Role of vitamins

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.

Key points about vitamins
Most New Zealanders can meet their daily vitamin needs by eating a range of food from the 4 main food groups.
That means most people do not need to take supplements.
However, if you’re thinking of getting pregnant, or are already, you need 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. Read more about eating and drinking during pregnancy.
Vitamin B12 is contained only in foods of animal origin, which means vegans and vegetarians need to watch out for low B12 levels.
Where do vitamins come from?
Most vitamins are provided by food – so they are classed as ‘essential’. Vitamins are team players – they help other nutrients work better, eg, vitamin D enhances the absorption of calcium, vitamin C is needed to absorb iron and B vitamins work together in cells.

Because only vitamins A, E and B12 are stored to any significant extent in your body, a regular intake of most vitamins is important. You can easily meet your daily vitamin needs by eating a range of food from the 4 main food groups:

vegetables and fruits
grain foods
milk and milk products
a group of foods consisting of legumes, nuts, seeds, fish and other seafood, eggs, poultry and/or red meat with the fat removed.
Vitamins are divided into 2 groups: fat soluble and water soluble.

Fat-soluble vitamins
Fat-soluble vitamins include vitamins A, D, E and K. These can be stored in your fat cells for later breakdown and use when needed. For this reason, these vitamins can build up to toxic levels if you eat them in larger amounts than your body needs. In extreme cases this can cause death. This means you should only supplement with these vitamins on the advice of your healthcare provider.

Vitamin D
You need vitamin D for strong bones, muscles and overall health. You can get it from sunlight and what you eat. If you don’t get enough of it, you may get aches, cramps and pain in your muscles and your bones may become soft and break more easily.

About 5% of adults in New Zealand are deficient in vitamin D. A further 27% are below the recommended blood level of vitamin D. People with darker skin, who spend less time outside or who have health conditions that make it hard to absorb nutrients are more at risk of vitamin D deficiency.

Vitamin D supplementation is not recommended for most New Zealanders, only those who are at risk of deficiency. Read more about vitamin D and vitamin D supplementation.

Vitamin E
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 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

Vitaimin 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
Vitamin K supplements (and foods fortified with vitamin K) can be dangerous for people taking blood thinning agents, like warfarin or aspirin, which will not work as effectively.

* RDI: Recommended Daily Intake; AI: Average Intake; UL: Upper Limit. See RDIs explained