Table 2.
Quality Assessment of Included Studies
Study ID | Descriptiona | Loss to follow-up | Compliance | Dietary advice |
---|---|---|---|---|
Collins et al.27 | Randomized (blinding not described) | n.a. | Compliance by measuring plasma lycopene | Four weeks of vitamin E supplement before initiation |
Carroll et al.28 | Randomized, double blinded | 11/58 18.9% |
Compliance by questioning volunteers, counting returned capsules monthly, and measuring plasma response | n.a. |
Hininger et al.29 | Randomized, single blinded | n.a. | n.a. | n.a. |
Kucuk et al.30 | Randomized (blinding not described) | n.a. | Compliance was assessed by performing remaining pill counts at the end of the intervention | Instructed to increase daily fruit and vegetable intake to five servings for control group |
Briviba et al.31 | Randomized, double blinded | 0 | No participant excluded for health problems, compliance, or other reasons | Instructed to refrain from carrot and tomato product 4 weeks before and during treatment |
Riso et al.32 | Randomized, double blinded | n.a. | Compliance by weekly interviews, frequency of consumption of fruits and vegetables | Instructed to maintain habitual diet |
Zhao et al.33 | Randomized, double blinded | n.a. | Compliance by counting pills, checking food calendar, 3-day food records, and food-frequency questionnaires biweekly | Instructed to exclude foods rich in carotenoids and to limit fruit and vegetable intake to two servings/day of light-colored fruit and vegetables for 2 weeks before and during treatment |
Neyestani et al.34 | Randomized, double blinded | n.a. | Dietary assessment was carried out after washout and after intervention | Instructed to follow a lycopene-free diet for a 2-week washout period and instructed to keep their diets and physical activities constant during the experimental period |
Devaraj et al.35 | Randomized, double blinded | 5/82 6.10% |
Compliance (93.9%) by food diary, tablet counting, and plasma lycopene measurement | Instructed to refrain from lycopene-containing food for 2 weeks before and during treatment |
Talvas et al.36 | Randomized, single blinded | 0 | Compliance by an interview with dietitian | Instructed to avoid sources of tomato/lycopene 2 weeks before and during treatment |
Mackinnon et al.26 | Randomized (blinding not described) | 5/65 7.69% |
Compliance by using supplement counting | Instructed to refrain from lycopene-containing food 1 month before and during treatment and from vitamins containing antioxidants and nutritional supplements during the study |
Kim et al.37 | Randomized, double blinded | 10/126 7.94% | Compliance (92.1%) at the end of the study using pill counting, food records, and measurement of plasma lycopene levels | Instructed to maintain usual lifestyle and dietary habits |
van Breemen et al.38 | Computer-generated pseudorandom number for randomization; the method of double blinding was described and it was appropriate. Allocation of concealment: subjects enrolled by the study manager |
26/131 19.85% |
Compliance (99%) by calendars to record capsules and capsule counting, reminded to take capsules during calls for 24-hour dietary recalls | Dietary intakes of lycopene and other carotenoids and nutrients at baseline and during the study were determined on the basis of five 24-hour dietary recalls |
Randomization and blinding, as described by the literature. Allocation of concealment was not described for any of the studies except for van Breemen et al.38