Vitamins and supplements are big business - but do they work?

By Dr Rachel Tyler, Stirling Road Surgery, St Budeaux

Walk down the aisles of any chemist or supermarket these days, and you are bound to stumble upon the huge, colourful and confusing vitamins and supplements section. There is no doubt that the supplement industry is big business, but is there any evidence that they do any good?

The very short answer is, if you eat a balanced diet, then probably not. Many of the everyday foods we consume are already fortified with essential vitamins and minerals – from breakfast cereals, bread and even table salt, so adding in extra vitamins is rarely necessary.

Surely it couldn’t harm to take a few vitamins just in case? Well, apart from the damage to your wallet, it is possible for over the counter supplements to have negative effects. Fat soluble vitamins in particular, such as A, D, E and K can be toxic if the recommended daily amount is exceeded and other popular over the counter supplements such as St John’s Wort can interfere with prescribed medication, such as the contraceptive pill or blood thinners. Never exceed the recommended daily allowance (RDA) of any vitamin and always let your doctor know if you are taking anything over the counter.

You may be wondering how manufacturers can sell these products if there is so little evidence that they actually work. Over the counter supplements are regulated by general food law, as opposed to those for pharmaceutical drugs, therefore the only standard they must reach is that they are fit for human consumption. Look carefully and you will see the wording used on the packaging is deliberately vague ‘may help fatigue and tiredness’, ‘designed to boost energy and vitality’, ‘contributes to bone health’, ‘can aid a good night’s sleep’, ‘traditionally used for . . .’ etc

All that said, there are a few groups in whom extra vitamins and supplements are recommended:

  • If you're pregnant or trying for a baby it's recommended that you take a 400 microgram folic acid supplement, which available over the counter, every day until you're 12 weeks pregnant. This is to help to prevent neural tube defects such as spina bifida.
  • Breastfed babies should be given a daily supplement containing 8.5 to 10 micrograms of vitamin D from birth, (even if the mother is taking a supplement containing vitamin D) Infant formula is fortified with vitamin D and other nutrients
  • Children aged six months to five years should take vitamin supplements containing vitamins A, C and D every day. Your health visitor is a good port of call if you have any questions about childhood vitamins.
  • People who are not often exposed to the sun – such as people who are frail or housebound, are in an institution such as a care home, or usually wear clothes that cover most of their skin when outdoors, should take a daily supplement containing 10 micrograms of vitamin D. This year the government provided a four month supply of Vitamin D to all care home residents, to counter the effect of the fact that many of these vulnerable residents would have had very little exposure to sunlight during the pandemic.
  • Many vegetarian and vegan patients ask me if they need to take extra vitamins. While maintaining a balanced diet can be more challenging for those excluding certain food groups, it is perfectly possible to eat a plant-based diet without the need for supplementation, provided you do your homework. NHS choices website has some useful guidance: https://www.nhs.uk/live-well/eat-well/the-vegan-diet/

My advice to my patients is simple - unless you fall into one of the at risk categories, you almost certainly can save your money. Maintaining a healthy weight, eating a wide, varied diet with fruit and vegetables and getting regular exercise is the real route to feeling better - and unfortunately, there are no shortcuts to that available over the counter.