A deficiency of evidence
Britain is obsessed with its low vitamin D levels, says Dr Shaba Nabi - but is it a problem we really need to fix?
When I was working as an senior home officer in psychiatry in 1993, I remember looking after a man in his early 40's. He was admitted following section 3 of the Mental Health Act as it was felt he was a risk to his health through his bizarre, restrictive diet and his failure to leave his squalid house. His severe muscle wasting was thought to be due to a combination of lack of exercise and malnutrition. It wasn't until his admission bloods revealed a low calcium and phosphate coupled with a high alkaline phosphatase, that a diagnosis of severe osteomalacia was made.
I was fascinated by this case and went on to look after his medical and psychiatric needs for the next six months. His case was a pivotal experience for me and my decision to change careers and work in general medicine for a few years before I became a GP.
I have not seen another case of osteomalacia since then, despite having a heightened awareness of it. Yet, as I moved from London to Bristol in 2007 to work in a multi-cultural inner city practice, I find the terms Vitamin D deficiency and osteomalacia are used interchangeably and treated as one condition.
So we are now in 2012 when virtually every newspaper, magazine and patient group is campaigning about the population's collective vitamin D deficiency and demanding something be done about it. It has even entered the race arena as certain populations are at higher risk of deficiency so if their treatments are restricted or unavailable, it becomes a race issue
So what are the facts? The truth is…..we don't know. There is remarkably little high quality evidence in this area and yet every year the vitamin D campaign gathers momentum. Patients are presenting on a daily basis demanding their vitamin D levels are checked on the basis of a wide variety of non specific symptoms. Their levels are low so…..there must be a causal relationship. For years, many healthy and asymptomatic populations have had "deficient" levels of vitamin D without any consequences. Surely, if virtually the entire population is being labelled as being deficient; there must be something wrong with the parameters?
It has become a routine blood test for TATT, (tired all the time) depression, chronic fatigue and any musculoskeletal symptom. In fact, it has become more of a screening test for many ethnic groups, despite the fact it doesn't fulfil any of the criteria for one. This mass indiscriminate testing is not helped by the fact that CKS (clinical knowledge summaries) recommends it as one of the routine blood tests for TATT (tired all the time); not because of any referenced research, but because the authors think it should be included.
Internis, the company who manufacture Fultium D3, the only licensed preparation of high dose vitamin D, originated in 2010. Two years from conception of a company to a license must be a small miracle but no original research has taken place to bring this product to market. Instead, its product profile resembles more of a literature review of current vitamin D research, which lacks any double blind randomised controlled trials to evaluate the efficacy of widespread replacement therapy for many of the non specific symptoms it is recommended for.
It's much easier to give someone a label and a quick fix than to tease out some of the complex physical and psychological reasons for undifferentiated symptoms, especially if this consultation has to be done through an interpreter as it often is. How many cases of depression, inflammatory arthritis and spinal pathology are being missed through diagnosing vitamin D deficiency as a primary cause?
GPs need some urgent direction as they are currently swimming in murky waters over this issue. Until there is some high quality evidence in this area, the responsibility to supplement the population's vitamin status needs to lie with the individual and public health – not with GP practices that are already overloaded with the burdens of commissioning and transfer of work from secondary to primary care.
In the meantime, I will carry on functioning with a vitamin D level of 27, despite eating at least 5 portions of oily fish per week (I am a pescatarian) and regularly sunbathing on the beaches of Spain and Long Island. I attribute my fatigue and occasional low mood to working twelve hours a day with a young family, rather than my vitamin D status!
Dr Shaba Nabi is a GP in Bristol