Table 2.

Characteristics of the included studies

Ref. no.	Study design	Samples	Interventions	Primary outcome	Secondary outcome
15	Randomized, placebo-controlled, double- blind with cross-over design	Thirty apparently healthy volunteers, 15 men and 15 women, with normal blood fluidity, without organ disease, obesity, hypertension, hyperlipoproteinemia or drug treatment other than oral contraceptives	Group 1: Four capsules (each 270 mg) of onion-olive-oil maceration product. Group 2: Identically prepared placebo capsules, with 0.25 l of unsweetened fruit tea, fluid intake was restricted to a total amount of 0.5 l.	Plasma viscosity, Hematocrit, side effects: There was a significant mean decrease in plasma viscosity of 0.03 mPa s, in group 1, whereas there was no change in group 2. There were no significant differences in hematocrit before and after treatment in both groups. No adverse events were reported during the study.	Erythrocyte aggregation, blood pressure, heart rate: There were no significant differences in erythrocyte aggregation before and after treatment in both groups. There was a slight but significant decrease in systolic blood in group 1. There were no significant changes in diastolic blood pressure and heart rate before and after treatment in both groups.
13	Randomized double-blind placebo-controlled	Twelve healthy adult subjects, 7 men and 5 women	Group 1: Ingested commercial, dried-bonito broth. Group 2: The placebo consisted of dried-bonito flavor, caramel, and sodium chloride, and was prepared so that the two test diets were indistinguishable. Both groups ingested 125 ml of the diet every morning in addition to their regular diet for four weeks.	Blood fluidity: The mean of blood passage time before and after treatment in the DBB group significantly decreased, while no significant change was observed in the placebo group.	The level of d-ROMs score, shoulder stiffness symptoms, visual fatigue symptoms: There was a significant improvement of d-ROMs score in the intervention group after 4 weeks. There were no significant changes of d-ROMs score in the placebo group after 4 weeks. There was a significant decrease in shoulder stiffness symptoms at week 3 compared to week 1 in the DBB group. There was a significant decrease in visual fatigue symptoms at week 4 of DBB ingestion compared to week 1.
14	Randomized clinical trial, pilot	Fourteen healthy women who all had routine physical check-ups, not on chronic medication, not overweight, and on normal omnivorous diets	Group 1: The usual diet and limited total calorie intake to 800–900 kcal/day for 6 weeks. Group 2: The same as group 1 calorie intake and also consumed no meat, fish, or products of meat or fish for 6 weeks.	Blood fluidity score, side effects: During the first 3 weeks of diets, there was no significant longitudinal change within either group. In the second half of the experiment, the BFS (3 vs. 6-week values) significantly increased in group 2, indicating an increment in blood fluidity. By contrast, in group 1, there was a significant decrease during the same time span (compared to baseline, there were no significant longitudinal changes in either group). No side effects were reported during the study.