TABLE 3.

Main characteristics of the included randomized controlled trials.

References	Country	Population	Duration	Intervention	Placebo group	Dietary	MeDi score	Baseline age	Subjects (N)	Loss	Outcome method	Results
Hardman et al. (62)	Australia	Healthy older adults	0.5 years	The diet group received a collection of recipes in keeping with MeDi diet style, and with the assistance of dietary consultants from Health Care 2	Maintenance of their current lifestyle	FFQ	0–9	EG: 77.68 ± 7.38 CG: 78.22 ± 5.81	EG: 18 CG: 25	EG: 28% CG: 7%	SUCCAB	The MeDi diet has the potential to improve aspects of cognition in aging population
Knight et al. (63)	Australia	Healthy older adults	0.5 years	Participants were closely monitored on a fortnightly basis in an informed meeting that followed MeDi diet food pyramids	Participants were asked to simply maintain their customary lifestyle and dietary pattern	FFQ	0–9	EG: 72.1 ± 4.9 CG: 72.0 ± 5.0	EG: 70 CG: 67	EG: 19% CG: 17%	A comprehensive battery of 11 cognitive tests	There was no beneficial effect of the MeDi diet intervention on cognitive function among healthy older adults
Martinez-Lapiscina et al. (64)	Spain	Cognitively normal participants at high CVD risk	6.5 years	Participants received intensive education and advice to increase adherence to MeDi diet. Participants received free allotments of either EVOO (1 L/week) or 30 g/day of raw, unprocessed mixed nuts (15 g walnuts, 7.5 g almonds and 7.5 g hazelnuts)	Participants received intensive education and advice to increase adherence to the low-fat diet and received advice to reduce all types of fat and non-food gifts as an incentive to improve compliance	FFQ	0–14	All: 67.38 ± 5.65	EGE: 224 EGN: 166 CG: 132	EGE: 36% EGN: 53% CG: 63%	MMSE, CDT	An intervention with the MeDi diet enhanced with either EVOO or nuts appears to improve cognition compared with a low-fat diet
Sanchez-Villegas et al. (65)	Spain	Cognitively normal participants at high CVD risk	3 years	The groups assigned to MeDi diet were advised to use extra virgin olive oil for cooking. Each participant had a personal interview with a trained dietician and a group session conducted by the same dietician every 3 months during these 4 years	Participants were advised to reduce all types of fat and were given recommendations according to the American guidelines	FFQ	0–14	EGE: 68.1 ± 6.1 EGN: 67.4 ± 5.7 CG: 68.0 ± 6.1	EGE: 91 EGN: 75 CG: 77	/	ELISA kit	Adherence to the MeDi diet was associated to an improvement in plasma BDNF concentrations in individuals with depression and to prevent depression and cognitive decline
Valls-Pedret et al. (66)	Spain	Cognitively normal participants at high CVD risk	4.1 years	Participants were educated on how to follow the MeDi diet and received supplemental foods at no cost. Participants received free allotments of either EVOO (1 L/week) or 30 g/day of raw, unprocessed mixed nuts (15 g walnuts, 7.5 g almonds and 7.5 g hazelnuts)	Participants were advised to reduce all dietary fat	FFQ	0–14	EGE: 67.9 ± 5.4 EGN: 66.7 ± 5.3 CG: 65.5 ± 5.8	EGE: 127 EGN: 112 CG: 95	EGE: 18% EGN: 24% CG: 34%	MMSE, RAVLT, subtest of Wechsler memory scale, animal fluency test, Wechsler adult intelligence scale, CTT	The MeDi diet supplemented with olive oil or nuts was associated with improved cognitive function

MeDi diet, Mediterranean diet; SUCCAB, Swinburne university computerized cognitive assessment battery; CDT, Clock drawing test; MMSE, Mini-Mental State Examination; EVOO, Extra virgin olive oil; EG, Experiment group; CG, Control group; EGE, Mediterranean diet plus Extra virgin olive oil; EGN, Mediterranean diet plus nuts; BDNF, Brain-derived neurotrophic factor; RAVLT, Rey Auditory Verbal Learning Test; CTT, Color trail test.