This is an observational case-control study which objective is to analyse differences in intestinal microbiota between patients with and without arterial stiffness, measured by pulse wave velocity. It will take place in two different research units located in Portugal and Spain.

Aim: analyse differences in intestinal microbiota between patients with and without arterial stiffness, measured by pulse wave velocity.

Design and setting: An observational case-control study. Study population: The investigators will select 324 subjects, between 30 to 75 years-old, from a database that combine data from four different studies: Triple A, Early vascular Aging (EVA) and Improving interMediAte Risk management (MARK) that took place in the Research Unit of La Alamedilla Primary Care Center, and Guimarães/ Vizela Study promoted by the Life and Health Sciences Research Institute in Minho University.

Measurements: 162 Cases will be defined by a Carotid-femoral Pulse Wave Velocity (cf-PWV)>10 mm/s determined using the SphygmoCor System. 162 controls will be selected by the propensity score. The composition of the gut microbiome in faecal samples will be determined by ribosomal ribonucleic acid (16S rRNA) gene sequencing. Other measurements: demographic data, lifestyle assessment (physical activity, adherence to the Mediterranean diet, alcohol and tobacco consumption). Anthropometric Variables: Weight, body composition by bioimpedance, size, body mass index (BMI), waist and hip perimeter, peripheral and central arterial pressure. Analysis of structure and vascular function and organ lesions target: pulse wave velocity, cardio-ankle vascular index and ankle-brachial index; Intimal median carotid thickness, central and peripheral rate of increase, renal and cardiac organic lesion. Blood analysis: short chain fatty acids, total bile acids, ursodeoxycholic acid

Inclusion Criteria:

• Patients with more than 40 years old who agree to participate in the study and do not meet any of the exclusion criteria.

Exclusion Criteria:

• Participants who are in terminal condition,
• Participants with a history of cardiovascular disease (ischaemic heart disease or stroke, peripheral arterial disease or Heart Failure),
• People with diabetes,
• diagnosed renal failure in terminal stages (glomerular filtration rate below 30%),
• chronic inflammatory disease or acute inflammatory process in the past 3 months.
• Patients treated with oestrogens, testosterone or growth hormone,

The investigators will select 324 subjects, between 40 to 75 years-old, from a database that combine data from four different studies: Triple A, EVA and Mark that took place in the Research Unit of La Alamedilla Primary Care Center, and Guimarães/ Vizela Study promoted by the Life and Health Sciences Research Institute in Minho University.

The 162 cases with a pathologic pulse wave velocity will be randomly selected, each of this subjects will be matched to an individual with the same or similar propensity score. Each one of these subjects will go through a PWV study to confirm that they're in the right group.