Alison Odey

I recently came across some very interesting notes on Vitamin D. I have always
felt that most people living in New Zealand get quite adequate Vitamin D simply
because most of us live much of our lives outside in the sun, however in modern times this of course, is now not always the case.

The form of Vitamin D produced in the body is Cholecalciferol (D3).
It is produced as a result of the conversion of a cholesterol-based precursor in the sebaceous glands of the skin when the skin is exposed to sunlight.

Vitamin D is necessary to support the development and maintenance of strong bones and teeth, cardiovascular, renal and prostate health, mood as well as overall immune function.
In recent years it has become known that Vitamin D has an important role in autoimmune disorders and research is continuing in this field.

It prevents rickets in children, Osteomalacia (softening of the bones), Hypocalcaemic (low calcium),  tetany and cramping in adults.

Vitamin D also has a role in maintaining muscle strength and possibly because of this factor supplementation can be associated with the reduction of falls in the elderly.

Recent research has suggested that during the summer months, only 10-15% of unprotected exposure to sunlight to 15% of the body was needed to maintain adequate Vitamin D levels.
This was outside the hours 10am to 3pm so there is no need to expose ourselves to the sun during ‘high burn times’. During the rest of the year up to an hour was needed.
This is generally not hard to obtain for most people but in the winter it is important to try and make the best use of those sometimes rare bright sunny days.

The exceptions to this of course are certain people in the community who are unable to obtain sufficient sun exposure.These can be:
– Elderly people with limited mobility living in residential homes.
– People who avoid sunlight by completely ‘covering up’.
– People excessively using sunscreens or even just using them on a regular basis.
– Young children living predominantly inside or in very dull sunlight conditions.
– Anyone who may have limited exposure due to work hours or for any other reason.
– Those with Crohn’s disease, coeliac disease or cystic fibrosis due to poor lipid digestion and absorption.
– Overweight individuals also have a tendency to have low Vitamin D levels.

Apart from sunlight exposure Vitamin D can also be obtained from certain foods.
These foods include oily fish such as sardines and mackerel, beef, liver, butter, cheese and eggs.
This is in the form of D3 (cholecalciferol) which is identical to the form produced in the body. It is important therefore to include these foods in the diet and more so if your
sun exposure is limited.

If you suspect that both dietary intake AND sunlight exposure are too low then you may have to supplement with Vitamin D.
It is often supplemented where there are signs of weakening bones in older people or it a blood test shows Vitamin D levels to be low.
Research shows that Vitamin D levels should ideally be higher than 100 nmol/L.

This can be done by supplementing with cod liver or halibut oil or Vitamin D capsules of 1000IU or better still eat more fresh fish!
Some research says that 2000IU is accepted amount needed daily to prevent osteoporosis.
For children the recommended intake is 200IU daily.

Up-dated Oct 2014