Doctor explains: Why I’ve lost faith in my favourite vitamin supplement 94



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Everyone loves D, the sunshine vitamin. Doctors, patients and the media have been enamoured with vitamin D supplements for decades. As well as their clear benefit in curing severe vitamin D deficiencies, endless headlines hail their magical ability to reduce a vast range of conditions from dementia to cancer.

Medical specialists such as myself have been promoting supplements to our patients with osteoporosis and other bone problems for decades. Many food products contain artificially added vitamin D with the aim of preventing fractures and falls and improving muscle strength although the vitamin also has been claimed to boost the immune system and reduce ageing. I used to sometimes take vitamin D myself and recommended it to my family to survive sun-starved winters.

However, a new paper on the risks that vitamin D may pose finally has convinced me that I was wrong. My view on vitamin supplements and the multi-billion dollar industry behind them altered radically after I began researching my book, The Diet Myth, in 2013. The industry and its PR is supported by celebrities who reportedly have high-dose vitamins drip fed into their veins, and around 50% of Americans and Britons take them regularly. But surprisingly, there is a lack of evidence to support the health benefit claims of virtually all vitamin supplements on the market.

One study based on the large SELECT trial suggested that supplements such as vitamin E and selenium actually increased prostate cancer in some men. And last year massive analyses combining 27 studies on half a million people concluded that taking vitamin and mineral supplements regularly failed to prevent cancer or heart disease. Not only are they a waste of money for the majority of us – but if taken in excessive quantities they can actually hasten an early death, increasing your risk of heart disease and cancer.

Virtually no vitamins or supplements have actually been shown to have any benefit in proper randomised trials in normal people without severe deficiencies. Rare exceptions have been lutein nutrients for macular degeneration, a common cause of blindness – and vitamin D, the golden boy of vitamins.

Since the 1980s, researchers (including myself) have written thousands of papers, associating a lack of our favourite vitamin with over 137 diseases. A 2014 BMJ report, however, found these links mainly to be spurious.

Won’t do you any harm?

Our genetic makeup influences vitamin D levels. We can use this information to tell if naturally low vitamin D levels might actually increase the risk of disease (rather than be a consequence of it). The evidence so far suggests (with the possible exception of multiple sclerosis and some cancers) that low vitamin D levels are either irrelevant or merely a marker of the disease.

Until now we haven’t worried about giving people extra vitamin D because we thought “it might help anyway and of course (as it’s a vitamin) doesn’t do you any harm”. With our increasing knowledge, we should now know better. Recent studies in the last five years have suggested that even calcium supplements as well as being ineffective in preventing fracture can increase the risk of heart disease.

While several studies in normal people failed to find any protective effects from vitamin D, others have been more worrying. One 2015 randomised study of 409 elderly people in Finland suggested that vitamin D failed to offer any benefits compared to placebo or exercise – and that fracture rates were, in fact, slightly higher.

The usual prescribed dose in most countries is 800 to 1,000 units per day (so 24,000-30,000 units per month). However, two randomised trials found that at around 40,000 to 60,000 units per month Vitamin D effectively became a dangerous substance.

One study involving over 2,000 elderly Australians, which was largely ignored at the time, and the one just published found that patients given high doses of vitamin D or those on lower doses that increased vitamin D blood levels within the optimal range (as defined by bone specialists) had a 20-30% increased rate of fractures and falls compared to those on low doses or who failed to reach “optimal blood levels”.

Explaining exactly why vitamin D supplements are often harmful is harder. Some people who don’t take supplements have naturally high blood levels which may be due to them spending large amounts of time outdoors in the sun or eating oily fish regularly – and there is no evidence that this is harmful. Higher than average levels can also be due to genes which on average influence about 50% of the differences between people. So our obsession with trying to bring everyone up to a standard normal target blood level is seriously flawed, in a similar way to our one-size-fits-all approach to diet.

Until now we have believed that taking vitamin supplements is “natural” and my patients would often take these while refusing conventional “non-natural” drugs. Our body may not view supplements in the same misguided way. Vitamin D mainly comes from UV sunlight converted slowly in our skin to increase blood levels or is slowly metabolised from our food. In contrast, taking a large amount of the chemical by mouth or as an injection could cause a very different and unpredictable metabolic reaction. For example, our gut microbes are responsible for producing around a quarter of our vitamins and a third of our blood metabolites and also respond to changes in vitamin levels picked up by receptors in our gut lining. Any artificial addition of large amounts of chemicals will upset some sensitive immune processes.

The news that even my favourite vitamin can be dangerous is a wake-up call. We should be taking our worldwide abuse of these chemicals much more seriously rather than routinely adding them to foods. The billions we waste on these products, assisted by the poorly regulated but rich and powerful vitamin industry should be spent on proper healthcare – and people should be educated to go in the sunshine and eat a diverse range of real food instead. For 99 per cent of people, this will provide all the healthy vitamins they will ever need.

The ConversationDo you take vitamin D supplements? Have you ever been advised to? Does this expert’s opinion change the way you view them?

Tim Spector, Professor of Genetic Epidemiology, King’s College London

This article was originally published on The Conversation. Read the original article.

The Conversation

The Conversation is an independent source of news and views, sourced from the academic and research community and delivered direct to the public. Their team of professional editors work with university, CSIRO and research institute experts to unlock their knowledge for use by the wider public. We republish The Conversation's content under Creative Commons License.

  1. I asked for a vitamin injection, I felt tired and run down, you all know what that is like , it has a name..getting old !! My doctor told me not to bother or bother taking vitamin pills, because we pay a lot of money for them, then just pee them down the toilet

    10 REPLY
    • My doctor said exactly the same thing Rosalind, he said there is no scientific proof that they have any benefit, it’s just making the companies that make them a fortune.

    • it may be the pacebo effect Susan Goodwin, if works for you then fine but I would not waste my money, I eat fruit and vegetable, they should give you all the vitmins you need and 10 or 15 minutes in the sun every day

    • Well my freind who is a pharmacologist and surgeon has similar knee problems to me and recommended my vitamin regime.I think he is undoubtably the smartest person I have ever met and he takes vitamins.
      But as you say if you try it and find no significant difference after being on them for at least a couple of months you have wasted a few dollars…you can buy reputable brands in the supermarket ir duscount pharmacies…however if you are like me I find a significant improvement and a return of my symptoms if I stop the supplements they ate worth the few cents a day I invest.Good luck.

    • I do the same my doctor wouldn’t give me pill or supplements he said eat healthy and and three meals a day plenty excersise never had a problem good doctor he was always stood by his advice he didn’t be leave in pill popping

    • My diet is good too Christine
      Being in a pension it is mainly fruit, veg and I make my greek yoghurt.

  2. Have to agree with this. Why would you take vitamins when you can get them through clean fresh food?

    3 REPLY
    • The problem is clean fresh food these days as in short supply. All mass produced in nutrient deficient soils and sprayed with all manner of toxic chemicals.

    • It is good to see someone realising the problems with the way we produce our food Dawn. I try to grow my own veggies, buy organic food, and do not eat factory farmed animals. I suspect that the pesticides and herbicides used so much are contributing to ill health.

  3. I have osteoporosis. Take 1.25mg Calciferol ( Vit D ) once a month. Get as much sun as poss and calcium rich diet. Also take Lutein supplement for eye problems. Very good health otherwise.

  4. I need a knee replacement.
    When I take 3000 mgs fish oil
    1500 mgs glucosamine
    My knee pain resolves.
    I still feel the bones grating against each other but the ache seems to subside.
    If I miss them for a week the pain returns.
    Placebo or not it works for me.
    Now I started on probiotics in 2015 as a precaution to travelling in Asia.
    I have kept them up because I felt they were doing me good.
    I have cared for my sick children and grandchildren and not picked up their bugs.
    Over Christmas I let them go and ended up at the doctors with urti…coincidence …perhaps…but Im back on them now.
    If it works for you go for it.
    I stopped vitamin D and instead just go outside a bit more.

  5. Mike here-I take warfarin & I don’t like to mess with my blood levels I’m in a high risk category. My blood INR is between 2.5 & 3.5. The INR can be affected by simple things like oats, green leaf veg anything with vitamin ‘K’. I can eat these things but no sudden gorging with them but even before the Warfarin I didn’t take any vitamins, June on the other hand takes whatever she feels she needs, I don’t think she’s gone onto ‘D’ vitamins yet

  6. Oh well, I am in the 2nd year of a medical trial for high dose vitamin D. Maybe I have been given the placebo but I will continue on as they might discover something useful in the final analysis.

    3 REPLY
  7. I’ve been taking vitamin b (as advised by a doctor) since about 1980, 2 a day. Last year we took a cruise so decided to go without and within that 2 wk period my nails started peeling, as soon as I went back on it my nails stopped peeling .

    3 REPLY
  8. Australians wouldn’t be taking Vitamin D unless prescribed/advised by their doctor anyway – most of us get our daily dose from the sun. I think most Aussie doctors would first suggest daily exposure to sunlight for a vitamin D deficiency, and only prescribe a supplement where this was not possible. The right supplements in the right doses are often very beneficial to some people.

    2 REPLY

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