HMB and Vitamin D: Is There A Link?

When it comes to finding the right supplements for your stack, sometimes it can be pretty straightforward, while other times it can be a complete headache.

You’re looking for the perfect combination of things that will boost strength, endurance, power, and force production, while simultaneously supporting a faster and more efficient recovery.

It’s all about finding that balance, but there are a few supplements that are generally non-negotiable. That’s things like creatine, BCAAs (sometimes), protein, pre-workout, and more recently, HMB.

HMB isn’t new to the fitness supplement world by any stretch of the imagination, but for many people, it still isn’t on their radar.

And while it may not rev your metabolism like a fat burner, light up your focus like caffeine, or help you push for an extra few reps like creatine or beta-alanine, it does something that’s on par with all of those.

And the end result is more muscle mass and better performance, so how could you go wrong?

But right now, we’re talking about something that keeps popping up—HMB and vitamin D.

Some people suggest that vitamin D may enhance the benefits of HMB, so we’re getting to the bottom of it and giving you what you need to know about the link between HMB and vitamin D, and if there is one.

Let’s get to it.

What Is HMB And Why Should I Take It?

Like we said, HMB is anything but new to the fitness supplement market. It’s been around for a while but only recently are athletes, bodybuilders, and fitness enthusiasts catching on to the benefits that HMB offers to performance.

But what is HMB, and why is taking it a game-changer?

Beta-hydroxy-beta-methylbutyrate, more simply referred to as HMB, is a metabolic by-product of leucine breakdown.

And if you’ve ever heard anything about amino acids, you’ve likely heard about leucine—one of the most powerful stimulators of muscle protein synthesis and a staple for anyone looking for serious gains; it’s one of the three branched-chain amino acids that are known to support muscle growth.

HMB, along with alpha-ketoisocaproate (a-KIC), result from the breakdown of leucine.

However, why pure HMB supplementation has become so popular among athletes is because only 20% of dietary leucine is shunted towards the production of metabolites, and of that 20%, only about 5% actually makes it to HMB ¹.

So, the conversion rate is pretty inefficient, which means that if you’re taking in loads and loads of leucine, you’re not actually getting that much HMB.

By now, you’re probably wondering why HMB is so great…

When it comes to protecting your hard-earned muscle, HMB is where it’s at. It’s possibly one of the most powerful nutrition supplements for preventing muscle degradation under various conditions, including fasted training.

Although it elicits profound effects for people engaging in fasted training or training in a caloric deficit, HMB can offer muscle-protective effects for everyone.

That’s because HMB has been shown to stimulate muscle protein synthesis via the mammalian target of rapamycin (mTOR) pathway and prevent the breakdown of muscle.

Despite leucine having a more profound effect on MPS, HMB may still induce acute muscle anabolism via a distinct and/or additional mechanism to leucine ².

But studies also show that HMB may stimulate protein synthesis through the growth hormone/IGF‐1 axis, which results in positive effects for resistance-trained athletes, some of which include improvements in strength, body fat levels, and muscle mass, along with better anaerobic performance and power output ^{3, 4}.

However, you have to keep in mind that while HMB may have some powerful anti-catabolic effects for muscle, it doesn’t surpass its parent amino acid leucine for inducing muscle protein synthesis.

The Role Of Vitamin D In Athletic Performance

Athletic performance may not be something you think about when vitamin D comes to mind, but research shows that there may actually be a link.

Due to its widespread prevalence in the body, vitamin D plays an active and essential role in immune function, protein synthesis, muscle function, cardiovascular function, inflammatory response, cell growth, and musculoskeletal regulation ⁵.

And studies show that for athletes with a vitamin D deficiency, supplementation can result in increased muscle strength, along with a reduced rate of injury and better sports performance ⁵.

But how does the sunshine vitamin boost athletic performance?

Vitamin D elicits its action through two different pathways: Endocrine and autocrine mechanisms ^{6, 7}. The endocrine mechanism is what we know as the classic vitamin D action—calcium regulation. It increases intestinal calcium absorption and osteoclastic activity, thereby supporting bone growth, density, and remodeling.

When concentrations of vitamin D drop below a certain threshold, parathyroid hormone (PTH) increases bone resorption to meet the body’s demands for calcium.

As such, a vitamin D deficiency leads to increased bone turnover with an increased risk of bone injury, which is common for athletes participating in sports with high physical demands.

The other mechanism of vitamin D involves an autocrine pathway, and while it’s not as well known, it’s essential for a host of key metabolic processes, including signaling processes, expression and genetic response, hormone protein synthesis, immune/inflammatory response, and cell synthesis ⁵.

Vitamin D works as a modulator of over 2000 genes involved in cell growth, immune function, and protein synthesis, so maintaining adequate serum concentrations is of the utmost importance ^{7, 8}.

The autocrine function of vitamin D is also important for skeletal muscle function. The vitamin D receptor is present in nearly every body tissue and regulates the expression in hundreds of genes that perform essential bodily functions, including muscle tissue.

Its ability to modulate genes means it plays an important role in physiological functions like bone health, muscle function, inflammation, and immunity, all of which are important for health, training, and performance.

Is There A Link Between Vitamin D And HMB?

With all of that said, there’s no denying that both HMB and vitamin D play essential roles in training and performance, but what’s the link between the two of them—if any?

While several studies show the benefit of HMB on muscle mass, muscle strength, muscle function, and protein kinetics, what’s interesting is that some research indicates that the benefit of HMB on muscle strength may highly depend on circulating levels of vitamin D ⁹.

One study found that participants who had sufficient vitamin D3 levels showed significant improvements in muscle strength with HMB/Arg/Lys supplementation, whereas those who had insufficient levels did not show as much improvement.

Researchers from this study concluded that adequate vitamin D levels may be essential for achieving optimal benefits with HMB, and because vitamin D deficiency is so pervasive—upwards of 50% of adults have insufficient vitamin D levels—supplementation becomes critical.

However, it’s important to note that while studies show a link between performance improvements when using HMB combined with vitamin D, the majority of studies are conducted in older populations.

For example, a 2020 study looked at the effects of calcium β-hydroxy-β-methylbutyrate (HMB) and vitamin D3 (D) supplementation on muscle function and strength in older adults ¹⁰.

Over a period of 12 months, 117 adults over 60 participated in random treatments comprising: (a) control + no exercise, (b) HMB+D3 + no exercise, (c) control + exercise, and (d) HMB+D3 + exercise.

Results showed that HMB+D3 supplementation had a significant benefit on lean body mass for the non-exercise group at six months, as well as peak torque in leg exercises.

Researchers concluded that the combination of HMB + D3 may enhance muscle strength and physical functionality in older adults regardless of exercise regimens.

Final Thoughts

All in all, both HMB and vitamin D can be beneficial for your performance, and while they may not be a direct and obvious link between HMB + vitamin D supplementation in the general population or for athletes, there’s no denying what both have to offer.

So, regardless of age, research suggests that there may be some benefit for supplementing HMB with vitamin D, and even if it doesn’t improve the action of HMB, it’s doing your body loads of other favors, so dose up!