D-Aspartic Acid – Does it raise testosterone?

Best D-Aspartic Acid Supplements
Aspartic acid is an amino acid that comes in two varieties, there is L-Aspartate and D-Aspartic Acid. The latter, also known as D-AA has become very popular with supplement companies because it is believed to be a testosterone boosting ingredient. But is this the case? As with many products in the supplement industry D-AA is hotly debated as to whether it’s effective or not.

In this article we will be looking at the purported benefits of D-AA, before delving into the relevant literature to see whether these claims stack up, or whether they have been exaggerated.

The Possible Benefits of DAA (D-Aspartic Acid)

The most well known potential benefit of D-AA is the increase in testosterone, but there are other lesser-known ones that we will check out first. These benefits are most likely linked to an increase in testosterone, so for example one of the benefits is increased muscle, while another is fat loss. Other benefits are increased power and increased fertility.

All of these benefits could be linked to increased testosterone production, as high testosterone levels can increase protein synthesis, increase fat loss, and increase strength. Now that we know the benefits, let’s examine whether they have been proven.

  1. Strength and D-Aspartic Acid (DAA)

In 2013 a study was taken that looked into a combination of D-AA supplementation and resistance exercise [1]. The study took place over 28 days and involved resistance-trained men (long time lifters). They found that the D-AA had no effect on strength or hypertrophy, nor did it create a significant hormonal change.

Now, one weakness of the study is the duration, 28 days isn’t usually enough time to witness any changes in a strength and conditioning program. Ideally the study could have been 12 weeks or more, which could potentially have made a difference to the results.

  1. Fat Mass and DAA

The same study also found that there was absolutely no change in fat mass in any of the men, in fact there seems to be no evidence that D-AA has ever been found to increase fat loss. Considering that the reason that most men take testosterone enhancing supplements is to lose weight, this is a pretty big deal.

  1. D Aspartic Acid for Male Fertility

Finally, a proposed benefit of D-AA that has some evidence backing it! A 2012 study found that D-Aspartic Acid can improve sperm quality in infertile men [2]. The study found that sperm motility increased after 90 days of D-AA supplementation. It’s early days yet and ideally there would be a few more similar studies to back it up, but D-AA supplementation may be effective at helping couples conceive.

  1. D-Aspartic Acid and Testosterone

So what about testosterone then? Does D-AA really increase testosterone levels, or is it just another one of the hundreds of useless ingredients that supplement companies add to their natural testosterone boosting products?

When you look at journal articles regarding D-AA you find that there does seem to be a link between supplementation and increased testosterone in animals (rats) [3]. But the evidence that D-AA increases testosterone in humans is unreliable. Whilst one or two studies has seen an increase in testosterone production [4]. The majority have found no correlation, and some have even reported a lowering of testosterone.

The study by Melville, Siegler, and Marshall (2015) compared the effects of 3g of D-AA, 6g of D-AA and a placebo [5]. They found that there was no significant difference between 3g per day and the placebo, and that 6g per day actually resulted in a lowering of testosterone levels.

The study paired the supplementation with exercise, which may have influenced the results, because exercise temporarily increases testosterone levels. But this only shows that 6g of D-AA may have had an even worse effect on testosterone levels without exercise.

Conclusion: D-Aspartic Acid Has Mixed Reviews and Newest Studies Suggest it Doesn’t Work

At present there is nowhere near enough evidence to conclusively say that D-AA is ineffective as a testosterone boosting ingredient. However, there is even less evidence supporting the belief that D-AA has a positive effect on testosterone production.

The possible increase in male fertility is interesting, and potentially worth considering if you are struggling to have a child (though obviously consult your doctor before taking anything). But this does not mean that the testosterone levels on fertile men will be in any way effected.

The truth of the matter is that no “legal” testosterone booster will increase the testosterone levels of a guy who already has high testosterone. If you have very low testosterone then yes, some supplement ingredients can help bring your levels back up, but they won’t do that much unless you also focus on getting a good night’s sleep [6] or exercising regularly with free weights [7], or even just increasing the amount of animal fat in your diet [8].

The absolute best way to increase your testosterone levels naturally is to eat a high protein diet, increase your fat intake, lower your body fat percentage, and increase your muscle size. It’s interesting that natural testosterone boosters always talk about how increasing your t levels will lead to a better body. But in reality, getting a better body is a better way to increase testosterone. It’s like they’ve got it backwards!

If you’ve tried everything and you’re still worried that your testosterone levels are low, then consult your doctor. If you have a real problem then natural testosterone boosters aren’t going to cut it. In that case, you will probably be prescribed testosterone patches which will increase your testosterone at a safe dosage.


[1] Willoughby, D., Leutholtz, B. 2013. 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 hypothalamo-pituary-gonadal axis in resistance-trained men. Nutrition Research 33(10): 803-810

[2] D’Aniello, G., Ronsini, S., Notari, T., Grieco, N., Infante, V., D’Angel, N., Mascia, F., Fiore, M., Fischer, G., D’Aniello, A. 2012. D-Aspartate a key element for the improvement of sperm quality. Advances in Sexual Medicine 2(4): 45-53

[3] Roshanzamir, F., Safavi, S. 2017. The putative effects of D-Aspartic acid on blood testosterone levels: A systematic review. International Journal of Reproductive BioMedicine 15(1): 1-10

[4] Topo, E., Soricelli, A., D’Aniello, A., Ronsini, S., D’Aniello, G. 2009. The role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosterone in humans and rats. Reproductive Biology & Endocrinology 27(7): 120

[5] Melville, G., Siegler, J., Marshall, P. 2015. Three and six grams supplementation of d-aspartic acid in resistance trained men. Journal of the International Society of Sports Nutrition 1(12): 15

[6] Penev, P. 2007. Association between sleep and morning testosterone levels in older men. Sleep 30(4): 427-32

[7] Shaner, A., Vingren, J., Hatfield, D., Budnar, R., Duplanty, A., Hill, D. 2014. The Acute Hormonal response to free weight and machine weight resistance exercise. Journal of Strength & Conditioning Research 28(4): 1032-40

[8] Belanger, A., Locong, A., Noel, C., Cusan, L., Dupont, A., Prevost, J., Caron, S., Sevigny, J. 1989. Influence of diet on plasma steroid and sex plasma binding globulin levels in adult men. Journal of Steroid Biochemistry 32(6): 829-833

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