Iron is a component of a number of proteins including haemoglobin. Haemoglobin is important for transport of oxygen to tissues
throughout the body.
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Thiamin is a water-soluble substance that occurs in free or phosphorylated forms in most plant and
animal tissue.
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Molybdenum is found in plant foods and reflects the soil content in which they grow. Legumes are
major contributors of molybdenum in the western diet, as are grain products and nuts.
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Recommended carbohydrate intake in adults and children is 45-65% of
dietary energy intake. There is believed to be an increased risk for Coronary Heart Disease at high carbohydrate intakes (>65%) and increased risk of obesity with low carbohydrate, high fat intakes (<45%).
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Vitamin D occurs in two forms. One is produced by the action of sunlight on skin (D 3 or cholecalciferol)
and the other is found in a limited range of foods (D 2 or ergocalciferol).
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It has been postulated that diets high in fibre have a lower energy density and may therefore help in moderating obesity.
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Manganese deficiency in animals is associated with impaired growth, reproductive function and
glucose tolerance as well as changes in carbohydrate and lipid metabolism. Manganese deficiency also interferes with
skeletal development.
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Water fills the spaces in and between cells and helps
form structures of large molecules such as protein and glycogen. Water is also required for digestion,
absorption, transportation, dissolving nutrients, elimination of waste products and thermoregulation.
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Vitamin B6 is found in a wide range of foods including organ meats, muscle meats, breakfast cereals,
vegetables and fruits.
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It has been hypothesised that poor
chromium status contributes to the incidence of impaired glucose tolerance and type II diabetes which
has led to interest in a potential role for chromium supplements in type II diabetes.
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Niacin is involved in energy metabolism,
DNA repair and calcium mobilisation. It functions as part of the intracellular respiration system and with
enzymes involved in oxidation of fuel substrates.
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Ingestion of fluoride in the pre-eruptive development of teeth has the effect of reducing caries due to
uptake of fluoride by enamel crystallites and formation of fluorohydroxyapatite.
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Haem iron is more bioavailable to humans than the non-haem. The presence of other nutrients such as vitamin C and organic acids such as citric, lactic or malic acid
can increase the absorption of non-haem iron.
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A seasonal variation in vitamin D levels occurs in Australia. In the
Geelong Osteoporosis Study, the mean vitamin D levels for winter were 58 nmol/L compared with
70 nmol/L in summer
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The parent fatty acid of the
n-3 series is alpha-linolenic acid (ALA). ALA primarily functions as a precursor for the synthesis of EPA, which in turn forms DHA (EPA and DHA are Long-Chain n-3 fatty acids)
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The potential role of selenium in cancer prevention has been assessed in humans. One prospective
study of 34,000 men using a nested case-control study design showed that high selenium intakes were
protective against prostate cancer.
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Molybdenum is absorbed very efficiently over a wide range of
intakes. No clear deficiency syndrome has been seen in animals even with
major reductions in molybdoenzymes.
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Because of its role in energy metabolism, niacin
requirements are, to some extent, related to energy requirements.
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Clinical deficiency of Vitamin B6 is rare. The symptoms of deficiency include seborrhaeic dermatitis, microcytic anaemia, convulsions, and
depression and confusion
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Vitamin B6 acts as a coenzyme in the metabolism of amino acids, glycogen
and sphingoid bases.
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The major role of vitamin E is to protect polyunsaturated fatty acids from oxidation. It acts as
an anti-oxidant in the lipid phase of cell membranes.
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Deficiency of niacin causes the disease pellagra which is associated with inflammation of the skin on
exposure to sunlight, resembling severe sunburn except that the affected skin is sharply demarcated. Pellagra is the disease of 'three Ds', namely dermatitis, diarrhoea and (in
severe cases) delirium or dementia.
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The major sources of Riboflavin are milk and milk products and fortified breads and cereals.
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Vitamin C, in addition to providing its own benefits, interacts with other nutrients. It aids in the absorption of iron and copper, the maintenance of glutathione in the reduced form, the regeneration, or sparing, of alpha-tocopherol and the
stabilisation of folate.
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The main source of vitamin E is fats and oils. It is also found in some vegetables, in the fats of meat,
poultry and fish and, to lesser degrees, in cereals and dairy foods.
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A 10-year study of skin cancer in the US initially found no effect of supplemental selenium at 200 μg/
day on basal cell or squamous cell skin cancer, but significant reduction in total cancer and cancers of
the prostate, lung and colorectum.
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Protein occurs in all living cells and has both functional and structural properties. Amino acids,
assembled in long chains, are the building blocks of protein.
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Copper is widely distributed in foods with nuts and seeds being major
contributors. Wheat bran cereals and whole grain products are also good sources.
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Saturated fats are found mainly in animal-based foods. They are the
main type of fatty acids found in milk, cream, butter and cheese, meats from most of the land animals,
palm oil and coconut oil as well as in products such as pies, biscuits, cakes and pastries.
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The reported health effects of chronic mild dehydration and poor fluid intake include
increased risk of kidney stones, urinary tract cancers, colon
cancer as well as diminished physical
and mental performance.
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Dietary intake of iron at levels found in some supplements can decrease zinc absorption, which is
of particular concern in the management of pregnancy and lactation.
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Avidin, a
protein found in raw egg white, binds biotin in the gut and prevents its absorption. Although rare, biotin deficiency has been seen in people who consume raw egg white over long
periods.
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Most of the early signs of deficiency are neurologic or neuromuscular defects that may develop with time into anorexia, nausea, muscular
weakness, lethargy, weight loss, hyper-irritability, hyper-excitability, muscular spasms, tetany and finally
convulsions.
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Choline is widely distributed throughout the food supply. Milk, liver, eggs and peanuts are particularly good sources. Wheat germ and
dried soybeans are good sources of choline for vegetarians.
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Functional indicators of iron deficiency may include reduced physical work capacity, delayed
psychomotor development in infants, impaired cognitive function, impaired immunity and adverse
pregnancy outcomes.
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Alcohol intakes
below about 5% of dietary energy are recommended.
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Osteoporosis is one of the major causes of morbidity amongst older Australians and New Zealanders,
particularly postmenopausal women.
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Manganese is an essential element involved in formation of bone. It is also involved in the metabolism
of carbohydrate, cholesterol and amino acids.
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The nine indispensable or essential amino acids, defined as those that the body is unable to synthesise
from simpler molecules, are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine,
tryptophan and valine.
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Energy is not a nutrient but is required in the body for metabolic processes, physiological functions,
muscular activity, heat production, growth and synthesis of new tissues.
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Sodium is important for maintaining the membrane
potential of cells and for active transport of molecules across cell membranes.
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Amino acids are used for the
synthesis of body proteins and other metabolites, and can also be used as a source of dietary energy.
The proteins of the body are continually being broken down and resynthesised in a process called
protein turnover.
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Leafy green vegetables, vine fruit such as tomatoes, cucumbers, zucchini, eggplant and pumpkin,
and root vegetables are particularly good sources of Potassium. It is also moderately abundant in
beans peas, tree fruits, milks, yoghurts and meats.
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With current food supplies
and patterns of eating, it is almost impossible to obtain sufficient vitamin D from the diet alone.
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In excess, Manganese can interfere with iron absorption.
Manganese is excreted rapidly into the gut through bile and lost primarily in faeces. Low bile excretion can therefore increase the potential for manganese toxicity
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Linoleic Acid, the most common Polyunsaturated fatty acid, is involved in the regulation of gene expression. Linoleic Acid is also found as a structural component of cell membranes and is important in
cell signalling.
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Phosphorus is the second most abundant inorganic element in the body and is a part of many important
compounds. Phosphorus as phosphate is a major buffer of acid in urine by
virtue of its monovalent, divalent and trivalent forms.
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Calcium is stored in the teeth and bones, where it
provides structure and strength.
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Inadequate folate intake leads to changes in bone marrow and other rapidly dividing tissues. As depletion progresses, eventually, full-blown anaemia results in weakness, fatigue, irritability and palpitations.
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Although there is a lack of direct evidence, it is thought that a relationship exists between thiamin
requirement, energy supply and energy expenditure.
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Unlike most animals, humans and primates lack a key enzyme necessary for the biosynthesis of
vitamin C. We therefore require a dietary source.
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Molybdenum is involved in catabolism of sulphur amino acids and heterocyclic compounds
including purines and pyridines.
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Vitamin B 12 can be stored in the liver
for many years.
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Folate is essential for DNA synthesis. Without folate,
living cells cannot divide. The need for folate is higher when cell turnover is increased, such as in fetal
development. It is also involved in amino acid interconversions.
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Polyunsaturated fatty acids contain two or more double bonds. The most common is Linoleic Acid. It is described as 'omega-6' due to the position of the double bonds and occurs in seed oils,
eg sunflower, safflower and corn.
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Dietary fibre intakes have been linked to reduced risk of CHD, mainly through an effect on
plasma cholesterol. Complete vegetarians typically have higher ratios of high density lipoprotein (HDL) "Good" cholesterol to total cholesterol than either lacto-ovo-vegetarians or nonvegetarians.
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Dietary fibre is the most effective treatment for all forms of constipation due to its influence on faecal
bulk and consistency.
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To achieve iron balance, adult
men need to absorb about 1 mg/day and adult menstruating women about 1.5 mg/day, although
this is highly variable. Towards the end of pregnancy, the absorption of 4-5 mg/day of iron is necessary.
Requirements are higher during periods of rapid growth in early childhood and adolescence
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Calcium is required for the normal development and maintenance of the skeleton as well as for the
proper functioning of neuromuscular and cardiac function.
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Beri beri is one of two distinct major diseases from deficiency of thiamin. In acute
beri beri there is a high output cardiac failure, warm extremities, bounding pulse, oedema and cardiac
enlargement.
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Cereal products provide about one-third of the intake of manganese and beverages (tea) and vegetables
are the other major contributors.
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Selenium is found in a range of foods, the content of which varies with geographic sources of the
food. Soil concentrations can range from <0.01 μg/g to >1,000 μg/g with plant food content reflecting
this range.
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The parent n-3 fatty acid, ALA, aids in the formation of EPA and DHA, but the conversion of ALA to EPA and DHA is limited, creating the need for a dietary source
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Adequate intake of
vitamin B 12 is essential for normal blood function and neurological function.
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High intakes of n-6 polyunsaturated fats have been associated with blood lipid profiles
associated with a lower risk of coronary heart disease.
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Cholesterol comes in 2 main forms: LDL (Low Density Lipoprotein) Cholesterol and HDL (High Density Lipoprotein) Cholesterol. LDL Cholesterol is harmful, and is associated with an increased risk of Coronary Heart Disease(CHD). HDL Cholesterol is beneficial, and reduces the risk of CHD.
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Retinoic acid plays an important role in
embryonic development, particularly in the development of the spinal cord and vertebrae, limbs, heart,
eye and ears
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Thiamin plays an essential role in the supply of energy to the tissue, in carbohydrate metabolism
and in the metabolic links between carbohydrate, protein and fat metabolism.
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Adequate dietary fibre is essential for proper functioning of the gut and has also been related to risk
reduction for a number of chronic diseases including heart disease, certain cancers and diabetes.
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In Australia, the National Nutrition Survey of 1995 indicated that 45% of dietary fibre comes from breads
and other cereal foods, 10% from fruit and 30% from vegetables.
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The major dietary sources
of vitamin K are green leafy vegetables such as kale, spinach, salad greens, cabbage, broccoli and
brussel sprouts and certain plant oils such as soybean and canola oils.
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Symptoms of biotin deficiency include dermatitis, conjunctivitis,
alopecia and Central Nervous System (CNS) abnormalities, including developmental delay in infants. People with
genetic biotinidase deficiency will have increased requirements.
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For infants, breast-feeding is recommended, as the iron in formula is much less bioavailable
(generally only 10-20% as available as that in breast milk)
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Vitamin C is a reducing agent (antioxidant). In humans, vitamin C acts as an electron donor for eight enzymes,
of which three are involved in collagen hydroxylation, and two are involved in carnitine biosynthesis.
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Riboflavin and its derivatives are
important for the body's handling of some other nutrients including conversion of vitamin B-6 to its
bioactive form, and conversion of tryptophan to niacin.
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Magnesium is a cofactor for more than 300 enzyme systems and is involved in
both aerobic and anaerobic energy generation and in glycolysis.
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In teeth that have erupted, ingestion of fluoride reduces caries due
to reduced acid production by bacteria and increased enamel remineralisation in acidogenic challenge.
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Chronically high levels of alcohol ingestion can negatively affect vitamin A status through an effect on
the liver.
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In general, zinc absorption from a diet high in animal protein will be greater than from a diet rich in plant
derived proteins. The requirement for dietary zinc may be as much as 50% greater
for vegetarians, particularly strict vegetarians whose major staples are grains and legumes.
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The best-known role for vitamin
K is the maintenance of normal blood coagulation. The vitamin K-dependent coagulation proteins that are made in the liver have both coagulant and anticoagulant properties.
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Calcium intake throughout life is a major factor affecting the
incidence of osteoporosis, however other factors, notably adequate vitamin D status and exercise, also
play a role.
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People with hypertension, diabetes and chronic kidney disease and greater age tend to be more
sensitive to the blood pressure raising effects of sodium chloride intake. Being overweight also appears to
increase susceptibility.
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The retinal form of vitamin A is required by the eye to change light to neural signals for vision
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Selenium functions as an antioxidant and in redox reactions and thyroid metabolism. It is thought to have a role in cellular antioxidant systems.
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Chromium is involved in potentiating the action of insulin. Chromium deficiency is relatively rare.
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Iron absorption is about 18% from a mixed western diet including animal foods and about 10% from a
plant-based diet; so vegetarians and vegans need higher intakes.
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Zinc is a component of various enzymes that help maintain structural integrity of proteins and
regulate gene expression. The biological function of zinc can
be catalytic, structural or regulatory.
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Vitamin C deficiency causes scurvy, symptoms of which include skeletal and vascular lesions with
gingival changes, pain in the extremities, haemorrhage, oedema, ulcerations and death.
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The major adverse effect of increased sodium chloride intake is elevated blood pressure, a risk factor
for cardiovascular and renal diseases.
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Pantothenic acid is
involved in fatty acid metabolism. It is essential to almost all forms of life
and is widely distributed in foods. Chicken, beef, potatoes, oat-based cereals, tomato products, liver,
kidney, egg yolks and whole grains are major sources in western diets.
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Riboflavin deficiency can
result in raised plasma levels of homocysteine that are associated with increased cardiovascular risk. The classic disease of riboflavin deficiency is ariboflavinosis, which manifests in growth disturbances, seborrhaeic dermatitis, inflammation of the oral mucosa and tongue, cracks at the corner of the mouth
and normocytic anaemia.
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Vitamin E deficiency symptoms have never been described. Deficiency occurs only as a result of genetic abnormalities, fat malabsorption syndrome, or protein-energy malnutrition.
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Saturated fatty
acids have both physiological and structural functions. They can be synthesised by the body so are not
required in the diet.
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Potassium blunts the effect of sodium chloride on blood pressure, mitigating salt sensitivity and lowering urinary calcium excretion.It has been hypothesised that high protein-low potassium diets could induce a low-grade metabolic acidosis that could induce demineralisation of bone, osteoporosis and kidney stones.
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Dehydration of as little as 2% loss of body weight results in impaired physiological responses and
performance.
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Omega-3 fatty acids are so named due to a double chemical bond at the n-3 position in the molecule. Humans are unable to insert a double
bond at the n-3 position of a fatty acid and thus require a dietary source.
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Potassium is the major cation of intracellular fluid and an almost constant component of lean body
tissues. Potassium requirements can be affected by climate and physical activity, the use of diuretics, and the
intake of other electrolytes, notably sodium.
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An increase in saturated fat intake leads to an increase in harmful LDL (Low Density Lipoprotein) cholesterol, which leads to a greater risk of Coronary Heart Disease.
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There is some evidence that choline may improve cognitive function and memory at all ages and,
by extension, choline deficiency has been implicated in poor performance for groups such as the
institutionalised elderly.
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Water is defined as an essential nutrient because it is required in amounts that exceed the body's ability
to produce it. All biochemical reactions occur in water.
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