D-aspartic acid

Whether you have low libido or are just looking to spice things up in the bedroom, this article may be for you. We will examine various drugs and supplements which have been shown to increase libido, in men and women.

Low libido affects around 15% of men and 32% of women (1). The leading causes of libido suppression include stress, anxiety, depression, diabetes, obesity, high blood pressure, and cholesterol. In addition, certain sex hormones decline with age, especially in men.

There are many lifestyle changes which can have a positive impact on sex drive, and these should be explored before considering drugs or supplements. Behaviors such as consuming a healthy balanced diet, exercising regularly, maintaining healthy levels of stress and anxiety and getting at least 7 hours of sleep a night can all can help with libido. However for those who have tried such changes or are still looking for an additional boost, there are a number of drugs and supplements which can be effective.

Most of the drugs and supplements which impact libido operate via one of 3 mechanisms of action; i) via dopamine and / or prolactin, ii) via androgenic hormones, or iii) through vasodilation.

The Dopamine / Prolactin connection

Dopamine and prolactin are closely linked to sex drive. It is theorized that dopamine increases sexual desire while prolactin reduces it, the link between dopamine and sex drive has been well established in men, but is less clear in women (2).

Dopamine is a key neurotransmitter, involved in many pathways in the brain. Dopamine is associated with motivation and concentration. Too much or too little dopamine can be detrimental, low dopamine can lead to Parkinson’s disease while abnormally high levels of dopamine have been linked to schizophrenia and other psychiatric disorders.

Prolactin is a hormone, so named because it has a key role in milk production, however it also has over 300 other functions in the human body playing a key role in reproduction, metabolism, regulation of fluids, regulation of the immune system and influencing behavior.

Dopamine and prolactin appear to move in opposite directions, when dopamine is high, prolactin is low, and vice versa. Prolactin is produced after orgasm and it has been suggested that it may be responsible for the sudden change in mood many men feel after ejaculation.

As Dopamine is the incentivization hormone, it drives the desire to have sex, once the prolactin is released, dopamine levels fall and all of a sudden, the man is left wondering where the desire came from in the first place. This relationship can be observed in the chart below.

One study showed that the ability for some men to achieve multiple orgasms, may be attributable to reduced prolactin production in those individuals (3). This suggests that blocking prolactin could allow the average man to also achieve such states. In comes Cabergoline.

Cabergoline

The drug Cabergoline blocks the release of prolactin and has been shown to increase erections and libido in men (4). In one study, 60 healthy males normally needed a break of 19 minutes between orgasms. After taking cabergoline, they were able to have several orgasms within a few minutes.

Cabergoline has also been reported to increase the intensity of male orgasms (5). Another study showed Cabergoline can be effective in increasing sex drive in both men and women, who are suffering from elevated levels of prolactin (6).

High doses of Cabergoline can have unwanted side effects, some studies have shown it can increase the risk of heart failure, however at normal doses the risk appears low (7). Also some level of prolactin is desirable as prolactin supports neurogenesis (growth in brain tissue) so blocking it completely for a long time period is not recommended.

Bromocriptine

Bromocriptine works in a similar way to Cabergoline. Bromocriptine stimulates dopamine production and simultaneously reduces the levels of prolactin, although not by as much as Cabergoline. Bromocriptine has been reported by many men and women to have a powerful impact on sex drive.

Bromocriptine has been shown to increase libido in men recovering from dialysis treatment (8). Bromocriptine was also shown to increase sex drive in women suffering from high levels of prolactin (9).

Like cabergoline, bromocriptine, especially in high doses can have unwanted side effects such as high blood pressure, seizure or stroke. It is not recommended to take any of these medications without the supervision of a doctor.

Mucuna Pruriens – a natural dopamine precursor

A safer alternative to increase levels of dopamine would be so use a natural supplement, such as Mucuna Pruriens.

Mucuna Pruriens, otherwise known as Velvet Bean is a tropical bean native to Africa and Asia. It has been used in Ayurvedic medicine to treat snake bites and Parkinson’s disease. The seeds of the plant contain between 3-6% L-Dopa. L-Dopa is a precursor to dopamine and has the advantage of being able to cross the blood-brain barrier, whereas dopamine cannot. Once L-Dopa has entered the central nervous system it is converted to dopamine. L-dopa supplementation is therefore more effective than direct supplementation with dopamine.

Mucuna Pruriens is widely sold as a supplement to increase motivation, improve mood and as an aphrodisiac. Unfortunately there is limited research on its effects on sex drive in humans however it has been shown to increase sexual behavior in male rats (10).

The Androgenic compounds

Androgens are natural or synthetic steroid hormones which regulate the development of male characteristics. Androgens are produced in the human body in the testes, ovaries and adrenal glands. The main androgen hormone in men is testosterone. Although testosterone is mainly thought of as a male sex hormone, women also produce testosterone although at lower levels.

Testosterone plays a critical role in libido and sexual arousal in both men and women. Testosterone levels are often lower in people who lead sedentary lifestyles, have poor diets or lack sleep. Testosterone levels also decline naturally with age. Testosterone supplementation has been shown to increase libido in men and women with suppressed testosterone levels (11) (12).

Testosterone is widely used in high doses in the bodybuilding community.

Direct supplementation of testosterone can lead to unwanted side effects such as acne, hair loss, deepening of voice, facial hair growth and in women enlargement of the clitoris – however these tend to only occur at higher doses such as those used for bodybuilding. In addition supplementing exogenous testosterone can inhibit the body’s natural production mechanism, making the problem of low testosterone worse once you stop supplementing.

Due to the side effects we would recommend avoiding direct supplementation with testosterone and rather suggest raising levels naturally through improved sleep, diet and exercise. If these factors alone aren’t sufficient you can try supplementing with Tribulus Terrestis or D-aspartic acid.

Tribulus Terrestis

Tribulus Terrestis is a small leafy plant which grows in Europe, Asia, Africa and the Middle East. The root and fruit of the plant have been used for centuries in traditional Chinese medicine and Ayurvedic medicine for a variety of purposes, including increasing libido.

The jury is still out on how effective Tribulus is at increasing testosterone levels, however it has shown promise in some studies in women. One study of postmenopausal women with low libido found that supplementation with Tribulus over a 120 day period increased levels of testosterone and sexual desire (13). However other studies have not been able to back up these findings, especially in relation to the broader population (14).

Another supplement which may be effective at increasing testosterone levels is D-aspartic acid. D-aspartic acid is a naturally occurring amino acid and it is important for brain and nerve development, as well as the development of testosterone.

However again the research findings are mixed. It seems D-aspartic acid is most effective at raising testosterone levels in non-resistance trained men (15). Studies in active resistance trained men found supplementation either had no effect or even reduced testosterone levels (16) (17) (18), therefore we would recommend supplementation only in individuals with suppressed testosterone levels and relatively inactive lifestyles.

There is no real research available on the efficacy of D-aspartic acid in women however as it works via stimulating the testes, it is unlikely to have the same effects for women.

Vasodilators

Another class of supplements works by increasing circulation, typically by increasing levels of nitric oxide. These compounds have less of an effect on sexual motivation but can improve erections in men and sensation in both men and women.

Nitric oxide (NO) is a molecule produced naturally in the body. NO is responsible for vasodilation, increased levels for NO cause the inner muscles of blood vessels to relax, which causes them to widen, thereby increasing circulation. The link between NO and erections is well established (19). Sildenafil (Viagra) works by inhibiting the enzyme which is responsible for breaking down NO in the genitals, thereby improving circulation in this area.

Viagra (Sildenafil) is a powerful vasodilator.

L-Citrulline

For anyone not wanting to take drugs such as Viagra another option is L-Citrulline. L-Citruline is an amino acid which is produced naturally in the body and is also found in various foods, including watermelon. L-Citriline has been shown to increase NO synthesis, thereby improving circulation (20). Supplementation with L-Citriline has been shown to improve erections in patients experiencing mild erectile dysfunction (21).

In conclusion

The causes of low libido can vary significantly from individual to individual, therefore no one treatment will work for everyone. The best approach is to ensure a healthy lifestyle with low stress, plenty of sleep and exercise and a healthy, balanced diet. For those looking for an additional boost a mixture of herbal remedies such as mucuna pruriens, Tribulus, D-aspartic acid and L-Citriline may help.