We review the scientific literature on testosterone boosting compounds and make it simple to understand. Walking you through how ingredients in popular testosterone booster supplements work, or don't and which if any natural testosterone boosters can actually deliver on the promises they make.
Medical science has come a long way in the last decade, and perhaps it comes as no surprise that a large part of the research has been focused around ways to fight or delay aging, that means finding ways to maintain delay declining hormone levels, or for men, a testosterone booster. Men's health in particularly is wildly effected by declining testosterone levels as we age, and with men's free testosterone levels dropping 2% ever year after 30 , this can rapidly become an issue. Testosterone production has become increasingly understood, however there are still areas where the science isn't quite complete thanks to external stressors playing such a large role in periodical fluctuations it can be a complex region to study. One of the many things we do know for sure is that the modern wester lifestyle is not good for testosterone production. The population at large has seen a decline in average testosterone levels of the average person this has also interestingly been around 1% year on year, meaning a 40 year old man born in 1982 will on average have 10% less free testosterone than a 40 year old man born in 1972 would have had in 2012 . This has also been corroborated by big data trends monitoring healthy testosterone levels (between 10 to 35 nanomoles per liter) provided by a national level healthcare provider.  As such, the world has been on the look out for an organic testosterone booster, that does not have the side effects, or permanent reliance associated with traditional hormone therapies.
This has lead to computational and clinical experimentation with everything from plant compounds, through minerals and even in some cases ground up pearls as scientists have seen fit to sift through every old wives tale in search of something that actually works and can be replicated.
This level of research, may initially sound rather drastic, but, it should come as no surprise seeing as declining testosterone production causes substantial issues for both the individual and the population at large. Resulting in declining fertility rates, increase in obesity, and plays a part in the current mental health crisis. And on an individual level, the results can be even more disastrous, with men falling into spirals of weight gain, stress, poor sleep all of which lower testosterone further, perpetuating a destructive cycle. When this is considered it's no wonder that we've looked everywhere possible for an effective testosterone booster.
This is perhaps a more complex question than you'd initially think. The answer is both yes and no. Or rather some do, some compounds look promising, and there are also a lot of charlatans selling snake oil rather than anything that even resembles a testosterone booster. There are a few compounds that show replicable results in raising testosterone naturally. So, let's start by covering the science that has actually been applied in human trials and successfully replicated before we start claiming that there are natural extracts that can boost testosterone levels naturally.
Ashwagandha - The most well known trial for Ashwagandha was performed in New Zeeland in 2018, participants were given 300mg of Ashwagandha and later a placebo and visa versa, levels notably raised during after supplementation and later dropped when supplementation was discontinued cementing it's example use as a testosterone booster. The participants were shown to have significantly higher levels of DHEA-S (T37 = 2.97, p = .005) and testosterone (T36 = 2.74, p = .010) during ashwagandha supplementation, in contrast to the placebo period (18.0% and 14.7%, respectively).  This study has since been replicated multiple times with varying dosages of the herb. It seems that the ideal dosage sits at 300mg, which is what we look for when looking for the best pre blended testosterone booster. The herb has also been shown to reduce cortisol levels (the stress chemical) although the significance level of these seems to vary between trials.
Vitamin D - Vitamin D supplementation has been the most significant of all natural testosterone boosters, and the most replicated. There are several core reasons for this. The first is that in the English speaking northern hemisphere, almost half of the adult population is vitamin D deficient, USA at 41%  the UK at 30%  and Canada showing between 70 and 97% deficiency rates.  The UK's relatively low deficiency level by contrast can be put down to the common practice of fortifying foods with Vitamin D in the country. Vitamin D3 is a precursor to 6 different steroid hormones  meaning it is required to facilitate their natural production in the body. As a result deficient men will produce testosterone at a lower rate, making vitamin D an effective testosterone booster for a huge portion of the population. Similar evidence has been displayed in Denmark and other countries. Beyond this, Vitamin D has a compounding effect. When tested humans were able to tolerate supplementation of up to 5000mg and still show consistent improvements in athleticism in otherwise healthy men . The exact nature of quite how impactful Vitamin D3 is still up for discussion and based on it's potential to improve athletic performance outside of testosterone levels. And as increasing active performance results in an increase in lean muscle mass, this in turn leads to higher testosterone production in those using vitamin d3 within testosterone supplements.
Zinc - Zinc's usage only applies in cases of deficiency, however, trials showed significant increases in serum testosterone levels. Particularly in cases of males suffering with low testosterone. Fortunately Zinc deficiency is not as common place as the Vitamin D3 counterpart. However, Zinc supplementation of even mildly zinc deficient men for six months resulted in an improvement to in serum testosterone from 8.3 +/- 6.3 to 16.0 +/- 4.4 nmol/L.  To put this simply, correctly even a mild zinc deficiency in men resulted in boosting testosterone production by 100% and reducing estrogen levels. The overall increase of free testosterone (the effective testosterone) was almost six fold. going from 2nmol/L to nearly 12nmol. This is the difference between incredibly low testosterone and being within a normal healthy range. As a result a lot of the best testosterone boosters work by correcting these common dietary issues. What we'll look for in the best testosterone booster supplements is simply that they contain enough zinc to ensure minimal recommend daily intake is met. The reason for this is that on males who meet their recommended zinc intake studies have shown no improvement to free or overall testosterone levels. 
DAA - D Aspartic Acid is perhaps one of the most interesting elements of supplementation in testosterone boosters. Testosterone supplements regularly make use of the amino acid. The core reasoning behind that is DAA is used in the biosynthesis of testosterone and protein synthesis . As a result of it's part in the production of lean muscle mass, it is most popular in products marketed as testosterone boosters for muscle. Interestingly the three most well known and replicated studies on the amino acid almost show conflicting results. The main variance of these two studies was the dosage. In untrained sedentary men with low testosterone, levels of testosterone were significantly increased by 42% (4.5–6.4 ng.ml−1) with 3 grams of supplementation . Conversely dosages of 6g daily resulted in significant decreases in total serum testosterone levels in both trained and untrained men . Trained men also responded positively to 3g daily of supplementation, with average increases across the group being (7.96 nmols/L) around a 50% increase to the groups baseline.  Several further tests have been conducted and ideal seems to be below 3g daily, however the exact ideal dosage is currently undetermined, it likely ranges between 1600mg and 2500mg based on current research. We will be looking for a testosterone booster that sits between these two numbers.
Ginseng - Panax Ginseng, and it does specifically have to be Panax Ginseng, does produce positive effects. American Ginseng however, does not, as a result it is seemed that the subspecies of Ginseng is an essential consideration when utilizing the herb as a testosterone booster. Ginsenosides (the active ingredient in ginseng vary between these subspecies and even by age, so this is not an unexpected development) . Panax ginseng supplementation has been shown to raise testosterone levels in both men  and women  with even more extreme results being demonstrated in older trial participants  with overall studies showing increases of around 60% in total testosterone and 50% increases in participants.
Both American and Panax Ginseng resulted in libido increase in animal studies with increased mounting behaviours , but this behaviour did not occur when only supplemented with isolated ginenosides, suggesting that there may well be another effect in Ginseng which is responsible for it's libido effect in humans . Specifically supplementation of Ginsenoside Rg1  has resulted in improvements to complete copulation. Whilst this is not something that has any testosterone related, libido concerns are commonly an issue of note for men seeking a testosterone booster so it bares mentioning. This is likely due to the effect that Ginsenosides have been shown to have on GABA receptors (the receptors responsible for fast synaptic transmission between the brain and nervous system), further study is required for complete understanding. Ideal supplementation seems between 100-150mg depending on body weight.
Luteolin - The flavonoid Luteolin has several roles in the production of testosterone. As such it's another common ingredient in testosterone boosters. It has the effect of blocking aromatase the enzyme which converts testosterone into estrogen in men . It also plays a part in the direct production of testosterone inside leydig cells . There are limited clinical trials of Luteolin as a testosterone booster, there are many for it's improvements to nootropic areas of memory, mental degradation conditions etc . That said, the cellular and computational studies are robust enough to suggest that Luteolin is effective at improving testosterone production and with it's proven bioavailability (ability for supplementation to be absorbed by humans) in other studies it should be effective. However, the ideal dosage is not currently known, however based on it's bioavailability it is expected to be somewhere in the region of 100mg.
Boron - Boron has a number of beneficial effects on the body’s use of estrogen, testosterone, vitamin D and magnesium absorption. It also protects against pesticide and heavy metal toxicity. Most studies suggest that the majority of the benefits can be achieved with supplementation of more than 3mg/day. 
Fenugreek - Fenugreek contains several flavonoids and steroidal saponins as well as vitamin and mineral complexes. It has been repeatedly clinically trialled to the point where it's efficacy for boosting testosterone seems to be in no doubt . The question around fenugreek as a testosterone booster is only which compounds are responsible for it's effects. The most well cited double blind clinical trial showed that Fenugreek extract supplementation of 100mg resulted in a notable increase testosterone production with an increase in free testosterone levels around 1.5nmol/l.  This does make it one of the least effective testosterone boosters on our top ingredients list, however, it is a this point confirmed to be effective. It is also seen to be well tolerated at higher levels with compounding effects  with the ideal dosages being around 600mg resulting in increases around 6nmol/L, after that point returns were diminishing. As a result we'll be looking for testosterone supplements with doses around this level.
Maca - Recent studies into Maca (Lepidium meyenii) have noted its efficacy at reducing cortisol (the stress hormone) build up and it has been shown to improve sexual function and desire in self report studies.  Cortisol build up has a direct implication in the reduction of testosterone production , so reducing stress improves testosterone levels. This is a secondary tangential benefit to other testosterone boosting supplements such as ashwagandha . Maca also has direct impact on free testosterone by reducing serum estridol levels , Maca showed no statistical difference in increases when dosed at 1500mg and 3000mg , meaning that the ideal dosage for testosterone supplements is likely around 1500mg.
Magnesium - Studies have repeatedly shown that magnesium supplementation improves overall testosterone levels within men with and without deficiencies.  However, the increases are higher in men who undertake large volumes of athletic activity. 
Bioperine - This black pepper extract is common place in testosterone boosters, it is not directly related to improved testosterone levels, however, it does improve bioavailability of the other ingredients, improving your body's ability to absorb them .
B Vitamins - B Vitamins are directly required for the body to produce testosterone. Whilst the deficiency would result in low testosterone levels, most people's diets contain enough of the vitamins . B12 in particular has a large role in overall testicular health . B vitamins are typically more important in energy production  which is beneficial in terms of weight loss and increasing muscle mass, which in turn can raise testosterone levels. With a weight loss of around 9% resulting in 2.87nmol in obese participants. 
Vitamin K or K2 - Vitamin K deficiency has been shown to result in lowered testosterone production . However, deficiency is relatively rare and whilst supplementation of vitamin K and it's more bioavailable counterpart K2 has been shown to boost testosterone levels naturally in animal studies  there have currently been no studies in healthy humans. It is known however to play an overall part in testicular health, but it's role is currently poorly understood, there is no harm in supplementing this and we do expect a good testosterone booster to cover all the essential vitamin and mineral cases.
Pre made testosterone booster supplements are currently available on the open market. These over the counter testosterone boosters are available for anyone to purchase. There is a lot of variety and most on the market have no scientific backing, in fact when 50 testosterone boosters we tested only 25% of the products actually worked, with 10% resulting in decreased testosterone levels. Fortunately the ones we have chosen to list were not amongst the failing products. Further trials are being conducted by Center TRT  with initial results looking positive for all of the testosterone boosters on our list.
Prime Male hits almost all of the most effective ingredients for testosterone boosters and in the ideal dosages. The supplement created by Roar Ambition has been on the market for the best part of a decade and they've updated the formula multiple times to keep up to date with scientific data. It promises to deliver an increase in testosterone levels, and based on the information available we believe that they should be more than capable. We would highly recommend this as the first choice option for men looking to boost testosterone naturally. Beyond that, we would expect that it should benefit athletic performance, although it's primary function is an all round testosterone booster.
We do also personally test any products we recommend although the evidence is anecdotal. We did note improved athletic performance after 30 days of supplementation, with max repetition ranges increasing by around 10-15% in 2 trained individuals and 35% in 2 untrained. All team members also noted improved mood, focus and no side effects. Our testosterone levels had also shown a notable increase of between 14-36%, but it should be noted all team members were within healthy levels and between the ages of 27-42. Verified customer reviews of the product also claim that the testosterone boosters are effective. However, this can not be used as an unbiased scoring factor. Visit Primemale.com
Prime Male contains the essential vitamins for testosterone boosters, Vitamin D3, Zinc, Magnesium, K2 with added B6 to assist with energy levels overall (all dosed for optimal levels, there is an argument for perhaps slightly higher vitamin D3, but 500% of the RDI is more than enough). The most interesting element is the blend of D Aspartic Acid (dosed at the lower end of the ideal range), Panax Ginseng (dosed ideally), Ashwaganda (dosed ideally), Luteolin (dosed within the ideal range). It also contains BioPerine and Boron again dosed within the ideal ranges for testosterone production. An argument could be made for the addition of Fenugreek. However, Prime Male serving sizes are currently 4 capsules per day, and as it is well studied people are unlikely to take more than 4 capsules a day and the addition of Fenugreek would require an additional capsule. Due to the ease and relative inexpensively, if this was a concern simply purchasing fenugreek capsules as well as Prime Male would be a better option.
Prime Male is functionally the ideal testosterone booster as far as the science goes and with it's serving size and costs in mind. We recommend this option as the go to testosterone booster supplements for anyone looking to try testosterone boosters whether that's for muscle gain, overall health, or healthy aging.
Testofuel is largely marketed towards being a work out focused testosterone booster. It will certainly aid in healthy testosterone production and has a wide range of celebrity endorsements, particularly amongst the body building community, with anecdotal evidence from several former Mr Olympia title winners like Robby Robinson. Much like Prime Male, Testofuel has been a mainstay in the testosterone supplements market and have had multiple formula reviews in line with updates to research. By comparison to the top pick for best testosterone boosters there isn't a great deal of difference in the formula, aside from the inclusion of Fenugreek and Maca over Ashwagandha. And their Oyster extract, which is for the most part a bit of a gimmick. Maca has a larger impact on sexual function than on testosterone itself, although it does also have some benefit. Fenugreek however, is particularly effective. It also contains a slightly higher amount of DAA, although this difference is negligible. Ultimately the choice between the two comes down Maca and Fenugreek v Ashwagandha. The latter has been shown to have increased effect as a testosterone booster in older populations , whereas several Fenugreek studies have shown it to be more effective as a supplement for "trained males". 
As with Prime Male we personally tested Testofuel, and it did boost testosterone production across our relatively small sample size. The increases we between 21-28% in total free testosterone levels, it should be noted that none of our team suffers with low testosterone. Customer reviews of Testofuel are positive with many claiming that they're the best testosterone boosters they've tried.
Testofuel covers all the bases that we would expect from a testosterone booster focused on athletic performance. Including the highest dosage of Vitamin D tested in humans for increased athletic performance and fenugreek. The inclusion of Maca whilst good, is more beneficial for erectile dysfunction and sexual function which is more common in individuals with lower body fat percentages. Along with these, which all fall within the ideal dosage ranges mentioned earlier it also contains the essential vitamins and minerals required for healthy testosterone production. Testofuel's serving size is also 4 capsules a day and whilst we have not experienced any side effects, there are some complaints of nausea by verified customers who took them on an empty stomach, which is to be expected from almost any supplement.
Our tests, along with the critical information we have available and verified purchases all claim that Testofuel has been effective all show TestoFuel in an incredibly positive light. It is certainly one of the best testosterone booster supplements on the market. We don't recommend many products in this field. Currently our list sits at only 2, with us seeking to add 2 more in the near future once our tests are finished. The parent company has a good reputation, the product is good, they seem to honor their money back guarantee to boost testosterone levels or give you a refund. The only downside to TestoFuel is that it is a relatively expensive supplement, but bulk deals do make it far more afforable.
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