Lots of people take vitamins, minerals and other remedies they buy from health shops – so called ‘over the counter’. It is a massive industry – estimated to be worth £1.86b in the UK alone. Is this just clever marketing?

The fact remains that a normal varied diet in the UK will provide all the nutrients you need. Even vegetarians do not normally need to take supplements. One of the commonest supplements is vitamin C but I have never seen a case of scurvy – vitamin C deficiency – in my lifetime. Vitamin C does not prevent colds or infections; this has been researched extensively and shown not to work. Vitamin C is water soluble and so most of it is simply eliminated in the urine, but high doses can produce excess acid in the blood causing heart and kidney failure.

A concern for doctors is that we never actually know what the patient is taking. If you are prescribed a drug it will have gone through years of rigorous testing and the actual contents will have to be published, but supplements are not regulated in the same way and the ingredients, if listed at all, are often in the form of plants and vegetables as opposed to chemical composition. The risk of an interaction with anaesthetics or other drugs is always in the back of my mind.

If a doctor has told you to take a supplement then please do so, but always remember to bring the supplement in its original container to hospital for me to see.

So are there any other exceptions? Well, patients who are anaemic may be given iron supplements. That is fine, but I normally stop them for five days before an operation and for a couple of weeks after to avoid unpleasant constipation.

Recent research suggests that both men and women lack vitamin D in the winter in the UK due to a lack of sunlight, so a single vitamin D3 tablet each day is a good idea.

There is some evidence folic acid, in a reasonably high dose of 800mcg a day, may reduce the risk of some cancers. It is cheap and side effects are very rare unless you take about five times this dose. Research some years ago suggested an even weaker effect for selenium. I am not advising anyone to take these supplements, merely pointing you to research. And glucosamine reduces painful joints.

Finally there are prescription or non prescription drugs which can be used to prevent as opposed to treat illness – so call prophylaxis. Statins, used to treat high levels of cholesterol in the blood, play a major role in reducing heart attacks and strokes in the normal population. Sadly there has been a combination of poor research and a group of doctors opposed to routine drug administration in the population but I believe the evidence is clear that if you can take statins without the side effects a minority of people get they are worth taking

Aspirin also reduces cardiovascular deaths but risks bleeding from the stomach which can be fatal. Research in the general population has been unclear as to whether the benefit outweighs the risk, so although you can buy aspirin over the counter I would strongly recommend you discuss this with your GP first. Interestingly it may also protect against bowel cancer but please talk to your GP!

Finally an interesting development – metformin. This incredibly cheap tablet is used to treat type 2 diabetes. However there is a lot of evidence that it may have antitumorigenic effects – reducing cancer and improving the efficacy of chemotherapy quite independent of its effects on blood sugar. There is also evidence it effects signalling within the cell, the metabolic pathway, oxygen radicals and cell proliferation. Mainstream scientists have been interested in the effect of metformin on ageing, although the most likely mechanism was disproved a couple of years ago and a lot of research does not meet the quality to be accepted. A large study found that low doses of metformin are safe and do not produce low blood sugars in non diabetics, so this is one to watch but it can’t be recommended for general use at present.

About the author

Dr Aubrey Bristow is a consultant anaesthetist in central London. These articles are his personal views and reflect individual issues of interest to patients. They are not a comprehensive review of the subject nor a substitute for a consultation with your anaesthetist.