Table 1.
Summary of the included publications for the meta-analysis
| Compartment | Nutrient | Total number of publications | Total number of AD patients/average age (years) | Total number of control subjects/average age (years) | Studies reporting significantly lower levels in AD patients than in controls | Studies reporting no significant differences between AD patients and controls | Studies reporting significantly higher levels in AD patients than in controls |
|---|---|---|---|---|---|---|---|
| Circulation | DHA | 13 | 488/78 | 1245/72 | Six studies [24], [25], [26], [27], [28], [29] | Seven studies [30], [31], [32], [33], [34], [35], [36] | |
| EPA | 13 | 488/78 | 1245/72 | Six studies [24], [25], [26], [28], [32], [35] | Seven studies [27], [29], [30], [31], [33], [34], [36] | ||
| Choline (as PC) | 4 | 87/76 | 76/73 | Two studies [37], [38] | Two studies [24], [39] | ||
| Vitamin B6 | 6 | 192/76 | 199/75 | Two studies [40], [41] | Four studies [34], [42], [43], [44] | ||
| Selenium | 17 | 660/77 | 536/72 | Seven studies [34], [45], [46], [47], [48], [49], [50] | Eight studies [51], [52], [53], [54], [55], [56], [57], [58] | Two studies [59], [60] | |
| Brain | DHA | 12 | 237/77 | 220/75 | Four studies [61], [62], [63], [64] | Eight studies [65], [66], [67], [68], [69], [70], [71], [72] | |
| Choline (1H-MRS) | 31 | 828/73 | 791/70 | Four studies [73], [74], [75], [76] | Twenty-seven studies [77], [78], [79], [80], [81], [82], [83], [84], [85], [86], [87], [88], [89], [90], [91], [92], [93], [94], [95], [96], [97], [98], [99], [100], [101], [102], [103] | ||
| Folate | 9 | 307/73 | 538/65 | Four studies [104], [105], [106], [107] | Five studies [108], [109], [110], [111], [112] | ||
| Vitamin B12 | 4 | 92/70 | 208/69 | Two studies [110], [113] | Two studies [114], [115] | ||
| Vitamin C | 5 | 102/74 | 79/70 | Four studies [41], [116], [117], [118] | One study [119] | ||
| Vitamin E | 5 | 127/73 | 100/70 | Three studies [116], [120], [121] | Two studies [117], [118] | ||
| Selenium | 13 | 487/76 | 353/76 | Three studies [122], [123], [124] | Ten studies [46], [58], [125], [126], [127], [128], [129], [127], [128], [129], [130], [131], [132] | ||
| Zinc | 16 | 496/73 | 306/71 | Five studies [122], [123], [133], [134], [135] | Ten studies [46], [125], [127], [128], [130], [132], [136], [137], [138], [139] | One study [126] | |
Abbreviations: AD, Alzheimer's disease; DHA, docosahexaenoic acid; EPA, eicosapentaenoic acid.