Last year, four major US retailers had their top-selling supplement brands and herbal supplements tested. The results were pretty bad: 80% of the supplements did not contain the ingredients stated on the label. Some had 0 per cent, and were made entirely of fillers.

These fillers included powdered garlic, rice, wheat and beans – some of which are potential allergens. Even more damning, 10 to 15 per cent contained prohibited substances, and a large percentage made nutritional claims not backed by any scientific evidence.

While supplements offer consumers the promise of enhanced performance, the reality is that for almost all these products, real food does a better job. There are, however, some products that can provide beneficial effects.

Here’s a short list of some of them:

During-exercise sports drinks //

The beneficial effects of carbohydrate and electrolyte drinks – on both high-intensity and endurance performance – is well supported by a host of studies. But beware: caution is needed here, as there is a minefield of unhealthy ingredients used in certain drinks to enhance flavour and palatability.

Beetroot juice //

The active ingredient in beetroot juice that enhances cycling performance is nitrate. The quantity needed is quite high: one litre a day of juice, in order to ingest 800mg of nitrate. The effects are enhanced endurance and sprint performance, along with faster reaction time.

Sodium bicarbonate //

The effects of sodium bicarbonate (BICA) on sprint performance have been demonstrated, but a recent study also showed its beneficial effects on endurance performance.

Twenty-one well-trained cyclists were given 0.3g/kg of body weight of BICA, or a 4g table salt placebo. The test consisted of cycling at 95 per cent of threshold followed by 110 per cent of threshold until exhaustion. There was a 10 per cent improvement in
time to exhaustion in the BICA group versus the placebo.

Caffeine //

In terms of quantity, the equivalent to two cups of coffee or 3mg/kg body weight is sufficient to enhance performance in anything from repeated bouts of five minutes’ high-intensity exercise to a 60-minute time trial.

Recovery drinks //

A study published in the International Journal of Sport Nutrition and Exercise Metabolism discusses the merits of chocolate milk over other sports recovery drinks. The study used nine male cyclists who rode to exhaustion, rested for four hours, then biked to exhaustion again. During the rest period, they drank low-fat chocolate milk, Gatorade (a popular sports drink), or Endurox R4 – a commercial recovery drink. During a second round of exercise, the chocolate milk drinkers cycled about 50 per cent longer than those who drank Endurox, and about as long as those who drank the Gatorade.

The list of legal performance-enhancing products is limited. There’s no magic bullet. To improve from month to month and year to year, the key is to eat healthily, train consistently, and train smart.

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