Human muscles may seem simple, but they are actually quite complex. Food, dietary supplements, exercise, and illness all play a role in muscle building and breakdown. Researchers have begun to learn more about the many compounds involved in muscle health. One such compound is β-hydroxy-β-methylbutyrate, or HMB.
HMB is made in the liver from an amino acid called leucine. Leucine, one of the three essential branched-chain amino acids, is required in the human diet for its role in promoting protein synthesis. Scientists estimate that a 150lb human can make 0.2 to 0.4 g of HMB per day, depending on how much leucine comes into the body from diet. One way to ensure the body produces enough HMB is to eat leucine rich foods, such as meat and dairy products. Alternatively, it is possible to take a supplement that contains HMB.
HMB has many jobs at the cellular level that keep muscles working as they should. It plays a role in repairing tissue by increasing the production of cholesterol (required for cell wall stability) and boosting the production of muscle stem cells. The substance also protects muscle cells by blocking processes that cause muscle cell death. Finally, HMB promotes protein synthesis in muscles by activating enzymes needed to make muscle fibers.
Given its integral role in muscle health, HMB is naturally popular in athletic training circles. Many years of research have identified specific benefits while exercising. These include improved effects on muscle strength, reduction of muscle damage, aerobic performance, fatigue and muscle rebuilding. One meta-analysis showed that taking HMB supplements while doing resistance training two or more times a week for at least three weeks increased lean mass and strength. The specifics of this improvement seem to be relevant only to exercisers, as other research does not support the use of HMB as a supplement for more active athletes.
An additional area of research is HMB’s impact on muscle preservation in elderly populations. The same muscle-supporting properties relevant for athletes become muscle-rescuing properties among the elderly, as the body is less efficient at maintaining lean muscle mass in older age. An animal study showed that HMB levels in blood plasma decrease with age, and a meta-analysis showed that taking HMB may prevent the loss of lean body mass without a change in fat mass. This research indicates the elderly may benefit from HMB supplementation.
Perhaps most interesting is the use of HMB after surgery or trauma, when muscle loss is likely and recovery is critical. Researchers are hoping to understand how HMB can help, and early results are promising. One study done in Taiwan suggests that two to four weeks of HMB supplementation may preserve muscle in bed-ridden nursing home residents.
Other research highlights how HMB taken in combination with other amino acids may also be beneficial to muscle maintenance. For example, a study of wound healing in diabetic hemodialysis patients showed benefits of HMB, arginine and glutamine supplementation after four weeks of taking supplementation. Researchers found improvements in metrics related to pressure ulcer healing in a majority of study subjects. Another study evaluated the impact of HMB, vitamin D and protein supplementation in older female patients who recently suffered hip fractures and underwent orthopedic surgery. After one month of supplementation, comparison of the control group against the treatment group showed faster wound healing and increased muscle strength in the women who took the supplement.
Understanding HMB’s role in the body elucidates how it can be instrumental after surgery or other events that take a toll on muscles. In such cases, ensuring an adequate supply of dietary leucine or supplementing with HMB should be a part of the treatment discussion.
Beta‐hydroxy‐beta‐methylbutyrate supplementation and skeletal muscle in healthy and muscle‐wasting conditions, Journal of Cachexia, Sarcopenia and Muscle, 2017.
The effect of oral supplementation with a combination of beta-hydroxy-beta-methylbutyrate, arginine and glutamine on wound healing: a retrospective analysis of diabetic haemodialysis patients, BMC Nephrology, 2013.
Effect of β-hydroxy-β-methylbutyrate on protein metabolism in bed-ridden elderly receiving tube feeding, Asia Pacific Journal of Clinical Nutrition, 2010.
Effect of Calcium β‐Hydroxy‐β‐Methylbutyrate (CaHMB), Vitamin D, and Protein Supplementation on Postoperative Immobilization in Malnourished Older Adult Patients With Hip Fracture, Nutrition in Clinical Practice, 2016.