Skip to main content Accessibility help
×
Home

Information:

  • Access
  • Cited by 3

Actions:

      • Send article to Kindle

        To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

        Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

        Find out more about the Kindle Personal Document Service.

        Psychosocial mediators of physical activity and fruit and vegetable consumption in the Faith, Activity, and Nutrition programme
        Available formats
        ×

        Send article to Dropbox

        To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

        Psychosocial mediators of physical activity and fruit and vegetable consumption in the Faith, Activity, and Nutrition programme
        Available formats
        ×

        Send article to Google Drive

        To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

        Psychosocial mediators of physical activity and fruit and vegetable consumption in the Faith, Activity, and Nutrition programme
        Available formats
        ×
Export citation

Abstract

Objective

Performing and publishing mediator analyses, whether significant or null, provides insight into where research efforts should focus and will assist in developing effective and powerful behaviour change interventions. The present study examined whether self-efficacy, social support and church support mediated changes in leisure-time physical activity (PA) and fruit and vegetable (F&V) consumption in a faith-based intervention.

Design

A 15-month PA and F&V intervention, guided by the structural ecological model, targeted the social, cultural and policy influences within the church. Outcomes and mediators were measured at baseline and follow-up. Data were collected from 2007 to 2011. MacKinnon’s product of coefficients tested for mediation.

Setting

Sixty-eight African Methodist Episcopal churches in South Carolina, USA.

Subjects

Five hundred and eighty-two (PA) and 588 (F&V) church members.

Results

Despite the significant increases in PA and F&V consumption, none of the hypothesized mediators were significant mediators of change in PA or F&V consumption. When examining each path of the mediation model, the intervention did not change any of the hypothesized mediators. However, changes in some mediators were associated with changes in outcomes.

Conclusions

Although there was no significant mediation, the association between changes in mediators and changes in PA and/or F&V consumption suggest that these variables likely play some role in changing these behaviours. Future studies should consider mediation analyses a priori, putting careful thought into the types of measures used and the timing of those measures, while also being cognizant of participant and staff burden. Finding a balance will be fundamental in successfully understanding how interventions exert their effects.

The health benefits of regular physical activity (PA) and a healthy diet are indisputable( 1 , 2 ). Despite this, many adults do not engage in these healthy behaviours. PA levels are particularly low among African Americans( 3 ), perhaps contributing to the health disparities that currently exist( 4 ). Faith-based health promotion programmes have been used to reach and improve the health of hard-to-reach and at-risk populations, including African Americans. The important role of religion and the church in the lives of African Americans( 5 ) has made the church an invaluable and natural collaborator in efforts aimed at improving their health and health behaviours. Results from faith-based studies thus far are promising in terms of improving health behaviours, including PA and dietary behaviours( 6 , 7 ), although much work remains. There is particular concern over the lack of theoretical basis that many faith-based interventions, particularly PA interventions, have( 8 ).

Although it is essential to test whether interventions successfully change the targeted behaviour, it is also important to understand how interventions change behaviour( 9 , 10 ). Mediation analyses allow researchers to understand how an intervention achieved its effects and can ultimately be used to improve interventions. A number of PA( 11 , 12 ) and dietary( 13 ) intervention studies targeting children, adolescents or adults have conducted mediation analyses. Findings from the reviews are mixed, although there is some evidence suggesting outcome expectancies (children) may be important for changing dietary behaviours( 13 ), whereas self-regulation (adults)( 12 ) and self-efficacy (children and adolescents)( 11 ) may be important for changing PA behaviour. However, much work remains in understanding which mediating variables interventions should be targeting.

Despite the fairly large number of outcome studies published( 6 ), very few faith-based studies targeting PA( 14 ) or fruit and vegetable (F&V) consumption( 15 , 16 ) have conducted and published mediation analyses. Of the three studies published, only one found evidence of significant mediation across the entire sample( 16 ). Fuemmeler et al.( 16 ) found that self-efficacy and social support mediated changes in F&V consumption in the Body and Soul programme. Formal mediation analyses should be routinely conducted and published for all faith-based intervention studies, regardless of whether findings are positive or null( 17 ).

Self-efficacy and social support have been tested as mediators in general PA( 12 ) and dietary interventions( 18 ), and in the few faith-based mediation studies conducted to date. The social cognitive theory( 19 ) proposes that behaviour is influenced by a dynamic interplay of behaviour, personal factors and the environment( 20 ). According to the social cognitive theory, individuals with more confidence in their ability to engage in and overcome barriers to PA and eating more F&V, and individuals with greater social support for PA and F&V consumption, would be more likely to improve these behaviours( 20 ). The structural ecological model acknowledges the influence of the social and physical environment on an individual’s behaviour( 21 ). As such, it is expected that individuals with a more supportive social and physical church environment for PA and F&V consumption (e.g. provide opportunities, media messages, create policies) would be more likely to improve these behaviours. Although church support has been examined as a mediator in only a single study( 14 ), this construct is highly relevant in faith-based studies and should be explored further.

The Faith, Activity, and Nutrition (FAN) study was a 15-month, PA and dietary intervention targeting African Methodist Episcopal churches in South Carolina, USA. Using a community-based participatory research approach, FAN targeted the social, cultural and policy influences within the church( 22 ). The structural ecological model( 21 ) and the social cognitive theory( 19 ) guided the development of FAN (described in more detail below) and thus served as the framework for the mediation analyses. The purpose of the present study was to examine whether self-efficacy, social support and church support mediated changes in PA and F&V consumption in the FAN programme.

Materials and methods

The methods of FAN are described in detail elsewhere( 22 , 23 ). FAN used a group randomized design and included three waves of implementation. Churches were randomized to receive the intervention immediately following baseline assessments (i.e. intervention group) or at the end of the 15-month intervention period, following post-test measurements (i.e. control group). The primary goals of FAN were to increase moderate- to vigorous-intensity PA and F&V consumption, and to improve blood pressure( 22 ). The mediator analyses performed in the present study were conducted as post hoc analyses. The study was conducted according to the guidelines laid down in the Declaration of Helsinki and all procedures involving human subjects were approved by the Institutional Review Board at the University of South Carolina.

Church recruitment

As reported in more detail elsewhere( 22 , 23 ), pastors from four geographically defined African Methodist Episcopal districts in South Carolina were sent letters from their presiding elder introducing the FAN programme and inviting participation. Follow-up telephone calls to pastors were made by programme staff to provide more details about the FAN programme and to answer any questions. Pastors from interested churches typically appointed a liaison to assist programme staff to schedule and coordinate measurement sessions and church intervention trainings.

Procedures

Liaisons from interested churches were asked to recruit members of their congregation to take part in a measurement session at baseline (pre-intervention), with recruitment goals a function of church size. Small churches (<100 members) were asked to recruit thirteen members to take part, medium churches (100–500 members) thirty-two members, and large churches (>500 members) sixty-three members. Written informed consent was obtained from all participants at the measurement session. To be eligible, participants had to be at least 18 years of age, free of serious medical conditions or disabilities that would make changes in PA or diet difficult, and attend church at least once per month. Upon providing consent, trained staff took physical assessments and participants completed a comprehensive survey. The same measures were repeated 15 months later (post-programme).

Intervention

The FAN intervention was developed using a community-based participatory research approach( 24 ) and targeted environmental (i.e. social, cultural, physical) and organizational (i.e. policies, practices) change within the church. Guided by the structural ecological model( 21 ), churches were asked to implement intervention activities focusing on PA and healthy eating that targeted each of the four structural factors thought to influence behaviour: (i) the availability and accessibility of products that are associated with health outcomes; (ii) physical structures that increase opportunities for healthy behaviours; (iii) social structures that promote or inhibit behaviours through organizational guidelines and support; and (iv) cultural and media messages that people see and hear frequently through large or small media and through stories and cultural practices.

Trainings

Each church formed a FAN committee, consisting of the pastor, health director, FAN coordinator and the cook or lead kitchen staff, and attended a full-day training provided by study staff. The purpose of the training was to provide an overview of the FAN programme and its goals, to engage the pastor in supporting FAN and to brainstorm activities the church could do to promote PA and healthy eating. Each committee developed a formal intervention plan that was in line with the overall FAN objectives. Upon submission, churches received a stipend (up to $US 1000) to assist with FAN-related activities.

Each FAN church sent two individuals to attend a one-day cooks training that focused on the Dietary Approaches to Stop Hypertension (DASH) diet plan. The participatory training was expected to provide church cooks with the knowledge and skills necessary to prepare healthy and flavourful foods that nourish and satisfy their congregations as well as themselves( 25 ). The participatory training workshop connected scripture to healthy eating, provided ideas on how churches could improve healthy meals and snacks within the church food programme, provided cooks with hands-on cooking with chef training, engaged cooks in menu building activities, encouraged and demonstrated how traditional recipes could be modified to be healthier, and demonstrated the development of flavour in foods through healthy ingredients( 25 ). A detailed description of the trainings can be found elsewhere( 22 , 25 ).

Other intervention activities

Although churches had a great deal of flexibility in what intervention activities they implemented (based on the needs and wants of the congregation), they were asked to implement a set of core activities, focusing on PA and healthy eating, which were consistent across churches. These activities were designed to increase church support (a targeted mediator) for PA and healthy eating, and included: distribute bulletin inserts focusing on PA or healthy eating (provided by study staff); share messages about PA and healthy eating from the pulpit (e.g. church announcements, sermons); pass out educational materials about PA and healthy eating (e.g. brochures, handouts provided by study staff); create a FAN bulletin board focusing on PA and healthy eating; and suggest policies and practices the pastor could set that promoted PA and healthy eating (e.g. incorporate PA breaks into church meetings).

FAN committees, cooks and pastors also received monthly mailings over the intervention period that focused on PA or healthy eating, a health condition and highlighted a health behaviour change strategy consistent with the social cognitive theory( 19 ). Social support and self-efficacy, both tested as mediators of the FAN intervention and constructs of the social cognitive theory, were targeted in many intervention mailings and church-wide activities. Table 1 provides examples of how intervention activities aligned with the three hypothesized mediators (i.e. church support, social support and self-efficacy). The FAN committee was instructed to share the monthly mailing materials, which would assist church members in meeting FAN goals, with its congregants. Finally, intervention staff made follow-up technical assistance calls to pastors, FAN coordinators and cooks to learn what types of activities were being implemented and to help problem-solve challenges.

Table 1 Intervention activities targeting the hypothesized mediators

SCT, social cognitive theory; SEM, structural ecological model; PA, physical activity; FAN, Faith, Activity, and Nutrition.

The FAN intervention did not look the same in all churches. The intervention activities targeting the mediators above were possible activities, with the exception of the required activities, designated with † above.

Measures

All measures were completed at baseline (i.e. prior to randomization) and at 15 months (post-test).

Sociodemographic and health-related variables

Participants self-reported their age, gender, race, marital status, educational attainment and rated their health status. BMI was calculated as kg/m2 using measured height and weight.

Physical activity

A thirty-six-item modified version of the Community Health Activities Model Program for Seniors (CHAMPS) questionnaire( 26 ) assessed the frequency and duration of leisure-time moderate-to-vigorous PA ‘in a typical week during the past four weeks’. This measure has been shown to have strong psychometric properties( 26 , 27 ). Hours per week of leisure-time moderate-to-vigorous PA (≥3·0 MET (metabolic equivalents of task), household and related activities removed) was calculated.

Fruit and vegetable consumption

The National Cancer Institute’s Fruit and Vegetable All-Day Screener measured F&V consumption (cups/d) in the past month( 28 ). Nine of the original ten items were used (consumption of French fries was excluded)( 29 ). This instrument has shown acceptable psychometric properties( 30 , 31 ).

Perceived church support for physical activity and healthy eating

Scales measuring perceived church support for PA (seven items)( 32 ) and healthy eating (six items)( 33 ) over the past 12 months were developed for the present study. Items that had face validity were developed to capture important types and sources of support in church settings based on experiences from a previous faith-based project( 34 , 35 ), input from church leaders and lay members, and the guiding theory for our intervention( 21 ).

In line with the intervention targets and the four pillars of the structural ecological model( 21 ), church support items asked about opportunities for PA and healthy eating at church services and events (e.g. ‘How often has PA been included before, during, or right after worship services?’) and how often the church and church leaders talked about and provided information about PA and healthy eating via the pulpit, handouts, bulletin inserts, bulletin boards, etc. (e.g. ‘How often has your church included written information about healthy eating in the Sunday bulletin?’). A four-point response scale ranging from 1 (‘rarely or never’) to 4 (‘most or all of the time’) was used. Internal consistency was high, in our sample, for both scales (PA, α=0·86; healthy eating, α=0·84).

Self-efficacy for physical activity and fruit and vegetable consumption

An adapted twelve-item version of Sallis’ scale( 36 ) measured self-efficacy for PA and a ten-item scale used in two other faith-based projects( 37 39 ) measured self-efficacy for F&V consumption. Using a four-point response scale, participants were asked how confident they were, in the next 6 months, that they could exercise when faced with common barriers (e.g. ‘when your family is demanding more time from you’, ‘when you have household chores to attend to’) and eat F&V when faced with common barriers (e.g. ‘when you are depressed or in a bad mood’, ‘when you eat out with friends’). Internal consistency for our sample was α=0·95 for PA and α=0·93 for F&V consumption.

Social support for physical activity and fruit and vegetable consumption

Social support for PA (three items) and F&V consumption (three items) over the past 12 months from family, friends/work colleagues and people at church was measured on a 4-point response scale (e.g. ‘How much encouragement do you get from your family to get more PA?’). The items used to assess family and friend/colleague support were derived from a study by Eyler et al.( 40 ), which were adapted from the Sallis et al.( 41 ) scale. The items assessing support from church members (e.g. ‘How much encouragement do you get from people at your church to eat more F&V?’) were similar to those used in another faith-based project( 37 ). Internal consistency for our sample was α=0·68 for PA and α=0·75 for F&V consumption.

Statistical analyses

All statistical analyses were conducted with the SAS statistical software package version 9·4. Baseline differences between the immediate and delayed intervention groups on survey variables were examined with χ 2 and t tests. Square-root transformations corrected skewness in baseline and post-programme PA and F&V scores. To account for church clustering, ANCOVA using SAS PROC MIXED was used. A random effect for church was included in all models. MacKinnon’s product of coefficients test (αβ) was used to test mediation( 42 ). For both outcomes (PA and F&V consumption), single mediator models were conducted first, followed by a multiple mediator model.

Two ANCOVA models were conducted for each mediator: the first performed the regression of the mediator v. intervention group assignment (α coefficient); the second performed the regression of the outcome variable v. intervention group and the mediator (β coefficient). All models controlled for gender, age, education (some college or higher v. high-school graduate or less), wave, church size and the measure(s) at baseline. Asymmetric confidence limits based on the distribution of the product were constructed using the PRODCLIN program( 43 ) to determine if the mediated effect was statistically significant. If the confidence limit did not include 0, there was significant mediation.

Results

The study flow has been described in detail elsewhere( 23 ). In brief, 1257 participants from seventy-four churches were included in the primary outcomes paper( 23 ). The present study includes only 582 (PA outcome) and 588 (F&V outcome) participants from sixty-eight churches with complete pre- and post-test data. Thirty-seven churches were randomized to the intervention group and thirty-one churches were randomized to the control group. Participants not included in the PA outcome analyses were significantly younger, less educated and less likely to be married than those included (all P<0·05). Participants not included in the F&V outcome analyses were significantly younger, had lower self-efficacy for F&V consumption and were less likely to be married than those included in analyses (all P<0·05).

Baseline characteristics of participants, by group assignment, included in the PA mediation analyses (n 582) and F&V mediation analyses (n 588) are shown in Table 2. In the F&V analyses, delayed participants were more likely to be married (P=0·04). In both the PA (P=0·01) and F&V analyses (P=0·02) delayed participants engaged in more PA at baseline. There were no other significant baseline differences between groups.

Table 2 Baseline characteristics of participants, by intervention group assignment, for the PA and F&V samples: church members from sixty-eight African Methodist Episcopal churches in South Carolina, USA, 2007–2011, FAN study

PA, physical activity; F&V, fruit and vegetable; FAN, Faith, Activity, and Nutrition.

Skewed distribution.

Changes in outcomes

Results from the FAN programme have been reported elsewhere( 23 ). In participants included in the present study, daily F&V consumption (P=0·02, data not shown) and PA (P=0·03, data not shown) were significantly higher in the intervention group than in the control group at post-intervention.

Table 3 Mediation effects of the FAN intervention on leisure-time PA among church members (n 582) from sixty-eight African Methodist Episcopal churches in South Carolina, USA, 2007–2011

FAN, Faith, Activity, and Nutrition; PA, physical activity; ICC, intra-class correlation coefficient.

The ICC for unadjusted baseline leisure-time PA was 0·064. The ICC for adjusted baseline leisure-time PA was 0·054 (adjusted for age, gender, education, church size and phase).

*P<0·05, **P<0·0001.

Transformed (square-root) value used in all models.

Mediation: leisure-time physical activity

As shown in Table 3, none of the hypothesized mediators were found to be significant mediators of changes in PA in the FAN intervention. An examination of the α and β paths indicated that the intervention did not change any of the hypothesized mediators (all P>0·05); however, increases in self-efficacy (P<0·0001) and social support (P=0·04) were associated with increases in PA. The relationship between increases in social support and increases in PA was no longer significant in the multiple mediator model (P=0·29); all other results were the same.

Mediation: fruit and vegetable consumption

As shown in Table 4, none of the hypothesized mediators were found to be significant mediators of changes in F&V consumption in the FAN intervention. An examination of the α and β paths indicated that the intervention did not change any of the hypothesized mediators (all P>0·05); however, increases in church support (P=0·002) and self-efficacy (P=0·001) were associated with increases in F&V consumption. Results from the multiple mediator model were the same.

Table 4 Mediation effects of the FAN intervention on F&V consumption among church members (n 588) from sixty-eight African Methodist Episcopal churches in South Carolina, USA, 2007–2011

FAN, Faith, Activity, and Nutrition; F&V, fruit and vegetable; ICC, intra-class correlation coefficient.

The ICC for unadjusted baseline F&V consumption was 0·040. The ICC for adjusted baseline F&V consumption was 0·031 (adjusted for age, gender, education, church size and phase).

*P<0·05, **P<0·01, ***P<0·001.

Transformed (square-root) value used in all models.

Discussion

Although progress has been made, much work remains in understanding the relationship between theoretical variables and behavioural outcomes and how interventions impact these mediating (theoretical) variables( 44 ). Advancements in this area of research may allow for more effective interventions targeting behaviours known to improve population levels of health. The present study examined the mediating effects of social support, church support and self-efficacy in a faith-based PA and dietary intervention targeting African Americans. None of the studied mediators were found to be significant mediators of change in PA or F&V consumption.

Despite the positive increases in PA and F&V consumption resulting from FAN, it is still unclear what caused the changes. It appears that other, unmeasured, mediators caused the changes in outcomes. Very few faith-based studies have performed and published mediation analyses( 14 16 ) and the findings have been mixed. Baruth et al.( 14 ) found no evidence for support (church, instrumental, emotional), self-efficacy or exercise enjoyment as mediators of change in a 1-year PA intervention. Shaikh et al.( 15 ) found that social support, self-efficacy and controlled motivation were not significant mediators of change in a 1-year F&V intervention; autonomous motivation was a significant mediator only in those with low baseline levels. Fuemmeler et al.( 16 ) found self-efficacy and social support to be significant mediators of change in F&V consumption in a 6-month intervention, whereas controlled and autonomous motivation were not. Although faith-based interventions targeting behaviours such as PA and F&V consumption have resulted in positive outcomes, the mechanisms by which faith-based interventions exert their effects are ambiguous, substantiating the need for additional research.

Results from the present study suggest that the FAN intervention may not have changed the studied mediators. It is possible that the FAN intervention was not intense or targeted enough to change the hypothesized mediators. In that case, adaptations to the intervention activities focusing on the targeted mediators may want to be considered. However, there are a number of other plausible explanations for the lack of relationship between group assignment and changes in mediators seen in the study. First, it is possible that the mediators tested did not map on to our conceptual model ideally. For example, although social support and self-efficacy were included in the monthly mailings to the church, they would not be considered ‘main targets’ of the intervention, and thus it is not surprising that significant changes in these variables did not take place. In contrast, mediators that mapped on to the structural ecological model (i.e. church support) were assessed with brief measures not previously validated. Additionally, it is possible that participants experienced a ‘response shift’, where participants’ self-evaluation and/or internal standards of the targeted mediators changed as a result of changes in PA and F&V consumption( 45 ). For example, it is possible that participants were confident (i.e. self-efficacy) in their ability to engage in PA or consume F&V at baseline, but as they changed their behaviour they encountered or realized additional difficulties that may arise in maintaining these behaviours, causing a shift (i.e. decrease) in their self-efficacy.

Second, the type and timing of the measures used may also explain, in part, the lack of findings. The self-report measures used in the present study may not have accurately assessed the mediators or may not have been sensitive enough to capture change( 46 ). This may be particularly relevant for church support, which was developed due to the paucity of measures in the existent literature. Although found to have high construct validity and internal consistency in our study, it is unlikely that it adequately captured all levels and aspects of church support, which was a critical aspect of the FAN intervention and guided many of the intervention activities. Furthermore, the dietary church support measure assessed support for healthy eating, not F&V consumption specifically. Unfortunately, due to study logistics, we were unable to validate the measure prior to the intervention and in consideration of participant burden were limited in the number of questions the measure included. Continued work on developing a valid measure that adequately captures the wide spectrum of church support, including emotional, instrumental and informational support, targeted in faith-based interventions is warranted. Doing so will assist researchers in understanding whether the intervention targets successfully changed church support and which aspects of the intervention need to be refined.

Third, it is possible that the intervention did in fact change the targeted mediators, but the timing of the measures did not capture it. When measurements are conducted is important, as it is possible to miss relationships if the timing of the changes in mediators differs from the timing of the measures( 47 , 48 ). For example, church support may have increased in the first 6 months of the FAN intervention, but it was not sustained at the 15-month follow-up. Because there were no intermediate follow-up periods (i.e. at 6 months), this increase would not have been captured. It is entirely possible that the initial increase in the mediator produced positive changes in the outcomes at the 15-month follow-up but, unfortunately, the timing of our measures did not capture it. Although intermediate follow-ups would have been ideal, it would have significantly increased participant and staff burden.

Much work remains in how to develop PA and dietary interventions that effectively change proposed mediators, as recent reviews examining mediators of PA( 12 ) and dietary change( 13 ) have found that, overall, interventions are not successful in changing targeted mediators. In fact, PA (adults) and dietary (youth) interventions were successful in changing the targeted mediators less than half of the time( 12 , 13 ). Developing interventions that target the hypothesized mediators with higher fidelity is imperative for successfully changing PA and dietary behaviours( 12 ).

Changes in some of the mediators were associated with changes in PA and/or F&V consumption, suggesting that these variables likely play some role and are important for behaviour change. Self-efficacy seems to be important for both PA and F&V consumption, social support may be important for PA (single mediator model only), and church support, which is a unique mediator not often studied in faith-based studies, may be important for changing F&V consumption and should be further investigated in future studies. Faith-based settings allow for unique social interactions, including support from church members, the pastor and the church environment (i.e. policies, physical environment), which are unlike those of many other community institutions. Future studies should continue to incorporate these levels of support into the development of interventions.

Mediation analyses were not initially proposed for the FAN study, but instead were conducted as a post hoc analysis. To really understand how interventions work, researchers should more carefully consider mediation analyses from the conception of the study and align intervention strategies with the hypothesized mediators from the start. Considerable thought should be given a priori to the selection and measurement (including the timing) of mediators, as it is very likely that the measures needed may not be available after the intervention is finished( 48 ). Assessing potential mediators with appropriate scales is important. Mediation analyses can be a challenge to do in community-based research such as FAN, as there is a fine balance between collecting adequate data and not overburdening the churches (organizations) and its members (participants).

Study limitations, including the high attrition rate, should be considered when interpreting the findings. Less than 50 % of participants included in the primary outcomes paper had complete pre/post data. High attrition rates, particularly when the follow-up exceeded 6 months, have been reported in PA interventions targeting African Americans( 49 ). Participants wanting to take part in the FAN evaluation were not rigorously screened prior to enrolment and were not provided with monetary incentives for measurement completion. These omissions may have reduced participant commitment and motivation for completing measurements.

Significant work remains in understanding how PA and dietary interventions exert their effects, particularly in faith-based studies. Performing and publishing mediator analyses, whether significant or null, provides insight into where research efforts should focus and collectively will assist in developing the most effective and powerful behaviour change interventions. Despite the positive increases in both PA and F&V intake outcomes resulting from the FAN programme, we found no evidence of mediation. Future studies should consider mediation analyses a priori, putting careful thought into the types of measures used and the timing of those measures, while also being cognizant of the burden that could be imposed on both participants and staff. Finding a balance will be fundamental in successfully understanding how faith-based interventions exert their effects.

Acknowledgements

Acknowledgements: The authors thank the leaders of the 7th Episcopal District of the African Methodist Episcopal church, especially the Bishop, participating Presiding Elders and participating pastors, for their support of FAN. The authors thank the many churches and members who have taken time out of their busy lives to participate in measurements and trainings and to implement FAN in their churches. The authors also thank the staff, investigators and students who have meaningfully contributed to FAN. Financial support: The project described was supported by the National Heart, Lung, and Blood Institute (grant number R01HL083858). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Heart, Lung, and Blood Institute or the National Institutes of Health. Conflict of interest: None. Authorship: M.B. assisted with data collection and cleaning, analysed the data and drafted the manuscript. S.W. obtained the funding (primary investigator), designed the study, carried out the study and helped draft/edit the manuscript. Ethics of human subject participation: This study was approved by the Institutional Review Board at the University of South Carolina.

References

1. Thompson, PD, Buchner, D, Pina, IL et al. (2003) Exercise and physical activity in the prevention and treatment of atherosclerotic cardiovascular disease: a statement from the Council on Clinical Cardiology (Subcommittee on Exercise, Rehabilitation, and Prevention) and the Council on Nutrition, Physical Activity, and Metabolism (Subcommittee on Physical Activity). Circulation 107, 31093116.
2. Lichtenstein, AH, Appel, LJ, Brands, M et al. (2006) Diet and lifestyle recommendations revision 2006: a scientific statement from the American Heart Association Nutrition Committee. Circulation 114, 8296.
3. Centers for Disease Control and Prevention (2011) Behavioral Risk Factor Surveillance System. http://apps.nccd.cdc.gov/brfss/race.asp?cat=PA&yr=2011&qkey=8271&state=UB (accessed March 2012).
4. Centers for Disease Control and Prevention (2013) CDC Health Disparities and Inequalities Report – United States, 2013. MMWR Surveill Summ 62, Suppl. 3, 1186.
5. Giger, JN, Appel, SJ, Davidhizar, R et al. (2008) Church and spirituality in the lives of the African American community. J Transcult Nurs 19, 375383.
6. Campbell, MK, Hudson, MA, Resnicow, K et al. (2007) Church-based health promotion interventions: evidence and lessons learned. Annu Rev Public Health 28, 213234.
7. DeHaven, MJ, Hunter, IB, Wilder, L et al. (2004) Health programs in faith-based organizations: are they effective? Am J Public Health 94, 10301036.
8. Bopp, M, Peterson, JA & Webb, BL (2012) A comprehensive review of faith-based physical activity interventions. Am J Lifestyle Med 6, 460478.
9. Bauman, AE, Sallis, JF, Dzewaltowski, DA et al. (2002) Toward a better understanding of the influences on physical activity: the role of determinants, correlates, causal variables, mediators, moderators, and confounders. Am J Prev Med 23, 514.
10. Baranowski, T, Anderson, C & Carmack, C (1998) Mediating variable framework in physical activity interventions. How are we doing? How might we do better? Am J Prev Med 15, 266297.
11. Lubans, DR, Foster, C & Biddle, SJ (2008) A review of mediators of behavior in interventions to promote physical activity among children and adolescents. Prev Med 47, 463470.
12. Rhodes, RE & Pfaeffli, LA (2010) Mediators of physical activity behaviour change among adult non-clinical populations: a review update. Int J Behav Nutr Phys Act 7, 37.
13. Cerin, E, Barnett, A & Baranowski, T (2009) Testing theories of dietary behavior change in youth using the mediating variable model with intervention programs. J Nutr Educ Behav 41, 309318.
14. Baruth, M, Wilcox, S, Blair, S et al. (2010) Psychosocial mediators of a faith-based physical activity intervention: implications and lessons learned from null findings. Health Educ Res 25, 645655.
15. Shaikh, AR, Vinokur, AD, Yaroch, AL et al. (2011) Direct and mediated effects of two theoretically based interventions to increase consumption of fruits and vegetables in the Healthy Body Healthy Spirit trial. Health Educ Behav 38, 492501.
16. Fuemmeler, BF, Masse, LC, Yaroch, AL et al. (2006) Psychosocial mediation of fruit and vegetable consumption in the body and soul effectiveness trial. Health Psychol 25, 474483.
17. Plotnikoff, RC, Pickering, MA, Rhodes, RE et al. (2010) A test of cognitive mediation in a 12-month physical activity workplace intervention: does it explain behaviour change in women? Int J Behav Nutr Phys Act 7, 32.
18. Shaikh, AR, Yaroch, AL, Nebeling, L et al. (2008) Psychosocial predictors of fruit and vegetable consumption in adults: a review of the literature. Am J Prev Med 34, 535543.
19. Bandura, A (1986) Social Foundations of Thought and Action: A Social Cognitive Theory. Englewood Cliffs, NJ: Prentice Hall.
20. Baranowski, T, Perry, CL & Parcel, GS (2002) How individuals, environments, and health behavior interact. Social cognitive theory. In Health Behavior and Health Education Theory, Research, and Practice, 3rd ed., pp. 165184 [K Glanz, BK Rimer and FM Lewis, editors]. San Francisco, CA: Jossey-Bass.
21. Cohen, DA, Scribner, RA & Farley, TA (2000) A structural model of health behavior: a pragmatic approach to explain and influence health behaviors at the population level. Prev Med 30, 146154.
22. Wilcox, S, Laken, M, Parrott, AW et al. (2010) The faith, activity, and nutrition (FAN) program: design of a participatory research intervention to increase physical activity and improve dietary habits in African American churches. Contemp Clin Trials 31, 323335.
23. Wilcox, S, Parrott, A, Baruth, M et al. (2013) Faith, activity, and nutrition program results. A CBPR intervention in African American churches. Am J Prev Med 44, 122131.
24. Israel, BA, Schulz, AJ, Parker, EA et al. (2003) Critical issues in developing and following community based participatory research principles. In Community-Based Participatory Research for Health, pp. 5379 [M Minkler and N Wallerstein, editors]. San Francisco, CA: Jossey-Bass.
25. Condrasky, MD, Baruth, M, Wilcox, S et al. (2012) Cooks training for faith, activity, and nutrition project with AME churches in SC. Eval Program Plann 37C, 4349.
26. Resnicow, K, McCarty, F, Blissett, D et al. (2003) Validity of a modified CHAMPS physical activity questionnaire among African-Americans. Med Sci Sports Exerc 35, 15371545.
27. Harada, ND, Chiu, V, King, AC et al. (2001) An evaluation of three self-report physical activity instruments for older adults. Med Sci Sports Exerc 33, 962970.
28. National Cancer Institute (2000) Fruit & Vegetable Screeners: Validity Results. http://riskfactor.cancer.gov/diet/screeners/fruitveg/validity.html (accessed March 2010).
29. Thompson, B, Demark-Wahnefried, W, Taylor, G et al. (1999) Baseline fruit and vegetable intake among adults in seven 5 a day study centers located in diverse geographic areas. J Am Diet Assoc 99, 12411248.
30. Thompson, FE, Subar, AF, Smith, AF et al. (2002) Fruit and vegetable assessment: performance of 2 new short instruments and a food frequency questionnaire. J Am Diet Assoc 102, 17641772.
31. Campbell, MK, Demark-Wahnefried, W, Symons, M et al. (1999) Fruit and vegetable consumption and prevention of cancer: the Black Churches United for Better Health project. Am J Public Health 89, 13901396.
32. Baruth, M, Wilcox, S, Blair, S et al. (2013) Perceived environmental church support and physical activity among Black church members. Health Educ Behav 40, 712720.
33. Baruth, M, Wilcox, S & Condrasky, MD (2011) Perceived environmental church support is associated with dietary practices among African-American adults. J Am Diet Assoc 111, 889893.
34. Wilcox, S, Laken, M, Anderson, T et al. (2007) The health-e-AME faith-based physical activity initiative: description and baseline findings. Health Promot Pract 8, 6978.
35. Wilcox, S, Laken, M, Bopp, M et al. (2007) Increasing physical activity among church members: community-based participatory research. Am J Prev Med 32, 131138.
36. Sallis, JF, Pinski, RB, Grossman, RM et al. (1988) The development of self-efficacy scales for health-related diet and exercise behaviors. Health Educ Res 3, 283292.
37. Resnicow, K, Jackson, A, Blissett, D et al. (2005) Results of the healthy body healthy spirit trial. Health Psychol 24, 339348.
38. Resnicow, K, Campbell, MK, Carr, C et al. (2004) Body and soul. A dietary intervention conducted through African-American churches. Am J Prev Med 27, 97105.
39. Resnicow, K, Jackson, A, Braithwaite, R et al. (2002) Healthy body/healthy spirit: a church-based nutrition and physical activity intervention. Health Educ Res 17, 562573.
40. Eyler, AA, Brownson, RC, Donatelle, RJ et al. (1999) Physical activity social support and middle- and older-aged minority women: results from a US survey. Soc Sci Med 49, 781789.
41. Sallis, JF, Grossman, RM, Pinski, RB et al. (1987) The development of scales to measure social support for diet and exercise behaviors. Prev Med 16, 825836.
42. MacKinnon, DP, Lockwood, CM, Hoffman, JM et al. (2002) A comparison of methods to test mediation and other intervening variable effects. Psychol Methods 7, 83104.
43. MacKinnon, DP, Fritz, MS, Williams, J et al. (2007) Distribution of the product confidence limits for the indirect effect: program PRODCLIN. Behav Res Methods 39, 384389.
44. Baranowski, T, Lin, LS, Wetter, DW et al. (1997) Theory as mediating variables: why aren’t community interventions working as desired? Ann Epidemiol 7, Suppl., S89S95.
45. Sprangers, MA & Schwartz, CE (1999) Integrating response shift into health-related quality of life research: a theoretical model. Soc Sci Med 48, 15071515.
46. MacKinnon, DP (1994) Analysis of mediating variables in prevention and intervention research. NIDA Res Monogr 139, 127153.
47. MacKinnon, DP (2008) Introduction to Statistical Mediation Analysis. New York: Taylor & Francis Group, LLC.
48. Kraemer, HC, Wilson, GT, Fairburn, CG et al. (2002) Mediators and moderators of treatment effects in randomized clinical trials. Arch Gen Psychiatry 59, 877883.
49. Pekmezi, D & Jennings, E (2009) Interventions to promote physical activity among African Americans. Am J Lifestyle Med 3, 173184.