Diet therapy

The sunshine nutrient – Vitamin D

Have you noticed that as the days lengthen and we head into summer everyone looks a lot happier.

Research has found that light does affect our moods and has an antidepressant effect. Sunlight is also important for Vitamin D production

What is it?

Vitamin D has been hitting the newspaper headlines a bit lately. This fat soluble vitamin is found in two forms:

  • Vitamin D3 (cholecalciferol) which is mostly formed in the skin when it is exposed to ultraviolet light from the sun. It is also found in cod liver oil, fatty fish, butter and animal liver.
  • Vitamin D2 (ergosterol) which is a plant sterol used in the pharmaceutical industry to fortify margarine, orange juice, milk etc.

Why do we need it?

We need Vitamin D in all its forms to aid calcium absorption to build strong muscles and bones. It also controls inflammation; blood pressure; regulates immunity, slows hardening of the arteries and more recently it has been found to improve insulin resistance and sensitivity that are both risk factors for diabetes. Also Vitamin D protects us from some forms of cancer.

How do we access it?

While putting on sun screens does reduce Vitamin D production according to research this is not enough to cause deficiency. In fact around 30minutes of sunshine on the face each day is considered more than enough for most of us to meet our needs.

Who is at risk?

Those people most at risk of deficiency are people who live at high altitudes; are covered from head to foot in clothing; spend almost all their time indoors or live in cities that are heavily polluted with smog so that the UV rays from sunlight are reduced. This can be particularly a problem in winter.

Here in New Zealand we need to be particularly careful of our elderly folk, especially those in institutions or residential care who through lack of mobility are unable to venture outside for fresh air and sunshine each day.

What about supplementation?

While it may be tempting to throw a supplement at the problem you do need to be careful because Vitamin D is accumulated by the liver and can be toxic in large amounts.

Talk to your doctor about your risk factors and if necessary he can refer you for a blood test to check adequacy and contact Lea for specialist dietary advice.

About the author View all

Lea Stening

Lea is one of New Zealand’s leading paediatric dietitians and also specialises in Sports Nutrition. She has specialised in Paediatric Nutrition for 31 years and in 1985 was the first paediatric dietitian to enter private practice in New Zealand. Lea helps families through her private consultations, public lectures, newspaper and magazine articles as well as television and radio interviews. Read more »

View all posts by Lea Stening »


Leave a Reply

Also in Diet Therapy View all »

Would you like to subscribe to our fantastic FREE monthly newsletter?

Each month we'll keep you up-to-date with the latest nutritional articles and healthy recipes from You are free to opt out at any time, but we think you'll enjoy what we've got in-store for you.

Plus as a bonus offer — subscribe today and receive FREE weight loss tips for two weeks! Learn how a number of foods, many one would consider 'healthy', may in fact be slowing your progress.


Yes please, it sounds great! (and it's FREE after all).



No thanks, I'm not interested (or I'm already a subscriber and really enjoying these fantastic newsletters!).