21 May, 2020

As Winter Approaches, Think Vitamin D

Why is Vitamin D important?

Vitamin D is fundamental for healthy bones, muscles, mood and overall wellbeing. It is particularly important in maintaining calcium levels in the body as calcium absorption is reliant upon sufficient activated vitamin D levels.  A deficiency in Vitamin D can result in:

  • Bone and joint pain
  • Osteoporosis
  • Increased risk of falls and bone fractures
  • Defects in bone formation of unborn children in pregnant women with vitamin D deficiency
  • Fatigue, mood imbalance and depression

 Vitamin D also plays a key role in immune function, and deficiency is associated with an increased risk of infection.  Vitamin D may even have some effect on the prevention of autoimmune diseases.

In the current climate of Covid-19, some researchers have hypothesized that the disparate rates of infection and mortality between the Northern  (Norway, Finland, Sweden, Denmark) and Southern European countries  ( Spain, France, Italy) may have something to do with varying Vitamin D levels that are paradoxically higher in the less sunny Northern European countries where food fortification and supplementation is common place.

Where does Vitamin D come from?

Most of our vitamin D is synthesized naturally in our skin, when exposed to Ultraviolet B light from the sun.  This form of vitamin D is then converted into its active form through processes involving the liver and kidneys. Smaller amounts of Vitamin D are derived from the foods we eat such as fish, eggs, some margarines and milk.

Given that most vitamin D production occurs from exposure to sunlight, it is no surprise that during the winter months, approximately 30% of Victorians are vitamin D deficient. As a consequence of home isolation, rates of Vitamin D deficiency may in fact be higher this year.

Those at greatest risk of vitamin D deficiency are:

  • Institutionalised individuals who spend little time outdoors.
  • People with naturally dark skin – the pigment in skin acts as a filter to UV radiation and reduces the production of vitamin D in the skin
  • Frail/elderly population – as we age our skin loses the ability to generate vitamin D
  • People with chronic medical conditions such as liver and kidney disease
  • People with bowel conditions affecting vitamin D absorption
  • People who are obese – vitamin D is oil soluble and can store in fat, becoming less accessible in the circulation.
  • People who take medications affecting vitamin D metabolism such as some anti-epileptic and anti-tuberculous drugs
  • Breastfed infants – breastmilk contains very little vitamin D

Safe ways to increase vitamin D levels:

  1. Adopt a balanced approach to sun exposure – UVB radiation from the sun is the best natural source of vitamin D synthesis, but be mindful of the risk of skin cancer. During the summer months, spending a few minutes outdoors each day will maintain adequate vitamin D levels. During late autumn and winter, it is advisable to spend 15 minutes outdoors in the middle of the day with a exposing a small amount of skin.
  2. Exercise daily. Regular exercise assists with the production of vitamin D
  3. Eat foods rich in vitamin D and high in calcium.
  4. If required, there are a variety of vitamin D supplements available that your doctor may recommend.