The main goal of this clinical study is to see if consuming pecan nuts will result in improvements in overall body metabolism such as in blood lipids, markers of inflammation, blood pressure, cognitive performance and changes in bacteria living in the gut in adults 45 to 75 years of age.

Participants will take part in two 3-month intervention periods, separated by 4-6 weeks, in random order ( a total of approximately 7 months). During one intervention period, they will include pecan nuts in their diet each day, while during the other intervention period they will avoid pecans in their diet. There will be an initial screening visit to evaluate eligibility and four study visits to the clinic.

Participants will be asked to complete some questionnaires about their diet, physical and cognitive health, and provide blood and stool samples, and have their blood pressure measured.

Inclusion Criteria:

BMI of 20-35 kg/m2, ability to understand the intervention instructions, Willingness to follow the dietary intervention, Willingness to provide biological samples (blood and stool) -

Exclusion Criteria:

Allergy to pecan or other nuts, Cognitive impairment due to dementia of any type and inability to understand or comply with intervention instructions, Use of menopausal hormone replacement therapy, Use of antibiotics or probiotics in the 2 months prior to enrollment, Uncontrolled diabetes with HbA1C of >9.5, Vegetarian/vegan, Any serious medical condition (such as chronic kidney disease of stage 3 or greater, heart failure, active cancer treatment, inflammatory bowel disease, etc.), Consumption of supplements that may interfere with vascular response or gut microbiome, Use of statin drugs for cholesterol lowering.

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