Most of the alleged health benefits of tongkat ali are not well researched, but some studies suggest that it may help treat male infertility, improve mood, and increase muscle mass.

May increase testosterone levels and improve male fertility

Tongkat ali’s potential to increase testosterone in men with low levels of this primary sex hormone is well known and well documented.

Low testosterone can result from aging, chemotherapy, radiation treatments, some medications, injury or infection of the testicles, and certain diseases, such as chronic alcoholism and obstructive sleep apnea.

Effects of inadequate testosterone levels include low libido, erectile dysfunction, and in some cases, infertility. Since compounds in tongkat ali may boost low testosterone, it could treat these issues.

A 1-month study in 76 older men with low testosterone found that taking 200 mg of tongkat ali extract per day significantly increased levels of this hormone to normal values in over 90% of participants.

What’s more, studies in both animals and humans show that taking tongkat ali stimulates sexual arousal and may improve erectile dysfunction in men.

Finally, tongkat ali may improve sperm motility and concentration, boosting male fertility.

One study in 75 male partners of couples with infertility found that taking 200 mg of tongkat ali extract per day significantly improved sperm concentration and motility after 3 months. The treatment helped over 14% of couples become pregnant.

Similarly, a 12-week study in 108 men ages 30–55 observed that taking 300 mg of tongkat ali extract daily increased sperm volume and motility by an average of 18% and 44%, respectively.

According to these studies, tongkat ali effectively treats low testosterone and infertility in some men, but more extensive research is needed.

May relieve stress

Tongkat ali may lower stress hormones in your body, decrease anxiety, and improve mood.

A 1999 study first identified the possible role of this remedy in treating mood issues and found that tongkat ali extract was comparable to a common anti-anxiety medication in reducing symptoms of anxiety in mice.

Similar effects have been seen in humans, but research is limited.

A 1-month study in 63 adults with moderate stress found that supplementing with 200 mg of tongkat ali extract per day reduced levels of the stress hormone cortisol in saliva by 16%, compared to those who received a placebo.

Participants also reported significantly less stress, anger, and tension after taking tongkat ali.

While these results are promising, more studies in humans are needed.

May improve body composition

Tongkat ali is often claimed to boost athletic performance and increase muscle mass.

This is because it contains compounds called quassinoids, including eurycomaoside, eurycolactone, and eurycomanone, which may help your body use energy more efficiently, reduce fatigue, and improve endurance.

In other words, the supplement may act as an ergogenic aid, which is a substance that can enhance physical performance and improve body composition.

A small, 5-week study in 14 men participating in a strength training program found that those who took 100 mg of tongkat ali extract per day experienced significantly greater increases in lean body mass than those taking a placebo.

They also lost more fat than participants in the placebo group.

What’s more, a 5-week study in 25 active older adults discovered that supplementing with 400 mg of tongkat ali extract daily significantly increased muscular strength, compared to a placebo.

However, a small study in cyclists observed that consuming a drink with tongkat ali during exercise did not improve performance or strength any more than plain water .

These conflicting results suggest that tongkat ali may exhibit some ergogenic effects, depending on the dose and length of treatment, but more research is needed.