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Confused over vitamin D?

In Health and Nutrition by robert.verkerkLeave a Comment

Courtesy of one or two recent papers, the extensive knowledge base on the efficacy of Vitamin D is being questioned by a few high profile academics who are not vitamin D experts themselves. This advice is being used to influence health authorities around the world to be very conservative about vitamin D recommendations.

It’s time to listen to the vitamin D experts

Vitamin D, the sunshine vitamin, was rapidly developing superhero status among the vitamins. That’s because a wealth of research in recent years shows that it does a bunch of very useful things when we have sufficient amounts of it (in the 25-hydroxyvitamin D form) in our blood.

There’s overwhelming evidence, for example, that low levels of vitamin D in the blood are linked to increased risk of osteoporosis and bone fractures, suppressed immunity, a higher risk of getting and dying from heart attacks and strokes, elevated risk of some cancers (especially colorectal and ovarian) as well as risk of death from those cancers. And, if that wasn’t enough, vitamin D deficiency leads to a greater risk of contracting certain kidney diseases as well as autoimmune diseases, like rheumatoid arthritis or multiple sclerosis.[1]

However, courtesy of one or two recent papers, all of this knowledge base is being questioned by a few high profile academics who are not vitamin D experts themselves. This advice is being used to influence health authorities around the world to be very conservative about vitamin D recommendations – so much so, that if you follow the Australian (or for that matter the US or UK) government recommendations, vitamin D experts are telling us you will, unnecessarily, increase your risk of getting a serious disease later in life.[2]

How come a simple vitamin can yield such a wide range of benefits? Well, that’s because this vitamin is fundamental to our existence, and it’s why we think of vitamin D as an essential vitamin; we simply can’t live without it.While rickets and other bone abnormalities are associated with gross deficiencies of vitamin D in children, we suffer a plethora of less obvious side effects if we’re vitamin D deficient. And yes, there’s a big debate in the scientific community as to what blood levels we should consider as deficiency thresholds, all of this made more complicated by the fact that the threshold for vitamin D’s bone health functions are lower than for some of its other functions, such as reducing cancer risk or modulating the immune system.

If you look at the recommendations made by the world’s leading vitamin D researchers, including Reinhold Vieth PhD at the University of Toronto and Mount Sinai Hospital, or Michael Holick PhD MD from the Boston University School of Medicine, their views are at odds with government advice [2]. Bear in mind that government advice, the world over, doesn’t include input from vitamin D experts but rather from scientists and bureaucrats that could be regarded as generalists in the field of nutritional science.

It sounds absurd to exclude the views of those who are most expert in a field, but that’s because health policy is often more about politics and economics than it is about science.And let’s not forget so-called ‘science’ isn’t always ‘objective science’. At many levels, science is infiltrated and distorted by politics and economics. Science can also be very conservative; so some generalist scientists are only willing to accept incontrovertible evidence such as the lower threshold required for vitamin D and bone health [3,4], while ignoring the more variable evidence associated with the link to cancer risk reduction. The trouble is that it’s those who lay their trust in what governments tell us about how we should manage our health that may have the most to lose, especially when it comes to vitamin D recommendations.

Why is vitamin D a vitamin superhero?

Vitamin D acts on our health in a very fundamental way. We can get a little bit of it (rarely more than 5% of our requirement) from fatty fish, mushrooms, some plants and seaweeds, but, from an evolutionary point of view, we’re adapted to get most of it from the sun. Humans evolved in hot places and for most of our existence as a species we’ve not been cooped up in buildings and cars, or been smothered in sunscreen. Vitamin D is made in the skin. As a key hormone precursor, vitamin D has been found to have profound anti-inflammatory and immune-modulating properties in the body. That’s apart from its key role in controlling calcium absorption in the small intestine and working with parathyroid hormone to both maintain bone density and calcium homeostasis in the blood stream.

To make vitamin D, we need to be exposed to UV(B) rays. These don’t penetrate clouds and are most abundant in the midday sun, exactly the time when most of us, courtesy of government health messaging, have been told to cover up, slap on the sunscreen or escape indoors.People with dark skins, even when exposed to the sun, produce less vitamin D; so are more at risk of vitamin D deficiency if they avoid the sun, cover up or wear high-protection sunscreens. Some safe tanning beds can also be used to make vitamin D, but you need to check that the type of sun-bed produces known amounts of UV(B). As with tanning in the sun, it’s important to not burn your skin; so time for your body exposure needs to be carefully controlled according to your skin type. A final, less known, fact is that the vitamin D made in your skin isn’t immediately absorbed into the blood stream. It can take up to 48 hours for the vitamin D to be absorbed fully through the skin. As vitamin D is fat soluble, it’s important to not wash thoroughly with soap those areas of the skin most exposed to the sun or UV(B) rays for up to two days following significant exposures; your armpits and groin can of course receive attention!

The most at-risk groups for vitamin D deficiency include housebound, community-dwelling older and/or disabled people, those in residential care, dark-skinned people (particularly if they are largely covered), and anyone else who regularly avoids sun exposure or works indoors.Those with Crohn’s or coeliac disease may also be susceptible because they generally suffer fat malabsorption issues and so don’t benefit as much from vitamin D in foods or supplements.

Contrary to popular belief, it’s younger, not older, people who are more likely to be deficient. With it we’re seeing rickets incidence soaring worldwide. One of the reason for this is because older folks are more likely to supplement, and women, especially, are made aware of the importance of vitamin D post-menopause because of the increasing risk of osteoporosis. The rest have been scared away from the sun, spend too much time indoors or are overly protected by sunscreens.

The bottom line is that, especially in the southern states, approaching one in two Australians suffer vitamin D deficiency during the winter months (Fig. 1), even by the overly low cut-offs used in Australia and New Zealand. If you look at the levels proposed by vitamin D experts, you’ll find more than 7 out of 10 Australians in the southern states are deficient in winter.

Fig. 1 Vitamin D deficiency by state as determined by Australian government thresholds, 2011-12 (Source: Australian Health Survey: Biomedical Results for Nutrients) [3]









Vitamin D controversies

It’s an irony that almost no one in the world has too much vitamin D as measured by circulating levels of 25(OH)D when taking into account safety thresholds established by vitamin D experts; yet we’re made to feel scared of taking too much in supplements. Vitamin D experts generally recommend taking at least 4,000 IU (100mcg) of vitamin D3per day for adults not exposed to the sun, and more for anyone who is severely vitamin D deficient.

The detractors come in various forms and tend to get their views across in editorials of heavyweight scientific journals that frequently publish studies plugging pharmaceutical drugs. For example, two professors, Paul Welsh and Naveed Sattar, weighed in on the subject in the British Medical Journalin 2014. Another leading, high profile critic of vitamin supplementation has been Paul Offit MD, chief of the infectious diseases division of the Children’s Hospital of Philadelphia and author of “Do You Believe in Magic? The Sense and Nonsense of Alternative Medicine” (Harper, 2013).

Countering these views is a very comprehensive study published earlier this year in the peer reviewed journal PLoS One. It shows clearly that doubling the circulating levels of vitamin D from the 50nmol/L (= 20ng/ml) threshold for adequacy to 100nmol/L (= 40ng/ml), results in a startling greater than 65% reduction of all invasive cancers combined.

For those wanting to look more closely at the science on vitamin D, I recommend you look at online resources such as the websites of the Vitamin D Council (, Grassroots Health ( and Vitamin D Wiki (


25-hydroxyvitamin D (25(OH)D) serum level recommendations
(blood serum levels for 25(OH)D given in nmol/L; to convert to ng/mL divide by2.496)





ABS National Health Measures Survey (NHMS) recommendations (Australia) [5]International Vitamin D experts’ recommendations [6]
 LowSevere deficiency:
<13nmol/LModerate deficiency:
13-29nmol/LMild deficiency:
Deficient: 0-100nmol/L

Adequate levels:
Target level: 78nmol/L

Sufficient: 100-200nmol/L

Target level: 125nmol/L

HighHigh Normal:




> 250nmol/l


Toxic: > 375nmol/L


1.     Don’t be frightened of the sun; we’re born to be exposed to it

2.     Get your serum vitamin D tested and aim for the 125nmol/L target recommended by the Vitamin D Council experts. Achieve this through good quality vitamin D3 supplements and/or with sun exposure.

3.     Don’t allow your skin to burn in the sun (or on a sunbed) – ever!

4.     You’ll get more UV(B) rays on your body when the sun is high in the sky, i.e., when your shadow is shorter than your height. Typically you won’t need more than around 20 minutes’ exposure of 80% of your body to allow your skin to produce its maximum daily yield of vitamin D (which equates to the equivalent of 10,000-20,000 IU [250-500mcg] taken orally).

5.     Don’t scrub your skin with soap after sun exposure for a couple of days to make sure absorption via the oil on your skin is optimised.

6.     It’s particularly important that vitamin D levels are maintained in pregnant, lactating and breastfeeding women, in older women and in children, as well as in those with dark skins and those more likely to be housebound or who are rarely exposed to the sun.


Robert Verkerk PhD is the founder, executive and scientific director of the non-profit, Alliance for Natural Health International ( Through his work over the last 30 years in academia, commerce and the non-profit sector, he has been an outspoken advocate of working with, rather than against, nature. His work has spanned the fields of agriculture, healthcare, energy and the environment.



1.        Kulie T, Groff A, Redmer J, Hounshell J, Schrager S. Vitamin D: an evidence-based review. J Am Board Fam Med.2009; 22(6): 698-706.

2.        Vitamin D Scientists’ Call To Action Statement []

3.        Australian Health Survey: Biomedical Results for Nutrients, 2011-12 []

4.        Lucas R, Neale R. What is the optimal level of vitamin D? Separating the evidence from the rhetoric. Aust Fam Physician2014; 43(3): 119-22 [].

5.        Nowson CA, McGrath JJ, Ebeling PR, Haikerwal A, Daly RM, Sanders KM, Seibel MJ and Mason, RS, 2012, Vitamin D and health in adults in Australia and New Zealand a position statement, Medical Journal of Australia196(11): 686-687 [].

6.        Vitamin D Council recommendations for serum vitamin D levels [].


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