There are a number of different calcium supplements; however, calcium citrate and calcium carbonate are absorbed the best. If a person does supplement, it is recommended that he or she supplements with 500 mg/day of calcium in the morning and 500 mg/day of calcium in the evening, in conjunction with 200 international units (IU) of vitamin D with each calcium dose. Two doses of calcium per day, combined with vitamin D, will maximize absorption. Calcium carbonate is best taken with meals, whereas calcium citrate can be taken with or without meals. Calcium status has been assessed in a number of different types of athletes. Zalcman et al. assessed the nutritional status of adventure racers, who are individuals who compete over several days, usually in teams, in a variety of events, including mountain biking, complete trekking, vertical techniques (e.g., climbing, rappelling), horseback riding, orienteering, sailing, etc. They reported low intakes of calcium in the women adventure racers. More recently, Lovell18 evaluated the calcium intake and serum vitamin D status of elite female gymnasts, 10 to 17 years of age. They reported that, of the 18 gymnasts evaluated, 13 had dietary calcium intakes below their recommended needs. In addition, 15 of the gymnasts had serum vitamin D levels (25-hydroxyvitamin D) that were 75 nmol/L (75 nmol/L is considered optimal for bone health), and six had serum vitamin D concentrations 50 nmol/L. Though these researchers had a small sample size, the low calcium intake coupled with the below normal serum vitamin D concentrations, demonstrate an increased risk of osteoporosis and certainly impaired performance in these young athletes.
In a study of 23 nationally ranked female adolescent volleyball players, Beals19 evaluated the nutrient intake by 3-day weighed food records, which increases the accuracy of the assessment. Beals19 found that these athletes consumed lower energy than they expended (energy intake 2248 414 kilocalories [kcal]/day, energy expenditure 2815 kcal/day), and consumed less than the recommended intake of many micronutrients, including calcium.
Beals also found that a high percentage of athletes had past or present menstrual disorders (amenorrhea, oligomenorrhea, or irregular menstrual cycles). The combination of low energy and micronutrient intake and menstrual irregularities demonstrates the need for long-term studies evaluating dietary intake and nutritional status among athletes of all levels and ages, and certainly predisposes these athletes to the female athlete triad.
