Supplementation - a thinking athlete's guide to planning a programme
With the explosion in sports nutrition products in recent years, the lure of pills, lotions and potions to gain a competitive edge is stronger than ever. But according to Ron Maughan, athletes need to think hard and exercise caution in order to reap potential benefits without the drawbacks
Most athletes at some stage in their careers use one or more dietary supplements – after all, when you invest a great deal of time, effort and money in training to improve performance, the extra investment in a supplement programme seems relatively small. However, the financial cost is perhaps the least important of the issues that need to be considered before using supplements.
While supplements can offer possible health and performance benefits, some can produce detrimental effects and may be potentially harmful to health and performance. These negative aspects are less often talked about, partly because there’s not so much information available, and partly because some people depend on supplement sales for their income.
Any serious athletes should take care to carry out a detailed cost-benefit analysis before embarking on a supplement programme. Much of the information needed for this analysis is not easily available, and in some cases is not available at all, but this is no different from other aspects of training and preparation, where the athlete or coach has to make assessments based on limited information.
Why take dietary supplements?
When athletes are asked why they take dietary supplements, the answers reveal that they often do so without detailed thought. At the highest levels of performance in sport, high financial stakes have increased the pressures on elite athletes to seek every possible advantage over the opposition. This alone would not support the multi-billion dollar supplement industry, but health, fitness, weight loss and physique are increasing preoccupations for many people, and this is where the market lies.
Many athletes believe that the stresses of intense training and competition cannot be met by food alone. Added to this, there is a popular perception that food quality has declined in recent years due to intensive farming methods and to modern food production processes. Supplements are easily available at (relatively) low cost and may seem to provide an attractive solution to an inadequate intake of essential nutrients.
The range of supplements on sale is enormous. One web-based advertisement boasts that over 12,000 different supplements are available. Faced with such a choice, the athlete has to decide what they are looking for. In some cases, the reasons are not different from those of their sedentary friends, though the need may be more acute. Such supplements would include those aimed at:
ensuring an adequate intake of essential vitamins and minerals;
weight loss and fat loss;
a tonic effect;
promoting immune function and resistance to infection;
maintaining joint health.
In addition, there are specific needs of athletes, though these will vary between sports:
promoting tissue growth and repair;
promoting recovery from and adaptations to training;
enhancing energy supply;
delaying fatigue by effects on the central nervous system.
There is also an enormous range of sports drinks, energy bars and other products, often fortified with various nutrients, targeted at the athlete.
Where to begin?
The first question that needs to be asked about any supplement is: Will it provide any benefit and, if so, under what conditions? Is it something to support training, or is it aimed at a specific performance improvement for competition? This means asking who will benefit – for example, the needs of the strength athlete are different from those of the endurance athlete. These first two questions cannot be separated from the next question: Are there any possible adverse effects of acute or chronic use?
Multi-vitamins and diet
If the aim of supplementation is to support training by ensuring an adequate intake of normal dietary components (vitamins, minerals etc) then we need to see if the dietary intake is already adequate. If not, the first aim should be to find a dietary solution to the problem, using supplements only if the necessary changes to the diet cannot be made.
Your diet may not supply enough essential nutrients if the amount of food you are eating is very small or if you exclude a number of foods or food groups from your diet. For athletes in regular training, food intake will normally be high, so deficiencies are unlikely.
Equally, many athletes are very regular in their habits, and they may choose from a very limited range of foods. Athletes often make excuses for poor diets – lack of time and money etc – but the reality is that a lack of information and understanding, often combined with poor food preparation skills, are the real reasons for poor diet. It costs no more to eat well than it does to eat badly. A supplement – even the best multi-vitamin/mineral supplement – will not provide many of the important food components that are likely to be lacking if poor food choices are made.
The roles of many of the antioxidants and other components of food are still not well understood, and many of these are not found in dietary supplements. The Consensus Statement produced by the IOC Medical Commission meeting on Nutrition in Sport in
‘Athletes are cautioned against the indiscriminate use of dietary supplements. The use of supplements does not compensate for poor food choices and an inadequate diet. Athletes contemplating the use of supplements and sports foods should consider their efficacy, their cost, the risk to health and performance, and the potential for a positive doping test.’
However, there are a few situations when it might be appropriate to add a broad-spectrum, low-dose multi-vitamin/multi-mineral supplement to the diet. These include periods of food restriction to achieve weight loss, prolonged periods of gastrointestinal disturbances, or times away from home when food availability or choices may be limited. Longer-term solutions are far better achieved by making appropriate food choices.
The use of iron supplements, for example, is popular, but it is not difficult to find a better option. A bowl of breakfast cereal that is fortified with iron will provide not only about one-third of the total daily requirement, but will also provide a range of essential B vitamins, carbohydrate and fibre. Add a glass of orange juice, and the vitamin C it contains, will help stimulate absorption of iron as well as provide essential antioxidant nutrients.
It is important also to remember that the quality control of some vitamin supplement manufacturers is not good. Many have been reported to contain small amounts of essential ingredients, while others may contain excessively high and potentially toxic doses. Some contain other things that should not be there (lead, broken glass, animal faeces etc) due to poor conditions of manufacture and storage. The safest way seems to be to get supplements from the reputable pharmaceutical companies, who are more likely to have good procedures in place.
Supplements with something to offer
The number of supplements where the evidence is strong enough to warrant definite recommendations is rather small. Several things must be borne in mind, however. The absence of evidence should not be interpreted as an absence of effect: in many cases, the experiments have just not been done. It is also important to remember that the science is not as precise as we might like. Small effects will not register in studies where only a few subjects are used, or where some respond to treatment and some do not. In sport, however, small effects can be vital: in the London Marathon of 2003, the difference between first place and sixth was only seven seconds. Matthew Pinsent won his fourth Olympic gold medal in
This leads to the argument that supplements may be worth a try, just in case there may be a benefit. The converse is also true, however, and there may well be negative effects that have not yet been recognised. The sensible athlete and the responsible coach will adopt a cautious approach, making the athlete’s health a priority.
A few supplements are supported by sufficient evidence to warrant a definite recommendation, but the athlete still needs to consider how and when to use these, how much to use, what form to take the supplement in, and whether the cost justifies the benefit or whether the money would be better spent elsewhere.
Most people consume caffeine on a daily basis, whether in tea, coffee, cola, chocolate or other common foods and drinks. It used to be thought that effects on performance were only achieved with high doses of caffeine, but we now know that even small amounts can improve performance and, importantly, more is not necessarily better. In a study by the Australian Institute of Sport, the amount of caffeine found in a couple of cans of cola was sufficient to produce significant improvements in well trained cyclists in a cycling time trial test.
In a recent review of all the available evidence, researchers from the
Improvements were seen, however, even in short-duration high-intensity exercise. Small amounts of caffeine (as little as 60mg or one cup of coffee) have been shown to have effects on decision making, alertness and reaction time, and amounts of 1-3mg per kg of bodyweight have been shown to enhance endurance performance. Higher doses of caffeine (more than 5mg per kg bodyweight) do not seem to have greater effects on performance than smaller dosages.
A study by the Australian Institute of Sport showed how small caffeine doses can be effective. A group of well-trained cyclists rode for three hours and drank one of the following during the last hour:
Cola (caffeine (90mg) plus carbohydrate);
Caffeine-free Cola (extra carbohydrate trial);
Half-strength Cola (caffeine (90mg) trial);
Half-strength caffeine-free Cola (control trial).
They rode a time trial in which they completed a fixed distance as fast as possible. The results in the chart below demonstrate the clear advantage afforded by caffeine ingestion.
These results seem clear: the risks associated with caffeine are very small, even though high doses may be harmful; the cost is small; and there is good evidence of beneficial effects on performance. However, athletes should be aware that high doses may produce undesirable side effects and also that caffeine taken late in the day may increase the time taken to fall asleep. The use of caffeine used to be limited in sport, but it was removed from the World Anti-Doping Agency (WADA) list in January 2004: WADA is still monitoring use, but athletes are free to use it.
The use of creatine by athletes has caused much controversy, with many calls for its use to be prohibited. The only justification for this seems to be that it is effective in improving performance: if this is the basis for banning it, then training should also be banned!
There is a sound theoretical basis for the use of creatine supplements. Creatine phosphate is an important energy source in high-intensity exercise, and is especially important in rapid recovery between multiple sprints with short recoveries. There is evidence that using creatine supplements can increase the amount of creatine and creatine phosphate in the muscles and can improve performance in strength and power events. It is also sometimes, but not always, associated with a rapid gain in body weight of about 1-4kg, which may be an advantage in some sports but may be a disadvantage in others.
Creatine is a normal component of muscle and the main sources in the diet are therefore meat and fish. The body needs about 2g of creatine per day to replace the amount that is broken down. Vegetarians have little dietary creatine intake, but meat eaters typically get about 1g per day from the diet. The rest of what we need is synthesised from amino acids supplied by the diet.
Although the primary use of creatine to date has been by athletes who want to build muscle or to increase strength and power, it may have some other important uses. When taken together with a series of high-carbohydrate meals after endurance exercise that has resulted in depletion of muscle glycogen, creatine has been found to stimulate glycogen synthesis.
This may be important in promoting recovery on a daily basis in athletes during periods of hard training, and it may be especially important when competitions take place with only one or two days of recovery between them. More investigation is needed, but these early results are a good example of the dilemma we face. Do we wait for the findings to be confirmed by other studies, or do we jump in and give it a try. The evidence for risk in this case seems small, and the potential for benefit is strong, so it seems worth a try.
Hard exercise increases the rate of oxygen use by muscles, generating oxygen free radicals. These are highly reactive chemical species that interact with other molecules in the body’s cells, and which may be involved in the damage that occurs to muscles during and after hard exercise. In theory, if the post-exercise damage can be reduced by an increased intake of antioxidant nutrients, then recovery after training and competition may be more rapid and more complete.
A number of vitamins, such as vitamins A, C and E are effective antioxidants, interacting with and neutralising the free radicals, and minerals such as selenium are also important. The evidence at present suggests that antioxidants may help recovery, but is not conclusive. It’s important to recognise that the body contains a complex mixture of antioxidants, which all work in harmony with each other, and there’s some evidence that very high doses of single antioxidants may do more harm than good. Foods that are high in antioxidants, including most highly coloured fruits and vegetables, may well be the best sources of these nutrients.
Regular training also increases the effectiveness of the body’s own antioxidant defence mechanisms, which means that even extremely intense exercise may not cause any excessive oxidative damage in well-trained athletes. If this is the case, it could be that antioxidant supplementation is unnecessary once a regular training routine is established.
A few dietary supplements may offer real benefits to the athlete and are supported by evidence that is strong enough to warrant a recommendation for their use, but they should be only a small part of the overall diet, training and lifestyle plan. It’s always better to invest time and effort in ensuring a good diet than to try to compensate for poor food choices by taking pills or potions. Most supplements will do no harm, but some may have negative consequences. The sensible athlete will want to see good reasons for taking supplements before using them.
1. J Appl Physiol 2002; 93(3):990-9
2. Int J Sport Nut & Ex Metab 2004; 14(6):626-46
3. Physiological Society abstract presented at Univ of Cambridge; Pre-Circulated C59 Oral Communications, 2003