D-Aspartic Acid and Testosterone: In-Depth Review

D-Aspartic acid testosterone

Here we have a detailed review of D-Aspartic Acid and its effects on testosterone. As well as its impact on libido, strength & muscle mass, and more.

Testosterone is a male hormone important for improving libido, muscle gains, and overall health. For this reason, many men look for ways to increase this hormone naturally.

If you’ve ever researched or used T-boosters, chances are you’ve come across an ingredient called D-Aspartic Acid. It’s an amino acid that’s claimed to boost the male hormone.

In this article, we’ll look into the science behind D-Aspartic Acid. This will help us find out if it can really boost your T-levels.

Let’s get straight to it.

What Is D-Aspartic Acid?

D-Aspartic Acid is one of two forms of aspartic acid that our bodies naturally produce. The other one is called L-Aspartic Acid.

The same chemical formula lies behind these two aspartic acids, but their molecular structures are completely opposite. [1]

Okay, so what exactly are amino acids? These are molecules that have a number of roles in our body. They are building blocks for proteins which are responsible for building muscle mass.

But amino acids don’t just build muscle. Among many of their functions, they also serve as the main building blocks for certain brain chemicals and hormones – including testosterone.

While D-Aspartic Acid isn’t one of the building blocks for proteins, it plays an important role in producing hormones within your body. [1, 2, 3]

Linking this to testosterone, D-Aspartic Acid increases the production of certain hormones that signal the body to produce testosterone. [2]

D-AA also plays a role in stimulating testes to produce and release more testosterone. [4]

It also plays a role in increasing testosterone production and release in the testicles (34).

This is the reason why many T-Boosters use D-Aspartic Acid among their ingredients.

But just how reliable D-AA is when it comes to increasing testosterone? Can it deliver long-term, noticeable results?

Keep reading to find out.

Can It Boost Testosterone?

Looking at the functions of D-Aspartic Acid, it must be of the best natural T-boosters out there… right?

The answer is: it depends.

See, modern research has shown mixed results when it comes to this ingredient. Some studies suggest that D-AA is a potent T-booster. Other studies showed the opposite results.

Let’s start with the positive studies first. In one study, they gave D-Aspartic Acid to a healthy group of men who were between 27-37 years old. The results were amazing.

In less than two weeks, most of these men experienced significantly increased testosterone levels – 42% on average, to be precise.

Even after stopping the supplementation, these men still had 22% higher testosterone levels than when they started the study. [5]

Another study showed similar results. This time they tested sedentary men between the ages of 27-43. After supplementing with D-Aspartic Acid for 90 days, this group of men experienced a 30-60% boost in their testosterone levels. [6]

Then came another study. This time, they tested overweight and obese men who took D-Aspartic Acid for roughly one month. Some of these men had no increases in their male hormone. But those who had lower T-levels to begin with, experienced a slight increase of 20% on average. [7]

Will D-AA Improve Testosterone in Physically Active Men?

There is one re-occurring pattern in the studies I showed you above. Most of these studies tested sedentary, overweight, or obese men who had low baseline testosterone levels.

But what about bodybuilding athletes and physically active people? These groups of people often have normal or elevated testosterone levels due to the effects of strength training.

So the main question is: Can D-Aspartic Acid still increase your testosterone if it’s already at optimum levels?

According to the studies, no it can’t.

One study found no increase in testosterone, strength, or muscle mass in young adults who regularly trained with weights and took D-Aspartic Acid. After 28 days of supplementing with this ingredient, they didn’t experience any benefits. [8]

Another study had even more shocking results. It found that men who regularly trained and took 6 grams of D-AA (a high dose) daily for two weeks experienced decreased testosterone levels! Not only did D-Aspartic Acid not work in their case, it actually negatively affected their male hormone.

But this was only a temporary drop in testosterone. After three months, they performed the same study with the same group of men. This time, they gave them a high dose of D-AA supplementation for three months. The results showed no change in testosterone. [10]

What Can We Conclude From This?

When we look at the studies from above, it’s clear that D-Aspartic Acid doesn’t work for everyone.

Specifically, it appears that D-AA boosts testosterone only in those men who suffer from low T-levels due to obesity, sedentary lifestyle, or other health problems.

However, in athletes and physically active men who already have normal testosterone levels, it appears that D-AA supplementation doesn’t offer many benefits.

To sum it up:

D-Aspartic Acid helps increase testosterone in inactive men who already suffer from low T-levels. But it hasn’t been shown to improve testosterone in men who do strength training.

Effects of D-AA On Strength and Muscle Mass

D-Aspartic Acid is thought to increase muscle mass and strength levels. Not only indirectly through boosting testosterone, but directly too.

There are a number of studies that examine whether these claims are true or not. And most of them show that they are not true. [8, 9, 10]

One study, in particular, tested this on a group of men who trained with weights for 28 days. During this period, they took D-Aspartic Acid. The results looked promising at first: these men gained an average 1.3kg of muscle mass.

However, another group of men who took a placebo pill instead of D-AA experienced the same muscle gains after 28 days of training. In fact, this group gained 1.4kg of muscle mass, which was even more than the group who took D-Aspartic Acid.

Ultimately, the study showed no correlation between D-Aspartic Acid supplementation and muscle or strength gains in men. [8]

What Do Other Studies Say?

There are more studies that prove the results of the study from above. They show that D-AA supplementation yields little to no results in increasing strength or muscle mass.

Such was the case with this study. They tested a group of men who trained regularly over a 3-month period. One part of the group took a placebo pill, while the other part took D-Aspartic Acid.

At the end of the study, both groups experienced the same boost in muscle mass and strength. It didn’t matter if they took D-Aspartic Acid or a placebo pill – there were no differences in results between the two groups.

Both of the studies from above tell us that D-Aspartic Acid might not work for you if you do strength training and have normal testosterone levels.

Unfortunately, there’s a lack of research that shows combining D-AA with other types of exercise. Such as cardio, HIIT, or something similar. Who knows, maybe D-Aspartic Acid could prove to be a game-changer in these situations.

To sum it up:

D-Aspartic Acid doesn’t improve strength or muscle gains when combined with a weightlifting program. However, we need more info on other types of exercises, such as cardio and HIIT – D-Aspartic Acid might prove useful in these scenarios.

Other D-Aspartic Acid Benefits

There are many D-Aspartic Acid benefits, besides its positive effects on testosterone.

Let’s have a look at some of them:

Improves Fertility and Sperm Quality

Although the research is limited, D-Aspartic Acid appears to boost sperm quality. It also shows promise in regards to helping men who suffer from infertility.

There was a study which gave D-AA daily to 60 men who suffered from fertility issues. After three months, their sperm count increased significantly. On top of this, the speed and mobility of their sperm also increased. [6]

During the study, 27% of the partners of these men became pregnant. The rate of pregnancies of their partners improved significantly after the men started supplementing with D-Aspartic Acid. Proving its amazing effects on male fertility.

But it isn’t just men who benefit from taking D-Aspartic Acid, in regards to fertility. Women too experienced improved reproductive health when supplementing with this amino acid. [11]

Supports Cognitive Function

D-Aspartic Acid might be a nootropic too.

While the research is limited to only a handful of animal and human studies, D-AA shows promises when it comes to boosting memory and cognitive function.

Several mice studies showed incredible results on the brain from taking D-Aspartic Acid. The results from the studies show an improved brain cell communication, cognitive function, and general memory from taking D-AA.

One human study proved this too. In the study, people who took this amino acid experienced raised levels of DAO enzyme, which improves memory and thought processing. [12, 13]

Dosage Guide

The majority of the studies that looked at the effects of D-Aspartic Acid on testosterone have used doses of around 3 g daily.

These doses are effective in males who are inactive and have low testosterone. But the same dose doesn’t work in young males who do strength training – like I already explained.

There were studies, as we’ve seen, that have used even higher dosages. Such as 6 grams per day. But these didn’t appear to be any more effective than lower doses.

Okay, so to conclude:


For boosting testosterone, 3g of D-AA daily is the optimal dose in physically inactive men. If your goal is to boost sperm quality and quantity, take 2.6g daily. Keep in mind though, it takes some time to notice D-AA’s effect on sperm. Up to 90 days in some cases.

Safety Profile

D-Aspartic Acid is a safe ingredient. So far, studies haven’t found any serious side effects related to it.

That said, there are some minor side effects reported by people in some studies, such as irritability, headaches, and nervousness.

Bear in mind though, that these side effects likely don’t have anything to do with D-AA, since the people who took placebo in the study reported the same effects. [8]

In another study, where they gave 2.6g of D-AA daily for 90 days, there were no reported side effects. The men in the study only experienced the benefits – increased testosterone, libido, and sperm quality. [6]

All in all, this leads me to conclude that D-Aspartic Acid is a safe ingredient to take. Even at high dosages, such as 6g per day for a prolonged period of time, it doesn’t produce any side effects.

Combining D-Aspartic Acid With Other Ingredients

Okay, so we have now established how D-AA works. So far, we know that it’s extremely beneficial for people who are physically inactive and suffer from low testosterone.

However, for active individuals who do strength training, it’s a different story. In these groups of people, D-Aspartic Acid hasn’t shown many promises so far.

However, it’s possible to stack D-AA with other testosterone boosting ingredients to improve its effectiveness. This is where D-Aspartic Acid really shines.

Here are some of the ingredients D-Aspartic Acid synergizes well with:

Ashwagandha– It’s an Ayurvedic herb known for combating stress, cortisol, as well as improving testosterone levels and fertility. Combined with D-Aspartic Acid, it could lead to major improvements in your sex drive and T-levels.

Vitamin D – Helps your testes produce more testosterone. Many T-boosters stack Vitamin D with ingredients such as D-Aspartic Acid to improve its effects.

Zinc – A mineral important for countless enzymatic functions in your body, including testosterone production. Studies suggest that zinc deficiency leads to low T-levels.

Oyster Extract – One of the most nutrient-dense foods on the planet. It’s packed full of vitamins and minerals (including zinc) which support your hormones.

Boron – Helps your body to block the Sex Hormone-Binding Globulin (SHBG) production, allowing for more free testosterone to flow through your veins.

Bioperine – It doesn’t boost testosterone directly, however, it improves the bioavailability of other ingredients. Making them more effective. When combined with D-Aspartic Acid, it can improve its effectiveness, and thus, your testosterone levels.

Final Word

Many people use D-Aspartic Acid to boost their testosterone. But will it work for you?

This depends on a number of factors…

First and foremost, if you’re an inactive person. Or you perhaps suffer from low testosterone levels. Then yes, D-Aspartic Acid will most likely be of great benefit to you. Studies show it to be extremely potent in people who have low T.

However, if you’re a healthy person with normal testosterone levels, and if you do regular strength training. Then D-Aspartic Acid might not be of much benefit. This is what studies have shown us so far.

Other benefits of D-Aspartic Acid include improved fertility and sperm count, improved reproductive health in females, and better cognitive function (memory and learning).

In terms of safety, D-AA is a fairly safe and reliable ingredient. People in studies took it for up to 90 days without experiencing any side effects.

That said, I suggest taking a break after 90 days, since we don’t have any research showing the effects of D-AA usage that’s longer than three months. Just to be on the safe side.


[showhide type=”links” more_text=”Show References” less_text=”Hide References”]

[1] Protein design with L- and D-alpha-amino acid structures as the alphabet.

[2] Occurrence of D-aspartic acid and N-methyl-D-aspartic acid in rat neuroendocrine tissues and their role in the modulation of luteinizing hormone and growth hormone release.

[3] D-Aspartic acid: an endogenous amino acid with an important neuroendocrine role.

[4] Involvement of D-aspartic acid in the synthesis of testosterone in rat testes.

[5] The role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosterone in humans and rats.

[6] D-Aspartate, a Key Element for the Improvement of Sperm Quality.

[7] Influence of a D-aspartic Acid/Sodium Nitrate/Vitamin D3 Dietary Supplement on Physiological Parameters in Middle-aged Men: A Pilot Study

[8] D-aspartic acid supplementation combined with 28 days of heavy resistance training has no effect on body composition, muscle strength, and serum hormones associated with the hypothalamic-pituitary-gonadal axis in resistance-trained men.

[9] Three and six grams supplementation of d-aspartic acid in resistance trained men.

[10] The effects of d-aspartic acid supplementation in resistance-trained men over a three month training period: A randomized controlled trial.

[11] Reproductive implication of D-aspartic acid in human pre-ovulatory follicular fluid.

[12] New insights on the role of free D-aspartate in the mammalian brain.

[13] Blood levels of D-amino acid oxidase vs. D-amino acids in reflecting cognitive aging.


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