Is LJ100® Safe? Weighing the Benefits and Risks of Tongkat Ali (Longjack)

Eurycoma longifolia, commonly known as tongkat ali or longjack, is a tall and slender, shrubby tree. It's native to parts of southeastern Asia, where it's one of the most well-known herbal folk medicines for treating various disorders and diseases, such as sexual dysfunction, diabetes, and cancer, among others.

Today, LJ100® — a patented supplemental form of Tongkat ali extract — has become increasingly popular, particularly as a testosterone booster. (The acronym LJ refers to "longjack.") As such, LJ100® is an integral component of Transparent Labs Vitality.

However, if you have thought about trying the extract, you might wonder whether it's safe or has any adverse effects.

This article explains everything you need to know about LJ100, including whether it's safe and its potential benefits for men's health.

Understanding LJ100®

LJ100®, also known as Physta®, is a patented form of Eurycoma longifolia/Tongkat ali root extract. It's standardized to contain 22% eurypeptides and 40% glycosaponins by mass.

While the extract contains rich sources of various classes of bioactive compounds, eurypeptides and glycosaponins are the most important since they exert most of tongkat ali's effects.

You can find LJ100 alone as a dietary supplement ingredient or combined alongside other ingredients that are typically marketed as testosterone boosters.

Most supplements provide the extract in a dose of 100 mg per serving, while other products provide up to 600 mg per serving.

Because data indicate that LJ100 may increase testosterone levels and improve sexual function, most LJ100-containing supplements are formulated to support men's health.

Is LJ100® Safe?

Because LJ100 has the potential to influence hormones — namely, testosterone levels — you may question its safety, among other reasons.

Safety studies in rodents have suggested that tongkat ali extracts are well-tolerated, even in high doses, but may harm the liver (1). However, clinical studies in humans have found no effect on the liver or kidney function with Tongkat ali supplementation, but minor side effects like digestive symptoms and itching have been reported with a dosage of 200-600 mg per day (2).

There is a lack of safety data in children, pregnant and lactating women, and men with prostate cancer and other chronic conditions like diabetes or heart disease, so supplementation with LJ100 or other tongkat ali extract-containing supplements is discouraged in these populations (3, 4).

In a small trial, women who were supplemented with 400 mg of tongkat ali for five weeks experienced significant increases in total and free testosterone. However, it's unknown whether this increase would be great enough to produce male characteristics such as vocal deepening or increased growth of body hair in women (5).

The increase in free testosterone — a better measure of testosterone status — was likely due to a decline in the hormone that binds testosterone called sex hormone-binding globulin.

Tongkat ali can also interfere with the effectiveness of propranolol, a common medication prescribed for blood pressure, so it's best to check with your doctor if you use this medication — or others — before taking LJ100.

Benefits of LJ100® Tongkat Ali

Several clinical trials have suggested that LJ100 increases testosterone levels and improves male fertility, sexual desire, and mood.

May Increase Testosterone Levels

Hypogonadism (low testosterone) affects up to 13% of middle-aged and older men, but the prevalence is increasing (2).

Low testosterone levels can reduce energy levels and sex drive, increase body fat, and lead to a depressed mood.

TRT or testosterone replacement therapy involves taking testosterone — usually as an injection — and is effective in restoring healthy levels, but the treatment can be costly and have adverse side effects in some people.

For this reason, men may prefer presumably safer alternatives, such as supplements promoted to increase testosterone, like LJ100 and KSM-66 ashwagandha.

LJ100 also appeals to men who may have normal testosterone levels but want to increase their levels to gain more muscle mass or improve sports performance.

However, a review of five studies — most of which used LJ100 — found that compared with the placebo group, the extract significantly improved total testosterone levels in men with and without low testosterone when supplemented at 100–600 mg per day for one to 24 weeks (2).

However, the low number of studies and differences in study designs among the trials warrant caution in interpreting these findings.

In either case, Tongkat ali is believed to increase testosterone by decreasing its conversion to estrogen and increasing the production of pregnenolone, a compound necessary for testosterone production (6).

May Improve Muscle Strength

Owing to its potential testosterone-boosting effects, LJ100 may improve muscle strength, power, and body composition.

In one study, young men who were supplemented with 600 mg per day of LJ100 experienced increases in total and free testosterone after two weeks.

The researchers suggest these increases in testosterone could translate to gains in muscle and strength (7).

However, other studies suggest that LJ100 may not impact exercise performance.

For example, one study found that well-trained rugby plays who supplemented with 400 mg per day of LJ100 for seven days experienced no improvements in exercise performance (8).

It's possible that no effect was found due to the short treatment period and well-trained status of the rugby players.

Well-trained participants are less likely to experience benefits from interventions like supplements than participants with some or no training experience.

Conversely, a different study demonstrated significant increases on a test used to measure quadriceps — or front thigh — muscle strength in middle-aged men with low testosterone who were supplemented with 200 mg of LJ100 and exercised three times weekly for six months (9).

May Improve Male Fertility

While fertility issues are commonly believed to be a women's issue only, men contribute to 50% of infertility cases overall (10).

Male infertility is associated with various factors related to hormones, namely testosterone and sperm quality, which refers to the sperm's ability to fertilize.

Research suggests that LJ100 may improve male fertility by increasing testosterone, improving sperm quality, and improving erectile function.

To this point, one study found that men with infertility due to an unknown cause experienced significant improvements in various measures of sperm quality, such as sperm count, motility, and morphology or shape, after supplementing with 200 mg of tongkat ali extract for nine months (11).

This improvement in sperm quality led to spontaneous pregnancies in 11 of the 75 participants.

LJ100 supplementation has also been shown to improve erectile dysfunction in men with low testosterone when supplemented with 200 mg for six months (12).

The improvement in erectile function was greater when the men exercised at least three times weekly.

Erectile dysfunction does not directly impact fertility, but it can make it more difficult for a couple to conceive.

While also not directly affecting fertility, Tongkat ali can also improve erectile performance and sexual desire and satisfaction (13).

May Improve Mood State

Tongkat ali extract offers adaptogenic properties, meaning it enhances the body's ability to adapt to stress and anxiety.

Through nonspecific ways, supplementing with tongkat ali may positively affect stress hormones and improve mood.

In one study involving moderately stressed subjects, daily supplementation with 200 mg of LJ100 for four weeks improved stress hormone profile and certain mood parameters, including tension, anger, and confusion (14).

These results suggest that Tongkat ali may be useful for shielding the body from the detrimental effects of chronic stress, including the stress of dieting, sleep deprivation, and training.

Should you try LJ100?

Based on the available evidence, LJ100 may increase testosterone, especially in men with low levels.

As a result of increased testosterone, among other reasons, LJ100 may increase muscle size and strength and improve male fertility and mood states.

Therefore, if you have one or more of these goals, LJ100 may be worth a try, especially since it's well-tolerated and safe at commonly supplemented doses (200 – 600 mg/day).

However, the long-term safety and efficacy of LJ100 remain largely unknown. Due to the lack of studies in men with chronic health conditions, it's best to talk with your medical doctor before trying LJ100, especially if you take any medications.

Studies on the effects of LJ100 in women are scarce, but one study indicated increased testosterone levels as a result of supplementation. It's unknown whether women would benefit from its other potential effects on fertility or mood state.

If you compete in natural bodybuilding or drug-tested sports, research suggests that supplementing with Tongkat ali — despite its potential testosterone-boosting effect — won't result in a failed drug test, at least when supplemented at a dose of 400 mg per day for up to six weeks (15).

This is because supplementation with the herb does not increase the ratio of testosterone to epitestosterone, which would suggest the use of testosterone or other anabolic steroid.

As a standardized extract, LJ100 has high quality and purity, but there are still risks due to adulteration or the presence of other ingredients with LJ100 that could result in a positive test.

In either case, in choosing a LJ100 supplement, look for brands that have undergone third-party testing so you know that you're getting what's on the label and nothing more or less.

FAQ – Frequently Asked Questions about LJ100

What are the potential side effects of Eurycoma longifolia supplements?

Eurycoma longifolia extract supplements are generally well-tolerated, but some people have reported digestive symptoms and itching with its use.

Can Tongkat Ali supplements be harmful?

Tongkat ali extract supplements — especially LJ100 — have a strong safety profile, but it's best to talk with your doctor before trying it if you a have a chronic health condition or take any medications.

What is the recommended dosage for Tongkat Ali supplements?

Based on the available scientific evidence, the recommended dose for tongkat ali root extract as LJ100 is 100 - 600 mg per day for increasing testosterone, and 200 - 400 mg for improving sexual function or mood.

Do Tongkat Ali supplements have any benefits for women?

There is a lack of data assessing the effects of tongkat ali supplements in women, but one study showed an increase in testosterone with supplementation. Additional studies are necessary to determine whether tongkat ali supplements affect fertility, sexual function, or mood in women.

What are the potential benefits of LJ100 supplements?

Supplementing with LJ100 in the recommended dose may increase testosterone levels, especially in men with low levels, muscle size and strength, sexual function and fertility, and enhance the body's resistance to moderate stress.

Can LJ100 supplements increase testosterone levels?

While more research is necessary, there are data to indicate supplementing with LJ100 can increase testosterone in both men and women.

The Bottom Line on LJ100 (Tongkat ali)

LJ100® is a standardized extract of tongkat ali root with high purity and potency. Dozens of clinical trials have demonstrated increases in testosterone, especially in men with low levels, muscle size and strength, male fertility, and mood states.

An effective dose of LJ100® extract is 100 – 600 mg daily for increasing testosterone, while 200 – 400 mg seems to be most effective for improving sexual function and mood. LJ100® is also well-tolerated and likely safe when used in the doses and treatment duration used in clinical trials.

Transparent Labs LJ100® capsules contain 100 mg of LJ100® per capsule for versatile dosing adjustments.

As always, it's best to talk with your medical provider before taking the extract if you have a chronic health condition like diabetes or heart disease, or you take medications. It's largely unknown whether women can benefit from LJ100 or will experience any adverse outcomes due to the lack of data.