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Sports Nutrition

Do the D

Testosterone. Test. The Big T. Whatever you call it, testosterone is universally known as the male hormone. It gives men bigger, leaner muscles, greater strength, more body hair, deeper voices and, of course, their sex drive. If you’re a man with suboptimal levels of testosterone, you will notice a deleterious difference in several of the above qualities — less muscle mass and strength, more body fat and reduced sex drive.

The problem with testosterone is that many things can work to lower it. The first is time. Most guys’ test levels peak in their early to mid-20s. By the time you’ve hit 30, your testosterone levels have already taken a slight hit, and it gets worse every year thereafter. Then there’s the stress of work, school, personal commitments. That can all add up to raise cortisol levels and decrease testosterone levels. Top that off with lack of sleep, a lot of alcohol, parabens from toiletries and even exposure to gasoline, and you should be surprised that your body is actually making any T.

The good news is that there are several natural testosterone-boosting ingredients out there that can help kick test levels back up a bit. In this article, we discuss the amino acid D-aspartic acid, also known as D-aspartate.

D-Aspartic Acid D-tails
Like arginine or glutamine, aspartic acid is an amino acid, and as such, it’s used to build proteins in the body. However, the only form of amino acids that the body recognizes for building proteins is the L (left-handed or levorotatory, which refers to the configuration of the molecule) form, such as L-arginine, L-glutamine, L-leucine and L-aspartic acid.

The other configuration that amino acids can be in is the D (right-handed or dextrorotatory) form. Most D-amino acids are not recognized by the body, yet D-aspartic acid is. D-aspartic acid is formed when the enzyme aspartate racemase converts L-aspartic acid into D-aspartic acid. This usually occurs in the testicles, pituitary gland and nerve cells. It’s this D-form of aspartic acid that has testosterone-boosting properties.

Anabolic Actions
When D-aspartic acid is produced in the pituitary gland of the brain, it appears to stimulate the release of luteinizing hormone. LH is then released into the bloodstream and travels to the testicles, where it encourages the production of testosterone.

When D-aspartic acid is produced inside the testicles, it acts on Leydig cells, special cells inside the testicles that produce testosterone. This appears to work through DAA’s ability to increase levels of the nucleotide cyclic AMP, which is a cellular messenger that acts to boost testosterone production. The amino acid also works to increase sperm production.

The Research
Most of the research that uncovered D-aspartic acid’s effects and how it works has been done in animals. However, Italian scientists did study the effects of DAA supplementation in men 27 to 37 years old. Every morning for 12 days, 43 men took either 3 grams of D-aspartate along with the B vitamins B-6, B-12 and folic acid or a placebo, which contained just the B vitamins without the D-aspartate. The researchers reported in a 2009 issue of the journal Reproductive Biology and Endocrinology that the subjects taking the D-aspartate supplement increased their LH levels by more than 30 percent and subsequently their testosterone levels by more than 40 percent as compared to the guys getting just the B-vitamin placebo.

Because the Italian study showed results from taking 3 grams of D-aspartate per day, most D-aspartate products supply that much per dose. We recommend going with 3 grams per day, as well. That dose not only is supported in the clinical study, but anecdotal reports also now further support that dose for improving testosterone levels. Although the clinical study supplied all 3 grams of D-aspartic acid in one pill, you can try splitting it throughout the day into two or three doses. Some guys report that D-aspartate supplements irritate their stomachs in a way similar to creatine before it was micronized. Taking smaller doses more frequently throughout the day may help to avoid these stomach issues while still providing testosterone-boosting benefits.

It is recommended to cycle most testosterone boosters because of what is known as a negative-feedback loop. In other words, when you increase testosterone levels, the higher levels influence the brain to lower LH levels, which eventually results in lower testosterone levels. You can try several different cycles with D-aspartate. The simplest is taking it for eight weeks and then stopping for four weeks before repeating. Another option is to take it for two weeks and stop for one week and cycle it in that fashion.

However, if you are a woman, you should not take D-aspartic acid at all. It will not increase testosterone levels in women because women obviously do not have testicles. An increase in LH results in an altogether different effect in women. Namely, it triggers ovulation. Falsely raising LH levels can interfere with the menstrual cycle.