Athletes and fitness enthusiasts are constantly seeking strategies to optimize their performance. While a balanced diet and regular exercise form the bedrock of physical fitness, certain supplements can provide an added advantage. Among these, Hydroxymethylbutyrate (HMB) and Vitamin D have garnered significant attention for their potential to enhance muscle health and overall well-being, especially in older adults. This article aims to provide a comprehensive overview of HMB and Vitamin D, exploring their individual benefits, synergistic effects, and practical recommendations for supplementation.
Understanding HMB
HMB, short for beta-hydroxy beta-methylbutyric acid, is a naturally occurring substance produced in the body during the breakdown of leucine, an essential branched-chain amino acid (BCAA) crucial for protein synthesis and muscle repair. Since the body produces HMB only in small quantities, dietary supplements are often used to increase HMB levels.
How HMB Works
HMB plays a vital role in regulating protein metabolism within the body. Given that muscles are primarily composed of protein, HMB can contribute to building muscle mass and preventing muscle loss. It exerts powerful effects on increasing lean body mass and strength during exercise.
Potential Benefits of HMB Supplementation
Studies suggest that HMB supplementation may offer several benefits, including:
- Increased Muscle Growth: Research indicates that HMB may promote muscle growth and strength, particularly in untrained individuals and older adults. A 2024 study found that HMB supplementation might help people with sarcopenia, a type of age-related muscle loss, though the evidence was limited. And a 2022 meta-analysis of nine studies also found benefits for older adults.
- Reduced Muscle Breakdown: HMB may help reduce muscle breakdown by suppressing genes and enzymes that promote the breakdown of muscle proteins. An analysis of 15 studies involving 2,137 participants with health conditions that promote muscle loss found that taking 3 to 4 grams of HMB daily for 7 days to 6 months was significantly more effective than a placebo at preventing muscle loss.
- Improved Exercise Adaptations: HMB could improve adaptations to exercise. A 2015 study of 16 elite rowers found that taking 3 grams of HMB daily over 12 weeks significantly increased aerobic exercise capacity and peak anaerobic power, and helped reduce body fat, compared with a placebo.
- Quicker Muscle Recovery: HMB may contribute to faster muscle recovery and reduced muscle damage after exercise.
- Other Potential Benefits: Some studies suggest that HMB may improve cognitive function with aging (though only in animal studies) and reduce inflammatory markers, such as after cancer surgery.
The Importance of Vitamin D
Vitamin D is a crucial nutrient that plays numerous roles in maintaining overall health, including supporting muscle function. In addition to its many other roles, vitamin D is essential for healthy muscle function. It is prudent not to assume our levels are normal without having a serum 25-hydroxyvitamin D blood test.
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Vitamin D and Muscle Health
Sufficient vitamin D levels are needed to maintain optimal athletic performance. Higher Vitamin D levels are associated with greater strength and superior muscle function, especially in older adults.
Vitamin D Deficiency
A large percentage of the population has insufficient vitamin D levels.
The Synergistic Effect of HMB and Vitamin D
Research suggests that combining HMB with Vitamin D may offer synergistic benefits, particularly for muscle health. A 2020 study published in the Journal of Gerontology Medicine Sciences looked at the effect of HMB supplementation combined with vitamin D on muscle strength in adults over 60 with low vitamin D status.
Enhanced Muscle Strength and Function
Studies have found that older adults taking HMB with vitamin D may have seen increased muscle strength - even without an exercise routine. A year-long randomised, double-blind, placebo-controlled study indicates that the combination of HMB and vitamin D3 improves muscle function in older adults, even without exercise.
Improved Physical Functionality
A study demonstrated the potential of long-term [intake] with calcium HMB and vitamin D3 to enhance physical functionality and muscle strength in older adults, even in individuals not engaged in a resistance exercise training program.
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Maintaining Muscle Size
HMB and vitamin D supplementation was evidenced to maintain muscle size in sedentary conditions, and to decrease IMAT in middle-aged women with vitamin D3 sufficiency, independent of exercise.
Research Findings: A Deeper Dive
Several studies have investigated the combined effects of HMB and Vitamin D on muscle health and physical function.
Iowa State University Study
A double-blinded, controlled study enrolled 117 men and women aged 60 years and older who had insufficient vitamin D levels of 15-30 nanograms per milliliter (ng/mL). Sixty-four subjects were assigned to a three day per week resistance training program for one year while the remainder did not participate in the program. The exercise and non-exercise groups were further divided to receive either a 3,000 milligram HMB plus 2,000 international units of vitamin D daily intervention, in a divided dose, or a placebo, over the course of the one-year trial.
Key Findings:
- Serum vitamin D levels improved over the course of the study in HMB and vitamin D participants.
- At three months, knee extension peak torque (a measure of muscular strength) was greater among participants who received HMB and vitamin D than the placebo groups, with a significant effect observed among those who did not engage in resistance exercise.
- At six months, increases in lean body mass were similar among exercisers who received HMB plus vitamin D and exercisers who received a placebo, while among non-exercisers, lean body mass was significantly greater among HMB and vitamin D participants compared to the placebo group.
- A composite functional index improved to a similar extent among HMB and vitamin D and placebo group exercisers, while among non-exercisers, only the HMB and vitamin D group experienced a significant improvement.
- The improvements seen in the composite functional index in the HMB and vitamin D non-exercisers were comparable to those seen in the exercising groups.
Additional Research
- A previous year-long, placebo-controlled study of HMB found it increased lean body mass in adults over age 65 but didn’t appear to improve strength. Because 70% of those study participants had insufficient vitamin D levels, researchers performed a retrospective analysis and found that only those who had sufficient vitamin D3 levels saw an increase in strength with HMB.
- In the recently published study, 117 healthy adults ages 60 and older were assigned to take HMB and a vitamin D3 or a placebo supplement. In each group, half of the subjects participated in a mild resistance training program, while the other half did not exercise.
- The results indicated that HMB’s long-term functional benefits are fully realized among older adults when there is sufficient vitamin D3 present.
- Among non-exercisers, participants taking HMB+D experienced greater improvements in physical function and tended to have greater increases in strength than did participants taking the placebo supplement, and they sustained this improvement over one year.
- Combining HMB+D and moderate resistance training did not provide any further benefit over either exercise or HMB+D alone.
Practical Recommendations for HMB and Vitamin D Supplementation
When considering HMB and Vitamin D supplementation, it's essential to follow these guidelines:
Dosage
- HMB: Although there’s no standardized dosage for HMB, most studies have used 3 grams per day. A 2019 review recommends that dosage for 3 to 4 weeks for competitive athletes.
- Vitamin D: Vitamin D supplementation should be guided by blood test results to achieve optimal levels in the body.
Safety and Side Effects
HMB appears to be generally safe in standard doses of 3 grams daily. In rare cases, people may experience stomach pain, constipation, or itching while taking HMB. Researchers have not studied the safety of long-term use of HMB.
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Consultation with a Healthcare Professional
As with any dietary supplement, it’s important to speak with a healthcare professional before taking HMB or Vitamin D, especially if you are on medications or have preexisting health conditions.
Additional Considerations
Protein Intake
Muscles are mainly composed of protein. Adequate protein intake is an essential component of human nutrition; however, many individuals fail to consume an optimal amount. Vegetarians and vegans, people recovering from surgery, bodybuilders and other athletes are among those who may need to give special attention to their protein intake.
Age-Related Muscle Loss
It’s important to preserve muscle mass throughout our lives to help maintain mobility and the ability to perform the activities of daily living. Older individuals in particular, who are at risk of aging-associated muscle loss (sarcopenia), may benefit from supplementing with HMB.3