Table 3 Interventions’ impact on or association with the demand for meat at the shortest follow-up

 Emmons et al., 2005, [26].

Sample size: IG: N = 1088, CG: N = 1131

Age: M = 49

Female: 66%

Comparison: IG vs CG, RCT

The intervention targeted consumption of red meat, fruit and vegetable, multivitamin, and physical activity. It comprised endorsement and tailored prescription to prompt behavior change by participants’ clinician, 1 × 20′ in-person and 4 × 10′ telephone counseling sessions with a health advisor, and tailored supporting material including information on barriers to change. The intervention focused on social determinants of behavior.

CG: Usual care.

The proportion of participants reporting consuming ≤3 servings/w of red meat over the past 4 weeks was assessed at the baseline and 8 months later with a semi-quantitative Food Frequency Questionnaire (FFQ).

In the IG the proportion of participants consuming ≤3 servings/w rose by 11.8%, while in the CG it decreased by 0.2%. The changes over time between the two conditions were significantly different (p < 0.001).

Desired direction

 Emmons et al. (a), 2005, [25].

Sample size: IG: N = 591, CG: N = 656

Age: Median: within 60–75

Female: 42%

Comparison: IG vs CG, RCT

IG: The intervention targeted consumption of red meat, fruit and vegetable, alcohol, multivitamin, physical activity, and smoking. It comprised 1 motivational and goal-setting telephone session and 4 telephone counselling sessions delivered at monthly intervals by health advisors, and tailored supporting materials.

CG: Usual care, gastroenterologist endorsement of the study’s behavioural targets, and CRC prevention leaflet.

The proportion of participants reporting consuming on average ≤ 3 portions/w of red meat was assessed at the baseline and 8 months later with a semi-quantitative FFQ.

Compared to the CG (12%) more participants in the IG reduced their meat intakes to < 3 portions/w (18%, p = 0.002).

Desired direction

 Schiavon et al., 2015, [27].

Sample size: IG: N = 18, CG: N = 75

Age: M = 51

Female: 100%

Comparison: IG vs CG, CT

IG: The 12 month intervention targeted consumption of red and processed meat and fruit and vegetables. It provided information bi-weekly phone calls, bimonthly 24-h dietary recalls followed by researchers’ feedback, and supporting material.

CG: Basic healthy lifestyle guidelines at the baseline and follow-up.

Red and processed meat consumption (in g/d) was assessed with an FFQ for Brazilian diets, directly post-intervention.

There was a significant difference in red and processed meat consumption between the groups in unadjusted analyses (B(exp) = 0.5, p < 0.05) and in analyses adjusting for post-intervention energy intake and baseline red and processed meat consumption (B(exp) = 0.6, p < 0.05). This effect was not detected when also adjusting for baseline saturated and monounsaturated fat, and carbonyl protein and reduced glutathione (B(exp) = 0.6, p > 0.05).

Desired direction

 Grimmet et al., 2016, [30].

Sample size: N = 29

Age: M = 65

Female: 62%

Comparison: Pre-post

IG: The 12 week intervention targeted consumption of red and processed meat, fruit and vegetables, and physical activity. It comprised 2 weekly telephone calls from the researcher and supporting materials including recipes. The intervention focused on goal setting, review of goals, self-monitoring, and feedback on performance.

Consumption of red (in g/w) and processed meat (in portions/w) was assessed with an FFQ before and directly post-intervention.

Red and processed meat consumption decreased from pre- to post-intervention (mean reduction for red meat: 147.4, p = 0.013; mean reduction for processed meat: 0.83, p = 0.002).

Desired direction

 Hawkes et al., 2009, [28].

Sample size: N = 20

Age: Median: 66

Female: 50%

Comparison: Pre-post

IG: The 6 week intervention targeted consumption of red and processed meat, fruit and vegetable, alcohol, weight management, physical activity, and smoking. It comprised 6 weekly 45′ telephone counselling sessions from a trained health coach, and supporting material. The intervention included lifestyle support, health risks information, behaviour change strategies, self-efficacy, and outcome expectations.

Consumption of red and processed meat (in servings/w) was assessed via phone, before and directly post-intervention.

There was a significant decrease in the intake of processed meat servings/w from baseline (Median = 1) to post intervention (Median = 0, p = 0.01). The proportion of participants eating ≤3–4 servings/w of red meat did not change from pre- (85%) to post-intervention (85%, p = 1).

Desired direction (processed meat)

No association (red meat)

 Hawkes et al., 2012, [29].

Sample size: N = 22

Age: M = 47

Female: 82%

Comparison: Pre-post

IG: The 6 week intervention targeted consumption of red and processed meat, fruit and vegetable, alcohol, weight management, physical activity, and smoking. It comprised 6 × 1-h telephone-coaching sessions with a trained health coach, focussing on motivation, expectations, values, mindfulness, action planning, goal-setting, and self-monitoring, and supporting material.

Consumption of red and processed meat (in servings/w) was assessed via phone before and directly post-intervention.

Processed meat consumption declined from pre- to post-intervention (mean change, 95%CI = − 1.2, − 1.8 to − 0.5, p < 0.01). Red meat consumption did not change from pre- to post-intervention (mean change, 95%CI = 0.02, − 0.6 to 0.6, p = 0.93).

Desired direction (processed meat)

Undesired direction (red meat)

 Carfora et al., 2017, [32],

Sample size: IG: N = 57, CG: N = 55

Age: M = 19

Female: 56%

Comparison: IG vs CG, RCT

IG: Daily text messages for a week, encouraging participants to self-monitor their consumption of processed meat and to ‘think about the regret they could experience’ if they were to exceed the recommended levels of processed meat consumption (50 g/d).

CG: No intervention.

Consumption of processed meat (in servings) was assessed using a 7-day food diary during the week preceding and the week concomitant to the intervention. Intention to eat ≤50 g of processed meat over the upcoming week was assessed with three items on a scale from 1 (strongly disagree) to 7 (strongly agree) before and directly post-intervention.

During the intervention the IG ate significantly fewer servings of processed meat (M = 1.74) than the CG (M = 3.29, p < 0.001, d = 0.7). At post- intervention, the IG reported higher intentions to eat ≤1 serving of processed meat in the upcoming week (M = 4.47) compared to the CG (M = 3.60, p < 0.008, d = 0.51).

Desired direction

 Carfora et al., 2017(a), [31].

Sample size: IG: N = 116, CG: N = 112

Age: M = 19

Female: 72%

Comparison: IG vs CG, RCT

IG: Daily text messages for a week, encouraging participants to self-monitor their consumption of red meat to not exceed a recommended maximum of two medium servings per week.

CG: No intervention.

Consumption of red meat (in servings) was assessed using a 7-day food diary during the week preceding and the week concomitant to the intervention. Intention to eat < 2 portions of red meat over the upcoming week was assessed with three items on a scale from 1 (strongly disagree) to 7 (strongly agree) before and directly post-intervention.

During the intervention the IG ate significantly fewer servings of red meat (M = 1.62) than the CG (M = 3.03, p < 0.001, d = 0.74). At post- intervention, the IG reported higher intentions to eat < 2 servings of red meat over the upcoming week (M = 4.80) compared to the CG (M = 4.07, p < 0.01, d = 0.41).

Desired direction

 Fehren-bach, 2013, [33].

Sample size: N = 187 (total study)

Age: Median: within 18–25 (total study)

Female: 57% (total study)

Comparison: IG vs CG, RCT

IG: A webpage on the health impact of eating meat, recommending practical strategies to eat less meat.

CG: A webpage about the Rolling Stones.

Intention to reduce meat consumption was measured directly post-intervention, with three items on a scale from 1 (strongly disagree) to 5 (strongly agree).

Post-intervention intention to eat less meat was higher in the IG (M = 3.90) than in the CG (M = 2.69, p < 0.001).

Desired direction

 Fehren-bach, 2015, [37].

Sample size: IG: N = 124, CG: N = 124

Age: 57 (total study)

Female: 57 (total study)

Comparison: IG vs CG, RCT

IG: A 4′ video about the health impact of eating meat, highlighting participants’ susceptibility to these outcomes.

CG: No intervention.

At the baseline and one week post-intervention, participants reported how many meat-containing meals they ate in the past 7 days. Intention to eat less meat in the upcoming 7 days was assessed with three 5-points scales, directly post-intervention.

Meat intakes did not differ between the IG (M = − 3.16) and the CG (M = − 1.92) or any other study groups (p = 0.31, d = 0.29). Intention to eat less meat was higher in the IG (M = 3.46) than in the CG (M = 2.57, p < 0.001).

Desired direction

 Fehren-bach, 2015, [37].

Sample size: IG: N = 124, CG: N = 124

Age: 57 (total study)

Female: 57 (total study)

Comparison: IG vs CG, RCT

IG: A 7′ video about the negative health outcomes of eating meat, highlighting participants’ susceptibility to these outcomes, the health benefits of low meat diets, and strategies to eat less meat.

CG: No intervention.

At the baseline and one week post-intervention, participants reported how many meat-containing meals they ate in the past 7 days. Intention to eat less meat in the upcoming 7 days was measured with three 5-points scales, directly post-intervention.

Meat intakes did not differ between the IG (M = − 2.11) and the CG (M = − 1.92), or any other study groups (p = 0.31, d = 0.29). Intention to eat less meat was higher in the IG (M = 3.69) than in the CG (M = 2.57, p < 0.001).

Desired direction

 Berndsen et al., 2005, study 1, [34].

Sample size: IG: N = 50, CG: N = 38

Age: M = 20 (total study)

Female: 59% (total study)

Comparison: IG vs. CG, CT

IG: Cognitively framed paragraph on the health consequences of eating meat.

CG: No intervention.

Three weeks post-intervention, participants reported whether they ate less meat in the past 3 weeks. Directly post-intervention, participants reported if they intended to eat less meat over the upcoming 3 weeks. The scales ranged from 1 (fully disagree) to 9 (fully agree).

Self-reported change in meat consumption did not differ between the IG (M = 2.78) and CG (M = 3.16, p > 0.05). Intention to eat less meat did not differ between the IG (M = 2.38) and the CG (M = 3.08, p > 0.05).

Undesired direction

 Scrim-geour, 2012, [35].

Sample size: N = 363

Age: M = 28

Female: 68%

Comparison: Pre-post, Crossover

IG: Information paragraph on the health impact of eating less meat.

Whether participants intended to eat less, the same, or more meat in the future was assessed pre- and post-intervention.

Compared to the baseline (M ≈ 2.18), participants’ intention to eat less meat was higher after the intervention (M ≈ 2.26, p < 0.001, d = 0.59). (c)

Desired direction

 Cordts et al., 2014, [36].

Sample size: N = 136

Age: Median: within 40–59 (total study)

Female: 45%

Comparison: Pre-post

IG: Article on the health impact of eating meat.

The number of participants intending to eat less meat was assessed pre- and post-intervention by asking whether they would eat less, the same, or more meat in the future.

The percentage of participants intending to reduce meat consumption increased from pre- (13.1%, N = 137) to post-intervention (23.5%, N = 136, p < 0.001).

Desired direction

 Berndsen et al., 2005, study 1, [34].

Sample size: IG1: N = 53, IG2: N = 50

Age: M = 20 (total study)

Female: 59% (for total study)

Comparison: IG1 vs. IG2, CT

IG1: Affectively framed paragraph on the health impact of eating less meat.

IG2: Cognitively framed paragraph on the health impact of eating less meat.

Three weeks post-intervention, participants reported whether they ate less meat in the past 3 weeks. Directly post-intervention, participants reported if they intended to eat less meat over the upcoming 3 weeks. The scales ranged from 1(fully disagree) to 9(fully agree).

Self-reported change in meat consumption did not differ between IG1 (M = 3.75) and IG2 (M = 2.78, p = 0.07). Directly post-intervention, IG1 (M = 3.48) had higher intentions to eat less meat over the upcoming 3 weeks than IG2 (M = 2.38, p < 0.05). (d)

N/A

 Bertolotti et al. 2016, [38].

Sample size: IG1: N = 25, IG2: N = 23, IG3: N = 24, IG4: N = 25

Age: M = 74 (total study)

Female: 73% (total study)

Comparison: IG1 vs. IG2, IG3 vs. IG4, IG1 vs IG4, CT

IG1: Factually framed paragraph on the health impact of eating less meat.

IG2: Pre-factually framed paragraph on the health impact of eating less meat.

IG3: Factually framed paragraph on the well-being impact of eating less meat.

IG4: Pre-factually framed paragraph on the well-being impact of eating less meat.

Selection of meat dishes was assessed in a simulated food choice task directly post-intervention.

Intention to eat red and processed meat in the upcoming month was assessed on a scale from 1 (“much less than before”) to 7 (“much more than before”) at post-intervention.

At post-intervention, IG1 chose fewer meat dishes than IG2 (p = 0.015) but had not significantly lower intentions to eat red or processed meat (p > 0.07). IG4 did not choose fewer meat dishes than IG3 (p = 0.089) but had lower intention to eat red (p = 0.046) and processed meat (p = 0.035). Intention to eat red and processed meat did not differ significantly between IG1 and IG4 (p > 0.28). There was no main effect of content (health vs well-being) or frame (pre-factual vs factual) on any outcome.

N/A

 Fehren-bach, 2013, [33].

Sample size: N = 187 (total study)

Age: Median: within 18–25 (total study)

Female: 57% (total study)

Comparison: IG vs CG, RCT

IG: A webpage on the environmental impact of eating meat, recommending practical strategies to eat less meat.

CG: Control web-site on the Rolling Stones.

Intention to reduce meat consumption was measured directly post-intervention, with three items on a scale from 1 (strongly disagree) to 5 (strongly agree).

Intention to eat less meat was higher in the IG (M = 3.71) than in the CG (M = 2.69, p < 0.001).

Desired direction

 Graham, 2017, [39].

Sample size: IG: N = 264, CG: N = 317

Age: Median: within 21–30 (total study)

Female: 69% (total study)

Comparison: IG vs CG, RCT

IG: A self-transcendent framed paragraph on the livestock related GHG emissions in NZ and the mitigation potential of reduced consumption.

Intention to eat meat in the upcoming month was assessed with three items on a scale from 1 (low intention) to 7 (high intention), directly post-intervention.

Intention to eat meat was lower in the IG (M = 3.9) than in the CG (M = 4.2, p < 0.05).

Desired direction

 Graham, 2017, [39].

Sample size: IG: N = 267, CG: N = 317

Age: Median: within 21–30 (total study)

Female: 69% (total study)

Comparison: IG vs CG, RCT

IG: A self-enhancement framed paragraph on the livestock related GHG emissions in NZ and the mitigation potential of reduced consumption.

Intention to eat meat in the upcoming month was assessed with three items on a scale from 1 (low intention) to 7 (high intention), directly post-intervention.

Intention to eat meat was lower in the IG (M = 4.0) than in the CG (M = 4.2, p < 0.05).

Desired direction

 Vibhuti, 2016, [40].

Sample size: IG: N = 183, CG: N = 225

Age: M = 36

Female: 54%

Comparison: IG vs CG, RCT

IG: An essay on the environmental impact of the meat consumption and production.

CG: No intervention.

Directly post-intervention participants completed six virtual food choices, selecting between a meat-based food and a comparable meat-free alternative.

The proportion of selected meat and meat-free products differed significantly between the CG (meat≈61%) and the IG (meat≈55%, p = 0.003, V = 0.06).

Desired direction

 Scrim-geour, 2012, [35].

Sample size: N = 363

Age: M = 28

Female: 68%

Comparison: Pre-post, Crossover

IG: Information paragraph on the environmental impact of eating meat and strategies to reduce consumption.

Whether participants intended to eat less, the same, or more meat in the future was assessed pre- and post-intervention.

Intention to eat less meat was higher at post-intervention (M ≈ 2.27) than at the baseline (M ≈ 2.18, p < 0.001, d = 0.27).

Desired direction

 Cordts et al., 2014, [36].

Sample size: N = 128

Age: Median: within 40–59 (total study)

Female: 45%

Comparison: Pre-post

IG: An article on the environmental impact of eating meat.

The number of participants intending to eat less meat was assessed pre- and post-intervention by asking whether they would eat less, the same, or more meat in the future.

The percentage of participants intending to eat less meat increased from pre- (13.4%, N = 127) to post- intervention (18.8%, N = 128, p < 0.001).

Desired direction

 Godfrey, 2014, [41].

Sample size: N = 6758 purchases during the intervention period, N = 4426 purchases during the control period.

Comparison: Pre-post

IG: A poster on the water footprint of meals containing vegetables (300 L/meal), pork, chicken or fish (590 L/meal), and beef (1350 L/meal) was displayed over 2 weeks in a university canteen.

Meat purchases were assessed using production reports of the dining centres indicating how many servings of each main course were made daily.

There was no difference in the proportion of meat dishes purchased in the control period (87.19%) and in the intervention period (87.82%, p > 0.05).

Undesired direction

 Godfrey, 2014, [41].

Sample size: N = 1176 purchases during the intervention period, N = 4426 purchases during the control period.

Comparison: Pre-post

IG: A poster on the water footprint of meals containing vegetables (300 L/meal), pork, chicken or fish (590 L/meal), and beef (1350 L/meal) and mentioning the daily water-friendly option was displayed for 4 days in a university canteen.

Meat purchases were assessed using production reports of the dining centres indicating how many servings of each main course were made daily.

There was no difference in proportion of meat dishes purchased in the control period (87.19%) and in the intervention period (91.58%, p > 0.05).

Undesired direction

 Scrim-geour, 2012, [35].

Sample size: N = 363

Age: M = 28

Female: 68%

Comparison: Pre-post, Crossover

IG: Information paragraph on the animal welfare implications of eating meat and strategies to eat less.

Whether participants intended to eat less, the same, or more meat in the future was assessed pre- and post-intervention.

Intention to eat less meat was higher at post-intervention (M ≈ 2.3) than at the baseline (M ≈ 2.18, p < 0.001, d = 0.65).

Desired direction

 Cordts et al., 2014, [36].

Sample size: N = 150

Age: Median: within 40–59 (total study)

Female: 55%

Comparison: Pre-post

IG: An article on the animal welfare implications of eating meat.

The number of participants intending to eat less meat was assessed pre- and post-intervention by asking whether they would eat less, the same, or more meat in the future.

The percentage of participants intending to eat less meat increased from pre- (15.6%, N = 147) to post- intervention (28%, N = 150, p < 0.001).

Desired direction

 Allen et al., 2002, [42].

Sample Size: IG: N = 103, CG: N = 113

Age: Median within: 45–65

Female: 59%

Comparison: IG vs CG, CT

IG: Participants were informed that people higher in social dominance orientation (SDO) eat more meat and fewer vegetables, while people lower in social dominance do the opposite.

CG: No intervention.

Intended consumption of red and white meat servings in the upcoming 3 days was assessed with a single item directly at post-intervention. Three weeks post-interventions participants reported their consumption of meat servings over the past 7 days.

Intended meat consumption did not differ between IG (High SDO = 1.45, Low SDO = 1.45) and CG (High SDO = 1.56, Low SDO = 1.37). Actual meat consumption remained unchanged in both groups from pre- (IG = 2.88, CG = 2.66) to post-intervention (IG = 2.87, CG = 2.61, p > 0.05).

Desired direction

(High SDO)

Undesired direction

(Low SDO)

 Cordts et al., 2014, [36].

Sample size: N = 149

Age: Median within: 40–59 (total study)

Female: 48%

Comparison: Pre-post

IG: An article on the social consequences of eating meat.

The number of participants intending to eat less meat was assessed pre- and post-intervention by asking whether they would eat less, the same, or more meat in the future.

The percentage of participants intending to eat less meat increased from pre- (9%, N = 145) to post-intervention (12.1%, N = 149, p < 0.001).

Desired direction

 Arndt, 2016, study 1, [43].

Sample size: IG: N = 29, CG: N = 40

Age: M = 37 (total study)

Female: 64% (total study)

Comparison: IG vs CG, RCT

IG: Paragraph on the impact of meat consumption of an average American on health, and personal finances, and animal welfare, and the environment, and personal appearance.

CG: No intervention.

Intended average daily meat consumption (in servings) was assessed with a single open question directly post-intervention.

Adjusted for baseline meat intake, intended meat consumption did not differ between IG (M = 2.21) and CG (M = 2.63), or among any other study groups (p = 0.19).

Desired direction

 Arndt, 2016, study 2, [43].

Sample size: IG: N = 37, CG: N = 40

Age: 37 (total study)

Female: 62% (total study)

Comparison: IG vs CG, RCT

IG: Paragraph on the impact of meat consumption on health, and personal finances, and animal welfare, and the environment, also stating that eating less meat can help fulfil one’s altruistic duty.

CG: No intervention.

Intended average daily meat consumption (in servings) was assessed with a single open question directly post-intervention.

Adjusted for baseline meat intake, intended meat consumption did not differ between IG (M = 2.24) and CG (M = 2.75), or among any other study groups (p = 0.45).

Desired direction

 Arndt, 2016, study 2, [43].

Sample size: IG: N = 38, CG: N = 40

Age: 37 (total study)

Female: 62% (total study)

Comparison: IG vs CG, RCT

IG: Paragraph on the impact of meat consumption on health, and personal finances, and animal welfare, and the environment, also stating that eating less meat could help fulfil one’s personal (egoistic) objectives.

CG: No intervention.

Intended average daily meat consumption (in servings) was assessed with a single open question directly post-intervention.

Adjusted for baseline meat intake, intended meat consumption did not differ between IG (M = 1.92) and CG (M = 2.75), or among any other study groups (p = 0.45).

Desired direction

Arndt, 2016, study 2, [43].

Sample size: IG: N = 30, CG: N = 40

Age: 37 (total study)

Female: 62% (total study)

Comparison: IG vs CG, RCT

IG: Paragraph on the impact of meat consumption on health, and personal finances, and animal welfare, and the environment.

CG: No intervention.

Intended average daily meat consumption (in servings) was assessed with a single open question directly post-intervention.

Adjusted for baseline meat intake, intended meat consumption did not differ between IG (M = 2.57) and CG (M = 2.75), or among any other study groups (p = 0.45).

Desired direction

 Klöckner et al., 2017, study 1, [44].

Sample size: IG: N = 246, CG: N = 235

Age: M = 40 (total study)

Female: 49% (total study)

Comparison: IG vs CG, RCT

IG: Access to one of three subsections of a web-page (selected at random) outlining (a) why to eat less beef, or (b) how to eat less beef, or (c) how to master challenges associated with eating less beef. The webpages included health, and environmental, and social reasons for eating less beef, practical strategies, statements triggering personal values, links to scientific sources, and videos of people’s stories.

CG: No intervention.

Change in beef consumption from pre- to 8 weeks post-intervention, was measured with a retrospective food diary.

Adjusted for baseline consumption, there was no difference in the changes in beef consumption between the IG (M = 54.42) and the CG (M = −37.09, simple contrast: p = 0.3).

Undesired direction

 Klöckner et al., 2017, study 1, [44].

Sample size: IG: N = 273, CG: N = 235

Age: M = 40(for total study)

Female: 49% (for total study)

Comparison: IG vs CG, RCT

IG: Access to a web-page outlining (a) why to eat less beef, and (b) how to eat less beef, and (c) how to master challenges associated with eating less beef. The webpages included health, and environmental, and social reasons for eating less beef, practical strategies, statements triggering personal values, links to scientific sources, and videos of people’s stories.

CG: No intervention.

Change in beef consumption from pre- to 8 weeks post-intervention, was measured with a retrospective food diary.

Adjusted for baseline consumption, there was no difference in the changes in beef consumption between the IG (M = 38.17) and the CG (M = −37.09, simple contrast: p = 0.79).

Undesired direction

 Klöckner et al., 2017, study 2, [44].

Sample size: IG: N = 975, CG: N = 970

Age: M = 43 (for total study)

Female: 47% (for total study)

Comparison: IG vs CG, RCT

IG: Access to one of three subsections of a web-page (selected at random) outlining (a) why to eat less beef, or (b) how to eat less beef, or (c) how to master challenges associated with eating less beef. The webpages included health, environmental, and social reasons for eating less beef, practical strategies, statements triggering personal values, links to scientific sources, and videos of people’s stories.

CG: No intervention.

Change in beef consumption from pre- to 8 weeks post-intervention, was measured with a retrospective food diary.

Adjusted for baseline consumption, there was no difference in the changes in beef consumption between the IG (M = 28.5) and the CG (M = −66.38, simple contrast: p = 0.79).

Undesired direction

 Klöckner et al., 2017, study 2, [44].

Sample size: IG: N = 974, CG: N = 970

Age: M = 43 (for total study)

Female: 47% (for total study)

Comparison: IG vs CG, RCT

IG: Access to a web-page outlining (a) why to eat less beef, and (b) how to eat less beef, and (c) how to master challenges associated with eating less beef. The webpages included health, environmental, and social reasons for eating less beef, practical strategies, statements triggering personal values, links to scientific sources, and videos of people’s stories.

CG: No intervention.

Change in beef consumption from pre- to 8 weeks post-intervention, was measured with a retrospective food diary.

Adjusted for baseline consumption, there was a significant difference in the changes in beef consumption between the IG (M = 13) and the CG (M = −66.38, simple contrast: p < 0.001) but these changes went in the undesired direction.

Undesired direction

 Berndsen et al., 2005, study 2, [34].

Sample size: IG: N = 45, CG: N = 47

Age: M = 20.6

Female: 58%

Comparison: IG vs. CG, CT

IG: Paragraph on animal welfare, and health, and environmental impact of eating meat.

CG: No intervention control.

Three weeks post-intervention, participants reported whether they ate less meat in the past 3 weeks. Directly post-intervention, participants reported if they intended to eat less meat over the upcoming 3 weeks. The scales ranged from 1(fully disagree) to 9 (fully agree).

There was no significant main effect of condition (p < 0.10). Interaction and post-hoc tests were not reported.

N/A

 Loy et al., 2016, [45].

Sample size: IG: N = 28

Age: M = 22

Female: 82%

Comparison: Pre-post

IG: A paragraph on the environmental, and ethical, and health, and socio-economic consequences of eating meat and written instructions for mental contrasting and intention implementation.

Meat consumption in g/d was assessed with a 7-day diary the week pre- and the week directly post-intervention.

Meat consumption decreased significantly from pre- to post-intervention (average reduction: 45.2 g/d, p < 0.001, d = 1.09).

Desired direction

 Loy et al., 2016, [45].

Sample size: IG: N = 30

Age: M = 23

Female: 75%

Comparison: Pre-post

IG: A paragraph on the environmental, and ethical, and health, and socio-economic consequences of eating meat.

Meat consumption in g/d was assessed with a 7-day diary the week pre- and the week directly post-intervention.

Meat consumption decreased significantly from pre- to post-intervention (average reduction: 26.4 g/day, p = 0.001, d = 0.63).

Desired direction

 Marette et al., 2016, [46].

Sample size: 124 (recruited)

Age: Median: within 40–49

Female: 54%

Comparison: Pre-post

IG: Four paragraphs outlining the health and environmental impact of red meat consumption and the respective benefits of alternative soy-based products.

Before and directly post-intervention, participants conducted a virtual food choice task in which they selected 5 items from either beef or soy burgers.

The selection of beef items declined from pre- (M = 3.52) to post-intervention (M = 2.69, p < 0.01).

Desired direction

 Leidig, 2012, study 1, [47].

Sample size: IG: N = 119

Comparison: Retrospective evaluation

IG: The Meatless Monday campaign toolkit was sent to all healthcare accounts in the US and it was posted on Sodexo’s intranet. The toolkit included information about various benefits of eating less meat, and practical suggestions for implementing a Meatless Monday campaign.

Three months post-intervention, the general managers of Sodexo’s healthcare accounts retrospectively assessed the change in meat purchases on a single scale with 5% increments ranging from 1 (10% + decrease) to 7 (10% + increase), with a score of 4 indicating no changes.

Three months post-intervention 8% of accounts reported increases, 35% reported declines, and the rest reported no changes in meat sales. Using the scale’s mid-points as the average changes in sales, an overall decline was observed M = −0.75%, p < 0.001).

Desired direction

 Leidig, 2012, study 2, [47].

Sample size: IG: N = 126

Comparison: Retrospective evaluation

IG: The Meatless Monday campaign toolkit was posted on Sodexo’s intranet for the corporate and governmental accounts to retrieve. The toolkit included information about various benefits of eating less meat, and practical suggestions for implementing a Meatless Monday campaign.

Three months post-intervention, the general managers of Sodexo’s healthcare accounts retrospectively assessed the change in meat purchases on a single scale with 5% increments ranging from 1 (10% + decrease) to 7 (10% + increase), with a score of 4 indicating no changes.

Three months post-intervention 14% of accounts reported increases, 20% reported declines, and the rest reported no changes in meat sales. There was no overall reduction in sales, when using the scale’s mid-points as average changes (M = − 0.33%, p = 0.23).

Desired direction

 Arndt, 2016, study 1, [43].

Sample size: IG: N = 37, CG: N = 40

Age: M = 37 (total study)

Female: 64% (total study)

Comparison: IG vs CG, RCT

IG: Tailored paragraph on how strongly a participant’s personal levels of meat consumption affect their health, or personal finances, or animal welfare, or environment, or personal appearance depending on which consequence participants valued.

CG: No intervention.

Intended average daily meat consumption (in servings) was assessed with a single open question directly post-intervention.

Adjusted for baseline meat intake, intended meat consumption did not differ between IG (M = 1.70) and the CG (M = 2.63), or among any other study groups (p = 0.19).

Desired direction

 Arndt, 2016, study 1, [43].

Sample size: IG: N = 37, CG: N = 40

Age: M = 37 (total study)

Female: 64% (total study)

Comparison: IG vs CG, RCT

IG: Tailored paragraph on how strongly a participant’s personal levels of meat consumption affect their health, and personal finances, and animal welfare, and the environment, and personal appearance.

CG: No intervention.

Intended average daily meat consumption (in servings) was assessed with a single open question directly post-intervention.

Adjusted for baseline meat intake, intended meat consumption did not differ between IG (M = 2.57) and the CG (M = 2.63), or among any other study groups (p = 0.19).

Desired direction

 Arndt, 2016, study 1, [43].

Sample size: IG: N = 36, CG: N = 40

Age: M = 37 (total study)

Female: 64% (total study)

Comparison: IG vs CG, RCT

IG: Tailored paragraph on the consequences of an average American’s meat consumption on health, or personal finances, or animal welfare, or the environment, or personal appearance, depending on which consequence participants valued.

CG: No intervention.

Intended average daily meat consumption (in servings) was assessed with a single open question directly post-intervention.

Adjusted for baseline meat intake, intended meat consumption did not differ between IG (M = 2.69) and the CG (M = 2.63), or among any other study groups (p = 0.19).

Undesired direction

 Arndt, 2016, study 2, [43].

Sample size: IG: N = 42, CG: N = 40

Age: 37 (total study)

Female: 62% (total study)

Comparison: IG vs CG, RCT

IG: Tailored paragraph on the consequences of meat consumption on health, or personal finances, or animal welfare, or the environment, depending on which consequence participants valued. The message stated that eating less meat is congruent with being responsible, or adventurous, or logical, or compassionate depending on participants’ self-schema.

CG: No intervention.

Intended average daily meat consumption (in servings) was assessed with a single open question directly post-intervention.

Adjusted for baseline meat intake, intended meat consumption did not differ between IG (M = 2.73) and the CG (M = 2.75), or among any other study groups (p = 0.45).

Desired direction

 Arndt, 2016, study 2, [43].

Sample size: IG: N = 30, CG: N = 40

Age: 37 (total study)

Female: 62% (total study)

Comparison: IG vs CG, RCT

IG: Tailored paragraph on the consequences of meat consumption on health, and personal finances, and animal welfare, and the environment. The message stated that eating less meat is congruent with being responsible, or adventurous, or logical, or compassionate depending on participants’ self-schema.

CG: No intervention.

Intended average daily meat consumption (in servings) was assessed with a single open question directly post-intervention.

Adjusted for baseline meat intake, intended meat consumption did not differ between IG (M = 2.13) and the CG (M = 2.75), or among any other study groups (p = 0.45).

Desired direction

 Arndt, 2016, study 2, [43].

Sample size: IG: N = 33, CG: N = 40

Age: 37 (total study)

Female: 62% (total study)

Comparison: IG vs CG, RCT

IG: Tailored paragraph on the consequences of meat consumption on health, or personal finances, or animal welfare, or the environment, depending on which consequence participants valued. The message stated that eating less meat can help fulfil one’s altruistic duty.

CG: No intervention.

Intended average daily meat consumption (in servings) was assessed with a single open question directly post-intervention.

Adjusted for baseline meat intake, intended meat consumption did not differ between IG (M = 1.97) and the CG (M = 2.75), or among any other study groups (p = 0.45).

Desired direction

 Arndt, 2016, study 2, [43].

Sample size: IG: N = 29, CG: N = 40

Age: 37 (total study)

Female: 62% (total study)

Comparison: IG vs CG, RCT

IG: Tailored paragraph on the consequences of meat consumption on health, or personal finances, or animal welfare, or the environment, depending on which consequence participants valued. The message stated that eating less meat can help fulfil one’s personal (egoistic) objectives.

CG: No intervention.

Intended average daily meat consumption (in servings) was assessed with a single open question directly post-intervention.

Adjusted for baseline meat intake, intended meat consumption did not differ between IG (M = 1.55) and the CG (M = 2.75), or among any other study groups (p = 0.45).

Desired direction

 Arndt, 2016, study 2, [43].

Sample size: IG: N = 29, CG: N = 40

Age: 37 (total study)

Female: 62% (total study)

Comparison: IG vs CG, RCT

IG: Tailored paragraph on the consequences of meat consumption on health, or personal finances, or animal welfare, or the environment, depending on which consequence participants valued.

Intended average daily meat consumption (in servings) was assessed with a single open question directly post-intervention.

Adjusted for baseline meat intake, intended meat consumption did not differ between IG (M = 2.86) and the CG (M = 2.75), or among any other study groups (p = 0.45).

Undesired direction

 Klöckner et al., 2017, study 1, [44].

Participants had to be adults

Sample size: IG: N = 275, CG: N = 235

Age: M = 40 (total study)

Female: 49% (total study)

Comparison: IG vs CG, RCT

IG: Depending on participants stage of change for eating less beef, they were given access to the ‘stage matched’ subsections of a web-page about: (a) why to eat less beef, or (b) how to eat less beef, or (c) how to master challenges associated with eating less beef. The webpages included health, environmental, and social reasons for eating less beef, practical strategies, statements triggering personal values, links to scientific sources, and videos of people’s stories.

CG: No intervention.

Change in beef consumption from pre- to 8 weeks post-intervention, was measured with a retrospective food diary.

Adjusted for baseline consumption, there was no difference in the changes in beef consumption between the IG (M = 81.12) and the CG (M = −37.09, simple contrast: p = 0.37).

Undesired direction

 Klöckner et al., 2017, study 2, [44].

Sample size: IG: N = 976, CG: N = 970

Age: M = 43 (for total study)

Female: 47% (for total study)

Comparison: IG vs CG, RCT

IG: See Klöckner et al. (2017) tailored intervention above.

CG: No intervention.

Change in beef consumption from pre- to 8 weeks post-intervention, was measured with a retrospective food diary.

Adjusted for baseline consumption, there was no difference in the changes in beef consumption between the IG (M = 23.79) and the CG (M = −66.38, simple contrast: p = 0.65).

Undesired direction

 Tian, 2016, study 1, [49].

Sample size: IG: N = 105, CG: N = 166

Age: M = 23 (total study)

Female: 79% (total study)

Comparison: IG vs CG, RCT

IG: Participants viewed a diagram displaying the meat products from various parts of a cow’s image and were asked to write a paragraph describing the figure. (e)

CG: No intervention.

Intention to eat beef was measured with 2 items ranging from 1 (low intention to eat beef) to 7 (high intention to eat beef), directly post-intervention

Intended beef consumption did not differ between CG and IG (Mean difference = −0.16, 95%CI = −0.6 to 0.27, p = 0.77).

Undesired direction

 Tian, 2016, study 1, [49].

Sample size: IG: N = 123, CG: N = 166

Age: M = 23 (total study)

Female: 79% (total study)

Comparison: IG vs CG, RCT

IG: Participants viewed a picture of a cow with a statement that the cow will be sent to another pasture the next day and were asked to write what would happen to the cow.

CG: No intervention.

Intention to eat beef was measured with 2 items ranging from 1 (low intention to eat beef) to 7 (high intention to eat beef), directly post-intervention

Intended beef consumption did not differ between CG and IG (mean difference = 0.11, 95%CI = −0.31 to 0.52, p = 0.91).

Desired direction

 Tian, 2016, study 1, [49].

Sample size: IG: N = 124, CG: N = 166

Age: M = 23 (total study)

Female: 79% (total study)

Comparison: IG vs CG, RCT

IG: Participants viewed a picture of a cow with a statement that the cow will be sent to the abattoir the next day and were asked to write what would happen to the cow.

CG: No intervention.

Intention to eat beef was measured with 2 items ranging from 1 (low intention to eat beef) to 7 (high intention to eat beef), directly post-intervention

Intended beef consumption did not differ between CG and IG (mean difference = 0.32, 95%CI = − 0.09 to 0.73, p = 0.19).

Desired direction

 Tian 2016, study 2, [49].

Sample size: IG: N = 129, CG: N = 120

Age: M = 32 (total study)

Female: 67% (total study)

Comparison: IG vs CG, RCT

IG: Participants were given a description of a beef dish together with an image of a cow to highlight its animal origin.

CG: No intervention.

Intention to eat beef was measured with 2 items ranging from 1 (low intention to eat beef) to 7 (high intention to eat beef), directly post-intervention

Intended beef consumption did not differ between CG and IG (Mean difference: − 0.05, 95%CI = − 0.47 to 0.37, p = 0.99).

Undesired direction