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science nutrition blog

science nutrition <strong>blog</strong>

 By Robert Schinetsky


Testosterone is the anabolic hormone that improves countless aspects of your health, fitness, and longevity. It gives you energy, enhances vigor, boosts libido, heightens mood, and supports muscle growth and fat loss. As men age, though, testosterone levels gradually decline with each passing year, and free testosterone levels decline more significantly than total testosterone. This fall in testosterone is believed to contribute to the declining mental and physical health of men across the lifespan.

It comes as little surprise why there is a massive market for dietary supplements that claim to help boost natural testosterone levels.

However, the overwhelming majority of products on the market are nothing more than woefully underdosed proprietary blends with little-to-no scientific backing. Basically, these products are an embarrassment, and they’re also a contributing factor to why so many individuals are skeptical about dietary supplements in general.

The good news is that there are a handful of supplements shown in human research to support healthy testosterone levels, which can yield further benefits such as increased muscle growth, greater strength, improved recovery, enhanced fat loss, and better sleep.

One standout ingredient that’s flown under the radar for many years is D-chiro-inositol (DCI). We’ll discuss the latest findings on DCI as well as highlight a few other of the best natural testosterone boosters (backed by science!).

The Power of D-Chiro-Inositol (DCI)

D-chiro-inositol (DCI) is an isomer of inositol -- a type of sugar that helps provide structure to your cells.

DCI is found predominantly in tissues that store glucose, such as the liver and skeletal muscles, as well as those involved in androgen production. It is a strong modulator of steroidogenesis and regulates various steroidogenic enzymes, including 17α-hydroxylase, 3β-hydroxysteroid dehydrogenase, and aromatase.[2]

Moreover, DCI also functions as a second messenger of insulin, which stimulates testosterone synthesis in Leydig cells.[3,4] These two actions alone make DCI worth further investigation!

A remarkable study published in 2021 found that men (average age: 37 years) receiving 500mg d-chiro-inositol twice daily (1 g/day) for 30 days experienced significant reductions in both estrone (-85%) and 17β-estradiol levels (−14.4%) and increases in testosterone (+23.4%), dehydroepiandrosterone (+13.8%) and epiandrosterone (+39%)![5]

Another research trial in older hypogonadal men (average age ~69 years old) consumed 600mg of DCI twice per day (1200mg, daily total) for 30 days. At the end of the month-long study, men receiving the 1,200mg d-chiro-inositol supplement demonstrated increased serum testosterone and androstenedione, and reduced oestradiol and oestrone.[39]

Most recently, a narrative review on DCI concluded that it “acts through a variety of mechanisms, acting as an insulin sensitizer, inhibiting the transcription of aromatase, in addition to modulating white adipose tissue/brown adipose tissue transdifferentiation.”[6].

To put it bluntly, DCI serves a number of alluring roles for men as it supports testosterone levels (by way of inhibiting aromatase and raising DHEA), insulin sensitivity & brown fat (fat-loss) thermogenesis. This makes it a “no-brainer” ingredient to seek out for aging men looking to build muscle, lose fat, and support cardiometabolic health.

Now, let’s turn our attention to another notable natural testosterone support supplement -- DHEA.

DHEA: Potent Testosterone Precursor

Dehydroepiandrosterone (DHEA) is one of the most abundant circulating steroids in the body and serves as an intermediary in the synthesis of testosterone.[7] Similar to testosterone, DHEA levels peak around age 30 and gradually decline with age (~2% per year)[8], thereby reducing recovery, muscle growth, and testosterone levels while increasing aging and muscle breakdown.

Other research finds an association between low DHEA and increased abdominal fat storage as well as a greater risk of cardiovascular disease.[9,10]

Fortunately, supplementing with DHEA has been found to benefit individuals looking to support DHEA levels, which in turn benefits testosterone levels!

Landmark research published in the European Journal of Applied Physiology found that men engaging in high-intensity training sessions who supplemented with 50mg of DHEA experienced greater increased free testosterone levels compared to high-intensity training alone[11]

Subsequent research in male athletes found that supplementing with 100mg DHEA for 4 weeks experienced significant increases in levels of DHEA and testosterone compared to placebo.[12]

DHEA has low androgenicity and does NOT negatively affect sex hormone-binding globulin (SHBG) or estrogen, in men or women.[13]

Keep in mind that DCI also helps to raise DHEA levels. This highlights the unique synergy that these two natural testosterone support ingredients exhibit when combined.

Other Noteworthy Natural Testosterone Support Supplements

DCI and DHEA are two exceptional natural testosterone boosting ingredients, but there are a handful of other beneficial nutrients to consider when seeking maximal testosterone support, beginning with:

  • Fenugreek: staple of Ayurveda that has been found in human research trials to inhibit aromatase and increase free testosterone levels.[14,15]
  • Eurycoma Longifolia (Longjack/Tongkat Ali): another Ayurvedic botanical traditionally used to boost libido. Human trials find that dosages between 100-400mg support increases in both free and total testosterone levels as well as muscle size and strength.[16,17,18,19]
  • Red Wine Polyphenols: regarded for their cardiovascular benefits, the polyphenols in grapes also are known to support free testosterone levels via a reduction of sex-hormone-binding globulin (SHBG).[20]
  • Vitamin D: plays a key role in testosterone production and deficiencies of the prohormone (which are quite common) are associated with lower T levels. Supplementing with Vitamin D3 may be effective for increasing testosterone levels (as much as 20%).[21,22] Other studies suggest that vitamin D supports testosterone levels by reducing in SHBG activity and aromatase expression, which helps limit the conversion of testosterone into estrogen.
  • Zinc: essential mineral involved in testosterone production, unfortunately deficiency is common, especially in highly active individuals. Supplementing with zinc may help to boost natural testosterone production.[23]
  • Boron: trace mineral involved in numerous physiological processes. Research demonstrates that supplementation with 10mg of boron per day for seven days may increase free testosterone up to 28% and decrease estrogen levels by 39%![24] Boron can also help reduce levels of SHBG, thereby leading to more free testosterone.

Test Boosters That Don't Work!

As we mentioned at the outset, the vast majority of natural testosterone boosters on the market contain a collection of underdosed and ineffective ingredients. Here are some of the more notorious ingredients you’ll find on supplement facts panels. These ingredients lack substantial amounts of evidence to warrant their inclusion in supplements sold to support natural testosterone levels.

  • D-Aspartic Acid (DAA): some research indicates that DAA may provide a small, transient boost in testosterone levels with effects subsiding after 4 weeks of continuous use. However, other studies find that DAA supplementation will lead to a significant drop in both free and total testosterone levels.[25,26]
  • Fadogia Agrestis: catapulted into the limelight be influencers and notable podcast hosts, fadogia agrestis is only supported by SIX studies in rats. There are NO human studies as of this publication. Extrapolating the doses used in rats to humans means an individual needs to consume between 1000-4500mg per day to potentially derive benefit. Most supplements on the market that contain fadogia do not contain near-enough of the ingredient.
  • Tribulus Terrestris: sold under the guise of a “Soviet secret”, tribulus was hypothesized to mimic the actions of luteinizing hormone (LH) and stimulate testosterone release in the testes. However, the pro-testosterone benefits of tribulus have not been successfully replicated in humans. Numerous well-controlled studies have found that tribulus has no effect on strength, body composition, or testosterone![27,28,29]
  • I3C & DIM: Indole-3-carbinol (I3C) is a compound found in cruciferous vegetables (broccoli, kale, collard greens, etc.) and can be broken down into diindolylmethane (DIM) in the body. In small amounts, I3C and DIM can affect estrogen metabolism and activity and may inhibit the aromatase enzyme.[30,31,32] However, taking too much DIM can actually increase aromatase enzyme functioning and result in greater estrogen synthesis and activity.[33]
  • Maca Root: known as “Peruvian ginseng”, maca is regarded for its libido and adaptogenic propert The current body of evidence indicates that maca DOES NOT increase testosterone levels or any other other hormones which impact testosterone production, including follicle-stimulating hormone (FSH) and luteinizing hormone (LH).[34,35,36]
  • Saw Palmetto: Frequently sold as a supplement for prostate health and testosterone enhancement, but well-designed studies show that saw palmetto does not improve measures of urinary flow or prostate size.[37,38]

The Best Testosterone Boosting “Hack”

Truth be told, there is no “hack” for boosting testosterone (or anything else related to the human body, for that matter).

The key to supporting natural testosterone production across the lifespan is a combination of regular exercise (especially intense exercise like resistance training), a healthy diet, quality sleep, and stress management.

When it comes to diet, we’re particularly fond of the Mediterranean Diet which is rich in monounsaturated fats as well as a small amount of saturated fats, both of which support testosterone levels. Plus, monounsaturated fats offer greater health promoting and cardioprotective benefits compared to other dietary fats.

For added natural testosterone support, we’ve eliminated the guesswork by creating a powerful stack in AML Test and AML DCI Test Booster, which deliver 50mg DHEA and 1,200mg DCI -- the same dosages used in human research studies!

For best results, we recommend taking a serving of AML Test and AML DCI Test Booster prior to training as this will work in combination with your intense workouts to support healthy testosterone levels.


† These statements have not been evaluated by the Food and Drug administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

© Published by Advanced Research Media, Inc. 2024
Reprinted with permission from Advanced Research Media, Inc.



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