Effect of protodioscin (Tribulus terrestris) on the well-being and sexual response of men with diabetes mellitus

K.M. Arsyad
Medical Biology Division of Andrology, University of Sriwijaya, Indonesia (1997)

SUMMARY

We conducted this trial to study the effect of Tribulus terrestris (protodioscin) supplement on the sense of well-being and sexual response of men suffering from diabetes mellitus. 30 men between the ages of 40 to 55 years were divided into two 15-men groups. The experimental and control groups were given Tribulus terrestris extract (Libilov tablets, 250mg) and placebo pills 3 times per day for 30 days, respectively. Both groups were not statistically different in age, body weight and fasting sugar levels.

Our results showed that Tribulus supplement is able to improve the sense of well being and sexual response of diabetic subjects. We found improvement in sex drive, erection, ejaculation and orgasm in the treated group and no improvement in these parameters in the control group.

INTRODUCTION

Diabetes mellitus (DM) is a metabolic disease which prevalence tends to increase steadily irrespective of social and economic status (1). Clinical symptoms of DM include symptoms related to the pancreatic compensation stages, including polyphagia, polydipsia, polyuria, and an increase in body weight. If left untreated, these symptoms could lead to nausea and diabetic coma. Other symptoms include that of the pancreatic decompensation stages and other chronic symptoms, such as asthenia, anorexia, hyperesthesia, blurred vision, myalgia, athralgia and a decrease in sexual drive. Diabetes could also be complicated by vasculopathy and neuropathy, or both. Furthermore, sexual dysfunctions in diabetic men are often diagnosed as erectile dysfunction, disorders in ejaculation and decreased libido. These sexual dysfunctions often occur before DM is diagnosed (2).

Sexual dysfunctions in diabetic men are caused by (3,4,5):

1. Disturbance in hormone productions
Reduction in blood vessels causes the subsequent reduction in blood flow to the testes tissues, leading to degeneration of these tissues and reduction in androgen production. Coupled with decreased hormone production in other glandular tissues, the decrease in total androgen levels is responsible for the decrease in libido.

2. Impaired erection
The destruction of blood vessels increases blood viscosity and abnormally affects the nervous system. This often results in impotence or disturbance in achieving erection.

3. Impaired ejaculation
Impairment in achieving ejaculation is most often caused by the destruction of the nervous system in vesica urinaria.

4. Impaired orgasm
Impairment in achieving orgasm is caused by the failure of fulfilling the appropriate sexual response phase.

The active ingredient in Tribulus terrestris extract, called protodioscin, has been reported to increase the level of dehydroepiandrosterone (DHEA) in the bloodstream. DHEA is a hormone involved in the immune system and has been attributed to be responsible in improving the general sense of well-being. It has been hypothesized that DHEA functions by improving the integrity and functions of cellular membranes, including those of the endothelial cells in the penile corpus cavernosum and other blood vessels (6,7). Treatment with Tribulus terrestris extract (Libilov™) at one tablet three times daily for 10 days has been reported to increase the DHEA level in diabetic and non-diabetic male subjects diagnosed with erectile dysfunction (8). Protodioscin increases the secretion of LH, but not that of FSH. Protodioscin has been shown to increase the density of the Sertoli cells, without changing the density of the Leydig cells; and to increase the number of spermatogonia, spematocytes and spermatids without affecting the diameter of the seminiferous tubules.

This clinical study was designed to determine the effect of protodioscin on the sense of well-being and the sexual response of men diagnosed with diabetes mellitus.

METHODS

This single-blind, case-controlled clinical trial was composed of 30 diabetic male volunteers between the ages of 40 and 55 years, divided into two groups of 15 men. Tribulus terrestris tablets (Libilov at 250 mg) was given to the treated group three times daily for 30 days, whereas placebo was given to the control group. Both groups were matched for age, body weight and fasting sugar level.

The parameters below were observed, by methods of questionnaire, and physical / laboratory examination:

1. The sense of well-being
The subject's sense of well-being included the evaluation of symptoms of weakness, hyperesthesia, myalgia and athralgia. Absence of the above symptoms scored positively in this parameter.

2. The sexual response
The subject's sexual response is determined by evaluating sex drive, erection, ejaculation and orgasm qualities.

3. The laboratory component
Fasting blood sugar level, liver and renal function tests and hormone levels were evaluated.

RESULTS

The treated and control groups were matched by age, body weight and fasting blood sugar levels. These parameters are shown in Table I.

Table I. Age, body weight and fasting blood sugar levels (BSN) of the control and treated groups prior to trial.

In Table II, we present the initial symptoms found in the control and treated group prior to treatment. 12 men (80%) in the control group and 13 men (86%) in the treated group complained of body weakness, 9 men (60%) in the control group and 10 men (66%) in the treated group complained of hyperesthesia, and 8 men (53%) in the control group and 7 men (46%) in the treated group complained of myalgia / athralgia.

Table II. Symptoms reported by subjects in the control and treated group before treatment.

After 30 days of treatment, the change in the symptoms of body weakness, hyperesthesia and myalgia athralgia are listed in Table III. In the control group, 6 men (60%) still complained of body weakness, whereas 5 men (42%) reported that their body weakness decreased or disappeared and one subject reported no change. In the treated group, 9 men (69%) reported that their body weakness decreased or disappeared, whereas only 4 (31%) subjects still reported body weakness. No subject in the treated group reported an increase in this parameter. In case of hyperesthesia, 6 men (67%) of the control group reported no improvement after treatment. 1 man (11%) and 2 men (22%) reported a decrease and an increase, respectively, of this parameter. In contrast, 6 men (57%) of the trial group reported a decrease or disappearance in hypereresthesia. 4 men (43%) reported no change in this parameter, whereas no subject reported an increase. Finally, in case of myalgia/athralgia, 5 men (62%) and 1 men (43%) of the control and trial groups, respectively, reported no change. 3 men (38%) and 4 men (57%) of the control and trial groups, respectively, reported a decrease or disappearance of myalgia/athralgia. No one from both groups reported an increase in this parameter.

Table III. Changes in the symptoms reported by subjects in the control and treated group after treatment. NC: no change; D: decrease or disappearance of symptom; I: appearance of symptom, reported as the number of subjects.

In Table IV, we present the sexual response data of the control and treated groups before treatment. Here, in the control group, 9 men (60%) reported moderate and 3 men (20%) reported low levels of libido. In contrast, 10 men (67%) and 2 men (13%) in the treated group, respectively. In the control group, 8 men (53%) reported moderate and 5 men (34%) reported flaccid erections. In the treated group, the same proportion reported moderate and flaccid erections. 9 men (60%) and 2 men (13%) of the control group reported moderate and bad ejaculations, whereas 8 men (53%) and 3 men (20%) of the treated group reported of the same complaints. Lastly, 9 men (60%) and 3 men (20%) of the control group reported moderate and inadequate orgasm, whereas 8 men (53%) and 4 men (27%) of the treated group reported moderate and bad orgasm qualities.

Table IV. The sexual response parameters of the control and treated group before treatment. H: high libido, good or rigid erection, good ejaculation and quality of orgasm; M: medium libido, moderate erection, ejaculation and quality of orgasm; L: low level of libido, flaccid erection, and low quality of orgasm.

We present the sexual response data of the control and the treated groups after treatment in Table V. Here, 3 men (20%), 10 men (67%) and 2 men (13%) of the control groups reported high, moderate and low libido. In contrast, 5 men (34%), 9 men (60%) and 1 man (6%) of the treated group reported high, moderate and low libido after treatment. 2 men (13%), 10 men (67%) and 3 men (20%) in the control group reported rigid, moderate and flaccid erections, respectively. In contrast, 4 men (27%), 8 men (53%), and 3 men (20%) in the treated group reported rigid, moderate and flaccid erections. On the ejaculation parameter of the control group, 4 men (27%) reported good ejaculation, 9 men (60%) reported moderate ejaculation and 1 man (6%) reported bad ejaculation. In contrast, in the treated group, 6 men (40%) reported good ejaculation, 8 men (53%) reported moderate ejaculation and 1 man (6%) reported bad ejaculation. Lastly, on the orgasm quality parameter, 3 men (20%), 10 men (67%) and 2 men (13%) of the control group reported good, moderate and bad qualities. This contrasted to the treated group, in which 5 men (34%), 9 men (60%) and 1 man (6%) reported good, moderate and bad orgasms.

Compared to the sexual response data before treatment, the sexual response parameters of the treated group reported improvements. For example, only 3 of the men in the treated group reported high sex drive before treatment, whereas 5 men reported high libido after treatment. 2 men and 4 men reported good ejaculation, before and after treatment, respectively. Similarly, the number of men reporting good qualities of ejaculation and orgasm increased by 13 % and 14%, respectively. This contrasted to ratio of men reporting high libido, rigid erection, good ejaculation and quality of orgasms in the control group which remained the same before and after treatment.

Table V. The sexual response parameters of the control and treated groups after treatment. H: high libido, good or rigid erection, good ejaculation and quality of orgasm; M: medium libido, moderate erection, ejaculation and quality of orgasm; L: low level of libido, flaccid erection, and low quality of orgasm.

We found that there was a decrease in the fasting sugar levels of both the control and treated groups after treatment, although the decrease in the control group was not statistically significant (p > 0.05) whereas the decrease in the treated group was (p < 0.05). There was no significant difference in the levels of FSH and LH in the two groups before and after treatments. There was a decrease in the level of testosterone in the control group after treatment (p > 0.05), and an increase in the level in the treated group (p > 0.05). These data are summarized in Table VI.

Table VI. Fasting blood sugar and hormones levels of control and treated groups before and after treatment. BSN: fasting blood sugar level, FSH: follicle-stimulating hormone, LH: luteinizing hormone.

There was no significant difference in the renal and liver functions as shown in Table VII and VIII. There was an increase in the HDL cholesterol level in the treated group, and an increase in the level of LDL cholesterol in both groups. Even so, these parameters still fell within normal range. There was a decrease in triglyceride level and an increase in the total lipid level of both groups after treatment (see Table IX).

Table VII. Renal function tests of the control and treated groups before and after treatment.

Table VIII. Liver function tests of the control and treated groups before and after treatment.

Table IX. Blood lipid levels of the control and treated groups before and after treatment.

The results of this study confirmed the benefits of Tribulus terrestris extract (Libilov) in restoring the sense of well-being and improving the sexual responses of diabetic men. The improvement in sexual response parameters in this trial agreed with the previously reported effect of protodioscin, the main ingredient in the Tribulus extract, in improving sperm count and motility, in restoring libido and sexual reflects on animal models as well as humans (9,10,11). Protodioscin has also been reported to increase the DHEA level. DHEA is a hormone involved in boosting the immune system and increasing the general sense of well-being. DHEA has been shown to improve the functions and integrity of endothelial cell membranes, including those in the corpus cavernosum and blood vessels (6,7). Adimoelja (8) reported that Tribulus (Libilov) treatment at one tablet three times daily for 10 days increased the level of DHEA in diabetic and non-diabetic subjects with erectile dysfunction.

Protodioscin has also been reported to have a selective effect on the hypothalamic hormone production, including increasing LH and testosterone secretions without affecting FSH level. The increase in testosterone was the most probable mechanism of the increase in libido and sex responses (11,12).

CONCLUSION AND SUGGESTION

Based on the results of this study, we concluded that:

1. Treating diabetic men with Tribulus terrestris extract (Libilov) resulted in a better sense of well-being and sexual responses as compared to those treated with placebo.

2. Treatment with Tribulus extract was successful in reducing the fasting blood sugar levels, and may be a viable option in reducing glucotoxicity impact on blood vessels and nervous system in diabetic subjects.

Because of the small sample size of this trial and the lack of homogeneity in the oral anti-diabetic medications used by a portion of the trial volunteers, we suggest a repeat of this study with a greater sample size and a control for the use of anti-diabetics medications in the clinical sample.

ACKNOWLEDGEMENT

The author wished to thank Alwi Shahab, M.D. and staff for their referrals of volunteers for this study, and PT Teguhsindo Lestaritama for supplying the Tribulus terrestris L extract (Libilov at 250 mg) and placebo pills for this study.

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