Supplement Basics

vitamin supplements

An estimated 40% of adults take vitamin, mineral and herbal supplements to help maintain their health. A wide range of products are available, and it is often difficult to know where to start.

While diet should always come first, a good multivitamin and mineral supplement acts as a nutritional safety net to ensure you obtain all the nutrients you need from your diet.

A scientific review of over 150 clinical trials published in the Journal of the American Medical Association showed that lack of many vitamins is a risk factor for heart disease, stroke, some cancers, birth defects, osteoporosis, bone fractures and other major chronic health problems.

In an accompanying editorial, the authors even state that ‘Pending strong evidence of effectiveness from randomised trials, it appears prudent for all adults to take vitamin supplements,’ although this remains controversial for many doctors!

If you choose to take a supplement, look at the labels to see how each supplement compares.

If you are under 50, select one providing at least 100% of the nutrient reference value (NRV, also known as recommended daily amount or RDA) of as many vitamins and minerals as possible. Those designed for the over-50s will generally contain more antioxidants and B group vitamins (which are absorbed less efficiently in later life) but less iron (as body stores of this mineral tend to increase in later life and excess may be harmful).

I also recommend that you take a supplement made to a pharmaceutical standard known as GMP (good manufacturing practice). This means they are checked at every stage of production for purity and to ensure they provide the correct, consistent dose.

What is GMP?

GMP stands for Good Manufacturing Practice and refers to the rules and regulations that ensure the consistent quality of medical drugs. These pharmaceutical guidelines can also be applied to the manufacture of food supplements, to ensure that each tablet or capsule contains the right ingredients, in the amounts specified, with no contaminants. Not all manufacturers do this because of the extra cost and effort involved, but it is important to ensure you obtain the same benefit from each dose. Multivitamin that is not made to GMP standards could have, for example, twice as much selenium in one tablet, and hardly any in another, compared with the amount claimed on the label.

If, like me, you value the quality of the supplements on which you spend your hard-earned cash, check the manufacturer’s website to see if they have a GMP statement. The easiest way to do this is to Google the manufacturer’s name plus the term (eg ‘Healthspan Good Manufacturing Practice’).

The principles of GMP ensure that:

  • Personnel involved in manufacturing processes are properly qualified
  • Premises are of a high standard and inspected regularly
  • All laboratory equipment is checked and calibrated according to rigorous schedules
  • Appropriate levels of hygiene and sterility are in place to prevent contamination
  • Every stage of the process is documented and double-checked to ensure consistency
  • Samples of all raw materials are tested to confirm their identity and purity
  • All ingredients are properly prepared and weighed
  • Samples are tested for quality control at specified stages during production
  • Finished supplements are tested to ensure they contain the right amounts of different ingredients
  • Internal and external audits are carried out to ensure every stage of production meets specified international standards (eg ISO 9001)
  • Samples of both raw ingredients and finished products are retained and stored for future reference, if required
  • Records enable the full history of each batch to be traced
  • Data are archived and retained for at least a year after the expiry of a finished batch
  • Studies are carried out to confirm the stability and ‘shelf life’ of finished products.

In the UK, compliance with GMP regulations is assessed by the MHRA (Medicines and Healthcare products Regulatory Agency).

In the US, the Food and Drug Administration (FDA) oversees compliance with regulations relating to the Dietary Supplement Current Good Manufacturing Practices (CGMPs) for quality control.

NB If you are pregnant or breast-feeding, only take supplements designed for use at these times, as some supplements may be harmful.

Do not exceed recommended doses.

Vitamin cover

The Essential Guide to Vitamins, Minerals and Herbal Supplements, available from and

Image credit: tinpalace/freeimages

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