; decreased wound-healing rate, easy bruising; nosebleeds; decreased ability to ward off infection
Amount required
mg/day
[RDA]
40-90
Good sources
Fruit and vegetables:
citrus, capsicums (peppers), strawberries, blackcurrants,
potatoes (esp skins), broccoli, brussels sprouts
Role in body
Converted into calcitriol which circulates in the blood and functions as a hormone which increases the uptake of calcium (Ca
2+) from the gut into the blood
Deficiency causes
Rickets (in children), osteomalacia (in adults) - bone deformities such as bowed legs caused by softening of the bone, possibly leading to curvature of the spine and thickening of the ankles, wrists and knees
- may also be caused by lack of the mineral calcium in the diet.
Amount required
mg/day
[RDA]
0.005 - 0.015
(5-15µg)
[Some sources suggest wider range - possibly due to lifestyle differences]
Good sources
Liver, fish, cod liver oil
Vitamin D is also produced in the skin by the action of ultraviolet light on various lipid molecules such as cholesterol. The intensity of ultraviolet light varies in different areas of the world, and this production is also affected by skin colour and amount of skin covered by clothing.
As such it may be an issue with dark skinned people in certain latitudes, or those who do not go outside in the sun or expose themelves to it.
Role in body
Antioxidant: it acts as a peroxyl radical scavenger, in conjunction with vitamin C, and prevents the oxidation of polyunsaturated fatty acids
It also acts as an enzymatic activity regulator in smooth muscle growth and has an effect on gene expression, specifically those responsible for the repair of wounds and regeneration of the tissue damaged during atherosclerosis.
Deficiency causes
Neuromuscular problems due to poor nerve conduction
possibly heart disease and atherosclerosis
Vitamin E deficiency is quite rare, and more likely to be caused by problems in the absorption of fat than by inadequate diet.
Good sources
Plant oils e.g. wheat germ, sunflower
Amount required
mg/day
[RDA]
3-4
Role in body
Cofactor in the formation of coagulation factors II (prothrombin), VII, IX, and X by the liver.
Also required for bone protein formation and calcification.
Deficiency causes
Problems with blood clotting and loss: anaemia, bruising, bleeding from the nose or gums, and heavy menstrual bleeding in women. Greater chance of "all-cause mortality", coronary heart disease, arterial calcification and osteoporosis.
Amount required
mg/day
[RDA]
0.075
(75µg)
Good sources
Green leafy vegetables: broccoli and spinach
vegetable oils, cereals
meat and dairy foods (small amounts) -
higher amounts in yoghurt and cheese
Minerals from a human/animal perspective
Some minerals are incorporated into major parts of the body such as the skeleton and teeth, and some form important parts of cells. Others are essential components of the blood and body fluids. The amount of each mineral required may vary according to age and lifestyle.
Certain minerals also participate in some of the same metabolic processes that vitamins are known for, so the distinction here is not so clear.
There is a subcategory of minerals that are needed in very small quantities: these are called trace elements.
Mineral
(element)
Role in body
Deficiency causes
Good sources
Amount required
mg/day
[RDA]
Mineral
Calcium
(Ca2+ ions)
Role in body
A (solid) component of bones and teeth (enamel)
-
in conjunction with phosphate and other ions
[Bones also have an organic matrix - mainly collagen]
Ca
2+ ions are
- participants in nerve-muscle interaction and muscular contraction
- required for blood clotting
- involved in many enzyme reactions
Deficiency causes
Osteoporosis - weakening of the bones (more common in women after the menopause)
Rickets (developing bone malformation in children) and osteomalacia (loss of skeletal calcium in adults) may be due to calcium deficiency, vitamin D (Calciferol) deficiency, or both.
Calcium may be withdrawn from bones and teeth ('resorption') to provide calcium ions for other body functions (including baby's bone formation in pregnancy)
Amount required
mg/day
[RDA]
750-800 (adults)
1000 (adolescents)
300-700 (0-9yrs)
Good sources
Milk, cheese and other dairy products, eggs, canned fish with bones (salmon, sardines),
green leafy vegetables, nuts, seeds, tofu
Finely ground chalk (creta preparata) may be added to white bread flour.
Carnivorous animals obtain calcium from bones consumed.
Note: calcium uptake is mediated by vitamin D (calciferol) - which may be limiting under certain conditions (reduced exposure to sunlight)
Mineral
Phosphorus
(as phosphate ions
PO43-)
but
HPO42- and H2PO4-
are more common in pH 5-9
Role in body
(Solid) component of bones and teeth (mostly as calcium hydroxyapatite)
Component of nucleic acids (DNA, RNA, nucleotides, ATP etc)
All cell membranes are phospholipids
Phosphate groups are involved in activation of carbohydrates in respiration and photosynthesis,
and also in control of enzymic processes and gene expression (phosphorylation)
Deficiency causes
Rickets, osteomalacia, osteoporosis
See above
Amount required
mg/day
[RDA]
700
Good sources
'Protein foods': milk and milk products, meat and pulses, such as beans, and lentils, nuts, and whole grains. Smaller amounts in vegetables and fruit.
Mineral
Iron
[iron(II) ions - 'ferrous ions' - (Fe2+)
& iron (III) ions- 'ferric ions' - (Fe3+)]
Role in body
Part of the haemoglobin molecule in red blood cells,
myoglobin in muscle cells,
cytochromes and catalase in all body cells
Deficiency causes
Anaemia, pale complexion, fatigue, low energy levels, rapid heartbeat, shortness of breath
May be compounded by menstrual blood loss in females
Amount required
mg/day
[RDA]
18 (women)
8 (men)
Good sources
Meat, seafood, liver, green vegetables, pulses
Breakfast cereals may contain finely divided iron particles
Mineral
Iodine
(iodide ions I-)
Role in body
Part of molecules of thyroid hormones triiodothyronine T3 (more active) and tetraiodothyronine T4 - thyroxine
These hormones control the basal metabolic rate of body cells.
Deficiency causes
Goitre - enlargement of thyroid gland in neck
to maximise conversion of dietary iodide to thyroglobulin (precursor to T3 and T4).
This condition is most common in areas furthest from the sea, and so least likely to consume seafood.
Amount required
mg/day
[RDA]
150 µg
Good sources
Seafood,
seaweed
(seawater contains 60 ppb of iodide, so these organisms absorb and concentrate it).
Iodide may be added to salt ('iodised salt')
Radioactive iodine I-131
Iodine-131 is an isotope of Iodine,
a major fission product of uranium and plutonium, produced in nuclear power plants and atomic bombs.
It is a beta-emitter with a half-life of 8 days, and may cause cancer, especially of the thyroid gland in which it concentrates after absorption.
If released into the environment, it represents a significant health hazard.
This was seen in atomic bomb tests in the 1950's, as well as after the Chernobyl nuclear power plant disaster in 1986 and in the Fukushima Daiichi nuclear crisis after an earthquake in 2011.
Control measures
In the event of a nuclear disaster, authorities may distribute uncontaminated, normal iodine (I-127) in the form of potassium iodide tablets.
These contain enough iodine to saturate the body's reserves (130mg per day), so radioactive iodine is not stored (in the thyroid) and is more likely to be excreted in urine.
Use in medical context
Iodine-131 may also be used to control thyroid cancer. It kills cancerous tissue here effectively without spreading significantly to other parts of the body.
Mineral
Potassium
(K+ ions)
Role in body
In blood and all body fluids, to establish an osmotic balance, (together with sodium and chloride ions). This may be called water-electrolyte balance.
Actively transported into cells, especially nerve cells.
Important in nerve and muscle cell activity.
Deficiency causes
Hypokalemia (blood serum levels below 3.5 mmol/L)
Symptoms may include tiredness, cramps, weakness, constipation and abnormal heart rhythm.
Good sources
A variety of fruit, meat and vegetables
Amount required
mg/day
[RDA]
3,500-4,700
(highest of all minerals)
needed to balance loss in urine
Mineral
Sodium
(Na+ ions)
Role in body
In blood and all body fluids, to establish an osmotic balance, (together with potassium and chloride ions) - water-electrolyte balance.
Actively transported out of cells, especially nerve cells. The main partner in co-transport of other ions across membranes.
Important in nerve and muscle cell activity.
Deficiency causes
Hyponatremia (blood serum sodium concentration below 135 mmol/L)
- may result from excessive sweating in high-endurance sport activities!
Amount required
mg/day
[RDA]
2400 - equivalent to 6g of salt (sodium chloride)
Good sources
Most foods contain some sodium, but added salt is a recurring point of contention.
Many processed foods contain excessively high levels of salt as a flavour enhancer and preservative.
Excess consumption can result in high blood pressure, which may cause strokes and heart attacks.
Mineral
Chloride
(Cl- ions)
Role in body
In blood and all body fluids, to establish an osmotic balance, (together with potassium and sodium ions) - water-electrolyte balance.
Chloride ions (along with hydrogen ions) are secreted by parietal (oxyntic) cells in the gastric glands of the stomach and this hydrochloric acid lowers the pH of the stomach contents, making proteins more accessible to the enzyme pepsin.
Deficiency causes
No specific effect
Amount required
mg/day
[RDA]
3400 - equivalent to 5g of salt (sodium chloride)
Good sources
Most foods contain some chloride in conjunction with sodium, but added salt is a recurring point of contention.
Mineral
Magnesium
(Mg2+ ions)
Role in body
Required in many enzyme-controlled reactions, especially in conjuction with ATP (and DNA and RNA)
Deficiency causes
Often no symptoms but may include the following:
Hyperexcitability, muscular symptoms (cramps, weakness), fatigue, loss of appetite, apathy, confusion, insomnia, irritability, poor memory, and reduced ability to learn
Most people do not include enough in their diet, and other lifestyle factors may reduce the availability of magnesium.
Amount required
mg/day
[RDA]
270-300
Good sources
Leafy green vegetables (chlorophyll contains magnesium), pulses e.g. soybeans, nuts, and fruit
Mineral
Molybdenum
(Mo2+ ions)?
Role in body
Part of several oxidase enzymes:
xanthine oxidase
aldehyde oxidase
sulphite oxidase
Deficiency causes
Molybdenum deficiency!
Amount required
mg/day
[RDA]
0.045
[trace element!]
Good sources
Legumes, whole grains, nuts
Other elements, (possibly) required in smaller amounts
Sulphur
Zinc
Chromium
Manganese
Copper
Selenium
Boron
Silcon
Arsenic
(Cobalt) - part of (cyano)cobalamin (vitamin B12)
Other related topics on this site
This topic has connections with other topics on this website:
Inorganic ions
Plant mineral nutrition
Web links
Vitamin
From Wikipedia, the free encyclopedia
Vitamins and minerals from NHS Choices
Vitamin and mineral requirements in human nutrition
Second edition Authors:
World Health Organization, Food and Agricultural Organization of the United Nations
Other vitamins and minerals
List of micronutrients