madman
Super Moderator
Testosterone Boosters Intake in Athletes: Current Evidence and Further Directions
Abstract
“Testosterone boosters” (TB)—are supplements that are claimed to increase testosterone levels in the human body. While the consumption of TB may be popular among athletes, there is insufficient evidence both about the safety and the real efficacy of TB. In our review, we searched MEDLINE/PubMed and Cochrane Library for studies on the effects of 15 substances that are claimed to increase testosterone levels Anacyclus pyrethrum; Bulbine natalensis; Epimedium (horny goat weed); L-arginine; L-carnitine; magnesium; Mucuna pruriens; pantothenic acid; selenium; shilajit Eurycoma longifolia (Tongkat Ali); Serenoa repens (saw palmetto); boron; Withania somnifera (ashwagandha); and Trigonella foenum-graecum (fenugreek) in athletes and healthy adults under 55 years of age. We found such studies regarding 10 out of 15 substances: L-arginine (3 studies); L-carnitine (2); magnesium (1); selenium (2); shilajit (1); Tongkat Ali (2); Serenoa repens (1); boron (3); ashwagandha root (2); and fenugreek (7). Many of them fail to prove the efficacy of these substances to increase testosterone levels. Tongkat Ali, ashwagandha, and fenugreek were the substances with the strongest evidence. The positive effect of magnesium and shilajit on testosterone concentration was shown in single studies. Conflicting data found that L-arginine, L-carnitine, Serenoa repens, selenium, and boron do not appear to increase testosterone levels. There is almost no data on the safety profile of various TB components; however, certain TB components may be linked to coagulation and pancreatic and hepatic disorders. Based on the review, the authors conclude that at present TB cannot be recommended for use by athletes due to insufficient data on their efficacy and safety.
1. Introduction
At the moment, there is a wide variety of supplements that, according to manufacturers, “increase serum testosterone level”—these supplements are called “testosterone boosters” (TB). Typically, TB contains a combination of a variety of natural substances but does not contain testosterone or other anabolic agents. The consumption of TB may be popular among athletes due to understanding the importance of testosterone in various aspects of sports performance, especially strength [1,2], and with the ever-improving detection of anabolic agents, which are on the WADA Prohibited List [3]. Another reason for the popularity of TB is the increasing recognition of RED-S (Relative energy deficiency in sport) syndrome, which includes low testosterone levels in athletes, and the constant seeking for legal strategies for increasing testosterone among such athletes [4]. At the same time, there is insufficient evidence, both about the safety and the real effectiveness of TB as an agent of increasing testosterone levels in the body. In this regard, the study of data on the effectiveness of various components of TB is of great interest.
Most research on TB focuses on the treatment of erectile dysfunction [5], decreased libido [6], late-onset hypogonadism [7], and benign prostatic hyperplasia [8]. Several components of TB may be effective in the treatment of these diseases. In addition, there is a growing interest in the effects of TB on muscle strength and power. One of the first such studies was performed in Bulgaria, where Tribulus Terrestris was promoted among weightlifters [9,10]. Other substances are also being actively researched. For example, Chen et al. showed that the combination of Eurycoma longifolia and resistance training improved peak power output in young males [11]. The relationship between boron intake and lean body mass changes was discussed in another study [12]. Ashwagandha may help to increase muscle mass [13] as well as velocity, power, and maximal oxygen uptake (VO2 max) in healthy young men [14]. It is assumed that if TB increases testosterone levels, then they may also improve strength, power, and other parameters related to testosterone [10,11].
However, at the same time, there is very little evidence that a particular substance contained in TB actually increases serum testosterone concentration. In one of the largest studies on this topic, Clemesha et al. analyzed the available evidence base of the effectiveness of 109 substances contained in the 50 most popular TB, which were given by the Google search engine [15]. In 90% (n = 45) of the cases, the manufacturer claimed that their TB “increases testosterone levels” or “increases free testosterone levels”. In 62% of cases (n = 31), the manufacturer stated that the supplement “helps to build muscle mass”, and in 50% (n = 25) that the supplement “increases libido”. On average, one TB contained 8.3 individual substances. The most commonly found substances were zinc, fenugreek, vitamin B6, Tribulus Terrestris, magnesium, boron, diindolmethane, Eurycoma longifolia, and maca. Clemesha et al. found that 67 out of 109 individual substances had no studies on their effects. For 19 substances (17.4%), there was only 1 study that examined their effect on testosterone levels; for 13 supplements (11.9%) there were 2 studies; for 3 supplements (2.8%) 3 studies; for 4 supplements (3.7%) 4 studies, for 1 supplement (0.9%) 5 studies; and for 1 supplement (0.9%) 6 studies were conducted. According to Clemesha et al., only in relation to 12 substances, all confirmed an increase in the concentration of testosterone: Anacyclus pyrethrum; Bulbine natalensis; Eurycoma longifolia (Tongkat Ali); fenugreek; horny goat weed; L-arginine; L-carnitine; magnesium; Mucuna pruriens; pantothenic acid; selenium; and shilajit [15].
Another review by Balasubramanian et al. analyzed the 5 most popular TB sold on Amazon.com and identified the 10 most common substances in them: Eurycoma longifolia (Tongkat Ali); horny goat weed; maca; nettle; ashwagandha root; Serenoa repens; boron; fenugreek; bioperine; and diindolylmethane [16]. According to these authors, only 5 out of 10 substances have scientific evidence that they can increase testosterone levels: Eurycoma longifolia (Tongkat Ali), Serenoa repens, boron, ashwagandha root, and fenugreek [16].
Our study aimed to evaluate the available evidence on the efficacy of individual TB components on healthy adults or athletes in order to establish the existing evidence base behind their use. The main hypothesis was that, for the vast majority of TB components, there is currently no high-quality evidence of efficacy in increasing testosterone levels in a group of healthy adults or athletes.
3. Results
The initial search identified 970 studies, of which 24 studies’ trials were identified as eligible following assessment using the selection criteria (Figure 1). As a result of the search—only for 10 out of 15 substances (L-arginine; L-carnitine; magnesium; selenium; shilajit; Tongkat Ali; Serenoa repens; boron; ashwagandha root; and fenugreek—24 studies were found that met the inclusion criteria. No such studies were found for five analyzed substances (Anacyclus pyrethrum, Bulbine natalensis, Epimedium (horny goat weed), Pantothenic acid, and Mucuna pruriens).
3.1. L-Arginine
3.2. L-Carnitine
3.3. Magnesium
3.4. Selenium
3.5. Shilajit
3.6. Eurycoma Longifolia
3.7. Serenoa Repens
3.8. Boron
3.9. Ashwagandha Root
3.10. Fenugreek
5. Conclusions
Currently, there are only a few studies on the effect of the most popular components of TB on serum testosterone concentration. Most of these studies are of high quality (RCTs), but most often are not performed on athletes.
There is almost no data on the safety profile of various TB components. However, several components may cause coagulation and hepatic and pancreatic problems; as such, caution is warranted with their use.
Since most TB contains several substances, a substance with unproven efficacy and safety may probably be ingested during TB course intake.
There is a need for further high-quality studies (e.g., RCTs with a structured approach using LC-MS/MS hormonal measurements) assessing the effect of isolated intake of substances contained in TB on serum testosterone concentration in groups of healthy adults.
Based on the review, the authors conclude that at present TB cannot be recommended for use by athletes due to insufficient data on their efficacy and safety.
Abstract
“Testosterone boosters” (TB)—are supplements that are claimed to increase testosterone levels in the human body. While the consumption of TB may be popular among athletes, there is insufficient evidence both about the safety and the real efficacy of TB. In our review, we searched MEDLINE/PubMed and Cochrane Library for studies on the effects of 15 substances that are claimed to increase testosterone levels Anacyclus pyrethrum; Bulbine natalensis; Epimedium (horny goat weed); L-arginine; L-carnitine; magnesium; Mucuna pruriens; pantothenic acid; selenium; shilajit Eurycoma longifolia (Tongkat Ali); Serenoa repens (saw palmetto); boron; Withania somnifera (ashwagandha); and Trigonella foenum-graecum (fenugreek) in athletes and healthy adults under 55 years of age. We found such studies regarding 10 out of 15 substances: L-arginine (3 studies); L-carnitine (2); magnesium (1); selenium (2); shilajit (1); Tongkat Ali (2); Serenoa repens (1); boron (3); ashwagandha root (2); and fenugreek (7). Many of them fail to prove the efficacy of these substances to increase testosterone levels. Tongkat Ali, ashwagandha, and fenugreek were the substances with the strongest evidence. The positive effect of magnesium and shilajit on testosterone concentration was shown in single studies. Conflicting data found that L-arginine, L-carnitine, Serenoa repens, selenium, and boron do not appear to increase testosterone levels. There is almost no data on the safety profile of various TB components; however, certain TB components may be linked to coagulation and pancreatic and hepatic disorders. Based on the review, the authors conclude that at present TB cannot be recommended for use by athletes due to insufficient data on their efficacy and safety.
1. Introduction
At the moment, there is a wide variety of supplements that, according to manufacturers, “increase serum testosterone level”—these supplements are called “testosterone boosters” (TB). Typically, TB contains a combination of a variety of natural substances but does not contain testosterone or other anabolic agents. The consumption of TB may be popular among athletes due to understanding the importance of testosterone in various aspects of sports performance, especially strength [1,2], and with the ever-improving detection of anabolic agents, which are on the WADA Prohibited List [3]. Another reason for the popularity of TB is the increasing recognition of RED-S (Relative energy deficiency in sport) syndrome, which includes low testosterone levels in athletes, and the constant seeking for legal strategies for increasing testosterone among such athletes [4]. At the same time, there is insufficient evidence, both about the safety and the real effectiveness of TB as an agent of increasing testosterone levels in the body. In this regard, the study of data on the effectiveness of various components of TB is of great interest.
Most research on TB focuses on the treatment of erectile dysfunction [5], decreased libido [6], late-onset hypogonadism [7], and benign prostatic hyperplasia [8]. Several components of TB may be effective in the treatment of these diseases. In addition, there is a growing interest in the effects of TB on muscle strength and power. One of the first such studies was performed in Bulgaria, where Tribulus Terrestris was promoted among weightlifters [9,10]. Other substances are also being actively researched. For example, Chen et al. showed that the combination of Eurycoma longifolia and resistance training improved peak power output in young males [11]. The relationship between boron intake and lean body mass changes was discussed in another study [12]. Ashwagandha may help to increase muscle mass [13] as well as velocity, power, and maximal oxygen uptake (VO2 max) in healthy young men [14]. It is assumed that if TB increases testosterone levels, then they may also improve strength, power, and other parameters related to testosterone [10,11].
However, at the same time, there is very little evidence that a particular substance contained in TB actually increases serum testosterone concentration. In one of the largest studies on this topic, Clemesha et al. analyzed the available evidence base of the effectiveness of 109 substances contained in the 50 most popular TB, which were given by the Google search engine [15]. In 90% (n = 45) of the cases, the manufacturer claimed that their TB “increases testosterone levels” or “increases free testosterone levels”. In 62% of cases (n = 31), the manufacturer stated that the supplement “helps to build muscle mass”, and in 50% (n = 25) that the supplement “increases libido”. On average, one TB contained 8.3 individual substances. The most commonly found substances were zinc, fenugreek, vitamin B6, Tribulus Terrestris, magnesium, boron, diindolmethane, Eurycoma longifolia, and maca. Clemesha et al. found that 67 out of 109 individual substances had no studies on their effects. For 19 substances (17.4%), there was only 1 study that examined their effect on testosterone levels; for 13 supplements (11.9%) there were 2 studies; for 3 supplements (2.8%) 3 studies; for 4 supplements (3.7%) 4 studies, for 1 supplement (0.9%) 5 studies; and for 1 supplement (0.9%) 6 studies were conducted. According to Clemesha et al., only in relation to 12 substances, all confirmed an increase in the concentration of testosterone: Anacyclus pyrethrum; Bulbine natalensis; Eurycoma longifolia (Tongkat Ali); fenugreek; horny goat weed; L-arginine; L-carnitine; magnesium; Mucuna pruriens; pantothenic acid; selenium; and shilajit [15].
Another review by Balasubramanian et al. analyzed the 5 most popular TB sold on Amazon.com and identified the 10 most common substances in them: Eurycoma longifolia (Tongkat Ali); horny goat weed; maca; nettle; ashwagandha root; Serenoa repens; boron; fenugreek; bioperine; and diindolylmethane [16]. According to these authors, only 5 out of 10 substances have scientific evidence that they can increase testosterone levels: Eurycoma longifolia (Tongkat Ali), Serenoa repens, boron, ashwagandha root, and fenugreek [16].
Our study aimed to evaluate the available evidence on the efficacy of individual TB components on healthy adults or athletes in order to establish the existing evidence base behind their use. The main hypothesis was that, for the vast majority of TB components, there is currently no high-quality evidence of efficacy in increasing testosterone levels in a group of healthy adults or athletes.
3. Results
The initial search identified 970 studies, of which 24 studies’ trials were identified as eligible following assessment using the selection criteria (Figure 1). As a result of the search—only for 10 out of 15 substances (L-arginine; L-carnitine; magnesium; selenium; shilajit; Tongkat Ali; Serenoa repens; boron; ashwagandha root; and fenugreek—24 studies were found that met the inclusion criteria. No such studies were found for five analyzed substances (Anacyclus pyrethrum, Bulbine natalensis, Epimedium (horny goat weed), Pantothenic acid, and Mucuna pruriens).
3.1. L-Arginine
3.2. L-Carnitine
3.3. Magnesium
3.4. Selenium
3.5. Shilajit
3.6. Eurycoma Longifolia
3.7. Serenoa Repens
3.8. Boron
3.9. Ashwagandha Root
3.10. Fenugreek
5. Conclusions
Currently, there are only a few studies on the effect of the most popular components of TB on serum testosterone concentration. Most of these studies are of high quality (RCTs), but most often are not performed on athletes.
There is almost no data on the safety profile of various TB components. However, several components may cause coagulation and hepatic and pancreatic problems; as such, caution is warranted with their use.
Since most TB contains several substances, a substance with unproven efficacy and safety may probably be ingested during TB course intake.
There is a need for further high-quality studies (e.g., RCTs with a structured approach using LC-MS/MS hormonal measurements) assessing the effect of isolated intake of substances contained in TB on serum testosterone concentration in groups of healthy adults.
Based on the review, the authors conclude that at present TB cannot be recommended for use by athletes due to insufficient data on their efficacy and safety.
