Ginko and Prolactin
- 10-23-2009, 12:39 PM
Ginko and Prolactin
Animal study: ginkgo is prolactin inhibitor (from ergo-log.com)
Ginkgo biloba supplements decrease the production of the testosterone-inhibiting hormone prolactin in the body, according to Taiwanese researchers in Hormones & Behavior. Ginkgo probably increases the dopamine levels in the brain. Dopamine inhibits the release of prolactin.
The Taiwanese tested male rats, which were given ginkgo daily for four weeks. The researchers used four groups of animals, which were administered zero, 10, 50 or 100 mg of ginkgo per kg body weight per day. During the month the researchers put the male rats together with female rats and recorded the number of times they had sex. The figure on the right shows the number of times the rats had sex during the last day of the test.
Because the researchers wanted to know how ginkgo stimulates the sexual behaviour of rats, they measured the testosterone and prolactin levels. The effect was most clear in the group of animals that had received 50 mg per kg body weight a day.
In high concentrations, prolactin inhibits the production of testosterone. But even when prolactin levels are too low to reduce the production of testosterone, prolactin can still reduce the sex drive. When the researchers examined the brains of the rats in the 50 mg group, they discovered higher concentrations of dopamine and its metabolite 3,4-dihydroxyphenylacetic acid. The Taiwanese researchers think that this is why ginkgo acts as a prolactin inhibitor. They also tested whether ginkgo influences the production of testosterone in the testes directly, but the results were inconclusive.
Ginkgo decreases cortisol levels after stress 16.08.2008
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Horm Behav. 2008 Jan;53(1):225-31.
- 10-23-2009, 12:48 PM
- 10-23-2009, 01:10 PM
10-23-2009, 01:47 PM
Sounds like it could prevent problems with prolactin. For me, at ~275 lbs it would take about 6 g./day. I'll have to check Ginko supplements to see if that's a feasable dose.
10-23-2009, 02:11 PM
10-23-2009, 02:28 PM
dsade, thanks. Why do you advise against 6 g./day? Is it just because that dosage level is not needed, or is there potential for negative side effects?
The 6 g./day dosage was based on the research study cited above that found the 50 mg./Kg. body weight dose to be the most efficatious (and my weight of ~275 lbs.)
10-23-2009, 02:32 PM
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10-23-2009, 02:38 PM
dsade, again, MUCH thanks! Now that you mention it, that does sound right; at any rate rat metabolism is overall much higher than human. Wow, thanks for the reminder.
10-23-2009, 02:40 PM
10-23-2009, 02:43 PM
i just bought some liquid Ginkgo.. says 1g 1-2 times daily... will 2 times daily have those type of sides?
10-23-2009, 02:44 PM
10-23-2009, 03:55 PM
10-23-2009, 03:59 PM
10-23-2009, 04:33 PM
10-23-2009, 04:41 PM
10-23-2009, 04:43 PM
10-23-2009, 07:11 PM
10-23-2009, 10:24 PM
10-24-2009, 03:26 PM
OK, another question dsade or Seth, what am I basing the 1 g./day dosage on: the mg. of extract in a product OR the total mg. of ginko leaf the extract is produced from? Now brand ginko--which Nutra carries--is 120 mg. of extract per capsule (at a 50:1 extract ratio). So, I'd need 9 caps/day divided into 3 doses at my bodyweight of ~275 lbs.?
10-25-2009, 01:19 AM
Seth Roberts cleared it up: say you weigh 220 lbs.=100Kg.. You take your weight in Kg.=100 x 10 mg. (1/5 the most effective dosage in the rat studies, in order to adjust for rats having a much greater metabolic rate)= 1000 mg. Now if your extract is a 50:1 extract (which the NOW brand is), a 60 mg. cap of extract is produced from 3 g. of Ginko--much more than the 1 g. you need.
In other words seth was saying that one 60 mg. cap/day should be enough to see prolactin inhibiting effects in anyone.
Pop those caps!
10-25-2009, 10:40 AM
10-25-2009, 11:27 AM
It just says Ginko, it never specifies it as an extract.
Seth also thinks (though he said he wasn't sure) that Ginko probably has a short half-life, and thus one would benefit from multiple doses of a lower potency extract: e.g., 20 mg. (at the 24/6% standardization) 3 x day, rather than 60 mg. 1 x day.
Although, as inexpensive as it is I see no reason not to just use 60 mg. 3 x day--that's still within the safety margin to avoid negative side effects. Another person commented that 240 mg. of a standardized extract is generally as high as people go on dosing Ginko.
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