Bulbine Natalensis is a traditionally used aphrodisiac and testosterone booster in South and South-Eastern Africa; in rat studies, it appears to both be quite potent in increasing testosterone but also appears to damage organ function in a similar manner to a steroid cycle.
Sources and Composition
Bulbine natalensis Baker is a plant from the family of Asphodelaceae that has been reported to possess aphrodisiac properties. The leaf sap is also used for topical purposes such as cracked lips and burns while the aqueous extract of the leaves is used for intestinal issues (diarhhea, vomiting, convulsions) and has been reported to be used for anti-diabetic and anti-rheumatoid purposes. It has been used by various cultures around where it grows (Northern and Eastern sections of Africa) and is called ingcelwane in Xhosa, rooiwortel in Afrikaans, and ibhucu in Zulu.
As a herbal compound, Bulbine Natalensis contains a variety of isolated compounds or classes of compounds. These include:
Interactions with Cardiac Health
Therapeutic doses of Bulbine Natalensis (25-100mg/kg bodyweight in rats) appear to be able to raise circulating cholesterol and triglyceride levels, and cause slight changes in lipoproteins (HDL, LDL) to induce a more pro-atherogenic state. Cholesterol levels can increase 51.9%, 38.9%, and 55.6% after 14 days of consuming 25, 50, and 100mg/kg bodyweight in rats respectively while triglycerides increase by 115.8%, 82.5%, and 45.6% respectively. Changes in triglycerides were seen after one day of administration, and were hypothesized to be due to increased lipolysis.
While LDL was unaffected, HDL cholesterol decreased from 1.73+/-0.07mmol/L down to 0.90, 1.04, and 1.02mmol/L in the 25, 50, and 100mg/kg dosage groups; respectively.
Interactions with Hormones
One study has been conducted with male Wistar rats fed Bulbine Natalensis (aqueous extract of the stem), which found increases in circulating testosterone with doses of 25, 50, and 100mg/kg bodyweight. The parameters of interest were not dose-dependent, and followed a bell curve; with 50mg/kg bodyweight being the most effective, followed by 25mg/kg and then 100mg/kg bodyweight.
With the control group just below 1ng/mL circulating testosterone, the most effective dose (50mg/kg) increased testosterone to approximately 3.3ng/mL (day 1), 4.2ng/mL (day 7), and 4.4ng/mL (day 14). Testicular levels of testosterone followed a similar pattern, and in both blood and testes the best dosage was 50mg/kg followed by 25mg/kg and then 100mg/kg.
Other studies looking at testosterone levels note increases of up to 346% of control level in male rats at 50mg/kg bodyweight, although 100mg/kg has been associated with a non-significant decline in testosterone levels below control.
Testosterone is reliably enhanced in rats, and fairly potently as well. However, the higher dosages of 100mg/kg appear to be either as potent at 25mg/kg or worse than nothing at all, decreasing testosterone. Dose is very important here, and a toxicological bell curve exists
Mechanistically, supplementation of the active dose (25-50mg/kg bodyweight Bulbine Natalensis) is associated with an increase in the activities of alkaline and acid phosphatases. The activity of the phosphatase enzymes correlates somewhat with increases in testicular and serum testosterone.
Increased testicular size (2-2.9 fold higher than control) as well as increased content of glycogen, protein, and sialic acid has been noted in rat testes alongside increased testicular testosterone levels, after about 7-14 days of supplementation.
LH has been shown to be increased with Bulbine Natalensis in male rats, and appears to be more drastic over time rather than an acute effect. The one study that noted increases in LH noted that the best dose (50mg/kg bodyweight) increased LH to 2ng/mL (with control around 0.6ng/mL) at day 1, but to 7ng/mL on day 14.
Luteinizing hormone does not appear to be influenced in female rats.
Follicle-Stimulating Hormone (FSH) is also increased in male rats following consumption of Bulbine Natalensis, and similar to Luteinizing Hormone seems to be more effective over a longer period of time but with less variance over time. Increases from 7+/-0.2ng/mL to 11.2+/-0.08ng/mL have been noted with 50mg/kg bodyweight.
FSH does not appear to be changed in female rats.
Doses of 25, 50, and 100mg/kg bodyweight in rats does not appear to significantly influence prolactin concentrations in serum of either rat gender.
Interactions with Organs
One toxicology study in rats found that oral ingestion of 25, 50, and 100mg/kg bodyweight was able to alter liver enzymes and induce histological changes that are known to be adverse. The adverse effects on liver enzymes increased dose-dependently and over time.
After ingestion of 25, 50, and 100mg/kg bodyweight Bulbine Natalensis in otherwise healthy rats, histological examination of the kidney's tubules (both proximal and convoluted) noted distortions in the architecture which may be indicative of some toxic effects.
Interactions with Sex Organs and Fertility
After supplementation of 25-100mg/kg of Bulbine Natalensis daily for 14 days rats have increased testicular size, increasing the testicle:body weight ratio from 0.35 to 1 over 14 days at 50mg/kg. Another study noting increases in testicular size with the same doses found that the epididymis, seminal vesicle, and prostate did not increase in size.
It is also able to increase testicular glycogen content (over time rather than acutely) as well as sialic acid content, protein content, and cholesterol content (all with significant increases on day 1, thus acute).
Sexuality and Concupiscence
At oral doses of 25-50mg/kg bodyweight, Bulbine Natalensis appears to exert aphrodisiac effects which may be secondary to testosterone. These aphrodisiac effects, when dosed at 25-50mg/kg bodyweight, are more effective than Viagra at 50mg/kg bodyweight.
Surprisingly, sperm parameters such as motility, viscosity, count and morhpology are unaffected at all tested doses of Bulbina Natalensis. Other functions related to sexuality and testosterone, such as increases in penile tumescence and a reduction in refractory period between ejactulations, are also noted with supplementation of Bulbine Natalensis.
Safety and Toxicology
Bulbine Natalensis does not appear to alter the profile of red blood cells (a standard toxicology test) in otherwise healthy rats, although it can alter the white blood cell population. Dosages of 25, 50, and 100mg/kg bodyweight over 14 days can increase white blood cell (WBC) count by 41.9%, 26.1%, and 38.5% respectively. Levels of neutrophils, eosinophils, basophils, and lymphocytes decreased while monocytes and platelets increased.
As mentioned in the sections on organs, Bulbine Natalensis appears to adversely affect the structure of the liver and kidneys at dosages used to increase testosterone. The prostate and related 'male' organs do not seem to be as adversely affected though.
A preliminary investigation into humans (poster presentation found here, financially supported by Sports Nutrition Research LTD which produced the tested supplement) ingesting 325mg of bulbine natalensis twice daily (650mg total, separated by 6 hours) for 28 days in otherwise healthy men noted a slight increase in ALP (2% while placebo decreased 2.4%) which were deemed to not be clinically relevant.
There appear to be repeated nonlethal toxic effects demonstrated in rodents from one research group based in South Africa, while the lone human study on bulbine (which is financially supported by a producer of bulbine) noted an increase in the liver enzyme ALP which was not to a clinically large degree.
Currently, the histopathological changes that have been noted in rats have not been sufficiently addressed in humans. While 650mg bulbine does not appear highly damaging according to preliminary evidence, a toxic effect cannot be ruled out