The effects of dietary hempseed on cardiac ischemia/reperfusion injury in hypercholesterolemic rabbits

Cardiac ischemia results from inadequate coronary artery flow and is commonly caused by coronary artery disease (CAD), a leading cause of death in the United States (1), Canada (2) and the United Kingdom (3). Because the myocardium is dependent on the blood supply delivered by the coronary arteries, a reduction or stop in blood flow as a result of CAD can trigger angina, arrhythmias and myocardial infarction. Restoration of blood flow through the coronary arteries is imperative but this can increase the generation of free radicals (4,5) and cause further ion disequilibrium (6,7), which may result in injury and increase the generation of arrhythmias. Nutrition has been recognized as an important factor in CAD (8). Therefore, it is not surprising that the inclusion of several foods, such as fish or flaxseed, in the diet has been shown to be cardioprotective (9–13). The polyunsaturated fatty acid (PUFA) content in these foods has been suggested to be the basis for their cardioprotective effect (14–20). It is now thought to be important to identify foods that may possess similar cardio-protective effects due to their enriched PUFA composition. Dietary hempseed contains omega-6 and omega-3 PUFAs in a 4:1 ratio, a proportion that has been recommended as having health benefits (21). This balance of PUFAs is typically lacking in the human diet due to the prevalence of omega-6 fatty acid consumption. While adequate sources of omega-3 PUFAs are available, these foods are not consumed regularly in many populations. There is limited scientific knowledge on the health-related benefits of hempseed. Its use has been documented in Arabic (22) and folk (23) medicine; however, this information must be viewed cautiously. In the past, hempseed most likely contained higher levels of tetrahydrocannabinol, a psychoactive substance, which may have given the impression of a beneficial effect. The hempseed that is available today has been selectively bred to contain very low levels of tetrahydrocannabinol (24). Thus, the existence of health benefits, specifically cardiovascular, remains unproven. The goal of the present preliminary study was to investigate the potential for dietary hempseed to provide cardioprotective effects during ischemia/reperfusion challenge.