HMB Calcium and Free Acid

What are the Differences Between HMB Calcium and Free Acid?

Many customers increasingly recognize HMB for its benefits to muscles, endurance, and reducing excess fat in the body. However, this nutrient exists in two primary forms: HMB Calcium and Free Acid, leading to the question of which is better. What scientific studies exist to evidence the capabilities of these two compounds? Please refer to the following article.


What Does HMB Do for Your Body?

Beta-Hydroxy Beta-Methylbutyrate (HMB) is a metabolite of the amino acid Leucine - one of the three branched-chain amino acids playing a vital role in protein synthesis and muscle recovery.

Several studies have suggested HMB's ability to enhance exercise recovery by reducing skeletal muscle damage in athletes or individuals training at high intensities. Furthermore, when combined with a proper exercise regimen, HMB can significantly reduce body fat mass (FM) [1].

Other research indicates that HMB is effective in increasing lean body mass (LBM) and muscle strength in weight-training individuals [2] and also plays a significant part in developing endurance [3].

It has been observed that HMB also helps to increase the protein synthesis process in muscle tissues throughout part or all of the human body, laying the foundation for anti-catabolic and anabolic effects previously identified in individuals [4].

What are the Differences Between HMB Calcium and Free Acid?

differences between hmb and free acid

In reality, HMB exists in two primary forms. The most widely studied form is HMB Calcium (CaHMB), a monohydrate calcium salt compound combined with HMB to form a powder. Then there's HMB Free Acid, a pure, acid-free form of HMB in a gel/liquid state.

Research on the differences between HMB Calcium and Free Acid has shown that:

The absorption rate of HMB FA into the blood is faster compared to HMB CA, with HMB CA typically taking 60 - 120 minutes to reach peak blood levels [3].

In contrast, consuming HMB FA only takes about 30 minutes to achieve peak HMB levels in the blood [5][6][7].

The effect of stimulating muscle recovery after exercise from HMB FA is higher than that of HMB CA due to its better absorption, peak concentration, and clearance abilities [8].

Additionally, when comparing HMB FA versus HMB CA, HMB FA offers many more benefits such as:

  • Increasing endurance by more than 200% from training [9].
  • Enhancing muscle thickness by over 200% [9].
  • Increasing lean muscle mass by up to 250% [9].
  • Accelerating body fat loss up to 210% [9].
  • Improving high-intensity exercise recovery [10].
  • Enhancing aerobic metabolism [11].
  • Reducing muscle breakdown by up to 57% [12].
  • Increasing muscle protein synthesis rate by 70% [12].

What Science Says About the HMB Calcium and HMB Free Acid?

what science says about hmb calcium and free acid

Scientifically, few studies indicate the difference between HMB Calcium and HMB Free Acid or which compound is superior in bringing the most benefits overall.

However, numerous studies are affirming the benefits and capabilities of each type.

Research on the impact of HMB CA on the protein metabolism of skeletal muscle in eight healthy young men showed that despite proposed differences in bioavailability, HMB Ca provides comparable anabolic and anti-catabolic abilities to HMB FA [13].

Another study on the effects of HMB FA on muscle mass and strength in resistance-trained individuals showed a 23.5% increase in lean muscle mass when using HMB FA during training throughout 8 to 12 weeks.

It also reduced the response to overexertion and increased recovery strength for the subsequent phase [14].

A study published in 2017 showed that HMB FA effectively increased anabolic hormone concentrations and decreased catabolic hormones, thereby achieving significant increases in strength and endocrine levels after resistance training [15].

However, another study found no interaction between growth factor groups (insulin, growth hormone, cortisol) when using the Leucine metabolite over the observation period.

Therefore, they concluded that supplementation with HMB FA or HMB CA does not help improve muscle development and strength in young men [17].

Aside from benefits, what does science say about the side effects of HMB FA vs CA?

According to research published by Nutrabio in 2019, a daily supplementation routine of 3g of HMB is considered the best intake practice without safety concerns or side effects [16].

HMB Fa vs HMB Ca: Which HMB Is Better to Choose?

As analyzed above regarding the difference between HMB Calcium and Free Acid, it is apparent that HMB CA and HMB FA provide relatively similar benefits regarding muscle health, resistance, fat reduction, and muscle recovery after training.

However, HMB CA will have a lower absorption rate than HMB FA. At the same time, HMB FA offers more effective muscle gain, increased resistance, and better fat reduction than HMB CA [18].

A notable point is that despite HMB FA offering better outcomes than HMB CA, many customers prefer using HMB CA for their health training processes. This preference is due to HMB CA being more widely distributed and more accessible to purchase compared to HMB FA.

How Should You Take HMB Free Acid and HMB Calcium?

ways to take hmb calcium and hmb free acid

No research has shown results on combining HMB Calcium vs Free Acid supplementation.

However, based on the studies analyzed above, these two compounds offer equivalent health effects, differing only because HMB FA is better absorbed into the bloodstream than HMB CA.

Therefore, you may use each compound separately to achieve the desired effect.

For HMB-FA, a dosage of 1g 30 minutes before resistance training has been shown to increase growth hormone, testosterone, and insulin-like growth factor 1 (IGF-1) levels after exercise [18].

For HMB CA, many studies have safely conducted experiments with a 3g/day dosage, yielding effective results without any side effects [19]. When used at higher doses of 6g/day, HMB does not produce higher results; therefore, it's essential to choose a reasonable and cost-effective dosage [20].


Conclusion The article above provides information about the differences between HMB Calcium and Free Acid, as well as some benefits of HMB for health, studies related to these two compounds, and how to use them. Hopefully, with the above sharing, you have found helpful knowledge for yourself.


[1] Wilson, Jacob M, et al. “International Society of Sports Nutrition Position Stand: Beta-Hydroxy-Beta-Methylbutyrate (HMB).” Journal of the International Society of Sports Nutrition, vol. 10, no. 1, 2 Feb. 2013,
[2] Jówko, Ewa, et al. “Creatine and β-Hydroxy-β-Methylbutyrate (HMB) Additively Increase Lean Body Mass and Muscle Strength during a Weight-Training Program.” Nutrition, vol. 17, no. 7-8, July 2001, pp. 558–566,
[3] Panton, Lynn B, et al. “Nutritional Supplementation of the Leucine Metabolite β-Hydroxy-β-Methylbutyrate (Hmb) during Resistance Training.” Nutrition, vol. 16, no. 9, Sept. 2000, pp. 734–739,
[4] Wilkinson, D J, et al. “Effects of Leucine and Its Metabolite β-Hydroxy-β-Methylbutyrate on Human Skeletal Muscle Protein Metabolism.” The Journal of Physiology, vol. 591, no. 11, 2013, pp. 2911–23,,
[5] Fuller, John C., et al. “Free Acid Gel Form of β-Hydroxy-β-Methylbutyrate (HMB) Improves HMB Clearance from Plasma in Human Subjects Compared with the Calcium HMB Salt.” British Journal of Nutrition, vol. 105, no. 3, 7 Dec. 2010, pp. 367–372,
[6] Gonzalez, Adam M., et al. “Effects of β-Hydroxy-β-Methylbutyrate Free Acid and Cold Water Immersion on Post-Exercise Markers of Muscle Damage.” Amino Acids, vol. 46, no. 6, 18 Mar. 2014, pp. 1501–1511,
[7] ---. “Effects of Leucine and Its Metabolite β-Hydroxy-β-Methylbutyrate on Human Skeletal Muscle Protein Metabolism.” The Journal of Physiology, vol. 591, no. 11, 2013, pp. 2911–23,,
[9] Wilson, Jacob M., et al. “The Effects of 12 Weeks of Beta-Hydroxy-Beta-Methylbutyrate Free Acid Supplementation on Muscle Mass, Strength, and Power in Resistance-Trained Individuals: A Randomized, Double-Blind, Placebo-Controlled Study.” European Journal of Applied Physiology, vol. 114, no. 6, 6 Mar. 2014, pp. 1217–1227, Accessed 19 Aug. 2019.
[10] ---. “β-Hydroxy-β-Methylbutyrate Free Acid Reduces Markers of Exercise-Induced Muscle Damage and Improves Recovery in Resistance-Trained Men.” British Journal of Nutrition, vol. 110, no. 3, 3 Jan. 2013, pp. 538–544,
[12] ---. “Effects of Leucine and Its Metabolite β-Hydroxy-β-Methylbutyrate on Human Skeletal Muscle Protein Metabolism.” The Journal of Physiology, vol. 591, no. 11, 2013, pp. 2911–23,,
[13] Wilkinson, D.J., et al. “Impact of the Calcium Form of β-Hydroxy-β-Methylbutyrate upon Human Skeletal Muscle Protein Metabolism.” Clinical Nutrition, vol. 37, no. 6, Dec. 2018, pp. 2068–2075,
[14] Lowery, Ryan P., et al. “Interaction of Beta-Hydroxy-Beta-Methylbutyrate Free Acid and Adenosine Triphosphate on Muscle Mass, Strength, and Power in Resistance Trained Individuals.” Journal of Strength and Conditioning Research, vol. 30, no. 7, July 2016, pp. 1843–1854, Accessed 14 June 2020.
[15] Asadi, Abbas, et al. “Effects of β-Hydroxy-β-Methylbutyrate-Free Acid Supplementation on Strength, Power and Hormonal Adaptations Following Resistance Training.” Nutrients, vol. 9, no. 12, 2 Dec. 2017, p. 1316,
[16] “HMB: Uses, Benefits, Side Effects, and Dosage.” NutraBio Brands, 21 Mar. 2019, Accessed 29 Mar. 2024.
[17] Teixeira, Filipe J., et al. “Leucine Metabolites Do Not Enhance Training-Induced Performance or Muscle Thickness.” Medicine and Science in Sports and Exercise, vol. 51, no. 1, 1 Jan. 2019, pp. 56–64,,
[18] ---. “Effects of β-Hydroxy-β-Methylbutyrate-Free Acid Supplementation on Strength, Power and Hormonal Adaptations Following Resistance Training.” Nutrients, vol. 9, no. 12, 2 Dec. 2017, p. 1316, Accessed 19 Aug. 2019.
[19] Wilson, Gabriel J, et al. “Effects of Beta-Hydroxy-Beta-Methylbutyrate (HMB) on Exercise Performance and Body Composition across Varying Levels of Age, Sex, and Training Experience: A Review.” Nutrition & Metabolism, vol. 5, no. 1, 3 Jan. 2008,
[20] “December 2000 - Volume 32 - Issue 12 : Medicine & Science in Sports & Exercise.”,
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Ralph S. Albert, with over 10 years of expertise in nutrition and research, now heads the Research division at Vinatura Supplements. His dedication and extensive knowledge ensure top-quality articles on nutrition and health, collaborating with a skilled team. He has successfully completed The VINATURA Expertise Research Training Program, underscoring his commitment to Vinatura's mission. Ralph has also published numerous articles and conducted valuable research in the field, making him a trusted resource for individuals on their wellness journey.

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