Long-term Effects of Avocado Consumption on Health in Pre-diabetic Individuals

Daily intake of avocado, a food rich in MUFA, PUFA and other essential nutrients such as folate and potassium, has previously been shown to lower systemic markers of cardiovascular risk as well as inflammation in overweight/obese individuals. Especially individuals with cardiovascular disease, or those at an increased risk for cardiovascular disease appear to benefit from regular avocado consumption. In addition to improvements in cardiovascular disease, large cross-sectional studies have linked avocado consumption to a lower risk for metabolic disease, including type 2 diabetes. Despite the beneficial systemic effects observed, the interaction of peripheral cardiovascular risk- and vascular function markers with brain vascular health remains unclear. Furthermore, the clinical implications of this interaction, especially in a population at risk, are unknown.

A total of 34 men and women between the ages of 40-75 years old, with overweight/obesity (BMI: 26-40 kg/m2) will consume a daily avocado (intervention) or no avocado for 12 week in a crossover design.

The primary outcome parameter of the intervention will be cerebral blood flow (CBF). Secondary outcomes include measures for endothelial function (brachial artery flow mediated vasodilation (FMD), carotid artery reactivity (CAR)) and arterial stiffness (pulse wave velocity (PWV), carotid artery distensibility). More cardiometabolic risk markers measured will include office blood pressure, serum lipids, lipoprotein and metabolite profiling, hemostatic factors and plasma biomarkers for low-grade systemic inflammation including IL-6, IL-8, TNF-α, CRP and SAA). Cognitive performance will be assessed in the domains of executive function, memory, psychomotor speed and attention with the Cambridge Neuropsychological Test Automated Battery (CANTAB) as well as the Erikson Flanker test.

Inclusion criteria

• Men and women, aged between 40-75 years
• Pre-diabetes: (A1C of 5.7%-6.4%, a fasting plasma glucose (FPG) of 100-125 mg/dL, or a 2-hour oral glucose tolerance test (OGTT) result of 140-199 mg/dL)
• BMI ³ 25 kg/m2
• Fasting serum total cholesterol < 8.0 mmol/L
• Systolic blood pressure < 160 mmHg and diastolic blood pressure < 100 mmHg
• Willingness to give up being a blood donor from 8 weeks before the start of the study, during the study and for 4 weeks after completion of the study

Exclusion criteria

• Age less than 40 years old or older than 75 years
• BMI < 25 kg/m2
• Type 1 or type 2 diabetes
• habitual consumption of more than 1 avocado/ week
• Left-handedness
• Fasting serum total cholesterol > 8.0 mmol/L
• Current smoker, or smoking cessation < 12 months
• Abuse of drugs
• More than 3 alcoholic consumptions per day
• Use medication to treat blood pressure, lipid or glucose metabolism
• Use of an investigational product within another biomedical intervention trial within the previous 1-month
• Severe medical conditions that might interfere with the study, such as epilepsy, asthma, kidney failure or renal insufficiency, chronic obstructive pulmonary disease, inflammatory bowel diseases, auto inflammatory diseases and rheumatoid arthritis
• Active cardiovascular disease like congestive heart failure or cardiovascular event, such as an acute myocardial infarction or cerebrovascular accident
• Contra-indications for MRI imaging (e.g. pacemaker, surgical clips/material in body, metal splinter in eye, claustrophobia)
• Blood donation in the 8 weeks before the start of the study
• Difficulties to draw blood