Sports supplements can’t outperform a balanced diet

Supplements bought online can be contaminated – and downright dangerous

Change your diet and you may not need to use supplements to boost your health. Photograph: Thinkstock

Many athletes use supplements as part of their training or competition routine. This practice may stem from the belief that a normal diet is not sufficient for optimum performance. Unfortunately, there is no substitute for good nutrition and a balanced eating plan. Additionally, an over-reliance on supplements can result in the athlete neglecting their core diet.

There is good evidence that certain supplements may improve the performance of physically mature adult athletes, especially where food intake or food choice is restricted by the type and the demands of a specific sport.

However, sports supplements are manufactured by a large variety of companies and the manufacturing process, labelling and marketing of these products is unwieldy.

Inadequate regulation of the sports supplement industry online means that athletes, particularly the younger and more impressionable ones, can be dazed by exaggerated claims and marketing hype.


Supplements bought online or from a supplier outside Europe might not reach the same safety standards as those permitted in Europe.

In the UK, the product DNP (2-4 Dinitrophenal) has been linked to three reported deaths.

The police, local authorities and the Food Standards Agency are collaborating to prevent further illegal sales of supplements such as DNP, specifically online.

DNP acts by speeding up the metabolism, and harmful side effects such as headaches, an unusually fast heartbeat, excessive sweating, dizziness, nausea, dehydration, fever and vomiting can result. DNP was popular among bodybuilders drawn in by assurances of rapid weight loss.

Sports supplements have also been found to contain ingredients that are not stated on the label.

A recent report by the Irish Sports Council highlighted that a "significant proportion of supplements available on the market are contaminated with substances which are on the World Anti-Doping Agency (Wada) Prohibited List.

“A scientifically verified study has shown that on examination of supplements bought from various sources, up to 14.8 per cent of the supplements were contaminated with undeclared substances which were on the Wada prohibited list.”

Contaminated products
While the brand names of the contaminated products were not provided in this study, they comprised common supplements such as amino acid supplements, protein powders, and products containing creatine, carnitine and herbal extracts, among others.

There is a suspicion that at least some manufacturers intentionally add ingredients to their supplements to boost the effects and increase sales. This is why it is imperative to know the source and production standards of the company making the supplements you buy.

If you wish to report a supplement or sports food that you have concerns about, you can contact the Food Safety Authority of Ireland, Abbey Court, Lower Abbey Street, Dublin 1, for help.

Unfortunately, it’s not an adequate defence to claim you were unaware that the supplement you purchased contained a prohibited substance. If you fail a drug test, you are responsible for any substance found in your body. Under Wada rules, it doesn’t matter how it got there.

If you take prescription or non-prescription medicines as an athlete, you can check them on . This Eirpharm Medicines in Sports Database has been updated to be in accordance with the Wada 2014 prohibited list. It covers medicinal products marketed in Ireland and is effective from January this year.

Rather than taking what everyone else is taking, you should find out what evidence there is to support supplement use at your level and in your sport.

The Irish Sports Council has produced 20 factsheets for athletes over 16 years of age in a bid to help athletes, coaches and parents to understand what supplements may be useful to whom and in what sport.

These consider a range of sports supplements and outline the potential benefits and risks of these products on Ask a qualified professional how much of the supplement you should take and when you should take it, if you’re unsure.

Athletes may also use the correct supplements inappropriately, according to Prof Ron Maughan of Loughborough University in the UK. They may take a supplement when there is unlikely to be any benefit. They may take too high or too low a dose, or take it at the wrong time.

Look at protein supplements, for example. Protein is important in building and maintaining muscle. Powders, shakes and bars are the most popular categories of muscle-building supplements. They are legally and widely available over the counter as well as online.

However, it is possible to achieve the same benefit by focusing on the quality, quantity and timing of the protein in your diet, without the additional expense and without the risk of buying a contaminated product .

A protein supplement may be a convenient and portable option immediately after training when whole foods are not available or cannot be tolerated. But athletes can focus on protein supplements at the expense of carbohydrates after a training session and fail to top up their glycogen stores adequately for effective refuelling and recovery.

Ideally, young athletes should avoid supplements and focus on a good eating and hydration practices, adequate sleep and recovery, structured training and motivation to support growth and optimum performance. None of these factors can be supplanted by the use of sports supplements.

Paula Mee is lead dietitian at Medfit Proactive Healthcare. @paula_mee

The Irish Sports Council checklist

Remember that there is a variable level of risk associated with supplements. Vitamins and minerals produced by reputable pharmaceutical companies, especially those with a marketing authorisation number such as a product authorisation (PA) number, are less likely to be associated with health risks or inadvertent drug tests.

Check if these products are listed on or on the Medication Checker app for smartphones for products bought in the Republic of Ireland.

Follow a dietary plan that will allow you to adapt your eating and drinking practices to maximise your performance.

Seek advice from a professional such as a sports dietitian ( before taking any supplement.

Make sure that the professional is familiar with the Wada prohibited list.

Remember that a change of diet may replace the need for any particular supplement.

Be aware that supplements which claim to be muscle-building or fat-burning are more likely to be associated with contamination by anabolic steroids, stimulants and other contaminants.

Do not take a supplement just because a team-mate or a competitor is taking it or recommends it.

Do not take any supplements made by a company that also manufactures substances which are on the Wada prohibited list as there is a risk of cross-contamination.

Do not take any supplements that make claims that sound too good to be true. Always validate product claims through non-biased sources.

Do not take any supplements made by a company that in the past has been associated with positive drugs tests.

Do not buy supplements either over the internet or through magazines as they are more likely to be associated with an increased risk of inadvertent doping, adverse health effects and other associated problems.

Do not exceed the recommended dose. Remember, more is not always better. Excessive use of one vitamin or mineral can have a negative effect on the availability or absorption of another.

Summary checklist adapted from the Irish Sports Council policy document, Supplements and Sports Foods 2012