Table 2. Intervention description and types of outcomes from included studies (n = 7).

First author, publication year	Intervention length	Follow-up (months)	Recruitment	Randomization	Intervention characteristics	Outcomes
						Anthropo-metric	Dietary	Blood	Blood pressure	Genetic
Bihuniak JD, 2016 [21]	12 weeks	2 years	Convenience	No	Advised by a dietitian on how to follow a MD, and substitute sources of saturated fat and refined carbohydrates by extra virgin olive oil (3 T/day), walnuts (1.5 oz/day), and fatty fish (3–5 servings/wk) which were provided at 3-week intervals.	Yes	Yes	Yes	No	No
Rodríguez AS, 2016 [15]	1 week	1 year	Recruited in two primary health centres in one province	Yes	Intervention group: receive 3 interactive educational workshops (cardiovascular disease, maintenance of healthy habits and MD). Control group: participants received information pamphlets about MD.	Yes	Yes	No	No	No
Vignini A, 2017 [17]	1 year	1 year	Recruitment was performed in the ambulatory centre of the local hospital	Yes	Intervention group: oral supplementation with 20 mL/d extra virgin olive oil (VOO) enriched with vitamins D3 (100% RDA), K1 (100% RDA), and B6 (30% RDA). Control group: oral supplementation with 20 mL/d VOO. Standardized MD prescribed for both groups.	Yes	No	Yes	No	No
Bajerska J, 2018 [20]	16 weeks	16 weeks	Recruited through advertisements	Yes, stratified for BMI	Both groups were advised to follow a hypocaloric diet without added salt, refined fats and sugar; and to maintain the usual level of physical activity. During the intervention period, participants picked up packaged main meals and the other meals were prepared by the participants according to the prescribed instructions. MED group: followed a MD food plan. Olive oil and nuts were consumed every day. The proportion of soluble to insoluble fiber was 20–80%. CED group: followed a CED food plan, with a special focus on high levels of fiber. The proportion of soluble to insoluble fiber was 35–65%.	Yes	Yes	Yes	Yes	No
Duś-Żuchowska M, 2018 [18]						No	No	Yes	No	No
Muzsik A, 2019 [19]						No	No	Yes	No	Yes
Lombardo M, 2020 [16]	2 months	2 months	Convenience, recruited in nutrition clinic	No	All participants were advised to follow a two-month hypocaloric, moderate fat and MD balanced diet individually tailored, with the use of herbs and spices instead of salt, reduction of red meat to less than twice a week and to eat fish at least twice a week. The main sources of daily added fat were 25–35 g of olive oil and 20 g of nuts per day. It was recommended to only performed minimal aerobic training.	Yes	No	Yes	Yes	No

Note: NR: Not reported; MD: Mediterranean diet; BMI: Body mass index; CED: Central European diet group; MED: Mediterranean diet group; VOO: Virgin olive oil