Many people
are looking for a natural way to boost testosterone.
Testosterone
is a well-known hormone responsible for muscle building and libido.
Therefore,
people of all ages are looking for natural ways to increase this hormone.
A
popular approach is to take dietary supplements that claim to boost
testosterone. These products typically contain the amino acid d-aspartic acid.
This
article explains what d-aspartic acid is and whether it increases testosterone.
What is d-aspartic acid?
Amino
acids are molecules that have multiple functions in the body. They are
components of all types of proteins as well as certain hormones and
neurotransmitters.
Almost
every amino acid can appear in two different forms. For example, aspartic acid
may be found as L-aspartic acid or D-aspartic acid. These forms have the same
chemical formula, but their molecular structure is a mirror image of each other
(1).
Therefore,
the l and d types of amino acids are often considered "left-handed"
or "right-handed".
L-Aspartic
acid is produced in nature, including in your body, for the construction of
proteins. However, D-aspartic acid is not used to build proteins. Instead, it
plays a role in the body's manufacture and release of hormones (1, 2, 3).
D-aspartic
acid can increase the release of hormones in the brain, ultimately leading to
the production of testosterone. (2）。
It also
plays a role in increasing the production and release of testosterone in the
testicles (3, 4).
These features are why D-aspartic acid is popular in testosterone-boosting supplements (5).
Summary: Aspartic
acid is an amino acid that exists in two forms. A d-aspartic acid is a form
involved in the production and release of testosterone in the body. Because of
this, it is often found in supplements that promote testosterone.
Effects on testosterone
Studies
on the effects of d-aspartic acid on testosterone levels have yielded different
results. Some studies have shown that d-aspartic acid can increase
testosterone, while others have not.
One
study of healthy men aged 27 to 37 years examined the effects of taking
D-aspartate supplements for 12 days (6).
The
results found that at the end of the study, 20 of the 23 men who took
d-aspartate had higher testosterone levels, an average increase of 42%.
Three
days after they stopped taking supplements, their testosterone levels were
still 22 percent higher on average than at the start of the study.
Another
study of overweight and obese men taking D-aspartate for 28 days reported
different results. Some men do not have an increase in testosterone. However,
those with low testosterone levels at the start of the study experienced more
than a 20% increase (7).
Another
study examined the effects of taking these supplements for more than a month.
Researchers found that when men aged 27-43 took D-aspartate supplements for 90
days, their testosterone increased by 30-60% (8).
These
studies did not specifically use people who were physically active. However,
three other studies did examine the effects of d-aspartic acid on active men.
One
study found no increase in testosterone in young adult men who underwent weight
training and took D-aspartate for 28 days. (5）。
What's
more, another study found that taking 6 grams of high-dose supplements daily
for two weeks actually lowered testosterone in young men who underwent weight
training (9).
However,
a follow-up study of 6 grams per day for three months showed no change in
testosterone (10).
There
are no similar studies on women, possibly because some of the effects of
D-aspartic acid are specific to the testicles. (4）。
Wraparound: D-aspartic
acid may increase testosterone in inactive men or men with low testosterone.
However, it has not been proven that it can improve the weight training of
testosterone in men.
It does not improve the response to exercise
Several
studies have examined whether d-aspartic acid improves response to exercise,
particularly weight training.
Some
people think it may increase muscle or strength due to elevated testosterone
levels.
However,
studies have shown that men who underwent weight training did not increase
testosterone, strength, or muscle mass after taking D-aspartate supplements. (5, 9, 10）。
One
study found that after 28 days of D-aspartic acid and weight training, men
gained 2.9 pounds (1.3 kg) in lean weight. However, the placebo group gained 3
pounds (1.4 kg) of weight (5).
What's
more, both groups had similar increases in muscle strength. Therefore, in this
study, d-aspartic acid was no better than placebo.
A
three-month long-term study also found that men who exercised had the same
increase in muscle mass and strength, whether they took D-aspartic acid or a
placebo. (10）。
Both
studies concluded that d-aspartic acid is not effective in increasing muscle
mass or strength when combined with a weight-training program.
There
is currently no information on combining these supplements with other forms of
exercise, such as running or high-intensity interval training (HIIT).
Wraparound: D-aspartic
acid does not appear to improve muscle or strength gains when combined with
weight training. There is currently no information on the effects of using
D-aspartic acid with other forms of exercise.
D-aspartic acid may
increase fertility
Despite
limited research available, d-aspartic acid shows promise as a tool to help
infertile men.
A study
of 60 men with fertility problems found that taking D-aspartate supplements for
three months significantly increased the sperm count they produced (8).
What's
more, the motility of their sperm, or its ability to move, has improved.
These
improvements in sperm count and quality seem to have paid off. During the study
period, the pregnancy rate of male partners taking d-aspartate increased. In
fact, 27% of partners became pregnant during the study period.
Although
most of the research on D-aspartic acid has focused on men because of its
effects on testosterone, it may also play a role in ovulation in women. (11）。
Summary: Although
more research is needed, D-aspartic acid may improve the quantity and quality
of sperm in infertile men.
Is there a recommended
dosage?
Most studies examining the effects of
D-aspartic acid on testosterone use doses of 2.6-3 grams per day (5, 6, 7, 8, 9).
As mentioned
earlier, studies have shown mixed results for its effects on testosterone.
Doses
of about 3 grams per day are effective in some young and middle-aged men who
may be inactive. (6, 7, 8)。
However,
the same dose is not effective for inactive young men (5, 9).
A
higher dose of 6 grams per day was used in two studies, but there were no
satisfactory results.
While a
brief study showed that using this dose lowered testosterone, longer studies
showed no change (9, 10).
Studies
reporting the beneficial effects of D-aspartic acid on sperm count and quality
used a dose of 2.6 grams per day for 90 days (8).
Wraparound: The
typical dose of D-aspartic acid is 3 g per day. However, studies using this
amount produced different results. Based on existing studies, a higher dose of
6 grams per day appears to be ineffective.
Side effects and safety
In a
study that examined the effects of taking 2.6 grams of D-aspartic acid daily
for 90 days, researchers conducted in-depth blood tests to check for any
undesirable side effects (8).
They
found no safety issues and concluded that the supplement was safe to consume
for at least 90 days.
On the
other hand, another study found that two out of 10 men taking D-aspartic acid
reported irritability, headaches, and nervousness. However, one male in the
placebo group also reported these effects (5).
Most
studies using d-aspartate supplements did not report on the occurrence of side
effects.
Therefore,
more research may be needed to confirm its safety.
Summary:
There is limited information about any potential side effects of
D-aspartic acid. One study showed no safety issues based on blood analysis
after 90 days of supplementation, but another study reported some subjective
side effects.
Conclusion
Many
people are looking for a natural way to boost testosterone.
Some
studies have shown that consuming 3 grams of d-aspartic acid per day can
increase testosterone in young and middle-aged men.
However,
other studies of active men have failed to show any increase in testosterone,
muscle mass, or strength.
There
is evidence that d-aspartic acid may benefit sperm count and quality in men
experiencing fertility problems.
While
it may be safe to consume for up to 90 days, there is limited safety
information available.
Overall,
more research is needed before d-aspartic acid is highly recommended for
testosterone boosting.