Calcium supplement raises free testosterone levels in athletes

The concentration of free testosterone in athletes after training is higher if the athletes have more calcium in their system. Sports scientists at the Selcuk University in Turkey discovered this. They published their findings in Biological Trace Element Research.

The researchers carried out a study on thirty athletes. It is not clear from the article what kind of athletes these were. The researchers divided their subjects into three groups of ten. Group 1 did no training for four weeks, but took a daily dose of calcium gluconate. Group 2 did train and also took calcium gluconate. The athletes trained five days a week for an hour and a half at a time. Group 3 trained but took no supplements.

Before the experiment started the researchers measured the athletes’ testosterone level at rest. [RBS] The researchers measured this again at the end of the experiment. [RAS] And at the start of the experiment the researchers got all the athletes to train, after which they also measured the testosterone concentration. [EBS] They then did the same at the end of the four-week period. [EAS] The effect of the calcium supplement on the total testosterone level was nil.


Effects: None.

But when the researchers looked at the free testosterone they did notice an effect. Group 2 had more free testosterone in their blood after training than Group 3. Free testosterone is active testosterone that can stimulate muscle growth.


The calcium dose the athletes took was 35 milligrams per kilogram bodyweight. So an athlete weighing one hundred kilos [easy calculation] would take 3.5 grams of calcium gluconate daily.

How calcium supplementation increases testosterone production the researchers don’t know. They suspect that calcium increases the sensitivity to messenger hormones such as LH and FSH in the testes.

“Our results suggest that calcium supplementation can be a beneficial addition to any training program by increasing testosterone values that in turn result in increased athletic performance”, the researchers conclude. The same group has also published results of animal and human studies in which zinc supplementation led to an increase in testosterone levels. [Neuro Endocrinol Lett. 2006 Apr 29;27(1-2).]

Calcium supplementation and calcium-rich diets are controversial issues in the field of nutrition. Some researchers have warned that a high-dairy diet (calcium is attached to dairy proteins) is correlated with an increased risk of hormone-associated cancer. This may be caused by the calcium, the protein or growth factors in milk. On the other hand, the effect on the risk of cancer is small, and a dairy protein diet is still far healthier than smoking, too little exercise, overweight or a junk food diet.

Testosterone levels in athletes at rest and exhaustion: effects of calcium supplementation.


The effects of 4 weeks of calcium supplementation on free- and total testosterone levels were established in active and sedentary adult males at rest and exhaustion. Thirty healthy male athletes were equally divided into three study groups, as follows: Group 1-non-exercising subjects receiving 35 mg calcium/kg body weight; Group 2-subjects receiving 35 mg calcium/kg body weight undergoing training routines for 90 min/day, 5 days a week and Group 3-subjects undergoing training routines for 90 min/day, 5 days a week. The testosterone levels were determined before and after supplementation, at rest and following a hard training routine. The plasma free- and total testosterone levels increased at exhaustion before and after supplementation relative to resting values (p < 0.05). This was also true when active subjects were compared to inactive subjects (p < 0.05). Our results show that training results in increased testosterone levels in athletes and that the increase is greater if accompanied by calcium supplementation, which may be useful for increasing overall athletic performance. PMID: 19099204 [PubMed - indexed for MEDLINE] Source: