HYDROXY-BETA-METHYLBUTYRATE

What is hydroxy-beta-methylbutyrate?

Hydroxy-beta-methylbutyrate, or HMB, is a substance made during the body’s breakdown of the amino acid leucine [^[1]].

What does hydroxy-beta-methylbutyrate do in the body?

HMB has many roles in the body. It is involved in forming proteins from amino acids, insulin activity, increase and growth of muscle cells, and stem cell growth and specialization into mature cells, among other functions [^[2]].

HMB reduces muscle damage from exercise, strengthens muscle, improves aerobic performance, and heightens fatigue resistance. In older people, HMB can reduce sarcopenia, or the loss of muscle and strength that occurs when people get older and exercise less. Optimal effects of HMB in older people occur with oral supplementation in conjunction with exercise [^[1]].

In frail older people, HMB supplementation helps reduce the decline of muscle mass and preserve muscle function, especially for older patients who are in hospital stays [^[2]].

HMB may regulate the immune and inflammatory responses, especially under stress. It was found to exhibit anti-inflammatory effects, protect against muscle breakdown, and improve pulmonary function in patients in the intensive care unit for chronic obstructive pulmonary disease [^[2]].

How can hydroxy-beta-methylbutyrate help alleviate certain Long COVID symptoms and pathophysiology? 

HMB’s role in supporting muscle mass, its immune and anti-inflammatory properties, and its effects on physiology affected by COVID-19 make it useful for people dealing with Long COVID. HMB may also potentially affect the brain and cognition [^[2]].

Butyrates such as HMB may be linked to chronic fatigue disease through “good” intestinal bacteria in the gut-brain axis [^[3]]. Since symptoms in chronic fatigue and Long COVID overlap, HMB may play a similar role for long-haulers, though more evidence is needed.