Are your energy levels up or down? Vitamins are vital for good health, but needed in much smaller amounts than macro-nutrients, like carbs and fats. They’re important for many daily bodily functions, such as cell reproduction and growth, but most importantly for the processing of energy in cells.
- Most New Zealanders easily meet their daily vitamin needs by eating a varied diet based on bread, cereals, fruit and vegetables.
- Upping your fruit and vege intake from 3 to 7 serves per day has been shown to increase vitamin C levels by 400%!
- Vitamin B12 is contained only in foods of animal origin, which means vegans and vegetarians need to watch out for low B12 levels.
- If you’re thinking of getting pregnant, or are already, it’s wise to take a daily folate supplement (400µg) until your 12th week of pregnancy. Low daily intakes are linked to spina bifida and other malformations in babies.
- Most people do not need to be taking vitamin supplements.
- If you do take vitamins, care needs to be taken with the amount you take and when taking them with other medications.
Where do vitamins come from?
Most vitamins are provided by food – so they are classed as ‘essential’ – and are divided into two groups: fat soluble and water soluble. You can easily meet your daily vitamin needs by eating a varied diet based on bread, cereals, fruit and vegetables, try to also include some meat, fish, eggs, milk, yoghurt and cheese. Because only vitamins A, E, and B12 are stored to any significant extent in the body, a regular intake of most vitamins is important.
Vitamins are team players - they help other nutrients work better, e.g. vitamin D enhances the absorption of calcium, vitamin C is needed to absorb iron, and B vitamins work together in cells.
Fat soluble vitamins
These are fewer in number than water soluble vitamins, and can be stored in our fat cells for later breakdown and use when needed. For this reason it’s possible to accumulate these vitamins to toxic levels if you eat them in larger amounts than your body needs - in extreme cases this can be fatal.
The key to avoiding such dangers is using common sense and moderation, and taking care with supplements. Almost anything can be poisonous if consumed in sufficient quantity.
|Vitamin A (retinol)||Forms part of the visual pigments in the eye.||Liver, oily fish (salmon, tuna, kahawai, herring), full-fat dairy products. Also from orange and yellow fruits and veges, leafy green veges.||Blindness and death from infections in children in 3rd world. In New Zealand, low levels may lead to low immunity against colds and flus. Early signs: dry, damaged skin and mucous membranes, and night blindness.||RDI: Men, 900µg.Women, 700µg.UL: 3,000µg/day.|
|Vitamin D (cholecalciferol, ergocalciferol)||Increases absorption of calcium and phosphorus into bones.||Cholecalciferol produced by action of sunlight on skin; and ergocalciferol comes from dark-fleshed fish (salmon, herring, mackerel), eggs and fortified margarines. Almost impossible to get enough from the diet alone, so it has to be obtained from exposure to sunlight.||Loss of calcium from bones, leading in severe cases to rickets in children, causing bowed legs and knocked knees. In adults, deficiency can lead to increased bone turnover and osteoporosis.||RDI: None available. AI:Males 19–50 yr 5μg /day,51–70 yr 10μg /day,>70 yr 15μg /day.Females
19–50 yr 5μg /day,
51–70 yr 10μg /day,
>70 yr 15μg /day.
Who is at risk of low vitamin D levels?
In Australasia, those at most risk from vitamin D deficiency are:
- dark-skinned people - and breast-fed babies from these groups
- veiled women (who see sunlight less often) - and breast-fed babies from these groups
- older people
Australasian studies have shown up to 41% of females 20–39 years may have some degree of deficiency at the end of winter. Others who may be affected:
- Those who have intestinal, liver, kidney or heart and lung disease.
- People taking anticonvulsants may also be at increased risk.
- People who always use sunscreen.
- People who wear protective clothing.
- Youngsters growing rapidly, with low calcium intakes.
Vitamin D fortification
In New Zealand, fortification of margarine or milk products with vitamin D is not mandatory. However, since 1996, voluntary fortification of margarine has been permitted. It is also permitted to add vitamin D to dried milk, dried skim milk and non-fat milk solids, skim milk and reduced fat cows’ milk, legume beverages and ‘food’ drinks, e.g. soy milk. This fortification is currently under evaluation.
Seasonal influences on vitamin D production
In winter, there's less UV light, people spend less time outdoors and wear more clothes, so vitamin D deficiency is more common. However, after regular sun exposure, people under the age of 50 can produce and store about 6 months’ worth of vitamin D, so it’s available during winter months. Older people are unable to make and store as much vitamin D as younger folk, so they are more at risk during the winter months.
Vitamin E (α-tocopherol) is an antioxidant that protects red blood cells, muscle cells, vitamin A and unsaturated fatty acids from oxidation (it destroys ‘free radicals’).
Vitamin D is important for protection from:
Vitamin E works together with:
- the mineral selenium
- a wide variety of plant foods
However, be careful as vitamin E is destroyed by cooking at high temperatures. Vitamin E deficiency is rare in humans, but can lead to:
- haemolysis (the bursting of red blood cells)
- sterility (in rats)
RDI (recommended daily intake) for vitamin E:
- men, 10mg
- women, 7mg
Vitamin K (phylloquinone and menaquinon) is needed to make prothrombin, important for blood clotting. Vitamin K works with vitamin A to keep bones and teeth healthy.
Vitamin K can be obtained from:
- our own gut bacteria
- eating wholegrain cereals
- leafy green veges
- vege oils
- green tea
- fortified milks such as Anlene
Deficiency can cause bleeding in newborns who lack the intestinal bacteria needed to produce vitamin K. There is currently no available RDI (recommended daily intake) for vitamin K.
Vitamin K - AI (average intake):
- men, 70μg/day
- women, 60μg/day
* RDI: Recommended Daily Intake; AI: Average Intake; UL: Upper Limit. See RDIs explained
Water soluble vitamins
These vitamins are also known as co-enzymes, and are needed during the breakdown of food to make energy. They are excreted by the kidney, so are not stored in the body.
|Vitamin B1(thiamin)||Works with other B group vitamins in breakdown of carbohydrates to make energy - mostly in muscles, brain, liver and kidneys.||Meat (especially pork), fish, wholegrain cereals and bread, fortified breakfast cereals, pulses (dried beans and lentils), nuts and yeast extract. Fortified breakfast cereals and bread mixes. 25% lost in cooking.||Mild: headache, tiredness, loss of appetite and muscle weakness. In most populations, deficiency doesn't occur, with exceptions found in chronic alcoholism, some older people, and those with chronic diseases involving vomiting, diarrhoea and anorexia.||RDI: Men, 1.2mg.Women, 1.1mg.UL: None estimated.|
|Vitamin B2 (riboflavin)||Works with other B vitamins helping with protein and carbohydrate use in cells. Helps with absorption of minerals iron, zinc and calcium.||Liver, dairy products, eggs, cereals and green vegetables. Easily destroyed by light.||Very rare: inflammation and breakdown of skin (particularly lips and corners of mouth), swollen tongue, eye irritation.||RDI: Males 1.3mg men 19-70 years, 1.6mg over 70 years, 1.1mg.Females, 19-70 and 1.3mg women >70.UL: Cannot be estimated|
|Vitamin B3(niacin, nicotinic acid)||Used in cells for energy transfer and to repair DNA.||Wide variety of foods: beef, pork, liver, beans, yeast extracts, eggs, wholegrain cereals, cow’s milk. Human milk contains more niacin than cow’s milk.||Deficiency very rare in New Zealand: fatigue, inflammation of the nerves and skin.||RDI: Men,16mg.Women, 14mg.UL: 35mg/day.|
|Vitamin B6 (pyridoxine)||Regulation of mental function and mood, and a role in the breakdown of homocysteine.||Found in most foods.||Deficiency: anaemia, irritability, convulsions, inflammation of nerves.Toxicity: in large amounts, this vitamin is toxic to sensory nerve cells.||RDI: Males, 19-64 years,1.3-1.9mg.Females, 19-54 years, 0.9-1.4mg, > 54 years, 0.8-1.1mg.|
|Vitamin B12 (cyaocobalamin)||Essential for the manufacture of DNA and normal blood and brain function.||All foods of animal origin: meat, especially liver, fish and seafood, eggs, and milk products. Soy milk is often fortified with vitamin B12.||Deficiency affects nearly all body tissues, particularly those containing rapidly dividing cells in times of growth. Most serious affect is pernicious anaemia and degeneration of the nervous system.||RDI: Adults 2.0µg|
|NB: Vitamin B12 is made only by certain bacteria found in the gut, and is contained only in foods of animal origin. This has implications for vegans. In addition, vitamin B12 can only be absorbed in the presence of ‘intrinsic factor’, a protein secreted by the stomach, which has implications mainly for the elderly and those who have undergone gastric surgery. These people may need regular replacement vitamin B12.|
|Folic acid(folate)||Formation of chromosomes and red blood cells, promotes normal digestion. Has been shown to prevent neural tube defects, like spina bifida, in babies, and thought to play role in reduction of chronic disease risk, from cardiovascular disease and dementia to bone fractures, cancers and DNA damage.||Good sources of folate come from: liver, yeast extract, some fortified breakfast cereals, pulses, wholegrain cereals, nuts, some fruits, asparagus and dark green leafy vegetables.*||Deficiency can cause some types of anaemia. Low daily intake in women trying to conceive and who are pregnant is linked to neural tube defects and other malformations in babies.||RDI: Men and women, 400µg.Pregnant women: 600µg per day dietary intake. plus a supplement.**Breastfeeding women: 500µg|
|Folate requirements can be affected by nutrient interactions, smoking, certain drugs and your genetic make-up.
|Pantothenic acid||Part of the body’s co-enzyme system, a key molecule in carbohydrate and fat metabolism, and essential to almost all forms of life.||Widely distributed in food: chicken, beef, potatoes, oat-based cereals, tomatoes, liver, kidney, egg yolks and whole grains are major sources.||Deficicency not seen in people who eat ‘real’ food, only in those fed synthetic diets; symptoms include irritability, restlessness, fatigue, apathy, malaise, sleep disturbance, nausea, vomiting and cramping, numbness, staggering gait, hypoglycaemia, increased insulin sensitivity.||AI: Men 6mg/day.Women, 4mg/dayUL: Not yet be determined.|
|Biotin||Fat metabolism.||Many foods, especially in egg yolk and liver.||Deficiency rare, but can be caused by over-consumption of raw egg white (protein combines with biotin and makes it unavailable). Can also occur when solely intravenously fed. Symptoms include dermatitis, conjunctivitis, alopecia,central nervous system abnormalities, including developmental delay in infants. Some people have a gene that makes them need more biotin than others.||AI: Men, 30µg/day.Women, 25µg/day.UL: None set.|
|Vitamin C (ascorbic acid or ascorbate)||Essential vitamin: helps make bone, neurotransmitters, collagen, teeth, cartilage, connective fibres. Maintains resistance to infection, frees iron to make haemoglobin. An antioxidant thought to be important in anti-cancer and anti-ageing processes. Aids the absorption of iron and copper.||Fresh and frozen fruit (not dried) and vegetables, particularly soft and citrus fruits. Those rich in vitamin C include: potatoes, broccoli, spinach, kumara, sprouts, strawberries, kiwifruit, oranges and melon, blackcurrants and guava*.||RDI: Men and women 45mg.In the UK, smokers’ RDI is 80mg or greater.UL: Not yet set, but the Nutrient Reference Values for Australia and New Zealand suggest 1000 mg/day is a prudent limit.|
|*The Australian bush food terminalia ferdinandiana is the richest source. Many manufactured foods, especially juices and cordials, contain vitamin C as an antioxidant to prolong shelf life.Vitamin C is susceptible to destruction by food heating and processing – damaged by cutting and bruising and leaching into cooking water. Microwaving and steaming is best way to preserve vitamin C in your cooked food. Vitamin C content can also be affected by season, transport, shelf life, storage time and chlorination of water.|
* RDI: Recommended Daily Intake; AI: Average Intake; UL: Upper Limit. See RDIs explained