The October 15, 2020 issue of the Journals of Gerontology Series A: Biological Sciences and Medical Sciences published findings from a recent randomized trial that revealed improvements in muscle strength and function in association with calcium beta-hydroxy-beta-methylbutyrate (HMB) and vitamin D3 intake among older men and women.

HMB is a metabolite of the amino acid leucine that has been found to support muscle strength and function in several studies. Vitamin D, while involved in numerous physiologic functions, also supports the body's muscles.

The current 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. Serum 25-hydroxyvitamin D levels and muscle strength and functionality were assessed at the beginning of the study and at three, six, nine and twelve months. Lean body mass was also measured at these time points, minus the nine-month measurement.

Unsurprisingly, 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. Similarly, a composite functional index (the sum of “Get Up” and Get Up and Go tests and left and right handgrip strength assessments) 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. Additionally, 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.

This study is the first long-term prospective investigation directly comparing calcium HMB and vitamin D3 [intake] in exercising and non-exercising healthy older adults, announced John A. Rathmacher, PhD, and colleagues at Iowa State University.

They concluded that the 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. While adequate nutrition and participation in resistance exercise training remain valuable for the maintenance of muscle strength, quality, and function, the combined [use of] calcium HMB and vitamin D3 may provide a unique protective effect for the substantial population of older adults who are unable or unwilling to exercise.