This is a single site, single-blinded, controlled randomized crossover clinical trial designed to compare the effects of black beans or whole grains or white rice at breakfast on postprandial vascular responses in males and females with arterial stiffness (n=10). Eligible participants will be asked to attend 3 in-person visits for comparative testing of black beans versus whole grains versus white rice.

This is a single site, single-blinded, randomized, controlled crossover study designed to compare the vascular responses of males and females with arterial stiffness before and 2 hours after ingestion of black beans or whole grains (wheat) or white rice (isocaloric comparator).

Recruitment will consist of a total of 10 participants with arterial stiffness. Participants will be recruited through advertisement from the local community.

The study will be conducted at the Asper Clinical Research Institute, St. Boniface Hospital. Participants will be asked to provide written informed consent prior to participation in the study. Participants who have provided written consent will be asked to attend an in-patient screening visit to provide a fasting blood sample (and females a urine sample) and assess the presence of arterial stiffness (by PWV) to determine eligibility. Should the participant be eligible to participate, they will be scheduled for three study visits to obtain fasting blood samples and assess postprandial blood vessel function. During the first study visit period, participants will be asked to complete a Food Habits Questionnaire.

Inclusion Criteria:

1. Male, or non-pregnant, non-lactating female, 45 to 65 years of age;
2. Brachial-ankle pulse wave velocity >1400 cm/s on at least one side;
3. Plasma creatinine ≤265 µmol/L;
4. Aspartate aminotransferase <160 U/L, andalanine aminotransferase <150 U/L;
5. Glycated hemoglobin ≤6.5%;
6. LDL-cholesterol <5 mmol/L;
7. Stable regime if taking vitamin and mineral/dietary/herbal supplements for the past 1 month and while participating in the study;
8. Has not donated blood or blood products (e.g. platelets) during the past 2 months and willing to continue doing so while participating in the study;
9. Not participating in another dietary intervention trial for the past month and willing to not start another dietary intervention trial for the duration of this study;
10. Willing to comply with the protocol requirements and procedures;
11. Willing to provide informed consent.

Exclusion Criteria:

1. Has experienced a cardiovascular event (e.g. heart attack, stroke) or had a surgical procedure for cardiovascular disease (e.g. bypass, stent), presence of clinically diagnosed cardiac arrhythmia or valve stenosis, chronic renal disease, liver disease (with exception of fatty liver), lung disease, rheumatoid arthritis, immune disorder or disease (e.g. multiple sclerosis, leukemia), cancer in the previous 5 years, neurological disorders, or gastrointestinal disorders;
2. Taking vasoactive medications (e.g., ACE inhibitors, ARBs, AGE-breakers, thiazolidinediones, beta-blockers, statins, insulin, etc.);
3. Blood pressure >160 mmHg systolic and/or >100 mmHg diastolic;
4. History of gastrointestinal reactions or allergies to beans, bean flour, wheat, wheat flour, gluten, or rice;
5. Body weight exceeds the capacity of the DEXA (350 lbs);
6. Current (within the past 30 days) bacterial, viral or fungal infection;
7. Bleeding disorder;
8. Amputations of upper or lower extremities on both sides;
9. Any acute medical condition or surgical intervention within the past 3 months;
10. Drug and/or alcohol abuse;
11. Psychological disorder(s);
12. Unable to fast overnight;
13. Unable to take prescribed medication without food;
14. Unable to obtain vascular function measurements and/or blood sample at the screening or first study visits;
15. Not fully vaccinated for COVID-19.