The goal of this double-blind crossover randomized clinical trial is to evaluate the impact of a phenolic natural compound called hydroxytyrosol (HT) on patients at cardiovascular risk (CVR). The main questions it aims to answer are:

• Evaluating the effect of HT caramels on CVR biomarkers.
• Assessing the impact of HT caramels on cellular phenotype.

Participants will take 4 caramels/day, each containing 15 mg of HT, consuming a daily intake of 60 mg for 28 days. One group will begin with HT caramel consumption for 28 days, while the other group will start with a placebo treatment. Following a 2-week washout period, the treatments will be switched between the groups. Those who initially consumed HT will then switch to the placebo treatment, and vice-versa, each for a duration of 28 days.

A 10-week randomized, crossover, double-blind controlled clinical trial was conducted between April 2022 and March 2023 in the Catholic University of Murcia Randomization divided the participants in two groups, depending on whether they started consuming the caramels supplemented with HT, or the group that started consuming the placebo caramels.

The patients totally consumed 60 mg of HT per day distributed into 4 caramels/day with 15 mg of HT per caramel. The caramels in treatment group contained encapsulated HT in cyclodextrins, xylitol sweetened. On the other hand, the caramels in placebo group contained cyclodextrins and they were xylitol sweetened too. Patients were segregated into 2 groups: the ones who started as HT-group and the ones who started as C-group.

HT-group consumed HT caramels for 28 days, while C-group consumed placebo caramels followed by a 2-week washout period. Suddenly, groups were switched for 28 days, the ones who started as HT-group became C-group and vice-versa. The patients completely performed 4 visits during the study. In every appointment, they had blood and faeces extraction with body composition measurement. In addition, a Food Frequency Questionnaire (FFQ) based on Mediterranean Diet Serving Score (MDSS) was given to the patients in order to assess diet variability during the study period.

Inclusion Criteria:

• Elevated cholesterol level: >200 mg/dL
• Elevated glucose level: >100 mg/dL

Exclusion Criteria:

• Not been under antihypertensive, antidiabetic and/or hypoglycaemic agents

Nor participant and care provider knew the treatment given.