Changes in total body bone mineral density following a common bone health plan with two versions of a unique bone health supplement: a comparative effectiveness research study

The Bone-Health Plans

To provide a health literacy component, with permission from the author, subjects were provided with reprints from Chapters 5, 8, 9 & 10 of a previously published book [9]. These chapters provided information on bone density, and on the pedometer-based physical activity program. Calorie estimation charts and glycemic load tables of over 300 common foods designed to increase the quality of carbohydrate intakes were also included [9].

To increase physical activity levels, subjects were asked to wear a pedometer during their waking hours and to record and track their daily activity levels using the charts and graphs provided in their health literacy booklet. They were also asked to follow the instructions for personalizing the pedometer program to their personal goal weight and stride length. In addition to the potential benefit for bone health, two reviews have suggested that the use of pedometers can lead to increased physical activity levels and significant health benefits [10, 11]. The Digi-Walker pedometer (HealthTech Products, LLC, San Antonio, TX) used in this study is generally considered among the most reliable and valid of pedometers available [12].

Subjects

As shown in Figure 1, a total of 274 adults aged 18-85 were contacted from the investigators' DXA database and from participants in a local health fair and were invited to complete a bone density test and to have the study explained to them prior to enrolling (AC-1). Of these 274 potential subjects, 158 agreed to participate and certified that they had reviewed the Informed Consent with their personal healthcare provider or physician and that they had no medical conditions that would preclude their participation. However, pregnant and lactating women were excluded irrespective of this certification. Subjects were asked to refrain from taking other bone-health supplements during the study. Of these 158 adults, 125 ultimately completed the study PP, which included providing weekly tracking data to Integrative Health Technologies' research center in San Antonio, TX

Upon completion of the study in which subjects used AlgaeCal 1, (AC-1) a second group, AlgaeCal 2 (AC-2) of 80 adults followed the identical pre-enrollment procedure as AC-1. Again, subjects and research technicians were blinded with regard to the subjects' baseline test results. Of this total, 58 agreed to participate, 51 of whom ultimately completed the study PP. Although subjects in this second group followed the same Plan, they took the revised version of the bone health supplement shown in Table 1.

Considerable effort was devoted to maintaining identical conditions for both groups in order to permit a comparison of the effects on mean BMD of the two versions of the bone health supplement. To encourage candid reporting for acquiring dose-related and compliance comparisons, subjects in both groups were paid a "reporting fee" of $2.00/day for providing daily reports of supplement usage and side effects. Throughout the study, subjects were repeatedly reminded that this fee was not an "incentive" for taking the product, but rather was for the purpose of obtaining candid information on the effects of different levels of adherence to the bone-health plan. Payment of the fee was contingent upon reporting tracking information weekly and completing the ending tests. Thus, compliance was used as an additional measure of efficacy on the assumption that if The Plan was efficacious, compliant subjects would outperform partially compliant subjects.

Outcome Measures

To assess efficacy, changes in BMD were measured at baseline and six months from baseline using dual-energy X-ray absorptiometry (DXA) total body scans (GE Lunar Prodigy, LUNAR Corporation, Madison, WI, USA). Longitudinal precision was monitored for all measurements using the same bone density phantom provided by the manufacturer. To compare changes in mean BMD over different study periods, data were converted to MAPC. For calculation of expected changes, we used age- and gender-adjusted norms from: GE Lunar, our database of over 26,000 total body measurements, and data from the National Osteoporosis Foundation [13]. We used an expected change for women under 40 yrs of +0.1%, for 41-55, -0.5%/yr, 56 and older, -1.0%/yr and used half these amounts for males. This may be a somewhat conservative estimate in view of population-based longitudinal studies suggesting that, starting at age 40, there is minor, but significant, annual bone loss [14] that increases to 0.5% to 0.9% a year in perimenopausal women [15–18], to above 1% after menopause [17, 18] after which the decline remains about 1% [14, 19, 20]. Other studies suggest after midlife there is an age-related yearly loss of bone in both sexes of 1% [21] which is accelerated to 2% for up to 14 years in women around the age of menopause [22]. In men, a small loss is detected in 40-year olds [14] that increases to a ~0.8% per year into old age [14, 19–21]. More recently, another review has suggested that women will lose 35% to 39%, men 17%-19%, of lifetime bone loss after achieving peak bone mass at ages 30-40 years [23], changes that are consistent with the previously cited studies. Additionally, and perhaps an even more conservative estimate, comparisons were also made using ±0%/yr for all subjects in both groups and sub-groups.

Compliance

To obtain a compliance rating, the research technician who had the most frequent contact with subjects rated the subjects' compliance with the protocol using a 5-point scale with "5" indicating "highly compliant" and "1" indicating "not at all compliant" with the protocol. This judgment was based on the subject's report of the amount of product he/her consumed, the number of steps reported on pedometer usage, whether or not they had acquired any information from the health literacy component, and her evaluation of the reliability of the subject's self-reported data based on her contact with the subject over the 6-month study period. Upon completion of the technician's ratings, one of the investigators (GRK) reviewed the data from the subjects' daily tracking forms and post-study anonymous questionnaires and compared it to the previous ratings. Finally, joint subjective evaluation of the subjects' overall compliance was made. Less than 10% of the technicians' ratings were changed as a function of this joint review. When making these ratings, both the technician and the investigator were blinded with respect to the subject's BMD measurements.

Statistical Methods

To address concerns of bias in industry-sponsored research, we provided an independent academic statistician who conducted all statistical analyses. He served as the Principal Investigator, had full access to all study data and source documents, and took responsibility for the integrity of the data and the accuracy of the data analysis.

Continuously distributed data were summarized with the mean and standard deviation, and binary outcomes were summarized with counts and percents. AC-1 and AC-2 were contrasted on MAPC with analyses of covariance with adjustment for age and sex. Group contrasts with regard to binary outcomes were made with Pearson's chi-square. All statistical testing was 2-sided with a significance level of 5%. SAS Version 9.1.3 for Windows (SAS Institute, Cary, North Carolina) was used throughout.

Study Weaknesses and Mitigating Factors

Although these data support a comparative effectiveness interpretation of the superiority of the AC-2 plan, absent a placebo-controlled arm, one could conclude that the increased MAPC from baseline and over-expected was attributable to using a sequential design resulting in unequal subject groups, a placebo effect or invalid expected change data. With regard to the equivalence of the groups, while it was impossible to rule out all potentially confounding variables, increased confidence in the similarity of the two groups was obtained from comparisons of a number of baseline measures associated with changes in BMD. There were no statistical differences between the groups on age, gender and BMD. Nor were there any significant baseline and pre- post-study differences on body composition variables that have been reported to affect BMD [26] (weight, lean mass, % fat, and BMI). Additionally, no differences were found between the groups on the QOL, lipid panel, C-reactive protein, serum calcium or thyroid levels. Of the 43 blood chemistries measured in both groups, only two (platelets and alkaline phosphatase) differed between the groups (p < 0.01). In neither group were there differences between volunteers and non-volunteers, nor between those subjects who completed versus those who dropped out. Taken together, these similarities provide considerable evidence that the two groups were reasonably equivalent at baseline.

With regard to placebo effects, it seems implausible to suggest that the reported changes in BMD were the result of placebo effects, particularly in view of a number of studies comparing changes in BMD that showed virtually no change in the placebo arms. For example, three randomized double-blinded placebo-controlled studies measuring the effects of strontium ranelate [27–29] found a progressive and linear decrease in BMD in each of three years with a 1% decline after 12 months--a decline virtually identical to the two age-gender adjusted expected changes used in this study.

In contrast to the absence of studies on placebo effects on BMD, a number of studies have suggested that consumption of the multiple nutrients in AC-1 and AC-2 could facilitate increases in BMD. Although we could find no studies on the effects on BMD of strontium citrate used in both formulas (as opposed to the plethora of studies on strontium ranelate), considerable evidence is available on the bone-health effects of the other nutrients in the AC formula--supplemental magnesium, vitamin K-2, [30, 31] and calcium and Vitamin D₃ [32]. Vitamin C has also been reported as an essential nutrient for collagen formation and normal bone development, particularly in older men and women [33, 34]. Further support for the increased BMD may be because AC is a plant-sourced supplement and some studies have suggested plant-sourced minerals may be more easily absorbed than non-plant-sourced calcium and minerals [35–39] suggesting that the body was able to use less than 10 percent of the synthetic minerals contained in the most popular brands of multivitamins as opposed to over 80 percent of minerals derived from plant sources. Other studies have also reported positive associations between fruit and vegetable consumption and BMD in elderly adults [40, 41], adolescents [42] and children [43].

With regard to the validity of the expected change data, the studies cited above suggest that the annual expected decrease in BMD is closer to -1.0% as opposed to the -0.67% and -0.63% used in this study. Additionally, although some studies have reported that supplementation with vitamin D₃ and calcium had no effect on the decline of age-related BMD [44, 45], the general consensus is that supplementation does result in a lower rate of annual bone loss [26]. These data would suggest that even with supplementation, the expected annualized change in BMD is between the -1.0% and -0.2%, particularly since there is no compelling evidence that supplementation leads to an increase in BMD.

No attempt was made to partition the effects of the three components of The Plan, since the goal of the study was to examine the effectiveness of the plans, not the individual components in the plans. However, the increased MAPC found in AC-2, as compared to AC-1, suggests that the modifications made to the nutritional profile of AC-2, while holding all other components constant, provided additional benefits over and above the benefits provided by the other components of The Plan.

Study strengths

One strength of this study is that it was conducted in "real world" conditions which maximized the inclusion criteria and minimized the exclusion criteria by enrolling adults of all age, gender and ethnicity, which increases confidence that the results could be generalized to populations that are most likely to use the product. Other strengths include the well established reliability and validity of DXA measurements of BMD, the analysis and absence of evidence of volunteer and attrition biases, baseline similarities between the two treatment groups, consistency of the expected within-groups differences in compliance, and the experience levels of the testing and research technicians.

With regard to safety, the use of pre- and post-study QOL inventories and independently-measured blood chemistries completed by both groups at baseline and end-of-study contribute to the safety of the study, as does the absence of reported adverse effects on these measures and on the daily tracking forms.