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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Vitamin B 12 is required for the
synthesis of fatty acids in myelin and, in conjunction with folate, for DNA synthesis.
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Magnesium is required for mitochondria to carry out oxidative phosphorylation. It plays a role in regulating potassium fluxes and in the metabolism of calcium.
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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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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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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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Chromium is involved in potentiating the action of insulin. Chromium deficiency is relatively rare.
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Iodine was one of the first trace elements to be identified as essential. In the 1920s it was shown
to be an integral component for normal growth and metabolism. Soon after, it was recognised as a key regulator of important cell processes.
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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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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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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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Dehydration of as little as 2% loss of body weight results in impaired physiological responses and
performance.
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The main sources of folate in Australia and New Zealand are cereals, cereal
products and dishes based on cereals (about 27%) and vegetables and legumes (about 29%). Fruit
provides about 8-10%. Orange juice is contributing a greater amount than in the past due to the recent
introduction of fortification with folate.
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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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Phosphorus is widely distributed in natural foods and also found in food additives as phosphate salts,
used in processing for retaining moisture, smoothness and binding.
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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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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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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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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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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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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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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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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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If sunlight exposure is adequate, dietary vitamin D can
be considered unnecessary.
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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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Adequate intake of
vitamin B 12 is essential for normal blood function and neurological function.
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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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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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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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Sodium is important for maintaining the membrane
potential of cells and for active transport of molecules across cell membranes.
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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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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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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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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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Long Chain (LC) n-3 fatty acids (EPA, DHA, and DPA) are found predominantly in oily fish such as mackerel,
herrings, sardines, salmon and tuna and other seafood.
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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
|
Thiamin is a water-soluble substance that occurs in free or phosphorylated forms in most plant and
animal tissue.
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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 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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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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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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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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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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Phosphorus is so widespread in the food supply that
dietary phosphorus deficiency is extremely rare, the exception being long-term, severe food restriction.
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Fluoride is a normal constituent of the human body, involved in the mineralisation of both teeth and
bones. Because of its role in the prevention of dental caries, fluoride
has been classified as essential to human health.
|
Pellagra, a disease caused by niacin deficiency, was a major problem in the Southern states
of the US in poor Blacks and Whites whose diet consisted of maize (American corn) and little else.
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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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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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Vitamin B 12 deficiency can produce haematological, neurological or gut symptoms. The underlying problem is interference with DNA synthesis leading to production of
abnormally large erythrocytes.
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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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Zinc is widely distributed in foods. Meats, fish and poultry are the major contributors to the diet
but cereals and dairy foods also contribute substantial amounts.
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Frank copper deficiency is rare in humans but has been
seen in certain circumstances in infants.
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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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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 dietary essentiality of choline was demonstrated in a study of healthy men with
normal folate and vitamin B 12 status who developed liver damage with lower plasma choline and
phosphatidylcholine concentrations when fed a choline-deficient diet.
|
Copper deficiency results in defects in connective tissue that lead to vascular and skeletal problems, and
anaemia related to defective iron metabolism. It can also affect the central nervous system and the immune and cardiovascular systems, notably in infants.
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All of the necessary amino acids can be provided in the amounts needed from plant
sources.
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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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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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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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Calcium is stored in the teeth and bones, where it
provides structure and strength.
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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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The amount of protein in the diet is a
factor contributing to the efficiency of zinc absorption as zinc binds to protein.
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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.
|
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.
|
The major function of Vitamin D in humans is to enhance the ability of the small intestine to absorb calcium from the diet. Vitamin D also plays a role
in enhancing absorption of phosphorus from the diet.
|
Because of its role in energy metabolism, niacin
requirements are, to some extent, related to energy requirements.
|
In the last decade, there has been
an exponential rise in publications on health benefits of omega-3 polyunsaturated fatty acids, particularly the longer chain
omega-3s, EPA, DPA and DHA.
|
Vitamin B 12 can be stored in the liver
for many years.
|
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
|
Energy is released from food
components by oxidation. The main sources of energy are carbohydrates, proteins, fats and, to a lesser
degree, alcohol.
|
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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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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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.
|
Amino acids are the building blocks of proteins. The essential amino acids are those that we cannot synthesise within the body, and so need to be included in the diet.
|
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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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.
|
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.
|
The amount of energy needed for the internal bodily functions necessary for life (eg cell metabolism, synthesis and metabolism of enzymes and hormones) is called the basal metabolic rate (BMR). BMR represents about 45-70% of daily energy expenditure.
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The major sources of Riboflavin are milk and milk products and fortified breads and cereals.
|
Various expert groups have made consensus recommendations for
consumption of ALA and/or the very long chain omega-3s.
The evidence is strongest for reduction of Cardio Vascular Disease risk by EPA and DHA.
|
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.
|
The primary role of dietary carbohydrate is the provision of energy to cells, particularly the brain that
requires glucose for its metabolism.
|
Vitamin K deficiency causes a bleeding tendency through a lack of activity of the procoagulant
proteins.
|
Vitamin B6 is found in a wide range of foods including organ meats, muscle meats, breakfast cereals,
vegetables and fruits.
|
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.
|
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.
|
Iron in foods can come in two general forms - as
haem or non-haem iron. Iron from animal food sources such as meat, fish and poultry may be either
haem or non-haem whereas the iron in plant sources such grains and vegetables is non-haem.
|
Iodine is an integral component of a key thyroid hormone. The thyroid hormones are required for normal growth and development of tissues such as the central nervous system and have a broader role in maturation of the
body as a whole. They are important for energy production and oxygen consumption in cells thereby helping to maintain the body's metabolic rate.
|
Vitamin B6 acts as a coenzyme in the metabolism of amino acids, glycogen
and sphingoid bases.
|
Cereal products provide about one-third of the intake of manganese and beverages (tea) and vegetables
are the other major contributors.
|
Manganese is an essential element involved in formation of bone. It is also involved in the metabolism
of carbohydrate, cholesterol and amino acids.
|
Sodium is found in most foods as sodium chloride, generally known as 'salt'. Sodium is a cation needed to maintain extracellular volume and serum osmolality.
|
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.
|
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.
|
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
|
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.
|
It has been postulated that diets high in fibre have a lower energy density and may therefore help in moderating obesity.
|
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.
|
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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