Vitamin B 12 can be stored in the liver
for many years.
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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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If sunlight exposure is adequate, dietary vitamin D can
be considered unnecessary.
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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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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.
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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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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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Alcohol intakes
below about 5% of dietary energy are recommended.
|
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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Calcium balance deteriorates at menopause. In post menopausal women, there is evidence that a high
calcium intake will slow the rate of bone loss and may reduce the risk of fracture.
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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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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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All of the necessary amino acids can be provided in the amounts needed from plant
sources.
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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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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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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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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.
|
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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Vitamin B6 is found in a wide range of foods including organ meats, muscle meats, breakfast cereals,
vegetables and fruits.
|
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.
|
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.
|
Phosphate helps to protect blood systemic acid/base balance, acts as a temporary store and transport mechanism for energy and helps in activating
catalytic proteins.
|
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.
|
Dehydration of as little as 2% loss of body weight results in impaired physiological responses and
performance.
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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.
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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.
|
Energy is released from food
components by oxidation. The main sources of energy are carbohydrates, proteins, fats and, to a lesser
degree, alcohol.
|
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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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
|
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.
|
Unlike most animals, humans and primates lack a key enzyme necessary for the biosynthesis of
vitamin C. We therefore require a dietary source.
|
Because of its role in energy metabolism, niacin
requirements are, to some extent, related to energy requirements.
|
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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Although there is a lack of direct evidence, it is thought that a relationship exists between thiamin
requirement, energy supply and energy expenditure.
|
Selenium functions as an antioxidant and in redox reactions and thyroid metabolism. It is thought to have a role in cellular antioxidant systems.
|
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.
|
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.
|
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.
|
Copper is widely distributed in foods with nuts and seeds being major
contributors. Wheat bran cereals and whole grain products are also good sources.
|
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.
|
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.
|
Manganese is an essential element involved in formation of bone. It is also involved in the metabolism
of carbohydrate, cholesterol and amino acids.
|
Vitamin C is found widely in fruits and vegetables. Fruits such as blackcurrants, guava, citrus, and
kiwi fruit and vegetables such as broccoli and sprouts are good sources.
|
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.
|
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.
|
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.
|
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.
|
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.
|
Iron is a component of a number of proteins including haemoglobin. Haemoglobin is important for transport of oxygen to tissues
throughout the body.
|
Chromium is involved in potentiating the action of insulin. Chromium deficiency is relatively rare.
|
Dietary fibre is the most effective treatment for all forms of constipation due to its influence on faecal
bulk and consistency.
|
Osteoporosis is one of the major causes of morbidity amongst older Australians and New Zealanders,
particularly postmenopausal women.
|
It has been postulated that diets high in fibre have a lower energy density and may therefore help in moderating obesity.
|
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.
|
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.
|
The environment within the gastrointestinal
tract, which can be affected by other dietary constituents, markedly influences the solubility and
absorptive efficiency of zinc.
|
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.
|
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.
|
Fluoride has a unique ability to stimulate new
bone formation and as such has been used as an experimental drug for the treatment of osteoporosis
|
The major sources of Riboflavin are milk and milk products and fortified breads and cereals.
|
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.
|
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
|
Adequate intake of
vitamin B 12 is essential for normal blood function and neurological function.
|
Vitamin K deficiency causes a bleeding tendency through a lack of activity of the procoagulant
proteins.
|
Sodium is important for maintaining the membrane
potential of cells and for active transport of molecules across cell membranes.
|
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.
|
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.
|
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.
|
Low intakes of calcium have been associated with a condition of low
bone density called osteoporosis which is quite common in western cultures and which often results in
bone fracture.
|
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.
|
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.
|
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.
|
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.
|
Dental caries is often identified
as the limiting factor in terms of an upper intake of cariogenic sweeteners, even in an era of fluoride
exposure.
|
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.
|
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.
|
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.
|
Saturated fatty
acids have both physiological and structural functions. They can be synthesised by the body so are not
required in the diet.
|
The major adverse effect of increased sodium chloride intake is elevated blood pressure, a risk factor
for cardiovascular and renal diseases.
|
The main monounsaturated fatty acid is oleic acid with one double bond. Olive, canola and peanut oils
are rich in oleic acid. The monounsaturates are synthesised by the body and are thus not required
in the diet.
|
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.
|
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.
|
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.
|
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)
|
Deficiency of Vitamin D results in inadequate mineralisation or demineralisation of the skeleton.
This can lead to rickets in young children, causing bowed legs and knocked knees. In adults, deficiency can lead to
increased bone turnover and osteoporosis.
|
Vitamin A is a fat-soluble vitamin which helps maintain normal reproduction, vision and immune
function. Vitamin A intakes or requirements are generally expressed in terms of retinol equivalents (RE). Retinol is required for the integrity of epithelial cells throughout the body.
|
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.
|
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.
|
Processing of food (cutting up,
cooking etc) greatly improves availability and thus absorption of carotenoids from foods.
|
Thiamin is a water-soluble substance that occurs in free or phosphorylated forms in most plant and
animal tissue.
|
Wernicke's encephalopathy is one of two distinct major diseases from deficiency of thiamin. It is usually seen in people who have been drinking alcohol heavily and eating very little. (Alcohol requires thiamin for its metabolism). The characteristic feature is paralysis of one or more of the external
movements of the eyes.
|
Vitamin B6 acts as a coenzyme in the metabolism of amino acids, glycogen
and sphingoid bases.
|
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.
|
Folic
acid supplementation in pregnancy can reduce both the occurrence and recurrence of neural tube
defects in the newborn.
|
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.
|
Chronically high levels of alcohol ingestion can negatively affect vitamin A status through an effect on
the liver.
|
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.
|
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.
|
High intakes of n-6 polyunsaturated fats have been associated with blood lipid profiles
associated with a lower risk of coronary heart disease.
|
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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