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Dietary supplements

July 2, 2019
 

Introduction

Dietary supplements are foodstuffs that differ from conventional foodstuffs either by their appearance or their way of use. Dietary supplements come in various forms: for example, as tablets, capsules or powders. Most commonly, they are used by athletes and exercise enthusiasts to advance performance capacity, recovery, muscle mass accumulation, weight loss, and health, as well as to ascertain the intake of energy and nutrients.

Dietary supplements are regulated in Finland by the Food Act and the regulatory authority is the Finnish Food Authority (formerly the Finnish Food Safety Authority Evira). However, the Finnish Food Authority does not evaluate the contents or the safety of dietary supplements or the claims made about them. For example, it does not require any scientific evidence for the effects of a preparation. The responsibility for dietary supplement safety lies with the manufacturer, the contract giver or the importer.

There are plenty of dietary supplements on the markets and dietary supplement advertisements can be convincing, as can website product demonstrations and sales pitches as well. Dietary supplement advertising has often been misleading and it is advisable to take a critical attitude toward the claims made by advertisements, public figures, and sellers. According to research, only a small portion of the dietary supplements on the markets can be of benefit and even then their effect is low. If a product or its effects are marketed as “revolutionary”, the claim hardly ever has any backing in practice.

Furthermore, since the athlete is always held personally responsible for any positive doping result possibly induced by some product, athletes should ascertain that the dietary supplement in question does not contain any compound that is prohibited in sports. The greatest risk relates to the various workout boosters and weight-loss preparations, which are intended to enhance the training output, but which may contain other substances: for example, prohibited stimulants.

Furthermore, testosterone precursors are often prohibited in sports, as are the products intended to increase the level of such. In general, the products ordered online or abroad are associated with a greater risk than those acquired in Finland. Dietary supplements are not doping substances per se. In some cases, however, dietary supplements are produced in the same facilities as substances that are classified as doping substances, whereupon there is a risk of contamination. So in principle, any preparation may contain prohibited compounds even though nothing of the kind should be present based on the information about the contents.

Jaakko Mursu
Doctor of Philosophy (PhD)
docent, authorized dietician
University of Eastern Finland

The most commonly used and researched dietary supplements

Carbohydrate preparations, such as sports drinks and gels, can improve performance capacity in long (over 1.5–2 hrs), high-intensity endurance performances. The effect is based on the fact that intakes of carbohydrates can maintain the blood sugar level and delay the exhaustion of the stores of glycogen. In practice, carbohydrates can help to maintain the performance output for longer and postpone the time it takes to become exhausted. The effect on performance capacity is relatively low: only a few percent. However, the effect can have practical significance, for example, in a competitive situation.

The recommended amount of carbohydrates is as follows: 30 g/hr for performances of one to two hours, 60 g/hr for performances of two to three hours, and 90 g/hr for performances exceeding two and a half hours. The recommended fructose and glucose/maltodextrin (a glucose polymer) ratio is 1:2. This ratio is based on the absorption capacities of the various carbohydrates. The maximum amount of fructose absorbed per hour is approximately 30 g while the maximum amount of absorbed glucose is clearly higher: approximately 60 g per hours. Most of the sports drinks and gels available on the markets contain the recommended proportions of carbohydrates.

Moreover, rinsing one’s mouth with a carbohydrate drink (for 5–10 seconds at intervals of approximately 5 minutes) would seem to enhance performance capacity in high-intensity endurance performances of short duration (of approximately 30–75 minutes). The effect on performance capacity would appear to be approximately 1–4%. The performance capacity enhancing effect is higher in people who have trained less and lower in people, such as athletes, who have trained more. In short-duration performances, the sufficiency of the stores of carbohydrates is not a limiting factor; rather, the performance capacity enhancing effect would appear to be mediated by central nervous systemic mechanisms.

Sufficient protein intake is important to people engaged in strength sports, but also to those involved in other types of sports. Protein is needed to serve as a building block of muscle mass and other kinds of body protein structures, such as tendons and the mitochondria that participate in energy production. The recommended intake is approximately 1.2–2 g/kg/24 hrs. In some situations, such as when one is engaged in the process of losing weight, the optimum amount can be a little higher (approximately 2.0–2.5 g/kg). Where a sufficient amount can be of benefit, so can regular intake (at intervals of approximately 2–4 hrs) and good protein quality.

Protein supplements, such as the commonly used whey protein, can be of benefit in increasing strength and muscle mass if the protein intake from one’s diet is relatively low otherwise. If the intake is high even without a supplement, using such will probably be of little benefit. Research has found that the beneficial effects would appear to be explained by the fact that a protein supplement raises the amount of protein to the recommended level. When the amount of protein exceeds 1.6 g/kg/24 hrs, the protein supplement has not been detected to be of any further benefit. Likewise, a protein-based recovery drink is probably of little benefit if the intake is high otherwise. Taking a protein supplement after practice can be a practical solution if there is no appetite after a workout or if eating is simply not possible. Hard practice can increase the protein synthesis for up to 1–2 days, so in order to support recovery and development, the protein intake should be sufficient for an extended period.

Amino acid preparations, such as the popular leucine or other branched-chain amino acids (BCAAs), would appear to be of no benefit to increasing strength or muscle mass. Protein synthesis requires the sufficient intake of all the necessary amino acids (8 different ones), so taking some isolated amino acids is not sufficient. Moreover, plenty of leucine and other BCAAs are already gained from food like milk products, so the use of supplements is not necessary.

The effects of creatine have been researched extensively since the 1990s and the preparation studied overwhelmingly the most is creatine monohydrate. Creatine supplement use increases the myocyte creatine level by 20–40%, whereupon one is able to produce energy for longer in high-intensity performances. Creatine supplementation can help to increase the amount of creatine phosphate (phosphocreatine) and the re-formation of adenosine triphosphate (ATP) from adenosine diphosphate (ADP). Creatine phosphate and ATP are used as sources of energy especially in high-intensity performances of less than 30 seconds.

Creatine enhances performance capacity in short-duration, high-intensity performances and it increases muscle strength and the amount of fat-free tissue. Creatine is of benefit in sports that consist of one or several high-intensity performances of short duration. The stores of creatine can be filled by fuelling with 0.3 g/kg/24 hrs (20–30 g/24 hrs) of creatine for approximately 4–7 days. With smaller doses of approximately 2–3 g/24 hrs, the stores can be filled in approximately one month. The use of creatine increases one’s weight by approximately 0.6–1 kg by raising the amount of internal fluid in the muscles. Creatine does not have any detected adverse health effects and there is no need to take time off from creatine use.

Caffeine (1, 3, 7-trimethylxanthine) is a stimulant affecting the central nervous system. The most well-known source of caffeine is coffee, which contains nearly 100 mg of caffeine per 100 ml of coffee. Moreover, energy drinks, tea, cola drinks, cocoa, and chocolate contain caffeine. The caffeine content of one caffeine tablet is 100 mg.

The effects of caffeine have been researched extensively already since the 1970s and its effects on endurance sports in particular are well known. Caffeine improves performance capacity in a number of different sports and through a variety of mechanisms. Caffeine can reduce the feeling of strenuousness during exercise, improve the activation of the motoric units, and economize muscle glycogen use by improving the use of fat for energy production. Caffeine improves both the aerobic and the anaerobic endurance characteristics and its effect on performance capacity is approximately 2–3%. According to research, caffeine also increases upper body strength and, to a slight extent, the loss of fat tissue.

The beneficial effects of caffeine have been detected with doses of approximately 3–6 mg/kg/24 hrs. Caffeine is absorbed quickly in approximately 30–60 minutes and the effects last a few hours. In the relevant studies, caffeine is generally ingested approximately one hour before the performance. Some of the side effects of caffeine include restlessness, nausea, and tremors with some people being more sensitive to the effects than others. Caffeine is not a doping substance; it was removed from the list of prohibited substances in 2004.

Baking soda is a compound affecting performance capacity and among the compounds that have been studied the longest. Sodium bicarbonate is an alkaline buffer, which neutralizes the acidic lactate and hydrogen ions that are born in high-intensity performances. The increased acidity in high-intensity performances weakens performance capacity, for instance, by weakening the contraction capacity of the myocytes. Sodium bicarbonate enhances performance capacity by 1–4% in high-intensity performances, which last approximately 1–7 minutes, and where acidity increases significantly. Baking soda can be of benefit, for example, in middle-distance running, speed skating, rowing, and sprint skiing. In performances lasting less than 30 seconds, baking soda is of no benefit because acidity does not have the time to increase as much.

A suitable dose is approximately 0.2–0.5 g/kg (equivalent to approximately 4–5 Tbsp) taken approximately 1–2 hours before the performance. The use of baking soda is limited by its side effects, namely, an increased need to defecate, nausea, and thirst. The side effects are common, but temporary. One can try to reduce them by dividing the dose into smaller portions (e.g. 5 x 1 Tbsp ingested over the course of 1–2 hrs) and having plenty of water. Due to the side effects, it is advisable to try the effects of baking soda beforehand and not in conjunction with something like a competition.

Beta-alanine is an amino acid, which together with histidine amino acid forms carnosine. Carnosine is an acidic buffer, which can be found, for instance, in the muscles. A high muscle carnosine level reduces muscle acidification in high-intensity performances.
 
Beta-alanine has been detected to increase the muscle carnosine level by 60–80% over the course of 4–10 weeks. Beta-alanine can help to improve the anaerobic (or high-intensity) practice capacity. Beta-alanine is of benefit in sustained or repeated maximal performances of short durations varying approximately from 30 to 240 seconds. It may be that it can also be of benefit in longer performances lasting up to 10 minutes. The proportion of the benefit gained is a few percent. In performances lasting less than 30 seconds, where acidity is not a factor limiting the performance, no benefit has been detected. A suitable dose is approximately 4–6 g/24 hrs, divided into smaller doses of 0.8–1.6 g. Tingling of the skin occurs as a side effect, but this is a harmless phenomenon.es is not warranted, however.
Nitrite is a compound, which occurs naturally in vegetables like beets and spinach. In the body, nitrate is reduced to nitric oxide, which expands the blood vessels and reduces blood pressure. This is thought to reduce the muscle oxygen demand and improve muscle work efficiency, thus enhancing endurance performance. Nitrite can postpone exhaustion and improve performance capacity in performances lasting approximately 5–30 minutes. However, the amount of clinical evidence available currently is small and the results are partly conflicting. Moreover, the significance of nitrates for health is unclear. In the body, nitrate can react with amines, creating compounds called nitrosamines, which increase the risk of cancer. Nitrate also induces some mild stomach upsets.

 

Nitrite:

Nitrite is a compound, which occurs naturally in vegetables like beets and spinach. In the body, nitrate is reduced to nitric oxide, which expands the blood vessels and reduces blood pressure. This is thought to reduce the muscle oxygen demand and improve muscle work efficiency, thus enhancing endurance performance. Nitrite can postpone exhaustion and improve performance capacity in performances lasting approximately 5–30 minutes. However, the amount of clinical evidence available currently is small and the results are partly conflicting. Moreover, the significance of nitrates for health is unclear. In the body, nitrate can react with amines, creating compounds called nitrosamines, which increase the risk of cancer. Nitrate also induces some mild stomach upsets.

Citrulline malate:

Citrulline malate has been claimed to have a number of effects, such as reducing body acidity during high-intensity performance and enhancing nitric oxide production, thereby enhancing blood circulation and muscle oxygenation. There are only a few studies on the effects of this compound and it is not currently possible to evaluate the effects reliably. In the first studies published, the results seemed highly promising as citrulline malate had been detected to significantly increase the number of repetitions in the consecutive series performed by strength sport trainees. Later studies have not been able to repeat these observations and this is why the effects of citrulline malate are currently unclear.

Beta-hydroxy beta-methylbutyric acid (HMB):

Beta-hydroxy beta-methylbutyric acid (HMB) is a metabolic product of the branched-chain amino acid leucine and it has been claimed to have anticatabolic and anabolic effects. In novice strength sport trainees and elderly people, HMB would admittedly appear to increase the amount of muscle mass and lower body strength slightly (0.5–1 kg in 3–6 weeks). However, in people with more training experience, the detected effects have been minimal and the significance of HMB is still unclear.

Workout boosters/chargers:

Preparations, which are taken before a workout, seek to enhance the workout output. The composition of the preparations on the markets varies. The most common active ingredient in the preparations is caffeine, which is added for its stimulating effect. The preparations may contain creatine, carbohydrates, amino acids, beta-alanine, citrulline malate, and other compounds.

Weight-loss preparations:

On the markets, there are plenty of different types of dietary supplements claiming to have a slimming effect. Weight loss always requires a long-term energy deficit, but permanent weight management demands permanent lifestyle changes. Various low-energy meal replacements can help one to lose weight, but then the energy intake will be lower than its consumption. Caffeine or green, conjugated linoleic acid (CLA) can slightly increase weight loss, but the effect is minimal: approximately 0.5–1 kg over the course of a few months. The slimming effect of caffeine and green tea is based on the slightly increased energy consumption. The effects have been detected mainly in people who are overweight and the potency is probably lower in those who are of normal weight.

Other commonly used supplements:

Of the various nutrient deficiencies, iron deficiency is the most common one and among exercise enthusiasts it can be more common than on average. The best known role of iron is to act as the oxygen-binding component of hemoglobin, advancing the transfer of oxygen from the lungs to the tissues. An iron deficiency first drains the stores of iron, whereupon the serum ferritin level falls. As the deficiency continues, hemoglobin will fall as well. A decreased hemoglobin level weakens physical performance capacity in endurance and power sports. A low ferritin level without anemia can weaken physical performance capacity as well. The correction of low hemoglobin (but possibly low ferritin as well) primarily by an orally administered iron preparation will probably improve the athlete’s performance capacity. The correction process generally takes 3–6 months.

For people aged 18–74 years, the use of 10 μg of a Vitamin D supplement is recommended during the wintertime (October–March) if the intake from the diet is low. The use of a dietary supplement is also warranted if the measured levels in the body are low (e.g. deficiency limit <50 nmol/l). If the intake of Vitamin D and its level in the body is sufficient, supplement use will probably be of little benefit to the exercise enthusiast in terms of health or exercise.

Exercise can increase the need for magnesium somewhat, but in the studies conducted, magnesium supplementation failed to reduce cramps or enhance sport performance. Then again, no studies have been conducted, for example, on the prevention of cramps in athletes.

Antioxidant supplements, such as Vitamin C or Vitamin E, beta-carotene or selenium, would appear to have benefits to target-oriented exercise enthusiasts. According to some studies, large doses gained via dietary supplements can reduce training-induced tissue damage. At the same time, however, they can reduce the practice-induced training response: for example, fitness development. A Vitamin C supplement can slightly reduce the duration and symptoms of upper respiratory tract infections and zinc can reduce the risk of such as well. The continued use of large dos

Citrulline malate has been claimed to have a number of effects, such as reducing body acidity during high-intensity performance and enhancing nitric oxide production, thereby enhancing blood circulation and muscle oxygenation. There are only a few studies on the effects of this compound and it is not currently possible to evaluate the effects reliably. In the first studies published, the results seemed highly promising as citrulline malate had been detected to significantly increase the number of repetitions in the consecutive series performed by strength sport trainees. Later studies have not been able to repeat these observations and this is why the effects of citrulline malate are currently unclear.

Beta-hydroxy beta-methylbutyric acid (HMB) is a metabolic product of the branched-chain amino acid leucine and it has been claimed to have anticatabolic and anabolic effects. In novice strength sport trainees and elderly people, HMB would admittedly appear to increase the amount of muscle mass and lower body strength slightly (0.5–1 kg in 3–6 weeks). However, in people with more training experience, the detected effects have been minimal and the significance of HMB is still unclear.

 

Preparations, which are taken before a workout, seek to enhance the workout output. The composition of the preparations on the markets varies. The most common active ingredient in the preparations is caffeine, which is added for its stimulating effect. The preparations may contain creatine, carbohydrates, amino acids, beta-alanine, citrulline malate, and other compounds.

 

On the markets, there are plenty of different types of dietary supplements claiming to have a slimming effect. Weight loss always requires a long-term energy deficit, but permanent weight management demands permanent lifestyle changes. Various low-energy meal replacements can help one to lose weight, but then the energy intake will be lower than its consumption. Caffeine or green, conjugated linoleic acid (CLA) can slightly increase weight loss, but the effect is minimal: approximately 0.5–1 kg over the course of a few months. The slimming effect of caffeine and green tea is based on the slightly increased energy consumption. The effects have been detected mainly in people who are overweight and the potency is probably lower in those who are of normal weight.

Of the various nutrient deficiencies, iron deficiency is the most common one and among exercise enthusiasts it can be more common than on average. The best known role of iron is to act as the oxygen-binding component of hemoglobin, advancing the transfer of oxygen from the lungs to the tissues. An iron deficiency first drains the stores of iron, whereupon the serum ferritin level falls. As the deficiency continues, hemoglobin will fall as well. A decreased hemoglobin level weakens physical performance capacity in endurance and power sports. A low ferritin level without anemia can weaken physical performance capacity as well. The correction of low hemoglobin (but possibly low ferritin as well) primarily by an orally administered iron preparation will probably improve the athlete’s performance capacity. The correction process generally takes 3–6 months.

For people aged 18–74 years, the use of 10 μg of a Vitamin D supplement is recommended during the wintertime (October–March) if the intake from the diet is low. The use of a dietary supplement is also warranted if the measured levels in the body are low (e.g. deficiency limit <50 nmol/l). If the intake of Vitamin D and its level in the body is sufficient, supplement use will probably be of little benefit to the exercise enthusiast in terms of health or exercise.

Exercise can increase the need for magnesium somewhat, but in the studies conducted, magnesium supplementation failed to reduce cramps or enhance sport performance. Then again, no studies have been conducted, for example, on the prevention of cramps in athletes.

Antioxidant supplements, such as Vitamin C or Vitamin E, beta-carotene or selenium, would appear to have benefits to target-oriented exercise enthusiasts. According to some studies, large doses gained via dietary supplements can reduce training-induced tissue damage. At the same time, however, they can reduce the practice-induced training response: for example, fitness development. A Vitamin C supplement can slightly reduce the duration and symptoms of upper respiratory tract infections and zinc can reduce the risk of such as well. The continued use of large doses is not warranted, however.



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