HMB

Hydroxymethylbutyrate (HMB)

Athletes and fitness enthusiasts are always looking for ways to improve their performance.

And while the right combination of diet and exercise can help fuel that performance, certain supplements may offer additional benefits.

HMB, short for beta-hydroxy beta-methylbutyrate, is a popular dietary supplement that has gained a lot of interest in the health and fitness community for its potential to aid muscle growth and exercise performance.

This article explains what HMB is and outlines its potential benefits. It also provides information on its safety and other recommendations.

What is HMB?

HMB is a substance that your body produces naturally.

It has a few different names, depending on the version of the molecule. It is also known as beta-hydroxy beta-methylbutyric acid, beta-hydroxy beta-methylbutyrate, and hydroxymethylbutyrate.

It’s made when your body breaks down leucine, a branched-chain amino acid (BCAA) that’s essential for protein synthesis and muscle repair).

However, your body only produces HMB in small amounts. So, many people take it as a dietary supplement to increase HMB levels in their body.

Studies have linked taking HMB supplements to certain benefits, such as increased exercise performance, reduced muscle breakdown, and increased muscle growth in untrained and older adults.

HMB is widely available from supplement stores, health food stores, and online. It comes in various forms, such as capsule, tablet, and powder.

Benefits of HMB

Studies have found that taking HMB may be associated with numerous benefits, especially in the area of body composition. These include increased muscle growth and reduced muscle breakdown.

While quite a few studies have examined the impact of HMB, additional research is needed to fully understand its effects in various populations.

Here are some of the promising benefits of taking HMB.

May aid muscle growth in certain people

Companies commonly market HMB as a supplement that aids muscle growth. However, research on HMB in this area shows mixed results and is inconclusive.

Older studies, from the early 2000s and before, have found that it may help in certain populations.

These studies looked at the effects of HMB in untrained individuals and older people. Those who combined taking HMB with doing resistance training experienced more muscle growth than those who did resistance training alone.

In addition, a review of 7 studies in 287 older adults looked at the effects of taking 2–3 grams of HMB daily over periods ranging from 8 weeks to 12 months.

Participants who took HMB gained an average of 0.78 pounds (0.35 kg) more muscle than those who received a placebo supplement.

However, other studies have found that HMB didn’t influence muscle growth.

For example, a review of 10 studies looked at the effects of HMB in 384 adults ages 50 and over.

It found that combining HMB supplements with physical exercise had little to no effect on changing body composition, strength, or exercise performance, compared with exercise alone.

One analysis of 6 studies in 193 participants found it may not improve these factors for trained and competitive athletes, either.

It found that when athletes took 3–6 grams of HMB daily for a period of 3 days to 12 weeks, they experienced no increases in strength or changes body composition.

In short, research on HMB and muscle growth shows mixed results. However, some research shows this supplement may benefit muscle growth for untrained individuals and older people.

May help reduce muscle breakdown

Research suggests HMB may help reduce muscle breakdown.

Test-tube studies suggest that HMB may help prevent muscle breakdown in various ways inside cells, such as by suppressing genes and enzymes that promote the breakdown of muscle proteins.

An analysis of 15 studies looked at the effects of taking HMB in 2,137 people. These participants had health conditions that promote muscle loss, such as cancer, HIV, kidney failure, and malnutrition.

The analysis found that taking 3–4 grams of HMB daily over a period of 7 days to 6 months was significantly more effective at preventing muscle loss than a placebo.

Similarly, other studies in older people have shown that taking HMB can help preserve muscle mass during periods of bed rest.

However, scientists need to do more research on HMB and its potential protective effects against muscle breakdown in a wider variety of participants, such as young people and healthy adults, before recommending it for this purpose.

May aid exercise adaptations

Some research has indicated that HMB could improve adaptations to exercise. This refers to a longer-term change rather than an immediate one.

For example, a 12-week study in 16 elite rowers found that taking 3 grams of HMB daily significantly increased aerobic exercise capacity and peak anaerobic power, and helped reduce body fat, compared with a placebo.

Anaerobic power refers to the maximum power you can produce during high-intensity exercise.

Similarly, another 12-week study in 42 combat sports athletes found that taking 3 grams of HMB daily significantly increased both aerobic and anaerobic exercise capacity, compared with a placebo.

Other studies in athletes and healthy adults have shown that taking 3 grams of HMB daily has similar effects on aerobic and anaerobic capacity.

Other potential benefits

Studies have associated HMB with several other benefits. However, there are fewer studies or weaker evidence to support these.

That’s why more research is needed on the potential benefits below before experts can understand them comprehensively and make recommendations.

A review of 9 studies in 254 participants looked at the effects of taking 1–3 grams of HMB daily in addition to a regular weightlifting program.

Participants experienced significantly reduced markers of muscle damage and better recovery.

Research from animal studies suggests HMB may help reduce age-related mental decline. However, scientists need to study these effects in humans.

Several test-tube and human studies have shown that taking HMB ay reduce inflammatory markers, such as TNF-α, IL-8, and INFγ.

A 4-week study in 11 people with diabetes who were on dialysis found that taking a supplement containing HMB along with arginine and glutamine significantly improved wound healing.

An older review of 9 studies found that taking 3 grams of HMB daily significantly lowered total cholesterol, LDL (bad) cholesterol, and systolic blood pressure compared with taking a placebo.

Systolic blood pressure is the upper number on a blood pressure reading.

However, it’s unclear whether HMB, exercise, or both were responsible for these effects.

More, higher quality research is needed to look into this further.