I've slimmed it down a bit. Maybe someone could be bothered posting it to the wiki or whatever or bookmark it if it's of interest to you.
You can also go to Examine.com and search "erections" and then click on the ingredient and it takes you to the studies and rates the strength of the effect (listed as minor by examine.com in all cases where an effect is demonstrated though) and the strength of the studies.
On the herbal and OTC supplements, here you go…
• Principal Proposed Natural Treatments
Carnitine; Ginseng; L-Arginine
Other Proposed Natural Treatments
Ashwagandha; Avena sativa; Butea superba; Catuaba; Cordyceps; Damiana;
Dehydroepiandrosterone (DHEA); Diindolylmethane (DIM); Eleutherococcus; Horny Goat Weed; Ginkgo; L-citrulline; Maca ( Lepidium meyenii) ; Macuna pruriens; Melatonin;
Molybdenum; Pine Bark Extract and L-Arginine; Muira Puama (Potency Wood); Polypodium vulgare; Pomegranate; Pygeum; Rhodiola rosea; Saw Palmetto; Schisandra; Suma;
• Traditional Chinese Herbal Medicine
Tribulus; Velvet Antler; Zinc
• Herbs and Supplements to Use Only With Caution
Licorice and Soy can reduce testosterone; Yohimbe has many problem drug interactions and the yohimbe content in the herbal product can be unpredictable.
If you are on blood pressure drugs or statins, both of these (some more than others) can mess up your wood. As there’s many varieties of them it’s maybe better to ask your doctor to switch them to different ones if you think they are the cause.
Back to OTCs and herbals, I’ll just list a few that are readily available legally and from the usual suppliers. Some supplements companies have a better rep than others, or better rep on specific products, which is also something worth looking into. I wouldn't rush to buy from Holland & Barrett for instance.
Korean Red Ginseng
Two double-blind, placebo-controlled trials, involving a total of about 135 people, have found evidence that Korean red ginseng may improve erectile function.
In the better of the two trials, 45 participants received either placebo or Korean red ginseng at a dose of 900 mg 3 times daily for 8 weeks. After a 1-week period of no treatment, the two groups were switched. The results indicate that while using Korean red ginseng men experienced significantly better sexual function than while they were taking placebo.
In an analysis combining the results of 6 controlled trials, researchers found some evidence for the benefits of Korean red ginseng. However, the small size and generally low quality of the studies left some doubt about this conclusion.
(There are several very different types of Ginseng, all with different properties. They also vary hugely on things like how well they are absorbed and the amounts of active ingredient.)
L-Arginine
Nitric oxide (NO) plays a role in the development of an erection. Drugs like Viagra increase the body's sensitivity to the natural rise in NO that occurs with sexual stimulation. A simpler approach might be to raise NO levels, and one way to accomplish this involves use of the amino acid L-arginine. Oral arginine supplements may increase nitric oxide levels in the penis and elsewhere. Based on this, L-arginine has been advertised as "natural Viagra." However, there is as yet little evidence that it works. Drugs based on raising nitric oxide levels in the penis have not worked out for pharmaceutical developers; the body seems to simply adjust to the higher levels and maintain the same level of response.
The main support for the use of arginine in erectile dysfunction comes from a small double-blind trial in which 50 men with erectile dysfunction received either 5g of L-arginine or placebo daily for 6 weeks. More men in the treated group experienced improvement in sexual performance than in the placebo group.
A double-blind crossover study of 32 men found no benefit with 1,500 mg of arginine given daily for 17days; the much smaller dose and shorter course of treatment may explain the discrepancy between these two trials.
L-arginine has also been evaluated in combination with other products. For example, a double-blind, placebo-controlled trial of 45 men found that one- time use of L-arginine plus the drug yohimbine (made from the herb yohimbe) 1-2 hours before intercourse improved erectile function, especially in those with only moderate erectile dysfunction scores. Arginine and yohimbine were both taken at a dose of 6g.
Note: yohimbe involves a number of safety risks.
Researchers have also studied a formulation of L- arginine and pine bark extract (pycnogenol). In a randomized study involving 124 men with moderate erectile dysfunction, those that were in the treatment group had an improvement in their symptoms.
L-citrulline converts to L-arginine in the body so can be considered comparable.
Carnitine
In a 6-month, double-blind trial of 120 men, average age 66. Carnitine (propionyl-l-carnitine (LPC) 2g a day plus acetyl-l-carnitine (ALCAR) 2g day and testosterone (testosterone undecanoate 160 mg/day) were separately compared to placebo.
The results indicated that both carnitine and testosterone improve erectile function; however, while testosterone significantly increased prostate volume, carnitine did not.
Another double-blind, placebo-controlled study found that propionyl-l-carnitine at 2 g/day enhanced the effectiveness of sildenafil (Viagra) in 40 men with diabetes who had previously failed to respond to sildenafil on at least eight occasions.
In another double-blind study, a combination of the propionyl and acetyl forms of carnitine enhanced the effectiveness of Viagra in men who suffered from erectile dysfunction caused by prostate surgery.
Other Treatments
A proprietary combination therapy containing arginine along with Ginkgo biloba, ginseng, and vitamins and minerals has shown some promise in an unpublished study.
A double-blind, placebo-controlled study enrolled 40 men with difficulty achieving or maintaining an erection who also had low measured levels of DHEA. The results showed that DHEA at a dose of 50 mg daily improved sexual performance; however, the authors failed to provide a statistical analysis of the results, making the meaningfulness of this study impossible to determine.
Severe zinc deficiency is known to negatively affect sexual function. Since marginal zinc deficiency is relatively common, it is logical to suppose that supplementation with zinc may be helpful for some men. However, this hypothesis has only been studied in men receiving kidney dialysis. (Careful with zinc as anything over the standard dose of 40mg a day is thought to be toxic.)
Weak evidence hints at potential benefit with pomegranate juice, ands also melatonin.
Based on exceedingly preliminary evidence, the herb maca, has been advertised as "herbal Viagra." In one study in rats, use of maca enhanced male sexual function. There is one published human trial as well. In this small, 12-week, double-placebo-controlled study, use of maca at 1,500 mg or 3,000mg increased male libido. While this was an interesting finding, the study did not report benefits in male sexual function — just in desire. Since loss of sexual function is a more common problem in men than loss of sexual desire, these results do not justify the herbal Viagra claim. Contrary to some reports, maca does not appear to affect testosterone levels. (It also tastes pretty awful in my opinion, in ‘shakes’ as if often recommended, or on food; but as viagra gives you wood without the desire, especially when it’s some Romanian skank, it might be of interest to some people).
There’s many others that are supposed to help but little or no evidence. This doesn’t mean they don’t just that there’s no proof, or in some cases fairly strong evidence that they don’t. Ashwagandha, for instance, strongly reduces anxiety. It also has been known mildly to reduce blood pressure. Lowest effective dose is 300-500mg, optimal dose is 2,000mg three times a day. Can make you a wee bit sleepy mind. It’s an adaptogen, as is Rhodiola Rosea, so ‘adapts’ by balancing hormones, managing your stress and adapting to what the body needs depending on the need in the moment. Some bodies anyway…
Ginkgo is promoted as having dramatic results, especially if your wood is being fucked up by antidepressants (try to get off the antidepressants unless it’s an emergency, they are basically shit candy). Unfortunately when double-blind, placebo-controlled studies have been performed it appeared that the power of suggestion worked better than Ginkgo or placebo.
A small study involving 21 men with erectile dysfunction found that those who took pine bark extract (120 mg/day for 3 months) experienced an improvement in their symptoms compared to placebo. Pycnogenol is a patented formula of one bark extract.
---------------------------------------------------------------- Happy wooding ...