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Vitamin & Mineral Supplementation

Background

Objectives:

  • To examine vitamin and mineral requirements for adult athletes (focusing on iron, antioxidants, calcium)
  • Dietary micronutrients intake versus vitamin/mineral supplementation
  • Vitamin/mineral supplements enhancing athletic performance

Introduction

Athletes and the general population are often deficient in many micronutrients, usually due to an inadequate diet. Low total caloric, low fat, and low red meat diets may not provide essential micronutrients, including vitamins (Venkatraman, Pendergast 2002:332).

Vitamin and mineral deficiency also occurs after intense, maintained physical activity (esp. decrease of serous iron), which indicates that micronutrient demands for athletes are higher than daily requirements for physically inactive individuals (Mehlenbeck et al. 2004).

However, athletes do not necessarily require vitamin/mineral supplements if they consume sufficient energy from a variety of foods to maintain their weight (Dressendorfer 2002:63).  
Vitamin/mineral supplements are encouraged in some cases (e.g. for athletes on low fat, low energy diets and vegetarians). Although micronutrient oral supplementation can be beneficial, it would not have been indicated for performance enhancement (Dresendorfer 2002: 64). 

Vitamin and mineral requirements for athletes

Iron

Iron plays an important role in exercise and energy metabolism.

Long duration exercise induces a physiological reaction similar to an acute phase immune response. Acute phase immune response includes redistribution of iron from extra-to intracellular compartment. In presence of reactive oxygen intermediates, iron catalyses the generation of hydroxyl radicals, which damage membrane lipids, proteins, and nucleic acids. Cells have to control intracellular iron levels in order to minimise iron toxicity and to satisfy their metabolic needs (Aguilo et al. 2004).  

The iron deficiency after intense physical activities is common in athletes and is usually associated with the reductions in hematocrit, hemoglobin and serum iron which is known as a sport anemia (Aguilo et al. 2004).

An antioxidant diet supplementation prevents the decrease of serous iron and iron saturation index; and positively influences iron metabolism (Aguilo et al. 2004).

Intestinal iron absorption may be increased by vitamin C intake (Aguilo et al. 2004).

Antioxidants

Strenuous exercise causes an oxidative stress when high oxidative metabolism increases production of oxygen free-radicals and lipid peroxidation in skeletal muscles. Rise in level of oxygen free-radicals that exceed the antioxidant defense capacity of the cells causes damage to DNA, proteins, enzymes and subcellular organs, resulting in possible muscle fatigue and soreness following exercise. Endogenous antioxidant enzymes and antioxidant vitamins scavenge reactive oxygen species, produced during oxidative stress. Vitamin- mineral supplements enhance activity of antioxidant enzymes , which fight against free radicals and decrease muscle damage.

Antioxidant supplements help to decrease oxidative-stress status and preserve neutrophil ratio (Aquilo et al. 2004).

Supplementation with antioxidant vitamins is beneficial for athletes on low-energy-balanced diets or vegetarians; otherwise, the requirements can be met through an energy balanced diet (Venkatraman, Pendergast 2002:326).

Supplementation with single antioxidant nutrients is not recommended because of hazards caused by excessive fat-soluble vitamins, or peroxidation and pro-inflammatory responses caused by excess ascorbic acid. The enhanced intake of vitamin B, ascorbic acid, tocopherol (vitamin E) and carotenoid- and flavonoid- rich foods is suggested to raise daily intakes to above RDAs for sedentary individuals.(Venkatraman, Pendergast, 2002:326).

To decrease production of oxygen- free radicals, athletes sometimes overdose vitamin supplements (10 to 1000 RDA), however this is not useful and may be harmful (Venkatraman, Pendergast, 2002:326).

Calcium

Adequate calcium intake is necessary for optimizing the peak bone mass, an important determinant of osteoporosis risk, in young athletes. Calcium supplementation enhances bone accrual in young adults. Inadequate calcium intake is often found in young adult female athletes although the daily calcium intake requirements are even greater for competitive athletes (Mehlenbeck et al. 2004).

Calcium intake influences an achievement of peak bone mass during adolescence and young adulthood; an inadequate calcium intake increases risk of stress fractures in physically active individuals (Mehlenbeck et al. 2004).

Dietary micronutrients intake versus vitamin/mineral supplementation

Strenuous endurance training does not affect plasma mineral status when dietary micronutrient intakes are adequate. Well- balanced diets prevent the development of mineral deficiencies in most athletes, however, the daily use of multivitamin/mineral supplements is not discouraged  because high sweat losses may increase requirement of selected minerals, e.g. magnesium and iron (Dressendorfer et al. 2002:63).

Low- energy, low- fat, low red meat, or vegetarian diets may not provide essential micronutrients, including vitamins.  Athletes following the abovementioned diet plans are often deficient in vitamin B12, iron, zinc, selenium, copper, and calcium (Venkatraman, Pendergast, 2002:326).
Vitamin B12, zinc, and iron are the key supplements in treating female athlete triad (disordered eating, amenorrhea and osteoporosis).

Vitamin/mineral supplements enhancing athletic performance

Iron is essential for oxygen delivery to the tissues as a compartment of hemoglobin and myoglobin, and acts as an enzyme cofactor involved in energy production. Adequate iron status is crucial to the optimal physical performance as well as immune function of athletes (Clark et al. 2003:318). Iron- deficiency anemia impairs athletic performance. In this case, iron supplementation together with hematopoietic nutrients additional intake can enhance athletic performance. Iron synergy with hematopoietic nutrients (folate, zinc, cobalamin- vitamin B12, pyroxidine- vitamin B6, ascorbate- vitamin C, tocopherol- vitamin E) can result in improved hematological status, increased VO2max, and increased performance (Colgan 1993:261). In athletes with normal iron status, iron supplementation does not enhance performance.

Conclusion

Essential minerals deficiency, production of oxygen free-radicals and oxidative tissue damage, occurring during exercise, increase need for vitamins (e.g. antioxidants), and minerals in athletes. Although oral vitamin/mineral supplementation can be beneficial, it is usually not necessary. In a well-balanced eating plan, the daily requirements for vitamins and minerals are easily met.

Vitamin/mineral supplementation can possibly enhance performance only if the performance has been decreased due to micronutrient deficiency (e.g. anemia). If the athlete’s mineral status is normal, supplementation is not going to increase performance.

References

  • Aguilo, Antoni, Fuentespina, Emilia, Tauler, Pere et al. (2004). Antioxidant Diet Supplementation Influences Blood Iron status in Endurance Athletes. International Journal of Sport Nutrition & Exercise Metabolism, 14 (2), (accessed September 20, 2004, from Academic Search Elite database).
  • Cavas, L., Tarhan, L. (2004). Effects of Vitamin- Mineral Supplementation on Cardiac Marker and radical Scavenging Enzymes and MDA Levels in Young Swimmers. . International Journal of Sport Nutrition & Exercise Metabolism, 14 (2), 133- 145.
  • Clark, Mandy, Reed et al. (2003). Pre- and Post- Season Dietary Intake, Body Composition, and Performance Indices of NCAA Division I Female Soccer Players. International Journal of Sport Nutrition & Exercise Metabolism, 13 (3), 303-319.
  • Dressendorfer, R.H., Petersen, S.R., Moss Lovshin, S.E., Keen, C.L. (2002). Mineral Metabolism in Male Cyclists During High- Intensity Endurance Training. International Journal of Sport Nutrition & Exercise Metabolism, 12,  63- 72.
  • Lukaski, H.C., Bolonchuk, W.W., Klevay, L.M., Milne, D.B., Sandstead, H.H. (2001). Interactions Among Dietary Fat, Mineral Status, and Performance of Endurance Athletes. International Journal of Sport Nutrition & Exercise Metabolism, 11, 186- 198.
  • Mehlenbeck, R.S., Ward, K.D., Klesges, R.C., Vukadinovic, CH.M. (2004). A Pilot Intervention to Increase Calcium Intake in Female Collegiate Athletes. International Journal of Sport Nutrition & Exercise Metabolism, 14 (1), (accessed September 20, 2004, from Academic Search Elite database).
  • Peake, J.M. (2003). Vitamin C: Effects of Exercise and Requirements with Training. International Journal of Sport Nutrition & Exercise Metabolism, 13 (2), (accessed September 20, 2004, from Academic Search Elite database).
  • Venkatraman, J.T., Pendergast, D.R. (2002). Effects of Dietary Intake on Immune Function in Athletes. Sports Medicine, 32(5), 323-337.

Additional materials:

  • Colgan M.(1993). Optimum Sports Nutrition, NY: Advanced Research Press.

Sports anemia features are low iron plasma levels and storage (Aguilo et al., 2004) which leads to decreased hemoglobin production, and thus decreased maximum oxygen uptake. Decline in maximum oxygen uptake causes decreased ability of muscle to use oxygen which is a cause of decreased athletic performance.

During physical exercise, a large amount of oxygen is inhaled into the body; the body is subjected to oxidative stress (Cavas, Tarhan, 2004:143).

Body fights back against oxidation with 3 main endogenous antioxidants- superoxide dismutase SOD, catalase CAT and glutathione peroxidase GSH-Px (Cavas, Tarhan, 2004:134).

Antioxidant vitamins- A, C, E,  Beta- carotenesCoenzyme Q10, selenium

E.g. iron and copper influence positively SOD and CAT activity (Cavas, Tarhanm, 2004:134).

E.g. overdosing vitamin C can cause diarrhea, joint pain, kidney stones; high levels of vitamin A intake can cause toxic effects and liver damage (Venkatraman, Pendergast, 2002: 326).


 
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