Vitamin D - Why It's So Important
Recently I read an article titled “Which Vitamin Will Improve Your Life Expectancy The Most”.
Researchers at Moores Cancer Center at the University of California, San Diego have recently got heads turning in the scientific world and they are all nodding too. A new study looking at the relationship between serum vitamin D levels and the risk of colon and breast cancer across the globe has estimated the number of cases of cancer that could be prevented each year if vitamin D levels met the target proposed by researchers.
Dr Cedric F. Garland and colleagues estimate that 250,000 cases of colorectal cancer and 350,000 cases of breast cancer could be prevented worldwide by increasing intake of vitamin D, particularly in countries that are furthest from the equator. “For the first time, we are saying that 600,000 cases of breast and colorectal cancer could be prevented each year worldwide”.
In a television interview Dr Garland said:
"Vitamin D has more potential than any other vitamin or micronutrient that we know of to prevent cancer; this is a powerful vitamin."
It doesn’t stop there either. They are now saying that 18 other forms of cancer are more common in people who don’t get sufficient Vitamin D and deficiency of this vitamin has recently been found to play a role in a wide variety of diseases including heart disease, stroke, autoimmune diseases (such as Multiple Sclerosis), diabetes, depression, osteoarthritis, osteoporosis and birth defects. This does not mean that vitamin D deficiency is the only cause of these diseases, or that you will not get them if you take vitamin D. What it does mean is that vitamin D, and the many ways in which it affects a person's health, can no longer be overlooked by the health care industry, nor by individuals striving to achieve and maintain optimal health.
Dr. Michael F. Holick a Professor of Medicine at Boston University and a leading authority on Vitamin D estimates that one billion people around the world have a deficiency of this essential vitamin with up to 50% of the entire population in the United States falling into this category.
What about New Zealand?
Associate professor Robert Scragg an epidemiologist at Auckland University has this to say; “New Zealand has a severe Vitamin D deficiency; local studies have confirmed this. Current guidelines have been based on 200 IU (International Units) from birth to 50 years of age and 400 IU for people in their 50’s to 70’s where from then on, the suggested intake is 600 IU." Professor Scragg says this is based on outdated research and the guidelines need to be urgently addressed.
He suggests that for optimum health and bone and muscle strength, 2000 IU is more appropriate. So how do we ensure that we get enough Vitamin D? Most of us know that the best place to get vitamin D is from your skin being exposed to the UV-B that is in normal sunlight. Vitamin D from sunlight acts as a pro-hormone, rapidly converting into 25-hydroxyvitamin D. The high rate of natural production of vitamin D3 cholecalciferol in the skin is the single most important fact every person should know about vitamin D because it has such profound implications for our wellbeing.
Exposure to sunlight for extended periods of time does not cause Vitamin D toxicity. This is because within about 20 minutes of ultraviolet exposure in light skinned individuals (3–6 times longer for pigmented skin) the concentration of vitamin D precursors produced in the skin reach an equilibrium, and any further vitamin D that is produced is degraded.
A single, twenty-minute, full body exposure to summer sun can trigger the delivery of 20,000 units of vitamin D into the circulation of most people within 48 hours. Professor Scragg says it would take approximately 20 times the dose of a typical Vitamin D supplement to obtain what would be gained during five minutes in the sun.
The problem is that even in Auckland we are 4,100 kms from the equator (Dunedin is 5,093 kms) and with the ‘slip slop slap’ sunscreen message foremost in our minds, we have been progressively limiting our exposure to the sun during the summer months. Thus we have no Vitamin D reserves to get us through the winter. We need UVB light in order to make Vitamin D (When your skin is exposed to the sun, UVB rays are the ones to ‘unlock’ the reactions that will give rise to the active form of vitamin D inside your body). Regardless of how much time we spend outdoors in the winter months the sun is too low on the horizon to allow UVB rays to reach us.)
Dietary sources of Vitamin D are limited and while in New Zealand we are now seeing fortified dairy products, only fish such as salmon, mackerel sardines tuna canned in oil provide useful levels around 300 IU.
Based on all of the above it is clear that we should know where we fit on the Vitamin D scale and work hard to maintain it at an optimum level throughout the year. Next time you are scheduled to see your doctor ask for a 25 (OH) D test (25-hydroxyvitamin D). This is a simple blood test and according to one of the world’s leading Vitamin D researchers William Grant PhD, you should be aiming for 45-50 ng/ml (115-128 nmol/l which is how it’s measured in New Zealand).
The last word goes to Dr. Michael Holick, University of Boston:
“Vitamin D deficiency and its consequences are extremely subtle, but have enormous implications for human health and disease. It is for this reason that vitamin D deficiency continues to go unrecognized by a majority of health care professionals."