The COCOA-PAD II Trial

Inclusion Criteria:

1. Age 55 and older

2. Presence of peripheral artery disease (PAD). PAD will be defined as either:

3. An ABI <= 0.90 at baseline.

4. Vascular lab evidence of PAD (such as a toe brachial pressure < 0.70 or anankle brachial index less than or equal to 0.90), or angiographic evidence ofPAD defined as at least 70% stenosis of an artery supplying the lowerextremities.

5. An ABI of >0.90 and <=1.00 who experience a a 20% or greater drop in ABI ineither leg after the heel-rise test will also be included.

Exclusion Criteria:

1. Above- or below-knee amputation

2. Critical limb ischemia

3. Wheelchair confinement or requiring a walker to ambulate

4. Walking is limited by a symptom other than PAD

5. Current foot ulcer on bottom of foot

6. Failure to successfully complete the one-week study run-in

7. Planned major surgery, coronary or leg revascularization during the next eightmonths

8. Major surgery, coronary or leg revascularization or major cardiovascular event inthe previous three months

9. Major medical illness including lung disease requiring oxygen, Parkinson's disease,a life-threatening illness with life expectancy less than eight months, or cancerrequiring treatment in the previous two years. [NOTE: potential participants maystill qualify if they have had treatment for an early stage cancer in the past twoyears and the prognosis is excellent. Participants who require oxygen only at nightmay still qualify.]

10. Mini-Mental Status Examination (MMSE) score < 23

11. Allergy to the study intervention

12. Potential participants who have taken cocoa supplements in previous three months,are unwilling to avoid taking cocoa flavanol supplements, or are consuming darkchocolate regularly (i.e. approximately 1.5 ounces of dark chocolate more than threetimes per week, or more than 4.5 ounces per week).

13. Non-English speaking

14. Participation in or completion of a clinical trial in the previous three months. [NOTE: after completing a stem cell or gene therapy intervention, participants willbecome eligible after the final study follow-up visit of the stem cell or genetherapy study so long as at least six months have passed since the finalintervention administration. After completing a supplement or drug therapy (otherthan stem cell or gene therapy), participants will be eligible after the final studyfollow-up visit as long as at least three months have passed since the finalintervention of the trial.]

15. Visual impairment that limits walking ability

16. Six-minute walk distance of <500 feet or >1600 feet.

17. Participation in a supervised treadmill exercise program in previous three months

18. Unable to tolerate caffeine

19. In addition to the above criteria, investigator discretion will be used to determineif the trial is unsafe or not a good fit for the potential participant