Bogus or beneficial? The verdict on vitamin D

Feb 28, 2021
A third of Aussies are deficient in vitamin D. Source: Getty

No one doubts that we all need vitamins, minerals and trace metals, and specific deficiencies are well described. But there is an ongoing debate in medical science about the importance and usefulness of supplementation.

With a modern, healthy diet, the vast majority of people derive all the micro nutrients needed to prevent a major deficiency disease. Problem is, fewer than 10 per cent of people consume the suggested two to three pieces of fruit a day, along with three-five servings of vegetables a day (a serving being about half a carrot, as an example). Fruit and vegetables are the most important source of micronutrients.

One area of research that is gaining a very strong evidence base is vitamin D. But, as with most aspects of supplementation, there are strong supporters and strong critics. Many of us who believe in supplementation are sick of hearing the tedious hackneyed comment about “all vitamins give you is expensive urine”. A more objective review of the current science is that supplements give us valuable blood and – for the purpose of this article – I will focus on the benefits of vitamin D, which is a vital natural substance, regardless of the source.

Because Australia is a sun-drenched country, we have embraced the slip-slop-slap message and are spending more time indoors due to increasing sedentary jobs and lifestyles. Subsequently, we are often not receiving adequate doses of vitamin D, with about one third of the Australian population showing insufficient vitamin D levels (of less than 50 nmoles per litre).

Initially it was thought that low vitamin D levels may predispose a person to osteoporosis, but research in the past decade has found a more far-reaching role for vitamin D.

Four studies from 2018 highlighted the diverse and important nature of maintaining normal vitamin D levels. The first, published in British medical journal The BMJ, comes from Japan, where 33,763 Japanese between the ages of 40-69 were followed for a 16-year period. During this time, there were 3,301 new cancer diagnoses. Those who had the highest blood levels of vitamin D had a 20 per cent lower cancer risk. Because of the nature of the study, it was difficult to relate this to specific cancers, although there appeared to be somewhere between a 30-50 per cent reduction in risk for liver cancer (especially for men), and no obvious link for lung and prostate cancer.

The second study, published in The Journal of Clinical Endocrinology & Metabolism, looked at the association between vitamin D and cardiovascular risk. This study from Norway looked at just over 4100 adults, average age 62, with a diagnosis of angina pectoris, who were followed up for 12 years. There were 895 deaths including 407 deaths from cardiovascular disease. Those with a normal vitamin D level compared with those with a vitamin D deficiency had a 30 per cent reduction in cardiovascular death.

The third study, published in Heart, Lung and Circulation, looked at the link between vitamin D and heart failure. This was a study in mice looking at particular cells known as cardiac colony-forming unit fibroblasts (cCFU-Fs), which promote the formation of a scar after the induction of a heart attack. The study clearly showed that vitamin D blocked the action of cCFU-Fs leading to reduced scar formation and therefore better cardiac function.

The final study, published in the journal Neurology, looked at the link between vitamin D and multiple sclerosis. This examined lifelong sun exposure in 151 women with multiple sclerosis average age 40 and compared this with 235 age-matched controls. They then examined altitude, latitude and cloud cover and found that those who came from sunny climates with the highest UV-B exposure had a 45 per cent reduction in risk for multiple sclerosis. In particular, those who lived in a sunny climate between the ages of 5-15 had a 51 per cent reduction in risk for multiple sclerosis. Those who spent a lot of time outdoors from the same demographic, a 55 per cent reduction in multiple sclerosis.

The research over the past decade has demonstrated a link between low vitamin D levels and osteoporosis, cardiovascular disease, cancer, multiple sclerosis, type II diabetes, asthma and depression. Vitamin D plays a clear role in cholesterol metabolism, many facets of immune function and certainly appears important in brain function.

Evidence last year, mainly from Europe, has also suggested that those people with the lowest levels of vitamin D had the highest rates of Covid-19, Covid complications and Covid deaths.

It is not as yet established as to whether you should obtain vitamin D from careful sun exposure, food sources or supplementation but with the evidence we have to date it is clear that low levels of vitamin D are associated with poor health outcomes.


Please note: This article was updated on Thursday, March 4. The paragraphs relating to the study published by the Berghofer Medical Research Institute in Queensland have been removed due to factual inaccuracy. 

 

IMPORTANT LEGAL INFO This article is of a general nature and FYI only, because it doesn’t take into account your personal health requirements or existing medical conditions. That means it’s not personalised health advice and shouldn’t be relied upon as if it is. Before making a health-related decision, you should work out if the info is appropriate for your situation and get professional medical advice.

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Do you take a vitamin D supplement regularly? Are you happy with the results?

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