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May 18, 2023
There is no doubt that increasing testosterone levels will help us to build muscle mass, increase muscle strength and boost our virility. While some people choose to put synthetic testosterone into their bodies, a far safer way to go is to boost the body's ability to produce it naturally. Natural testosterone boosting supplements contain herbal compounds and other natural ingredients designed to stimulate that natural hormone production. These products, though, are only as good as the ingredients that they contain.
An ingredient found in many natural testosterone boosters is the amino acid d-aspartic acid. In this article, we provide an in-depth look at the ability of this compound to stimulate testosterone production in the body.
We'll cover the following:
D-aspartic acid (D-AA) is a naturally occurring endogenous amino acid that the body uses to create new proteins. It is an enantiomer, which means that it is the opposite of L-aspartic acid, another type of aspartic acid.
Amino acids are most well-known as the building blocks of protein. However, they are also involved in the production of hormones. Generally, the 'L' form of an amino acid is responsible for protein production, while the 'D' form is involved in the release of hormones.¹
The main function of D-aspartic acid is thought to be to promote the body's production of various hormones, mainly testosterone. It has become popular among athletes and bodybuilders who want to improve their athletic ability, muscle growth, and strength.
In the early 2000s, scientists began to pay attention to the relationship between D-AA and testosterone. Researchers from Italy's University of Naples produced one of the groundbreaking papers in this area in 2012. The "D-Aspartate, a Key Element for the Improvement of Sperm Quality" study investigated the impact of D-AA supplementation on sperm quality and also noted a rise in testosterone levels in healthy males after 12 days of supplementation.² We will refer to this study frequently throughout this analysis.
Following this initial investigation, other studies started examining the potential influence of D-AA on testosterone levels and associated variables. Some of these studies found that testosterone levels briefly increased after short-term supplementation.
The link between D-AA and testosterone received increased attention in the sports and fitness areas as the research developed. As a result, D-aspartic acid supplements labeled as testosterone boosters became popular among sportsmen and bodybuilders looking for potential performance-enhancing effects.
D-aspartic acid is naturally produced in the body, mostly in the testes, pituitary, and hypothalamus. It functions as a neurotransmitter and is involved in the production and release of several hormones, including the crucial testosterone-producing hormones luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
One suggested mechanism by which D-AA stimulates testosterone production is by facilitating the release of gonadotropin-releasing hormone (GnRH) from the hypothalamus. The release of LH from the pituitary gland is stimulated by GnRH. LH then instructs the testicular Leydig cells to create testosterone.
According to animal studies, D-AA can boost GnRH secretion, which in turn causes LH levels to rise. This increase in LH may then encourage the manufacture of testosterone in the testes.
Another theory is that D-AA might directly influence the activity of the enzymes responsible for testosterone production. Through a series of enzymatic processes, cholesterol is converted into testosterone. According to certain studies, D-AA may increase the activity of enzymes necessary for testosterone synthesis, including 3-hydroxysteroid dehydrogenase (3-HSD) and cholesterol side-chain cleavage enzyme (P450scc).³
D-AA may also affect the expression of genes involved in testosterone synthesis. According to studies, taking D-AA supplements can boost the expression of genes involved in steroidogenesis—the process by which the testes produce steroid hormones like testosterone—in the body.⁴
It is important to remember that the effects of D-AA on testosterone levels may differ from person to person. Age, body composition, baseline testosterone levels, and individual metabolism are just a few variables that can affect how well D-AA supplementation works. Further study is required to properly understand the implications of D-AA supplementation because its long-term effects and safety have not yet been thoroughly demonstrated.
Over the past couple decades, there has been some fascinating research connecting D-aspartic acid with testosterone. Here's an overview of the benefits of taking D-AA in relation to testosterone based on that research.
A number of indicators, such as sperm count, motility (movement), and morphology (form and structure), are used to evaluate sperm health, which is a critical component of male fertility. The success of fertility therapies and naturally occurring pregnancy depends on maintaining optimal sperm health.
A 2012 study looked at the impact of D-AA on sperm parameters. When compared to baseline values, the participants' sperm count and motility significantly increased after 90 days of receiving D-AA supplementation. In addition, the treatment with D-AA led to a marked increase in the number of pregnancies occurring in the partners of the study subjects.⁵
In a systematic review and meta-analysis on D-AA and sperm quality that was published in 2017, researchers assessed several studies. Randomized controlled trials (RCTs) examining the impact of D-AA supplementation on sperm characteristics were included in the analysis. In comparison to a placebo, the results showed that taking D-AA supplements significantly increased sperm motility and count.⁶
Even though these studies point to a possible beneficial effect of D-AA on sperm health, the precise processes underlying these benefits are still not fully understood. One theory is that D-AA may increase the release of several hormones that are important for sperm development and function, including testosterone and follicle-stimulating hormone (FSH).
The pituitary gland secretes luteinizing hormone (LH), a hormone that is essential for controlling testosterone synthesis. The Leydig cells in the testes are stimulated by LH, which increases testosterone synthesis.
The effects of D-AA supplementation on hormone levels in healthy men were examined in a 2009 study. The findings demonstrated that 12 days of D-AA supplementation significantly raised LH levels relative to baseline levels. Temporary increases in testosterone levels were connected with this surge in LH.⁷
These findings demonstrate that D-AA may affect the pituitary gland's release of LH, increasing testosterone production. The increase in LH and testosterone levels seen in these studies was brief and returned to baseline within a few days after cessation of supplementation.
We don't fully understand the precise methods by which D-AA impacts LH levels yet. One theory suggests that gonadotropin-releasing hormone (GnRH) may be stimulated by D-AA by interacting with certain receptors in the brain. LH is then released as a result of GnRH's action on the pituitary gland.
When viewed as a whole, the results of studies looking into D-AA's ability to increase testosterone levels produce mixed results. The 2009 study mentioned in the previous section is a key piece of research in support of its use. The 12 days of D-AA supplementation had a significant impact on the subjects' testosterone levels compared to baseline values. This brief increase in testosterone levels was accompanied by a rise in LH. Of the 23 men who took part in the study, 20 of them increased their testosterone levels, with the above increase being 42%. Though testosterone levels did decline after they stopped taking the supplement, it was still 22% higher than the baseline three days after the study ended.⁸
However, other research has shown less impressive results. A 2015 study focused on the effect of taking D-AA on overweight and obese men. After 28 days of taking D-AA, the increase in free and total testosterone was 5%, which was not deemed to be statistically significant. Some men showed no increase at all, while those with very low testosterone baseline levels had the best improvement.⁹
In another study, healthy men between the ages of 27 and 43 who took D-AA for three months had an average increase in serum testosterone concentrations of 45%.¹⁰
All of the studies mentioned so far were on men who did not engage in resistance training. A 2013 study specifically focused on the effects of D-AA supplements on resistance-trained men. Two groups of men were given either a placebo or 3 grams of D-AA over a period of 28 days. During that period, the men did four workouts per week. Although muscle and strength levels increased in both groups, there was no significant change in free and total testosterone levels and the level of luteinizing hormone.¹¹
Another study compared different D-AA dosages. Twenty-four study participants were put into one of three groups. The first was given a placebo, while the second was given 3 grams of D-AA per day. The third group supplemented with 6 grams of D-AA. Surprisingly, the 6-gram per-day group actually experienced a decline in free testosterone. There were no notable differences in the other two groups.¹²
A 2016 study focused on the effects of giving D-AA to young men who were experienced weight trainers. The men in the study were all aged 22, so they had not yet experienced any age-related decline in natural testosterone production. After 14 days of supplementation, all of the participants experienced increases in their one-rep max on the squat and bench press. The placebo group experienced no change in their performance. However, there was no change in testosterone levels in either group.¹³
According to the consensus of research, D-aspartic acid supplementation may help men's testosterone levels increase, especially in men with low baseline testosterone levels and who are inactive. However, the boost in endogenous testosterone levels seen with D-AA supplementation is often transient and returns to baseline after a few days of cessation.
There is still much to learn about the precise mechanisms through which D-AA affects testosterone levels. According to one theory, D-AA may facilitate the release of gonadotropin-releasing hormone (GnRH) from the hypothalamus. The pituitary gland releases LH when GnRH is stimulated, and LH acts on the testes to increase testosterone production.
D-AA may have an impact on the activity of the enzymes responsible for testosterone production, which is another potential pathway. Through a series of enzymatic processes, cholesterol is converted into testosterone. According to research, D-AA may increase the activity of some enzymes necessary for the production of testosterone, including the P450scc cholesterol side-chain cleavage enzyme and the 3-hydroxysteroid dehydrogenase.¹⁴
As previously covered, it is important to remember that different people may respond differently to D-AA's effects on testosterone levels. Age, baseline testosterone levels, and individual metabolism are just a few variables that possibly affect how well D-AA supplementation works.
When used in the recommended dosage, D-aspartic acid is regarded as safe. However, some people may experience some negative effects. It's important to remember that every person will react differently, and side effects may appear more frequently or be more severe in some. The following are some possible negative effects of taking D-AA supplements:
More research is needed to completely understand the long-term effects and safety of D-AA supplementation. Also, individual factors, including age, health status, and other medications being taken, may affect the ideal dosage, duration of use, and potential benefits or hazards of taking a D-AA supplement.
The best way to gauge the effective dosage of an ingredient like D-AA is to look at the dosages that were used in clinical studies. When you do that, you'll find that they range between 2.6 and 3 grams per day. The 2012 study that is most cited in support of this amino acid's ability to increase testosterone levels used a daily dosage of 2.6 grams. It should be taken into consideration that this study was conducted with men who were not regular exercisers.
As noted in the previous section, dosages of 3 and 6 grams per day were not effective in increasing D-AA levels in men who were regular weight trainers.
Most testosterone boosters that contain D-AA dose it at between 2 and 3 grams.
Some people do prefer to buy their own D-AA powder to find the perfect dose for them.
D-aspartic acid is touted by some as a breakthrough supplement ingredient when it comes to boosting testosterone levels naturally. When we drill down on the scientific research, however, the results are decidedly mixed. As more human studies are done, we will get a clearer picture, but at this stage, it appears that D-AA may be effective in helping sedentary men and those with low baseline testosterone levels to naturally increase production. However, it does not appear to do so in healthy men who are involved in a weight training program.
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