The PRISMA flowchart is shown in Fig. 1. A total of 12,893 studies were identified in the database search. After removing duplicates and initially screening titles and abstracts, 69 studies were selected. After full text review, 19 studies were included in our systematic review.

Flow diagram of the selection process

Table 1 shows the characteristics of the included studies. Among the 19 included studies, 9 were parallel RCTs [26,27,28,29,30,31,32,33,34], 8 were crossover RCTs [35,36,37,38,39,40,41,42], and two were self-controlled trails [43, 44]. Five studies were conducted in Spain [28,29,30, 32, 38], followed by the United States (n = 3) [41, 43, 44], Sweden (n = 2) [36, 37], Denmark (n = 2) [39, 42], Italy (n = 2) [34, 40], Australia (n = 1) [35], Mexico (n = 1) [26], China (n = 1) [27], Germany (n = 1) [31], and Netherlands (n = 1) [33]. The sample sizes ranged from 17 [44] to 362 [32]. The baseline age of participants ranged from a mean of 22.2 ± 3.4 years [44] to a median of 67 (63–70) years [36]. Three studies only contained male participants [29, 30, 37]. Four studies [28,29,30, 36] enrolled participants diagnosed with CVD diagnosed, four studies [31, 38, 39, 44] enrolled participants with metabolic syndrome, and seven studies [26, 27, 32, 34, 35, 41, 42] included participants with at least three CVD risk factors.

Seven studies described the Mediterranean diets [28,29,30, 32, 35, 38, 40], followed by the low-fat diets (n = 5) [26, 28,29,30, 35], the plant-based diets (n = 4) [36, 40, 43, 44], the whole grain diets (n = 4) [33, 37, 39, 42], the fasting diets (n = 2) [27, 31], and the polyphenol-rich diets (n = 2) [34, 41]. Among the studies that conducted the Mediterranean diet intervention, four studies [28,29,30, 35] used the low-fat diet as the control group, and one [40] used the vegetarian diet as control. Among the studies conducted the whole grain diet intervention, three [33, 39, 42] of them used a refined grain diet as control, and one compared whole grain rye diet and whole grain wheat diet [37]. The intervention duration ranged from 6 days [43] to 2 years [28, 29], with 15 studies lasting no more than 3 months [26, 27, 31,32,33,34,35,36,37,38,39,40,41,42,43,44].

Eleven studies reported the outcome of cardiometabolic parameters, with the most reported measures being TC, TG, HDL-C, and LDL-C (n = 10) [26, 27, 30, 32, 36,37,38, 42,