Table 1.
General characteristics of included studies
| Study | Design | Country | Group (gender: %M) | Age (year) | Type of diet: diet assessment method | Diet assessment perioda | History of diabetes, % | History of CVD, % | History of Pulmonary disease, % | Outcome measure |
|---|---|---|---|---|---|---|---|---|---|---|
| Hou et al. (2022) 4 | Cross‐sectional | Switzerland | 509 (52.8) | 52.2 ± 16.6 | Plant‐based: self‐reported questionnaire (vegetarian, vegan, ovo‐lacto vegetarian, lacto‐vegetarian, ovo‐vegetarian) | 1 year | NR | NR | NR | Infection, hospitalization |
| Kim et al. (2021) 5 | Cross‐sectional | France, Germany, Italy, Spain, UK, USA | 2884 (27.5) | 48 ± 10 | Plant‐based: self‐reported questionnaire for 22 food items (fruits, vegetables, potatoes, legumes, nuts, refined grains, dark or whole grain breads, sweets and desserts, eggs, dairy, poultry, meat, fish and seafood, soups, croquettes, sugar‐sweetened beverages, fruit juices, vegetable oil, butter, alcohol, coffee, and tea) | 1 year | NR | NR | NR | Infection, hospitalization |
| Merino et al. (2021) 6 | Cohort | UK, USA | Low: 148143 (60.5) | 52 ± 10.5 | Plant‐based: leeds short form food frequency questionnaire for 18 food items (wholegrains, fruits, vegetables, nuts, legumes, vegetable oils, tea and coffee, fruit juice, refined grains, potatoes, sugar sweetened beverages, sweets and desserts, animal fats, dairy, egg, fish and seafood, meat, miscellaneous) | 1 year | 4.1 | 3.5 | 11.8 | Infection, hospitalization |
| Middle: 296286 (68.4) | 57 ± 10.5 | 3.4 | 3.6 | 10.5 | ||||||
| 2.6 | 3 | 9.6 | ||||||||
| High: 148142 (75.5) | 57 ± 10 | |||||||||
| Perez‐Araluce et al. (2021) 7 | Cohort | Spain | Low: 3276 (56.2) | 50.1 ± 10.8 | Mediterranean: Mediterranean diet score for 10 food items (cereals, fruits, nuts, vegetables, legumes, fish, meat, dairy products, alcohol, and ratio of monounsaturated to saturated fat) | 10 year | 2.4 | 4.3 | 6.9 | Infection |
| Middle: 5036 (55.5) | 53.4 ± 12.7 | 3.6 | 4.7 | 6.1 | ||||||
| High: 1101 (50.1) | 57.7 ± 13.8 | 4.3 | 5.2 | 4.5 | ||||||
| Yue et al. (2022) 8 | Cohort | USA | T: 4466 (2) | 66.2 ± 6.1 | Mediterranean: Mediterranean diet score for 9 food items (vegetables, fruits, nuts, whole grains, legumes, fish, meat, alcohol, and ratio of monounsaturated to saturated fat) | 4 year | 7.4 | 0.7 | NR | Infection |
| C: 4213 (6.5) | 66.8 ± 6 | 3.5 | 0.4 |
Abbreviations: C, control group; CVD, cardiovascular disease; not reported; T, treatment group.
a
This period indicates the time period before the date of COVID‐19 diagnosis.