Proposed ergogenic value
Summary of research findings
Boron has been marketed to athletes as a dietary supplement that may promote muscle growth during resistance training. The rationale was primarily based on an initial report that boron supplementation (3 mg/d) significantly increased β-estradiol and testosterone levels in postmenopausal women consuming a diet low in boron.
Studies which have investigated the effects of 7 wk. of boron supplementation (2.5 mg/d) during resistance training on testosterone levels, body composition, and strength have reported no ergogenic value [280, 281]. There is no evidence at this time that boron supplementation during resistance-training promotes muscle growth.
1000 mg/d (ages 19–50)
Involved in bone and tooth formation, blood clotting, and nerve transmission. Stimulates fat metabolism. Diet should contain sufficient amounts, especially in growing children/adole  scents, female athletes, and postmenopausal women. Vitamin D needed to assist absorption.
Calcium supplementation may be beneficial in populations susceptible to osteoporosis . Additionally, calcium supplementation has been shown to promote fat metabolism and help manage body composition [727, 728]. Calcium supplementation provides no ergogenic effect on exercise performance.
Males 35 mcg/d
Females 25 mcg/d (ages 19–50)
Chromium, commonly sold as chromium picolinate, has been marketed with claims that the supplement will increase lean body mass and decrease body fat levels.
Animal research indicates that chromium supplementation increases lean body mass and reduces body fat. Early research on humans reported similar results , however, more recent well-controlled studies reported that chromium supplementation (200 to 800 mcg/d) does not improve lean body mass or reduce body fat [287, 291].
Males 8 mg/d
Females 18 mg/d (age 19–50)
Iron supplements are used to increase aerobic performance in sports that use the oxygen system. Iron is a component of hemoglobin in the red blood cell, which is a carrier of oxygen.
Most research shows that iron supplements do not appear to improve aerobic performance unless the athlete is iron-depleted and/or has anemia .
Activates enzymes involved in protein synthesis. Involved in ATP reactions. Serum levels decrease with exercise. Some suggest that magnesium supplementation may improve energy metabolism/ATP availability.
Phosphorus (phosphate salts)
Phosphate has been studied for its ability to improve all three energy systems, primarily the oxygen system or aerobic capacity.
Recent well-controlled research studies reported that sodium phosphate supplementation (4 g/d for 3 d) improved the oxygen energy system in endurance tasks [504,505,506]. There appears to be little ergogenic value of other forms of phosphate (i.e., calcium phosphate, potassium phosphate). More research is needed to determine the mechanism for improvement.
An electrolyte that helps regulate fluid balance, nerve transmission, and acid-base balance. Some suggest excessive increases or decreases in potassium may predispose athletes to cramping.
Although potassium loss during intense exercise in the heat has been anecdotally associated with muscle cramping, the etiology of cramping is unknown [732, 733]. It is unclear whether potassium supplementation in athletes decreases the incidence of muscle cramping . No ergogenic effects reported.
Marketed as a supplement to increase aerobic exercise performance. Working closely with vitamin E and glutathione peroxidase (an antioxidant), selenium may destroy destructive free radical production of lipids during aerobic exercise.
During the first several days of intense training in the heat, a greater amount of sodium is lost in sweat. Additionally, prolonged ultraendurance exercise may decrease sodium levels leading to hyponatremia. Increasing salt availability during heavy training in the heat has been shown to help maintain fluid balance and prevent hyponatremia [160, 736].
Vanadyl sulfate (vanadium)
Vanadium may be involved in reactions in the body that produce insulin-like effects on protein and glucose metabolism. Due to the anabolic nature of insulin, this has brought attention to vanadium as a supplement to increase muscle mass, enhance strength and power.
Males 11 mg/d
Females 8 mg/d
Constituent of enzymes involved in digestion. Associated with immunity. Theorized to reduce incidence of upper respiratory tract infections in athletes involved in heavy training.