Vitamins are not able to provide energy for the body, they do not participate in metabolic processes as energy sources, but they are essential compounds for the maintenance and the function of basic life processes. During regular, high-intensity physical activity and other conditions (e.g. pregnancy, illness), the daily energy and macronutrient and micronutrient requirements increase and thus vitamin and mineral requirements too. Physiological processes, on which performance is based, are supported by several vitamins and minerals. The adequate micronutrient status and its monitoring can help athletes with the early recognition of the deficiencies and the reduction of the potential performance-impairing effects resulting from the deficiency; furthermore, micronutrient deficiency is also related to the development of injuries. Not only the vitamin deficiency, but the overdose of certain vitamins may also cause performance degradation, which is particularly true of fat-soluble vitamins. Intense exercise leads to the release of free radicals (increased oxygen flow, inflammatory reactions) which may damage the tissues and thus they may contribute to muscle fatigue and muscle damage. As protective antioxidants, some vitamins are extremely useful for the body because they are able to fight against the oxidative muscle damage. There are no special micronutrient intake recommendations developed for athletes, because it is not obvious that the recommended intake amount for the adult population does not cover the requirements of the athletes. However, there are some vitamins which play a key role in the protection of the athletes’ health and maintenance of their athletic performance, especially when their diet is one-sided, insufficient and it does not meet the individual requirements (Ledochowski 2010; Raschka & Ruf, 2017). Vitamins participate in the regulation of carbohydrate, protein and fat metabolism; their direct and indirect effect on metabolism is presented by the first figure.


Figure 1. The direct and indirect effect of vitamins on metabolism


The role of vitamins in sport nutrition

Vitamins can be divided into two groups: fat-soluble vitamins (vitamins A, D, E, K) and water-soluble vitamins (vitamin C, vitamin B family). Water-soluble vitamins are not stored in the body; therefore, it is worth striving to keep the daily recommended intake levels because if their intake is lower than the minimum quantity, it will result in typical deficiency symptoms after even 3 or 4 weeks (e.g. disorders of digestion, an increased vulnerability to infectious diseases) (Hanh et al., 2016). The recommended daily vitamin intake drawn up by German, Austrian and Swiss nutrition societies and the physiological role of the fat-soluble and water-soluble vitamins as well as their functions in sport are presented in the first and second tables (Raschka & Ruf, 2017).



Table 1. Daily vitamin requirement, physiological role of water-soluble vitamins and their function in sport


The fat-soluble vitamins are present in plant tissues in the form of provitamins; vitamin will develop from them in the human body. Their common feature is that, unlike the water-soluble vitamins, they are stored in the body; therefore, overdose (hyperviatminosis) can occur when exceeding the recommended intake level for a longer term. For instance, the overdose of vitamin A can cause diarrhoea and headache.

 

Table 2. Daily vitamin requirement, physiological role of fat-soluble vitamins and their function in sport


Essential vitamins for athletes

The role of vitamin D in performance enhancement and prevention

Nutrition and physical activity have a crucial role in the maintenance of bone health. In addition to calcium, particular attention should be paid to the adequate vitamin D intake, since vitamin D is responsible for the function of calcium homeostasis and phosphate metabolism. Furthermore, the active 1.25-dihydroxyvitamin increases phosphate absorption from the bowel, tubular reabsorption of calcium from the kidney and thus it enables bone mineralisation. According to the most recent researches, vitamin D may also play a role in muscle growth because vitamin D promotes the influx of calcium into the muscles to the receptors freely, thus it can create bonds between the specific intracellular receptors responsible for protein synthesis, thereby increasing the protein synthesis. The expression of receptor genes decreases with age, which provides an explanation for the age-specific loss of muscle mass. An increasing number of studies have already proven the relationship between vitamin D level and the prevention of injuries, the rehabilitation, the function of better nerve-muscle connection, the increased size of type II muscle fibre, the reduced inflammation, the risk of fracture caused by injury and the acute respiratory diseases. Athletes who primarily train indoors and participate in competitions are more likely to be exposed to vitamin D insufficiency (25(OH) D= 50-75 nmol/L) or deficiency (25(OH) D< 50 nmol/L).

Only a few food products contains vitamin D in a larger quantity, including oily fish (e.g. herring), egg yolk, liver, vitamin-enriched margarine and mushroom. For the adequate vitamin D status, food products are often supplemented, however, it raises the question if there is a difference between the impact of vitamin D2 (of plant origin) and vitamin D3 (of animal origin) intake on vitamin D serum level. Preliminary results show that after the consumption of food products supplemented with vitamin D3, 25(OH) vitamin D level of blood serum has significantly increased in the healthy Caucasian population. The most recent research was conducted with women participants aged 20-64 (n=335), who consumed placebo, juice supplemented with 15 μg vitamin D2, biscuit supplemented with 15 μg vitamin D2, juice supplemented with 15 μg vitamin D3, or biscuit supplemented with 15 μg vitamin D3 daily for 12 weeks. Serum 25(OH)D was measured by liquid chromatography-tandem mass spectrometry at baseline and at weeks 6 and 12 of the study. In the group consuming food supplemented with vitamin D3, a significantly greater change was detected in serum 25(OH)D level comparing the values measured in the group consuming food supplemented with vitamin D2 (Tripkovic et al., 2017).

In addition to increasing protein synthesis, vitamin D intake is also important for the maintenance of bone health. Inadequate vitamin D status is connected to the increased risk of fatigue fractures. Fatigue fractures are included in the most common injuries among athletes. Further examinations are required on the effect of vitamin D supplementation on the risk of the development of fatigue fractures. On the basis of the research results of Smith et al, athletes need to consume 10-30 µg vitamin D per day in winter in order to reach serum concentration >25–50 nmol/L; however, this intake value depends on the limit value of the selected serum. On the other hand, as regards the impact of different vitamin D sources on vitamin D level, further, methodologically impeccable, placebo-controlled, double blind researches need to be carried out, whose results could be of particular importance for the food industry, in the fields of product development and innovation (Darling et al., 2014). Due to the potential performance-enhancing effect of vitamin D, many athletes try to reach the serum value of 100 nmol/L (or 4000-5000 IU/day intake). It is proven that vitamin D supplementation can enhance aerobic performance, the level of the serum correlates to the aerobic performance, but it is important to note that following 4000-5000 IU/day intake on a long term is not recommended.

More than 90% of the population suffers from vitamin D deficiency, and the inadequate vitamin D status has also become obvious among athletes. Vitamin D status highly depends on the chosen sport (indoor vs. outdoor); researches showed that among those who do indoor sports, the development of vitamin D deficiency is much more frequent. Other aspects and life-style habits can also increase the risk of vitamin D insufficiency and deficiency, such as dark complexion, high body fat percentage, early morning and evening trainings, when UVB level is low, the excessive protection against UVB light (by clothing, equipment, UV filtering/protection creams). In order to determine vitamin D status, in addition to serum 25(OH) vitamin D, the free fatty acids (EPA/arachidonic acid ratio), the assessment of dietary intake (energy, protein, carbohydrate, calcium and vitamin D) as well as the predictor of bone metabolism, the definition of cross-linked n-telopeptides of type 1 collagen (NTX) and parathyroid hormone (PTH), the geographical position of the athlete and the number of hours/days of sunshine are required. These parameters help in monitoring the vitamin D deficiency; however, today there is no gold standard method for the determination of vitamin D status for athletes (Moran et al., 2013).

Antioxidants

Antioxidants have an important role in the protection of cell membrane from the oxidative damage. Training increases oxygen consumption, therefore, regular, high-intensity training can contribute to the constant oxidative load of the cells, it elevates level of lipid peroxide

by-products and it can lead to the net increase of the native antioxidant system’s functions and the reduction of lipid peroxidation. For athletes, one of the key roles of the antioxidants is the minimisation of the muscle damage caused by load. A well-trained athlete can have a much more developed endogenous antioxidant capacity than an adult who does not do sport regularly, so it is possible that not in all cases does a top athlete benefit from the vitamin supplementation with antioxidant effect, especially if its diet includes antioxidant-rich food. There is little scientific evidence that dietary supplements containing vitamins with antioxidant properties would increase sport performance; in addition, the low methodological qualities of the studies make it harder to use the existing research results. There are some research results showing that the antioxidant supplementation may influence the adaptation to the training negatively, however, this hypothesis has not been proven yet. The current academic recommendations do not support the consumption of dietary supplements containing vitamins with antioxidant properties in order that athletes could prevent the development of oxidative stress caused by training. Those athletes are endangered by the inadequate intake of antioxidants, who follow low-energy or extreme low-fat diet, and whose diet includes small amount of fruit, vegetable and food made of whole grain cereals. From the vitamins with antioxidant effect, β-carotene is present in a greater amount in carrot, squash, spinach, melon; the main dietary sources of vitamin E are wheat germ oil (squash, sunflower), egg, while vitamin C can be found in fresh, non-heat-treated fruits and vegetables and potato (Thomas et al., 2016).


Place and role of dietary supplements containing vitamins in sport nutrition


Vitamins with antioxidant effects, namely vitamins A, C and E can have disease prevention effect on the basis of a consensus recommendation which suggests the combined intake of 4 mg of β-carotene, 100 mg of vitamin C and 23-100 mg of vitamin E. Antioxidants have performance-enhancing effect only if there was a confirmed deficiency (hypovitaminosis) before; however, the excessive, unjustified supplementation is not recommended because antioxidants may produce a pro-oxidative effect. The consumption of dietary supplements containing vitamins can be beneficial for athletes following a vegetarian diet or an alternative form of nutrition, for those who pursue one-sided diet or follow a weight loss diet over a longer period. The safest and most efficient method regarding the adequate vitamin intake is when the athlete follows a varied, balanced and personalised diet which includes food products rich in vitamins and antioxidants. However, if an athlete decides to use dietary supplementation, it is not recommended to exceed the safe upper intake level, because the excessive intake might have a negative effect on sports performance (Raschka & Ruf, 2017).

"> Vitamins are not able to provide energy for the body, they do not participate in metabolic processes as energy sources, but they are essential compounds for the maintenance and the function of basic life processes. During regular, high-intensity physical activity and other conditions (e.g. pregnancy, illness), the daily energy and macronutrient and micronutrient requirements increase and thus vitamin and mineral requirements too. Physiological processes, on which performance is based, are supported by several vitamins and minerals. The adequate micronutrient status and its monitoring can help athletes with the early recognition of the deficiencies and the reduction of the potential performance-impairing effects resulting from the deficiency; furthermore, micronutrient deficiency is also related to the development of injuries. Not only the vitamin deficiency, but the overdose of certain vitamins may also cause performance degradation, which is particularly true of fat-soluble vitamins. Intense exercise leads to the release of free radicals (increased oxygen flow, inflammatory reactions) which may damage the tissues and thus they may contribute to muscle fatigue and muscle damage. As protective antioxidants, some vitamins are extremely useful for the body because they are able to fight against the oxidative muscle damage. There are no special micronutrient intake recommendations developed for athletes, because it is not obvious that the recommended intake amount for the adult population does not cover the requirements of the athletes. However, there are some vitamins which play a key role in the protection of the athletes’ health and maintenance of their athletic performance, especially when their diet is one-sided, insufficient and it does not meet the individual requirements (Ledochowski 2010; Raschka & Ruf, 2017). Vitamins participate in the regulation of carbohydrate, protein and fat metabolism; their direct and indirect effect on metabolism is presented by the first figure.


Figure 1. The direct and indirect effect of vitamins on metabolism


The role of vitamins in sport nutrition

Vitamins can be divided into two groups: fat-soluble vitamins (vitamins A, D, E, K) and water-soluble vitamins (vitamin C, vitamin B family). Water-soluble vitamins are not stored in the body; therefore, it is worth striving to keep the daily recommended intake levels because if their intake is lower than the minimum quantity, it will result in typical deficiency symptoms after even 3 or 4 weeks (e.g. disorders of digestion, an increased vulnerability to infectious diseases) (Hanh et al., 2016). The recommended daily vitamin intake drawn up by German, Austrian and Swiss nutrition societies and the physiological role of the fat-soluble and water-soluble vitamins as well as their functions in sport are presented in the first and second tables (Raschka & Ruf, 2017).



Table 1. Daily vitamin requirement, physiological role of water-soluble vitamins and their function in sport


The fat-soluble vitamins are present in plant tissues in the form of provitamins; vitamin will develop from them in the human body. Their common feature is that, unlike the water-soluble vitamins, they are stored in the body; therefore, overdose (hyperviatminosis) can occur when exceeding the recommended intake level for a longer term. For instance, the overdose of vitamin A can cause diarrhoea and headache.

 

Table 2. Daily vitamin requirement, physiological role of fat-soluble vitamins and their function in sport


Essential vitamins for athletes

The role of vitamin D in performance enhancement and prevention

Nutrition and physical activity have a crucial role in the maintenance of bone health. In addition to calcium, particular attention should be paid to the adequate vitamin D intake, since vitamin D is responsible for the function of calcium homeostasis and phosphate metabolism. Furthermore, the active 1.25-dihydroxyvitamin increases phosphate absorption from the bowel, tubular reabsorption of calcium from the kidney and thus it enables bone mineralisation. According to the most recent researches, vitamin D may also play a role in muscle growth because vitamin D promotes the influx of calcium into the muscles to the receptors freely, thus it can create bonds between the specific intracellular receptors responsible for protein synthesis, thereby increasing the protein synthesis. The expression of receptor genes decreases with age, which provides an explanation for the age-specific loss of muscle mass. An increasing number of studies have already proven the relationship between vitamin D level and the prevention of injuries, the rehabilitation, the function of better nerve-muscle connection, the increased size of type II muscle fibre, the reduced inflammation, the risk of fracture caused by injury and the acute respiratory diseases. Athletes who primarily train indoors and participate in competitions are more likely to be exposed to vitamin D insufficiency (25(OH) D= 50-75 nmol/L) or deficiency (25(OH) D< 50 nmol/L).

Only a few food products contains vitamin D in a larger quantity, including oily fish (e.g. herring), egg yolk, liver, vitamin-enriched margarine and mushroom. For the adequate vitamin D status, food products are often supplemented, however, it raises the question if there is a difference between the impact of vitamin D2 (of plant origin) and vitamin D3 (of animal origin) intake on vitamin D serum level. Preliminary results show that after the consumption of food products supplemented with vitamin D3, 25(OH) vitamin D level of blood serum has significantly increased in the healthy Caucasian population. The most recent research was conducted with women participants aged 20-64 (n=335), who consumed placebo, juice supplemented with 15 μg vitamin D2, biscuit supplemented with 15 μg vitamin D2, juice supplemented with 15 μg vitamin D3, or biscuit supplemented with 15 μg vitamin D3 daily for 12 weeks. Serum 25(OH)D was measured by liquid chromatography-tandem mass spectrometry at baseline and at weeks 6 and 12 of the study. In the group consuming food supplemented with vitamin D3, a significantly greater change was detected in serum 25(OH)D level comparing the values measured in the group consuming food supplemented with vitamin D2 (Tripkovic et al., 2017).

In addition to increasing protein synthesis, vitamin D intake is also important for the maintenance of bone health. Inadequate vitamin D status is connected to the increased risk of fatigue fractures. Fatigue fractures are included in the most common injuries among athletes. Further examinations are required on the effect of vitamin D supplementation on the risk of the development of fatigue fractures. On the basis of the research results of Smith et al, athletes need to consume 10-30 µg vitamin D per day in winter in order to reach serum concentration >25–50 nmol/L; however, this intake value depends on the limit value of the selected serum. On the other hand, as regards the impact of different vitamin D sources on vitamin D level, further, methodologically impeccable, placebo-controlled, double blind researches need to be carried out, whose results could be of particular importance for the food industry, in the fields of product development and innovation (Darling et al., 2014). Due to the potential performance-enhancing effect of vitamin D, many athletes try to reach the serum value of 100 nmol/L (or 4000-5000 IU/day intake). It is proven that vitamin D supplementation can enhance aerobic performance, the level of the serum correlates to the aerobic performance, but it is important to note that following 4000-5000 IU/day intake on a long term is not recommended.

More than 90% of the population suffers from vitamin D deficiency, and the inadequate vitamin D status has also become obvious among athletes. Vitamin D status highly depends on the chosen sport (indoor vs. outdoor); researches showed that among those who do indoor sports, the development of vitamin D deficiency is much more frequent. Other aspects and life-style habits can also increase the risk of vitamin D insufficiency and deficiency, such as dark complexion, high body fat percentage, early morning and evening trainings, when UVB level is low, the excessive protection against UVB light (by clothing, equipment, UV filtering/protection creams). In order to determine vitamin D status, in addition to serum 25(OH) vitamin D, the free fatty acids (EPA/arachidonic acid ratio), the assessment of dietary intake (energy, protein, carbohydrate, calcium and vitamin D) as well as the predictor of bone metabolism, the definition of cross-linked n-telopeptides of type 1 collagen (NTX) and parathyroid hormone (PTH), the geographical position of the athlete and the number of hours/days of sunshine are required. These parameters help in monitoring the vitamin D deficiency; however, today there is no gold standard method for the determination of vitamin D status for athletes (Moran et al., 2013).

Antioxidants

Antioxidants have an important role in the protection of cell membrane from the oxidative damage. Training increases oxygen consumption, therefore, regular, high-intensity training can contribute to the constant oxidative load of the cells, it elevates level of lipid peroxide

by-products and it can lead to the net increase of the native antioxidant system’s functions and the reduction of lipid peroxidation. For athletes, one of the key roles of the antioxidants is the minimisation of the muscle damage caused by load. A well-trained athlete can have a much more developed endogenous antioxidant capacity than an adult who does not do sport regularly, so it is possible that not in all cases does a top athlete benefit from the vitamin supplementation with antioxidant effect, especially if its diet includes antioxidant-rich food. There is little scientific evidence that dietary supplements containing vitamins with antioxidant properties would increase sport performance; in addition, the low methodological qualities of the studies make it harder to use the existing research results. There are some research results showing that the antioxidant supplementation may influence the adaptation to the training negatively, however, this hypothesis has not been proven yet. The current academic recommendations do not support the consumption of dietary supplements containing vitamins with antioxidant properties in order that athletes could prevent the development of oxidative stress caused by training. Those athletes are endangered by the inadequate intake of antioxidants, who follow low-energy or extreme low-fat diet, and whose diet includes small amount of fruit, vegetable and food made of whole grain cereals. From the vitamins with antioxidant effect, β-carotene is present in a greater amount in carrot, squash, spinach, melon; the main dietary sources of vitamin E are wheat germ oil (squash, sunflower), egg, while vitamin C can be found in fresh, non-heat-treated fruits and vegetables and potato (Thomas et al., 2016).


Place and role of dietary supplements containing vitamins in sport nutrition


Vitamins with antioxidant effects, namely vitamins A, C and E can have disease prevention effect on the basis of a consensus recommendation which suggests the combined intake of 4 mg of β-carotene, 100 mg of vitamin C and 23-100 mg of vitamin E. Antioxidants have performance-enhancing effect only if there was a confirmed deficiency (hypovitaminosis) before; however, the excessive, unjustified supplementation is not recommended because antioxidants may produce a pro-oxidative effect. The consumption of dietary supplements containing vitamins can be beneficial for athletes following a vegetarian diet or an alternative form of nutrition, for those who pursue one-sided diet or follow a weight loss diet over a longer period. The safest and most efficient method regarding the adequate vitamin intake is when the athlete follows a varied, balanced and personalised diet which includes food products rich in vitamins and antioxidants. However, if an athlete decides to use dietary supplementation, it is not recommended to exceed the safe upper intake level, because the excessive intake might have a negative effect on sports performance (Raschka & Ruf, 2017).

" /> Közép-Kelet-Európai Rekreációs Társaság
Central- Eastern- European Recreational Association
Magyar nyelv Angol nyelv Román nyelv
Reports
2018/4
Title
Angol zászlóVitamins in sport

Authors:
Dr. habil. Fritz Péter, Kiss Anna, Pfeiffer Laura
DOI:
10.21486/recreation.2018.8.4.1
Abstract
Vitamins are not able to provide energy for the body, they do not participate in metabolic processes as energy sources, but they are essential compounds for the maintenance and the function of basic life processes. During regular, high-intensity physical activity and other conditions (e.g. pregnancy, illness), the daily energy and macronutrient and micronutrient requirements increase and thus vitamin and mineral requirements too. Physiological processes, on which performance is based, are supported by several vitamins and minerals. The adequate micronutrient status and its monitoring can help athletes with the early recognition of the deficiencies and the reduction of the potential performance-impairing effects resulting from the deficiency; furthermore, micronutrient deficiency is also related to the development of injuries.
Report

Vitamins are not able to provide energy for the body, they do not participate in metabolic processes as energy sources, but they are essential compounds for the maintenance and the function of basic life processes. During regular, high-intensity physical activity and other conditions (e.g. pregnancy, illness), the daily energy and macronutrient and micronutrient requirements increase and thus vitamin and mineral requirements too. Physiological processes, on which performance is based, are supported by several vitamins and minerals. The adequate micronutrient status and its monitoring can help athletes with the early recognition of the deficiencies and the reduction of the potential performance-impairing effects resulting from the deficiency; furthermore, micronutrient deficiency is also related to the development of injuries. Not only the vitamin deficiency, but the overdose of certain vitamins may also cause performance degradation, which is particularly true of fat-soluble vitamins. Intense exercise leads to the release of free radicals (increased oxygen flow, inflammatory reactions) which may damage the tissues and thus they may contribute to muscle fatigue and muscle damage. As protective antioxidants, some vitamins are extremely useful for the body because they are able to fight against the oxidative muscle damage. There are no special micronutrient intake recommendations developed for athletes, because it is not obvious that the recommended intake amount for the adult population does not cover the requirements of the athletes. However, there are some vitamins which play a key role in the protection of the athletes’ health and maintenance of their athletic performance, especially when their diet is one-sided, insufficient and it does not meet the individual requirements (Ledochowski 2010; Raschka & Ruf, 2017). Vitamins participate in the regulation of carbohydrate, protein and fat metabolism; their direct and indirect effect on metabolism is presented by the first figure.


Figure 1. The direct and indirect effect of vitamins on metabolism


The role of vitamins in sport nutrition

Vitamins can be divided into two groups: fat-soluble vitamins (vitamins A, D, E, K) and water-soluble vitamins (vitamin C, vitamin B family). Water-soluble vitamins are not stored in the body; therefore, it is worth striving to keep the daily recommended intake levels because if their intake is lower than the minimum quantity, it will result in typical deficiency symptoms after even 3 or 4 weeks (e.g. disorders of digestion, an increased vulnerability to infectious diseases) (Hanh et al., 2016). The recommended daily vitamin intake drawn up by German, Austrian and Swiss nutrition societies and the physiological role of the fat-soluble and water-soluble vitamins as well as their functions in sport are presented in the first and second tables (Raschka & Ruf, 2017).



Table 1. Daily vitamin requirement, physiological role of water-soluble vitamins and their function in sport


The fat-soluble vitamins are present in plant tissues in the form of provitamins; vitamin will develop from them in the human body. Their common feature is that, unlike the water-soluble vitamins, they are stored in the body; therefore, overdose (hyperviatminosis) can occur when exceeding the recommended intake level for a longer term. For instance, the overdose of vitamin A can cause diarrhoea and headache.

 

Table 2. Daily vitamin requirement, physiological role of fat-soluble vitamins and their function in sport