Vitamins: Their Importance, RDAs and Sources

      Vitamin A

      RDA: 900mcg

• An antioxidant which slows ageing process and protects body from cancer, heart disease and pollution. 
• Helps immune function
• Is needed for mucous membranes and bone and tooth growth
• Is essential for healthy vision: it’s a component of rhodopsin, a protein that absorbs light in the retinal receptors. It also supports differentiation and functioning of conjunctival membranes and the cornea
• Helps your cells communicate to each other
• Has a critical role in the normal formation and maintenance of the heart, lungs, kidneys and other organs

Vitamin A comes in two forms:

• Retinol / retinyl ester (animal form) found in meat (especially liver), fish (especially oils), eggs and dairy
• Carotenoid (mainly betacarotene) found in orange and yellow fruits and vegetables (provitamin A carotenoids) and leafy greens

Signs of Deficiency:

• Low iron levels (anaemia)
• Increased severity of infections, particularly diarrhoea and measles
• People with cystic fibrosis, pregnant and lactating women most at risk of deficiency (and thus breastfed children whose mothers are deficient)

B Vitamins

• Vital for turning food into mental and physical energy
• Richest in fresh fruit and vegetables
• Cannot be stored in the body so must be eaten daily
• Most people can get their RDA in their normal daily diets (vegans and vegetarians may need supplements)

Thiamin (Vitamin B1)

RDA: 1mg (men) and 0.8mg (women) daily

Keeps nerves and muscle tissue healthy

Found in:

• Vegetables (especially peas)
• Fresh and dried fruit
• Eggs
• Wholegrain breads
• Some fortified breakfast cereals
• Liver

Riboflavin (Vitamin B2)

RDA: 1.3mg (men) and 1.1mg (women) daily

• Helps your body use other B vitamins
• Keeps skin, eyes and nervous system healthy
• Helps body release energy from carbohydrates
• UV light can destroy riboflavin so these foods should be kept out of direct sunlight

Found in:

• Milk
• Eggs
• Fortified breakfast cereals
• Rice

Niacin (Vitamin B3)

RDA: 17mg (men) and 13mg (women) daily

Keeps nervous and digestive systems healthy

Found in:

• Meat and fish
• Wheat and maize flour
• Eggs
• Milk

Pantothenic Acid

Found in virtually all meats and vegetables, good sources include:

• Chicken
• Beef
• Kidney
• Potatoes
• Tomatoes
• Broccoli
• Eggs
• Wholegrains (brown rice and wholemeal bread)
• Some breakfast cereals if they have been fortified with pantothenic acid

Pyridoxine Vitamin B6

RDA: 1.4mg (men) and 1.2mg (women) daily

• Taking more than 200mg a day for a long time can lead to loss of feeling in arms and legs (peripheral neuropathy) which is reversible once you stop taking supplements
• Helps body make and use protein and glycogen which is the stored energy in muscles and liver
• Helps form haemoglobin which carries oxygen in your blood
• Requires zinc and magnesium to convert it into its active form
• Zinc, magnesium and B6 combined relieve symptoms of PMS

Found in:

• Pork
• Poultry
• Fish
• Bread
• Oatmeal, wheat germ, rice
• Soya beans, chickpeas and lentils
• Peanuts
• Vegetables (including potatoes)
• Eggs and milk
• Nuts and sunflower seeds
• Some fortified breakfast cereals

Folic Acid

RDA: 0.2mg daily (adults)

• Helps make red blood cells and prevent anaemia
• If pregnant or trying to conceive, take 0.4mg (400mcg) daily from the time you stop using contraception until the 12^th week of pregnancy to help prevent birth defects of the central nervous system such as spina bifida
• If you have family history of spina bifida, may need to take 5mg daily until 12^th week pregnancy
• Women with diabetes or taking anti-epileptic medicines should speak to their GP

Found in:

• Broccoli, spinach, Brussels sprouts, asparagus, peas
• Liver
• Chickpeas
• Brown rice
• Fortified breakfast cereals

Vitamin B12

RDA: 0.0015mg daily (adults)

• Helps to make red blood cells and keeping nervous system healthy
• Involved in processing folic acid to make DNA
• It becomes harder to absorb as you get older
• Meat, fish and dairy eaters should be able to get enough Vit B12 from their daily diet, but vegetarians and vegans will need to supplement this vitamin as well as looking out for fortified breakfast cereals which contain vitamin B12.

Biotin

Allows your body to use protein, fat and carbohydrate from food

Found in:

• Sweet potatoes
• Skimmed milk and yoghurt
• Peanuts and almonds
• Eggs
• Lover
• Soy protein

Vitamin C (Ascorbic Acid)

RDA: 40mg (adults) daily

• An antioxidant which helps prevent cell damage and reduces the risk for certain cancers and heart disease
• Necessary for maintenance of healthy connective tissue, which gives support and structure for other tissue and organs, protects cell walls
• Helps wound healing and gum health
• Boosts immune system and protects from infection
• Increases the amount of iron absorbed
• Lack of Vitamin C can lead to scurvy
• Taking more than 1,000mg per day can cause stomach pain, diarrhoea and flatulence which will disappear once you stop taking supplements
• Smokers need an extra 35mg daily

Found in wide variety of fruit and vegetables. Good sources include:

• Oranges, mangoes and papaya
• Red and green peppers
• Strawberries, blackcurrants and kiwi
• Broccoli and Brussels sprouts
• Potatoes

Vitamin D

RDA: 5mg (Most people get this amount through a healthy diet and being out in the sun)

• We get most of our Vitamin D from the sun; it is made when our body reacts to sunlight
• It supports calcium balance to help keep bones and teeth healthy and strong
• Increases amount of phosphorus absorbed
• It’s stored in bones
• Lack of Vitamin D leads to bone deformities such as rickets in children and bone pain and tenderness as a result of osteomalacia in adults

 It is found in:

• Oliy fish (salmon, sardines and mackerel)
• Eggs
• Fortified fat spreads
• Fortified breakfast cereals
• Powdered milk

Vitamin E

RDA: 4mg (men) and 3mg (women) daily

• An antioxidant which helps to maintain cell structure by protecting the cell membranes
• Richest sources are plant oils such as soya, corn and olive oil. 

Other sources are:

• Nuts and seeds
• Wheat germ found in cereals
• Avocados

Vitamin K

RDA: 0.001mg daily for each kg of body weight

• Needed for blood clotting, it helps heal wounds properly
• Involved in making proteins for blood, bones and kidneys
• People taking Warfarin must consume the same amounts of Vitamin K foods each day, a sudden increase or decrease could affect how the medication works

Found in:

• Leafy greens such as broccoli and spinach
• Vegetable oils
• Cereals
• Small amounts can be found in meat and dairy