(The information in this article was taken or adapted from the High Performance Coaching Program Study Guide.)
As mentioned previously, vitamins and minerals are necessary for the human body to function properly. At the same time, vitamin and mineral supplements are widely used by tennis players to meet dietary deficiencies, but they are also used with the hope that performance will be enhanced as well.
B-complex vitamin supplements are particularly popular, because of their important role as coenzymes in helping carbohydrate and fat to be used for energy. However, despite the essential role of these and other vitamins in a variety of physiological processes, unless a player has a vitamin deficiency, vitamin supplementation will not enhance performance. Importantly, excessive vitamin intake (especially in fat-soluble vitamins A, D, E, and K and even water-soluble vitamins such as the B-complex ones) can have a toxic effect, negatively affecting the immune system, for example.
Additional vitamin C and vitamin E intake, however, might be worth considering, because of their demonstrated beneficial antioxidant and other health-related properties. There is further evidence that athletes may need more vitamin C compared to those that do not exercise regularly and additional vitamin E intake may reduce exercise-related muscle tissue damage.
Minerals are also necessary for growth, metabolism, and a variety of other physiological processes. Like vitamins, a player’s mineral requirements can be easily met by a well-balanced diet. Certain minerals, however, may need to be given special attention by some players. These “special nutrients” typically include calcium, iron and sometimes zinc. In addition, excessive and repeated sweating may cause a progressive sodium deficit (covered previously). Calcium and iron deficits can be prompted by trying to reduce or limit calorie intake (this often includes low intake of protein and dairy products), and may be further encouraged by other dietary influences and excessive sweating. Women should also appreciate that iron status can be further challenged by menstrual bleeding, as iron is an important component of blood.
As a guide, all players should regularly eat foods that are rich in calcium and iron (e.g., meat, chicken, fish, milk, yogurt, dark, leafy green vegetables, whole-grain breads and fortified cereals, etc.); this will help to ensure adequate intake of these and most other minerals. Players should be very careful about arbitrary excessive mineral supplementation – it can also have deleterious effects on health and can interfere with the absorption of other minerals.
For many tennis players, it is sometimes a challenge to maintain a well-balanced diet, especially when traveling to unfamiliar tournament locations. For this and other reasons related to preventing a vitamin or mineral deficiency, it is generally safe and prudent to regularly take a one-a-day multi-vitamin/mineral supplement that provides no more than 100% of the Recommended Dietary Allowance (RDA) for any one vitamin or mineral. Further emphasis on obtaining adequate vitamins C and E intake can be assured through careful food selection (e.g., fruits, vegetables, legumes).