There is an ongoing debate in medical science about the importance and usefulness of supplementation. No one doubts that we all need vitamins, minerals and trace metals and specific deficiencies are well described. With a modern, healthy diet, the vast majority of people derive all the micro nutrients needed to prevent a major deficiency disease.

But, there is no doubt that in modern society less than 10% of people consume the suggested 2–3 pieces of fruit per day along with 3–5 servings of vegetables per day (a serving being around ½ a carrot as an example). Fruit & vegetables are the most important source of micronutrients.

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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 & 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, & (for the purpose of this article), I will focus on the benefits of Vitamin D. Vitamin D is a vital natural substance, regardless of the source.

A recent study published by the Berghofer Medical Research Institute in Queensland was a very extensive, placebo-controlled trial using Vitamin D 60,000 I.U. taken as one capsule per month. This study followed 16,000 Australians aged 60–84 for 5 years. 2,600 of these people filled in a questionnaire every year about the colds & flu experienced throughout the preceding year. The study concluded that Vitamin D didn’t stop this older age group experiencing respiratory tract infections but appeared to reduce the length and severity of these types of infections.

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I found the conclusion of this study quite unusual as the researchers stated that vitamin D appeared to be of no benefit. Firstly, I challenge anyone to accurately remember the length, the severity and the number of respiratory tract infections they experienced in the preceding year, although some more anally retentive people may have recorded this as they knew they had to fill in a questionnaire at the end of the year.

Regardless, the vitamin D (in this rather unusual dose) did not cause any harm and seemed to reduce the length and severity of a respiratory tract infection.

Recent evidence, mainly from Europe, has suggested that those people with the lowest levels of vitamin D had the highest rates of COVID, COVID complications and COVID deaths.

Initially it was thought that low vitamin D levels may predispose to osteoporosis but research over the past decade has found a more far reaching role for adequate vitamin D levels. Unfortunately, around one third of the Australian population has vitamin D levels less than 50. nmoles per litre. Despite the fact that Australia is a sun drenched country, we have embraced the “slip slop slap” message and also, with increasing sedentary jobs and lifestyles, are spending more time in doors. Thus, we are often not receiving adequate doses of Vitamin D.

Four new studies have highlighted the diverse and important nature of maintaining normal vitamin D levels. The first, published in the BMJ, comes from Japan where 33,763 Japanese between the ages of 40–70 were followed up for a 16 year period. During this time, there were 3300 new cancer diagnoses. Those who had the highest blood levels of vitamin D had a 20% 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% reduction in risk for liver cancer and no obvious link for lung and prostate cancer.

The second study, published in the Journal of Clinical Endocrinology and 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 (chest pain), 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% 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 scar tissue 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 of 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% reduction in risk for multiple sclerosis. In particular, those who lived in a sunny climate between the ages of 5–15 had a 51% reduction in risk for multiple sclerosis. Those who spent a lot of time outdoors from the same demographic, a 55% reduction in multiple sclerosis.

The research over the past decade has clearly 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.

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.

Dr Walker is an expert in the field of preventative cardiology and has published seven books. He gives lectures nationally and internationally.