The goal of this chapter was to identify essential vitamins and trace minerals, review studies of supplementation with combinations of vitamins and trace minerals, and point out some largely unexplored areas in sports nutrition that affect physical performance.
At this point, what is known about the most commonly used dietary supplement — multiple vitamin-mineral products — and their effects on physical performance? Consumers of multiple vitamin-mineral products want to know whether the pills they are popping keep them healthy and performing at peak efficiency. Consumers want to know if multiple vitamin-mineral products are a waste of money that creates expensive sewage, as many health care professionals claim. Consumers want to know whether these products are safe and contain the amounts of nutrients listed on the label. The following points are based on the evidence to date, along with a familiarity of research from non-exercise fields:
• Deficiencies of water-soluble vitamins, antioxidant vitamins, and key trace minerals (iron, zinc) can decrease physical performance.
• Exercising individuals most at risk are those who do not consume sufficient foods, who ingest mostly refined carbohydrates, who overtrain and who exercise in extreme manners or conditions.
• Multiple vitamin-mineral products with DV amounts of essential vitamins and trace minerals are not associated with improvement in performance and cannot be relied upon to prevent deficiencies of key micronutrients (antioxidants, iron) or favorably affect micronutrient status.
• Multiple vitamin-mineral products containing more than the DV of essential water-soluble vitamins, vitamin E and trace minerals may be associated with improved micro-nutrient status, maintaining physical performance or improving performance if nutrient deficiencies were pre-existing.
• Multiple vitamin-mineral products containing more than the DV of essential water-soluble vitamins, vitamin E and trace minerals do not appear to enhance physical performance for a majority of users.
• Indirect effects (mental effects, fewer illnesses, fewer injuries, better recovery) may account for perceived benefits to performance.
• Apparent exercise intensity or workload effects (i.e., more exercise means more need for supplementation larger than the DV).
• Apparent duration of supplementation effects (longer use brings more and/or larger results).
• More micronutrients (more complete formulas) are associated with better results than incomplete formulas.
• Toxicity from multiple vitamin-mineral products in exercising individuals appears to be extremely uncommon; however, care must be taken to limit intakes of vitamin A (retinols) and minerals, which have lower upper limits of safety than water-soluble vitamins.
In conclusion, the recommendation from a review article by investigators from Harvard Medical School published in the Journal of the American Medical Association that it appears prudent for all adults to take vitamin supplements17 is also appropriate for adults who exercise regularly. The evidence also suggests that regular exercisers who do not perform optimally should consider a trial of increased intakes of antioxidant vitamins and B vitamins along with a multiple vitamin-mineral product with DV amounts of micronutrients (see amounts listed in Tables 1.2, 1.3 and 1.4) — the easiest, least expensive and most trustworthy way to assess utility of essential vitamins and trace minerals.
Was this article helpful?