Purus Labs positions D-Pol as a “Natural Hormone Amplifier” which derives its test-boosting ability from D-Aspartic Acid…[Skip to the Bottom Line]
Out of the three human studies done specifically to test the effect of D-Aspartic Acid on Testosterone, two have shown a significant increase in Testosterone levels and one has failed to do so.
A 2012 study from “Advances in Sexual Medicine”, the subjects of which were infertile men (initially low Testosterone) found that 2.66g of D-Aspartic Acid was able to significantly increase Testosterone levels when measured after 90 days of supplementation. These results were in-line with those of an earlier (2009) study in which D-Aspartic Acid supplementation raised Testosterone by 42% after 12 days in healthy men (initially normal Testosterone).
However, a 2013 study published in “Nutrition Research” found that athletes who supplemented with D-Aspartic Acid for 28 days showed no difference in testosterone levels.
The researchers in the failed study noted abnormally high levels of D-aspartate oxidase, the enzyme which degrades D-Aspartic Acid, indicating that prolonged supplementation in individuals with healthy Testosterone levels may cause “negative feedback” which reduces the effects.
Ultimately, D-Aspartic acid is an effective short-term Test-booster for healthy individuals with initially normal Testosterone levels, but the effects may fade after a few weeks of supplementation. Those individuals with abnormally low Testosterone levels may benefit from longer term supplementation however. D-Pol contains 3.12g of D-Aspartic Acid per serving, precisely in-line with the doses shown to boost Testosterone in the short-term. It’s worth noting that D-Aspartic Acid is the only ingredient in D-Pol that can outright boost Testosterone levels above normal (albeit for a short time), so when Purus Labs states “42% increase in Testosterone”, this accomplished solely by D-Aspartic Acid.
Purus Labs utilizes two forms of Nitrate, Beetroot and Nitratene. Beets are naturally very high in Nitrates whereas Nitratene is simply pure Sodium Nitrate. For all intents and purposes, these two ingredients provide the same function.
A 2007 study from “Acta Physiologica” found that dietary Nitrate supplementation increased the efficiency of oxygen utilization during exercise (less oxygen needed for the same amount of work). These results were replicated in a 2011 study, published in “Journal of Applied Physiology”, which found that this increased efficiency resulted in better endurance in runners.
A 2012 study, published in “Journal of the Academy of Nutrition and Dietetics”, found that increased dietary nitrate intake (in the form of Nitrate-rich whole Beetroot) improved running performance in healthy adults.
A 2013 study, published in the “European Journal of Applied Physiology”, found that Nitrate supplementation (from beetroot juice) effectively elevated plasma Nitrate levels which translated to improved performance during high-intensity exercise in athletes.
A 2013 Meta-Analysis, which looked specifically at 17 separate studies using doses of 300-600mg Nitrate from various sources, concluded that supplementation is associated with a moderate improvement in time to exhaustion at a given work load.
Purus Labs discloses that D-Pol contains 480mg of Nitrates per serving, a highly effective dose according to the existing research. Just as DAA is the only ingredient capable of boosting Testosterone, Nitratene is the only ingredient in D-Pol capable of boosting Nitric Oxide, though it tends to be quite effective at doing so.
Studies investigating the relationship of Vitamin D to Testosterone have found a strong correlation between adequate levels of Vitamin D and normal Testosterone levels, indicating that Vitamin D plays a role in normalizing Testosterone. However, when looking at the research as a whole, nowhere is there an indication that excess Vitamin D supplementation may result in above normal Testosterone levels. Individuals who receive the proper amount of Vitamin D, either from direct sunlight or through supplementation, will not experience increases in Testosterone as a result of excess Vitamin D consumption.
THE BOTTOM LINE:
D-Pol is a concise blend of DAA, Nitrates, Vitamin Bs, and Vitamin D. DAA can raise Testosterone in the short term (a few weeks), but the effects are not likely to last. Nitrates are, of course, moderately effective at Nitric Oxide levels and conveying the associated benefits. Vitamin Bs and D will not provide any noticeable benefits in non-deficient individuals, but may simply help to encourage optimal Testosterone production. At about 80 cents per serving, D-Pol is more or less appropriately priced, though given it could be pretty easily reconstructed for slightly less, we wouldn’t consider it much of a bargain.
- Topo, Enza, et al. “The role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosterone in humans and rats.” Reprod Biol Endocrinol 7.120 (2009): 6.
- D’Aniello, Autimo, Anna Di Cosmo, Carlo Di Cristo, Lucio Annunziato, Leonard Petrucelli, and George Fisher. “Involvement of D-Aspartic Acid in the Synthesis of Testosterone in Rat Testes.” Life Sciences 59.2 (1996): 97-104.
- D’Aniello, Gemma, et al. “d-Aspartate, a key element for the improvement of sperm quality.” Advances in Sexual Medicine 2 (2012): 45.
- Willoughby, Darryn S., and Brian Leutholtz. “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-pituitary-gonadal axis in resistance-trained men.” Nutrition Research 33.10 (2013): 803-810.
- Larsen, F. J., et al. “Effects of dietary nitrate on oxygen cost during exercise.”Acta physiologica 191.1 (2007): 59-66.
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- Larsen, Filip J., et al. “Dietary nitrate reduces maximal oxygen consumption while maintaining work performance in maximal exercise.” Free Radical Biology and Medicine 48.2 (2010): 342-347.
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- Hoon, Matthew W., et al. “The effect of nitrate supplementation on exercise performance in healthy individuals: a systematic review and meta-analysis.”International Journal of Sport Nutrition & Exercise Metabolism 23.5 (2013).
- Bailey, Stephen J., et al. “Dietary nitrate supplementation reduces the O2 cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans.” Journal of Applied Physiology 107.4 (2009): 1144-1155.