| No. | Name of Lifestyle | Third Class | Second Class | First Class | Type | No. of Studies |
|---|---|---|---|---|---|---|
| 1 | toenail Selenium+high bcarotene | NA | Selenium(Se)+bcarotene | Joint effect | No statistical significance factor | 1 |
| 2 | toenail Selenium+low bcarotene | NA | Selenium(Se)+bcarotene | Joint effect | Protective factor No statistical significance factor | 1 |