Vitamins and minerals PDF

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Vitamins -

Differentiate between fat- and water-soluble vitamins List the sources and RNIs of vitamins in the diet Discuss the functions, absorption and metabolism of vitamins Discuss vitamin deficiency and excess in relation to health

History -

Vital [to human health] + amine [nitrogen containing] = vitamine  vitamin [changed due to the establishment that many of the substances don’t contain nitrogen]

What are vitamins? = group of organic compounds that are essential to body functioning in small amounts - Diverse in function and chemical structure - Do not provide energy - Requirements change across life stages - Some cannot be synthesised by the body - Others cannot be synthesised in sufficient quantity to meet metabolic needs - Others can only be synthesised from specific dietary precursors - Classification gives some indication to likely food sources, function and distribution in the body, and potential toxicity Fat soluble vitamins A, D, E, K - Stored in the liver so don’t have be consumed daily - Excess is not readily excreted so over consumption can lead to toxic overload - Absorbed from the gut and transported with the fat o So malabsorption of fat can increase risk of deficiency Water soluble vitamins B and C - Stores are generally smaller, so a more regular supply is usually required - Excesses usually excreted in the urine

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Deficiencies tend to occur sooner due to lack of storage

Functions -

Maintenance of health and metabolism o Coenzymes [mainly B vitamins] o Hormonal role [vitamin D] o Anti-oxidants [A, C, E] o Special functions [K – prothrombin cofactor]

Requirements -

Vary according to age, sex and physiological state [e.g. pregnancy] RNI is used [cover 97.5% of population]

Deficiency -

Primary  dietary origin Secondary  due to disease - disturbances in intestinal absorption [coeliac – difficult to absorb calcium and iron – damage to brush borders], transport in the blood [iron deficiency anaemia] , tissue storage, metabolic conversion [metabolic disorder] o May be deficient in fat soluble vitamins if fat intake is too low

Excessive intake -

In some cases, excessive intake is harmful or even fatal Water soluble – cannot be stored in the body and are excreted if too much is consumed Fat soluble – can be stored in the body and excessive consumption can be harmful

Sources -

Food and drink Synthesised [e.g. vitamin D] Supplements Fortification

Antioxidants [vitamins A, C, E] -

Man-made or natural substances to prevent or delay some types of cell damage caused by free radicals [highly unstable molecules formed during exercise and food conversion into energy; as well as environmental from cigarette smoke and sunlight]

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Antioxidants are found in many foods - esp. fruit and vegetables [colourful] Some vitamins are antioxidants [A, C, E – free radical quenching activity] High dose supplements of antioxidants can be linked to health risks: o Beta carotene – increase risk of lung cancer in smokers o Vitamin E – increase risk of prostate cancer and stroke o May interact with some medicines

Fortification -

Deliberately increasing content of an essential micronutrient in food to provide a public health benefit o E.g folic acid fortification of flour – reduces incidence of neural tube defects

Biofortification -

Nutritional quality of food crops is improved through conventional plant breeding or modern biotechnology o E.g. vitamin A biofortification of sweet potatoes to reduce risk of blindness in developing countries

Vitamin

RNI

Function

Source

Deficiency

A [retinol]

700 / 600ug

Aids immune system Aids vision in dim light Essential to normal structure and function of skin Reproduction Cellular communication

Retinol [active form] from animal sources - Dairy - Liver - Cheese - Butter Carotenoids [inactive form] plant sources - Carrots - Dark green leafy veg - Orange coloured fruit Veg Fruit

Night blindness Increased susceptibility to infection

B1 [thiamin]

1/0.8mg

Help break down and release energy from CHO

Headache Nausea

Risk factors for deficiency Poor diet Low fat Fat malabsorption

Diet dependent on rice.

Toxicity Risk of toxicity if you are pregnant and consume a lot of liver based products – avoid supplements Abdominal symptoms Blurred vision Headaches Increase bone brittleness N/A

Keep nervous/CV system healthy

Wholegrain breads Nuts Meat [pork]

Milk Eggs Fortified cereals Liver Legumes Mushrooms Green veg Meat Wheat and maize flour Eggs Dairy Yeast In most animal and plant foods

B2 [riboflavin]

1.3/1.1m g

Skin, eyes and NS healthy Help body release from CHO, fat and protein Transport and metabolism of iron

B3 [niacin]

17/13mg

Release energy from foods Keep NS and skin healthy

B5 [Pantothenic Acid]

5mg

B6 [pyridoxine]

1.4/1.2m g

Precursor of CoA Helps release energy from CHO and FAs Manufacture RBCs Synthesis of cholesterol Sex/stress-related hormone production Metabolism of amino acids Breaking down of glycogen Help form haemoglobin

Poultry White fish Milk Eggs

fatigue Beri-beri – peripheral NS disease Wernicke-Korsakoff syndrome – CNS disease Cracking at corners of mouth Raw lips

Alcoholism.

Absence of milk

N/A

Pellagra disease Diet dependent [Dermatitis, on maize and not diarrhoea, dementia] including highprotein foods

Can lower plasma cholesterol in high doses

Abnormal skin sensations induced by warmth

Rarely seen

No reports

Anaemia Raw lips Fatigue Dermatitis

Rare

Neurotoxic in high doses [tingling in hands and feet]

B9 [folate [folic acid = synthetic form]]

200ug [Women 19-40 400ug]

Form healthy RBCs Reduce risk of neural tube defects in unborn babies

B12 [cobalamin]

1.5ug

Makes RBCs Keeps NS healthy - Production of myelin sheath Involved in using folic acid

C [Ascorbic Acid]

40mg

Protect cells and keep them healthy – immune system Maintain heathy skin, blood vessels, bones, cartilage Helps wound healing Increase absorption of nonhaem iron Precursor of calcitriol [hormone produced to increase calcium transport] Regulates deposition of bone mineral Neuromuscular function

D 10ug [Cholecalciferol]

Whole grains Soya beans Peanuts Brown rice Peas Oranges bananas Green vegetables Whole grain cereals Meat Fish Milk Eggs Fermented foods Citrus fruits Berries Green veg Peppers Tomatoes Potatoes Can be synthesised from sunlight [D3] From the diet: [D2] - Eggs - Meat - Fatty fish - Fortified cereal

Megaloblastic anaemia [large, irregular, fragile RBCs] Irreversible damage to spinal cord Megaloblastic anaemia Neuropathy [demyelination and degeneration of spinal cord] Growth stunts in children Scurvy Poor wound healing

Rickets/osteomalacia Osteoporosis Reduced growth Muscle weakness Increased risk of infection Dental decay

Poor diet Poor absorption Prolonged heating destroys folate

N/A

Vegan diet Poor absorption due to inadequate production of intrinsic factor in stomach Diet of mainly preserved foods Absence of fruit and veg Smoking/alcohol

N/A

Inadequate sunlight Pigmented skin Elderly people

Diarrhoea Kidney stones

Most acutely toxic. Elevated Ca in blood/urine, calcification of soft tissues, kidney stones

E [a-tocopherol] 4/3mg

Antioxidant Strengthen immune system Healthy skin and eyes Stabilise cell membranes

K

Assists blood clotting by formation of prothrombin Regulate blood calcium Bone metabolism

Biotin [vit H]

80/60ug

Metabolism of CHO, fats and amino acids Important for normal embryonic growth

Minerals

Seeds and nuts Vegetable oils Wheat germ [cereals] Wholegrain cereals Dark green leaves Avocado Synthesised by bacteria in LI Liver Green vegetables Milk Some veg oils Synthesised by bacteria in LI

Degeneration of nerves Muscle atrophy Retinopathy

Medical disorder affecting fat absorption; newborns with immature GIT

N/A

Excessive bleeding and bruising easily

New-borns Poor fat absorption

N/A Will interfere with anticoagulant therapy

Hair loss Dry scaly skin Cracking in corner of mouth Swollen tongue

Element

LRNI

Function

Source

Deficiency

Calcium

700mg

Present in bones and teeth. Necessary for blood clotting, muscle contraction and nerve activity.

Rare. Vitamin D deficiency  poor absorption

Phosphorus

550mg

Sodium

Salt [alone and in foods such as bread, cereal and meat products]

Heavy sweating

Magnesium

1.6g [x Na intake by 2.5 to get salt intake required] 170mg

Present in bones and teeth. Essential for energy storage and transfer, cell division and reproduction. Component of phospholipids Present in extracellular fluids as Na+ Essential for maintenance of fluid balance, nerve activity, muscle contraction.

Milk Cheese Fortified bread and flour Cereals Green vegetables Canned fish All of natural foods [as a component of all plant and animal cells]

Muscle weakness, spasms, anorexia, nausea, vomiting

Renal disease, diabetes, alcoholism, gut conditions

Diarrhoea

Iodine

140ug

Leafy veg Wholegrains Nuts Seafood Legumes Seafood Fruit Veg Milk Iodised salt

Cretinism and myxoedema

Living in inland areas where iodine soil content is low, and no seafood eaten

Disturbances in thyroid function  hyperthyroidism

Present in bone and cell fluids. Needed for activity of some enzymes to turn food into energy Maintain normal function of parathyroid glands Component of thyroid hormones which in turn keep cells and metabolic rate healthy

Risk factors for deficiency Lack of dairy products in diet. Vitamin D deficiency

Toxicity GIT symptoms, hypercalcaemia, calcification of tissues, renal impairment.

High salt  hypertension [leading to strokes, heart rates, renal failure]

Helps immune system work properly Aids reproduction Prevents damage to cells and tissues by free radicals Present in intracellular fluids as K+ Essential for maintenance of fluid balance, nerve activity, muscle contraction, acid-base balance

Cereals Meat Fish Eggs Vegetables Fruit and fruit juices Milk

7-9.5mg

Helps making new cells and enzymes Helps process CHOs, fat and protein

8.7-14.8mg

Essential component of haemoglobin, myoglobin and cytochromes

Meats Wholegrain cereals Pulses Shellfish Meat Offal Fish Cereals Vegetables

Selenium

70ug

Potassium

2500mg

Zinc

Iron

Progressive cardiomyopathy [Keshan disease]

Low levels in the soil

Selenosis – skin lesions, changes in hair and nails, neurological

Muscle weakness, changes in cardiac function, reduced gut motility, depression, confusion Anorexia, growth reduction, reduced immunity, slow healing, skin lesions, hair loss Anaemia - Poor pregnancy outcome, impaired physical and mental development, reduced work capacity

Many children, elderly have low intakes

Non reported

Diets with lots of unleavened bread

Interferes with copper and iron absorption.

Chronic blood loss from heavy menstruation, cancer. Vegetarian diet – low bioavailability

Irritates GIT constipation, diarrhoea, nausea, vomiting...