Supplements

The dietary supplement industry is increasing rapidly every year with many different special foods, pills and powders all promising to make us better athletes. The main reasons to support the use of these supplements are
  • to compensate for less than adequate diets or lifestyles
  • to meet high nutrient demands induced by heavy exercise
  • to produce a direct effect on performance.

    There are two main types of supplements. Dietary supplements or sports supplements contain nutrients similar to recommended dietary intakes to help athletes meet their increased demand for nutrients and energy. Examples of these supplements are sports drinks, gels, liquid meal replacements and vitamin/mineral supplements. It is important to remember that these supplements per se do not produce a performance enhancement. Rather, it is the use of a supplement to achieve sports nutrition goals that allows the athlete to train and perform optimally. Dietary supplements are generally acknowledged as valuable sources to provide nutrients to athletes as well as to the general public to help ensure optimum nutrient intake, however it is important to maximize healthy food intake before seeking the help of supplements.

    Sports Supplements

    Multivitamins and minerals are only recommended in cases where athletes restrict their total energy intake (for weight maintenance or weight loss) or make restrictive food choices (such as vegetarians) to help prevent deficiencies. Supplementation with antioxidants such as vitamin C and E, or selenium may help decrease oxidative stress caused by high levels of physical activity but benefits may have been too small to quantify in scientific studies. Iron supplementation may be useful particularly in females with chronic low intake and effects of menstruation.

    Protein powders are readily available but many people are using them unnecessarily. Regular exercise does increase an individuals requirements for dietary protein, but levels above 1.6 g/kg of body mass has not shown any added benefits and it is easy to achieve this amount though food sources which is always superior to taking supplements. Protein powders may be beneficial for athletes that follow a low energy diet (therefore low protein) in order to make weight for their sport. Risks of high protein diets are that they may promote increased calcium loss, increased risk of gout in susceptible people and possibly displace other important nutrients in the diet.

    Liquid meal replacements are generally used for those who need to gain lean body mass, athletes who are undergoing a growth spurt and can help athletes cope with heavy training loads. They are compact source of carbohydrates with moderate protein and micronutrients to help athletes meet nutritional goals without too much preparation involved. These replacements are more expensive than whole foods so it's important to weigh up the benefits and practicality of using them.

    Sports drinks are a convenient way to help increase fluid consumption during exercise as well as providing a supply of glucose for energy. The sodium content helps to replace sweat losses but also enhances the absorption of the water and glucose in the small intestine. Consuming sports drinks has been shown to enhance performance in endurance events lasting longer than 1 hour but is also useful in aiding re-hydration post exercise. Sports waters are also available and contain a lower concentration of carbohydrates which suits those who are exercising at a low intensity, do not require the extra kilojoules, or need a small amount of flavour to stimulate thirst.

    Sports gels are a highly concentrated, compact source of carbohydrate that are easy to carry during events to provide a large fuel boost. Make sure you consume them with plenty of fluid and do test usage during training as high intake may cause gastrointestinal upsets.
    Sports bars also provide a more compact, solid source of carbohydrate to satisfy hunger during prolonged exercise and provide high levels of energy and nutrients for athletes. They are more expensive than whole foods, however are more portable and provide a useful snack when traveling.

    All these sports supplements are there to help the athlete achieve adequate nutrition for their sports but whole foods should always be considered first as they will always be superior to processed foods.

    Ergogenic Aids

    The other broad category of supplements is generally termed ergogenic aids, which suggest an enhancing effect on sports performance. Many of these products rely on theoretical support rather than scientific support and are generally not supported by nutrition experts unless scientific trials consistently show a performance enhancing effect.

    Creatine is a compound derived from amino acids which is primarily stored in skeletal muscle. A large amount of this creatine is combined with phosphate to form creatine phosphate which provides a rapid source of energy for the muscle in the initial stages of exercise. The major benefit of creatine supplement appears to be an increase in the rate of creatine phosphate resynthesis during the recovery between bouts of high intensity exercise, producing higher creatine phosphate levels at the start of the subsequent exercise period. Evidence of creatine supplementation enhancing performance in endurance running and swimming has been inconsistent, although it has been shown to aid cyclists and team and racquet sports (where repeated high intensity bouts are required) and people who do interval and resistance training.

    Caffeine is a naturally occurring stimulant of the central nervous system, and has been shown to enhance sporting performance through increasing mobilisation of fat, lowering feelings of fatigue, accelerating adrenaline response, and stimulating effects on cardiac muscle. The effects differ between individuals depending on mode of exercise, duration, training status of the athlete and habitual intake. It is important to note that high caffeine intake can have unfavorable effects such as increases in heart rate and over-arousal that can interfere with recovery and sleep patterns.

    Glycerol is used by athletes to hyperhydrate when planning to embark on prolonged intense exercise in hot and/or humid environments where sweat losses are going to be high. When consumed orally with substantial fluid it temporarily helps to increase fluid retention in the body. In general, studies show that the use of glycerol prior to an event may help performance but use should be monitored by a professional as side effects include nausea, gastrointestinal distress and headaches.

    Bicarbonate supplementation has been shown to enhance the body's ability to buffer lactic acid and enhance performance of anaerobic exercise lasting 3-7 minutes. These benefits may also transfer to team sports but more research is needed. The main concern of bicarbonate supplementation is the reports of gastrointestinal upsets.

    Amino Acids

    • Several amino acids have been claimed to help increase muscle mass and decrease fat. Arginine, ornithine and lysine have been marketed as muscle growth stimulators but so far there have been no convincing evidence to prove that these supplements promote an enhanced response to resistance training. These amino acids can be easily obtained by consuming recommended amounts of dairy products and eggs.

    Glutamine is also an amino acid that is being sold as a supplement as some research has found low levels of glutamine in overtrained athletes may be the cause of lowered immune function. However study methodology is flawed and glutamine supplementation is only beneficial for true glutamine deficiency.

    Ginseng and other related herbal products have a history in eastern medicine but have only recently been used by athletes. Lack of scientific evidence cannot support the claims that these products cure fatigue, relieve pain or headaches and improve mental function and some have been found to contain banned substances such as ephedrine.

    Carnitine has been suggested to enhance fatty acid oxidation and transport, helping to decrease body fat and increase fat usage in submaximal endurance events. So far there is no high quality scientific evidence showing these benefits.

    Coenzyme Q10 is believed to have a role as an antioxidant, which may decrease the oxidative damaged caused by increased exercise. Studies have shown mixed results and the jury is still out on this supplementation.

    Colostrum is a protein-rich substance secreted in breast milk in the first few days after a mother has given birth. The supplements available are typically from cow sources. Colostrum supplementation is claimed to improve exercise performance and recovery though the studies to date haven't sufficiently demonstrated improvements and this product doesn't come cheap.

    HMB or ?-hydroxy ?-methylbutyrate is a by product of the amino acid leucine and is claimed to decrease protein breakdown and therefore enhance muscle size, promote fat loss and reduce exercise induced muscle damage. Small improvements have been seen with resistance training in previously untrained men, but further research is needed, as this is a relatively new product.

    It is important to remember that to meet nutritional demand, first focus on your food intake. Any supplement will never replace a well chosen diet. There is a small risk that some sports supplements may lead to a positive doping test if you decide to participate in professional sporting events, so make sure you check out the supplement carefully and consult the professionals. What may work for some individuals may not work for others and sometimes it's just the placebo effect that may give you the edge.


    By
    Michelle Blunden BPhEd, BSci

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