Table 1.
Characteristics of reviewed studies on the association of vegan or vegetarian diet with inflammatory biomarkers.
| Study characteristics | Diet group characteristics | Studied | SQS | ||||
|---|---|---|---|---|---|---|---|
| Vegetarians | Vegans | Omnivores | biomarkers | ||||
| Mezzano et al. (1999)17 | |||||||
| Country | Chile | n | (n = 26) | (n = 26) | CRP | 5 | |
| Study design | Cross-sectional | Agea | 47.0 ± 12.7c | 39.5 ± 12.2c | |||
| Study population (n) | Apparently healthy (n = 52) | BMIb | 23.0 ± 3.3ci | 23.0 ± 3.3ci | |||
| Male % (n) | 46.1% (n = 24) | Durationa | ≥ 1 | ||||
| Šebeková et al. (2001)18 | |||||||
| Country | Slovak Republic | n | (n = 19) | (n = 9) | (n = 19) | CRP | 5 |
| Study design | Cross-sectional | Agea | 36.1 ± 2.5d | 36.6 ± 3.0d | 30.5 ± 1.6d | ||
| Study population (n) | Apparently healthy (n = 61) | BMIb | 22.0 ± 0.05d | 20.6 ± 0.8d | 23.8 ± 0.04d | ||
| Male % (n) | 38% (n = 23) | Durationa | 8.2 ± 0.8c | 7.2 ± 1.0c | |||
| Szeto et al. (2004)19 | |||||||
| Country | China | n | (n = 30) | (n = 30) | CRP | 3 | |
| Study design | Cross-sectional | Agea | 44.2 ± 9.0c | 44.0 ± 9.2c | |||
| Study population (n) | Apparently healthy (n = 60) | BMIb | NR | NR | |||
| Male % (n) | 10% (n = 6) | Durationa | 21.8 ± 12.2c | ||||
| Krajcovicova-Kudlackova et al. (2005)20 | |||||||
| Country | Slovak Republic | n | (n = 133) | (n = 137) | hs-CRP | 6 | |
| Study design | Cross-sectional | Agea | 46.2 ± 1.4d | 47.2 ± 1.4d | |||
| Study population (n) | Apparently healthy (n = 270) | BMIb | 22.9 ± 0.2e | 24.7 ± 0.3e | |||
| Male % (n) | 35.5% (n = 96) | Durationa | 10.4 ± 0.4c | ||||
| Šebeková et al. (2006)21 | |||||||
| Country | Slovak Republic | n | (n = 90) | (n = 46) | hs-CRP | 5 | |
| Study design | Cross-sectional | Agea | 37.7 (35.1–40.3)f | 37.7 (33.5–40.7)f | |||
| Study population (n) | Apparently healthy (n = 136) | BMIb | 22.7 (22.1–23.3)f | 23.8 (22.7–24.9)f | |||
| Male % (n) | 36% (n = 49) | Durationa | 2–25 | ||||
| Chen et al. (2008)22 | |||||||
| Country | Taiwan | n | (n = 99) | (n = 99) | hs-CRP | 5 | |
| Study design | Cross-sectional | Agea | 51.2 ± 8.9c | 49.4 ± 9.6c | |||
| Study population (n) | Apparently healthy (n = 198) | BMIb | 22.9 ± 2.8c | 23.8 ± 3.6c | |||
| Male % (n) | 43.9% (n = 87) | Durationa | ≥ 1 | ||||
| Hung et al. (2008)23 | |||||||
| Country | Taiwan | n | (n = 71) | (n = 388) | CRP | 5 | |
| Study design | Cross-sectional | Agea | 49.1 ± 11.2c | 50.6 ± 9.5c | |||
| Study population (n) | Apparently healthy or metabolic syndrome (n = 459) | BMIb | 22.6 ± 2.7c | 23.9 ± 3.1c | |||
| Male % (n) | 57.7% (n = 265) | Durationa | NR | ||||
| Chen et al. (2011)24 | |||||||
| Country | Taiwan | n | (n = 173) | (n = 190) | hs-CRP | 6 | |
| Study design | Cross-sectional | Agea | 54.0 ± 9.7c | 49.9 ± 9.8c | |||
| Study population (n) | Apparently healthy (n = 363) | BMIb | 22.9 ± 2.9c | 23.3 ± 3.5c | |||
| Male % (n) | 0% (n = 0) | Durationa | ≥ 1 | ||||
| Su et al. (2011)25 | |||||||
| Country | Taiwan | n | (n = 49) | (n = 41) | hs-CRP | 3 | |
| Study design | Cross-sectional | Agea | 58.6 ± 6.0c | 57.2 ± 5.4c | |||
| Study population (n) | Apparently healthy (n = 90) | BMIb | 23.2 ± 2.7c | 23.1 ± 2.9c | |||
| Male % (n) | 0% (n = 0) | Durationa | 10.8 ± 7.5c | ||||
| Wu et al. (2011)26 | |||||||
| Country | Taiwan | n | (n = 19) | (n = 299) | hs-CRP | 5 | |
| Study design | Cross-sectional | Agea | 63.3 ± 2.6c | 57.5 ± 1.2c | |||
| Study population (n) | Haemodialysis patients (n = 318) | BMIb | 22.7 ± 0.3c | 20.2 ± 0.8c | |||
| Male % (n) | 46.9% (n = 149) | Durationa | NR | ||||
| Lee et al. (2014)27 | |||||||
| Country | Republic of Korea | n | (n = 357) | (n = 357) | hs-CRP | 6 | |
| Study design | Cross-sectional | Agea | 52.8 ± 8.5c | 53.8 ± 8.7c | |||
| Study population (n) | Apparently healthy or metabolic syndrome (n = 714) | BMIb | 24.9 ± 2.9c | 23.7 ± 3.3c | |||
| Male % (n) | 42.9% (n = 306) | Durationa | NR | ||||
| Montalcini et al. (2015)28 | |||||||
| Country | Italy | n | (n = 26) | (n = 26) | IL-6 | 5 | |
| Study design | Cross-sectional | Agea | 32.6 ± 8.4c | 30.5 ± 6.7c | TNF-α | ||
| Study population (n) | Apparently healthy (n = 52) | BMIb | 21.9 ± 2.0c | 21.8 ± 2.0c | MCP-1 | ||
| Male % (n) | 50% (n = 26) | Durationa | ≥ 3 | ||||
| Chuang et al. (2016)29 | |||||||
| Country | Taiwan | n | (n = 686) | (n = 3423) | CRP | 7 | |
| Study design | Cross-sectionalh | Agea | 42.2 ± 12.3c | 45.1 ± 12.2c | |||
| Study population (n) | Apparently healthy (n = 4109) | BMIb | 22.1 ± 3.1c | 22.9 ± 3.2c | |||
| Male % (n) | 27.1% (n = 1115) | Durationa | ≥ 3 | ||||
| Kandouz et al. (2016)30 | |||||||
| Country | United Kingdom | n | (n = 16) | (n = 122) | CRP | 5 | |
| Study design | Cross-sectional | Agea | 71.7 ± 11.6c | 63.7 ± 16.9c | |||
| Study population (n) | Kidney failure (n = 138) | BMIb | 25.4 ± 5.2c | 26.5 ± 6.0c | |||
| Male % (n) | 63.9% (n = 88) | Durationa | early adult hood | ||||
| Lee et al. (2016)31 | |||||||
| Country | Taiwan | n | (n = 54) | (n = 100) | hs-CRP | 4 | |
| Study design | Cross-sectional | Agea | 65.1 ± 11.3c | 57.7 ± 10.5c | IL-6 | ||
| Study population (n) | Type 2 diabetes (n = 154) | BMIb | 24.9 ± 6.2c | 26.5 ± 5.7c | |||
| Male % (n) | 41.5% (n = 64) | Durationa | ≥ 1 | ||||
| Ou et al. (2016)32 | |||||||
| Country | Taiwan | n | (n = 21) | (n = 42) | hs-CRP | 4 | |
| Study design | Cross-sectional | Agea | 56.2 ± 13.7c | 56.3 ± 11.7c | |||
| Study population (n) | Dialysis Patients (n = 63) | BMIb | 20.4 ± 2.1c | 22.5 ± 3.4c | |||
| Male % (n) | 22.6% (n = 12) | Durationa | ≥ 1.5 | ||||
| Acosta-Navarro et al. (2017)33 | |||||||
| Country | Brazil | n | (n = 44) | (n = 44) | hs-CRP | 6 | |
| Study design | Cross-sectional | Agea | 45.5 ± 7.8c | 46.8 ± 9.6c | |||
| Study population (n) | Apparently healthy (n = 88) | BMIb | 23.1 ± 2.9c | 27.2 ± 4.8c | |||
| Male % (n) | 100% (n = 88) | Durationa | 17.8 ± 12.5c | ||||
| Franco-De-Moraes et al. (2017)34 | |||||||
| Country | Brazil | n | (n = 102) | (n = 66) | (n = 100) | CRP | 5 |
| Study design | Cross-sectional | Agea | 49.6 ± 8.6c | 49.6 ± 8.5c | 49.1 ± 8.2c | E-selectin | |
| Study population (n) | Apparently healthy (n = 268) | BMIb | 24.2 ± 3.9c | 23.2 ± 4.1c | 26.4 ± 4.7c | TNF-α | |
| Male % (n) | 45.8% (n = 123) | Durationa | ≥ 1 | ≥ 1 | |||
| Tseng et al. (2018)35 | |||||||
| Country | Taiwan | n | (n = 15) | (n = 140) | hs-CRP | 5 | |
| Study design | Cross-sectional | Agea | 63.2 ± 2.5c | 58.5 ± 1.3c | |||
| Study population (n) | Haemodialysis patients (n = 155) | BMIb | 20.2 ± 0.5c | 22.4 ± 0.2c | |||
| Male % (n) | 45.1% (n = 70) | Durationa | NR | ||||
| Ganie et al. (2019)36 | |||||||
| Country | India | n | (n = 179) | (n = 141) | hs-CRP | 7 | |
| Study design | Cross-sectional | Agea | 26.5 ± 6.0c | 26.6 ± 4.1c | IL-6 | ||
| Study population (n) | Apparently healthy (n = 320) | BMIb | 24.0 ± 4.2c | 24.0 ± 3.6c | TNF-α | ||
| Male % (n) | 0% (n = 0) | Durationa | NR | Adiponectin | |||
| Study population (n) | PCOS (n = 144) | n | (n = 82) | (n = 62) | Resistin | ||
| Male % (n) | 0% (n = 0) | Agea | 25.7 ± 3.8c | 26.1 ± 4.4c | |||
| BMIb | 24.9 ± 3.6c | 24.6 ± 3.5c | |||||
| Durationa | NR | ||||||
| Menzel et al.(2020) 37 | |||||||
| Country | Germany | n | (n = 36) | (n = 36) | hs-CRP | 6 | |
| Study design | Cross-sectional | Agea | 37.5 (32.5–44.0)g | 38.5 (32.0–46.0)g | IL-18 | ||
| Study population (n) | Apparently healthy (n = 72) | BMIb | 22.9 ± 3.2c | 24.0 ± 2.1c | IL-1 RA | ||
| Male % (n) | 50% (n = 36) | Durationa | 4.8 (3.1–8.7)g | ICAM-1 | |||
| Adiponectin | |||||||
| Omentin-1 | |||||||
| Resistin | |||||||
aReported in years; b reported in kg/m2; cexpressed as mean ± SD; dmean ± SE; emean ± SEM; f mean (95%-CI); g median (IQR); h using baseline values; i mean across both diet groups; SQS: Study Quality Score (using Newcastle—Ottawa Quality Assessment Scale adapted for cross-sectional studies); NR: not reported.