Why Bone Health Formulation Goes Beyond Calcium

Forty-seven years in the dietary supplement industry, 40 of them spent actively formulating products, gives Gene Bruno, MS, MHS, RH(AHG), chief scientific officer of Nutraland USA, a particular vantage point when evaluating bone health ingredients. At The Outlook on Women's Wellness conference, Bruno walked attendees through a curated set of nutraceuticals supported by clinical trial data, with an eye toward what actually fits in a finished product at a viable cost.

"You want something that will substantiate claims, but you also want things that look right in there and are useful, and hopefully something that won't be so expensive that you can't really sell it," he said.

The session covered S-equol, milk basic protein, bioactive collagen peptides, vitamin D, vitamin K2, calcium, and magnesium, touching on mechanism of action, trial design, key efficacy findings, and formulation feasibility for each.

What Is S-Equol and Why Does It Matter for Postmenopausal Bone Health?

S-equol is a metabolite of the soy isoflavone daidzein, produced in the gut through bacterial metabolism. It acts as a selective estrogen receptor-beta modulator and lacks the strong estrogenic stimulation of reproductive tissues, which distinguishes it from conventional estrogenic compounds.

The critical variable in its clinical use, Bruno explained, is that only approximately 25–35% of women naturally produce equol from dietary daidzein, meaning the majority of women are non-producers who would not benefit from soy isoflavone consumption alone, making a direct S-equol supplement a potentially more reliable formulation strategy.

Two randomized, double-blind, placebo-controlled trials were highlighted. The first, a 1-year study in 93 postmenopausal Japanese women who were confirmed non-equol producers, tested 2 mg, 6 mg, and 10 mg/day of S-equol versus placebo. At the 10 mg dose, urinary deoxypyridinoline. a marker of bone resorption, decreased by nearly 24% compared with approximately 3% in the placebo group, and whole-body bone mineral density was maintained during the intervention.¹

The second trial combined 10 mg/day S-equol with 25 mg/day resveratrol over 12 months in 60 postmenopausal women, finding significant improvements in bone turnover markers and a statistically significant increase in whole-body bone mineral density compared with placebo.²

Bruno also noted evidence from additional trials showing 10 mg/day S-equol reduced hot flash frequency and severity, improved climacteric symptoms broadly, and reduced crow's-feet wrinkle area, a formulation consideration for manufacturers targeting the broader menopause wellness market. "Whenever you find a nutraceutical that has good research on it for a given indication, it's kind of cool when it does other stuff, because those are things that you can choose to highlight in your marketing," he said.

What Does the Clinical Research on Milk Basic Protein Show for Bone Density?

Milk basic protein is a bioactive whey protein fraction derived from bovine milk, rich in lactoferrin and lactoperoxidase. Bruno described it as "a primary bone-building compound in milk besides calcium," with a mechanism of action involving promotion of osteoblast proliferation and differentiation while suppressing excessive osteoclast activity.

What distinguished the ingredient in Bruno's presentation was both the breadth and the speed of results across multiple six-month randomized, double-blind, placebo-controlled trials, a relatively compressed timeframe. At a consistent 40 mg/day dose, trials demonstrated significantly increased bone mineral density at the heel, lateral forearm, and lumbar spine across populations including healthy adult women, healthy young women, and menopausal women.³ A separate 1-year trial in 79 women aged 65–86 found that milk basic protein maintained bone density and reduced bone loss markers, with a significant interaction between supplementation and exercise.⁴

"Across the board, they found benefits in every single age group,” Bruno noted, adding that 40 mg represents a dose easily incorporated into a tablet or capsule formulation.

Can Bioactive Collagen Peptides Support Bone Mineral Density, Not Just Skin?

Collagen constitutes 30–90% of bone organic matrix, depending on skeletal site, and functions as a flexible scaffolding for mineral deposition. Bruno presented data on a specific bioactive collagen peptide ingredient standardized for bone applications, delivered at a 5 g/day dose, acknowledging upfront that this rules out conventional capsule formats and points toward stick packs or powder formats.

A 12-month randomized, double-blind, placebo-controlled trial in 131 postmenopausal women found significant increases in femoral neck and spine bone mineral density compared with placebo, alongside a statistically significant increase in collagen.⁵ A 4-year continuation of that trial in 31 women showed spine bone mineral density continued to increase over time, with cumulative improvements of 5.79–8.16% in the spine and 1.23–4.21% in the femoral neck.⁶ "That means that if you start using it, the results just keep getting better and better as you go along," Bruno said.

Bruno clarified a common misconception around collagen supplementation: ingested collagen peptides do not directly become the body's own collagen, but rather stimulate endogenous collagen production and provide bioavailable amino acids needed for synthesis.

What Role Do Vitamin D, Vitamin K2, Calcium, and Magnesium Play in a Multi-Ingredient Bone Formula?

Bruno reviewed the foundational micronutrients in the context of combination use, citing meta-analytic data rather than individual trials given the volume of research available.

On vitamin D, a meta-analysis of 11 randomized controlled trials covering more than 43,000 participants found that 400 IU vitamin D combined with 1,000 mg calcium produced a statistically significant increase in pelvic bone mineral density. A separate meta-analysis of seven trials found that vitamin D combined with vitamin K2 significantly reduced undercarboxylated osteocalcin and produced a meaningful increase in bone mineral density.⁷ Bruno emphasized that vitamin D alone is generally insufficient to affect bone mineral density, the clinical value comes from combination use.

Regarding vitamin K2, Bruno addressed both the MK-7 and MK-4 forms. A 3-year placebo-controlled trial in 244 men and postmenopausal women found that 180 mcg/day MK-7 co-supplemented with calcium and vitamin D significantly decreased age-related bone mineral density decline at the lumbar spine and femoral neck and improved bone strength. For MK-4, Bruno noted that while early research used 45 mg/day doses, more recent trials have identified meaningful effects on bone turnover markers at doses as low as 0.5–5 mg/day, with a 9-week study suggesting that 5 mg/day may represent an effective lower-dose threshold.

When it came to calcium, he cited a meta-analysis of 43 randomized controlled trials showing improved bone mineral density and bone mineral content, and a meta-analysis of 23 trials in individuals over 50 showing significant fracture risk reduction, with greater effect at doses of 1.2 g/day or higher.

For magnesium, Bruno pushed back against a tendency to prioritize newer, more commercially differentiated magnesium salts over forms with the strongest direct trial evidence. Magnesium oxide, which he called "arguably unsexy," is the only magnesium salt with randomized controlled trial evidence directly demonstrating improved bone mass accrual, and it delivers approximately 58% elemental magnesium by weight. "If you want to substantiate claims for your product, you have to balance how sexy the mineral salt is versus how effective it is and what evidence you have to support it," he said.

When it comes down to it, a quote from his Bruno his email signature puts it best in noting that, "Without data, you're just another person with an opinion."

References

1. Tousen Y, et al. Natural S-equol decreased bone resorption in Japanese postmenopausal women: a pilot randomised placebo-controlled trial. Menopause. 2011;18(5):563–574. doi:10.1097/gme.0b013e3181f65d9b

2. Corbi G, et al. The combination of equol and resveratrol on bone health in postmenopausal women: a randomized, double-blind, placebo-controlled trial. Int J Mol Sci. 2023;24(15):12063. doi:10.3390/ijms24151206

3. Aoe S, et al. A controlled trial of the effect of milk basic protein (MBP) supplementation on bone metabolism in healthy adult women. Biosci Biotechnol Biochem. 2001;65(4):913–918. doi:10.1271/bbb.65.913

4. Aoyagi Y, et al. Milk basic protein supplementation and resistance exercise improve bone mineral density in postmenopausal women. Int Dairy J. 2010;20(10):724–730. doi:10.1016/j.idairyj.2010.03.014

5. König D, et al. Specific collagen peptides improve bone mineral density and bone markers in postmenopausal women — a randomized controlled study. Nutrients. 2018;10(1):97. doi:10.3390/nu10010097

6. Zdzieblik D, et al. Specific bioactive collagen peptides in osteopenia and osteoporosis: long-term observation in postmenopausal women. J Bone Metab. 2021;28(3):207–213. doi:10.11005/jbm.2021.28.3.207

7. Kuang X, et al. The effects of vitamin K on serum levels of osteocalcin: a systematic review and meta-analysis. Food Funct. 2020;11(4):3280–3297. doi:10.1039/c9fo02782e