At the moment Vitamin D is a hot topic. It seems that almost every other person who gets their levels tested, are revealed to be deficient. I often get asked if this is something of a conspiracy! People wonder if the reference range of what is a ‘normal’ level has changed, or if a pharmaceutical company is behind it all. Well, I don’t think that it is a conspiracy; a lot of people are deficient and there are many factors that can contribute to this.
The primary source of Vitamin D is through sunlight~ our skin synthesises Vitamin D during exposure to UVB radiation from sunlight. This is likely to be the main reason for the increased incidence of low Vitamin D levels in many people. UVB radiation does not penetrate glass or sunscreen, or the atmosphere in the early morning or late afternoon. Although difficult to precisely determine appropriate sun exposure time as variations of season, latitude, skin colour, age and genetic factors affect the synthesis of the Vitamin, during summer in the middle part of the day (between 1oam and 3pm) it takes about 15 minutes of exposure on 25% of the body to create a sufficient amount of Vitamin D per day. This is at odds with current health messages regarding sun safety and skin cancer reduction.
I recently attended a seminar on Vitamin D presented by Prof. Michael Holick, who brought forward much research on the health issues and risk factors associated with Vitamin D deficiency. One thing he said that has stuck with me is that human beings were originally designed as ‘outdoor plants’ and but most of us are now living as ‘indoor plants’ hence the increased incidence of lower than optimal Vitamin D levels.
Vitamin D is not just a vitamin; it is a hormone and a chemical messenger that is involved in many biological processes, including immune system regulation, inflammatory responses, healthy cell division and replication, nervous system function and bone structure maintenance. Over the past 20 years research has identified a wide variety of health conditions as being associated with low Vitamin D levels including rickets, osteomalacia and osteoporosis, 17 different types of cancer, Alzheimer’s disease, type 1 and 2 diabetes, metabolic syndrome, hypertension, upper respiratory infections, tuberculosis, multiple sclerosis, autoimmune conditions, depression, asthma, psoriasis and eczema.
People who are at risk of deficiency include people with darker coloured skin, overweight individuals, people with limited sun exposure- for example immobile or elderly people, shift workers, people who wear robes or coverings for cultural or religious reasons, and people who spend a lot of time indoors at school or work with little time spent outside.
There are very few food sources of vitamin D and our dietary intake contributes to less than 10% of our overall Vitamin D status. The foods highest in Vitamin D are Cod Liver Oil, oily fish, eggs (from free range/sun exposed chickens) white mushrooms, beef and dairy.
By Natalie Trevaskis – Naturopath
