The endothelium, a thin membrane that lines the inside of the heart and blood vessels, plays a vital role in circulatory health.
Oxidative stress, or damage from free radicals, can impact the function and health of this circulatory lining. When the endothelium sustains damage, it can lead to a loss in nitric oxide production, one of the most important molecules for maintaining blood vessel health.
As a vasodilator, nitric oxide functions to relax blood vessels, which in turn, lowers blood pressure. Our body uses nitric oxide to maintain balanced and healthy circulatory functions.
Studies have found that Quercetin supports the health of our endothelium by counteracting free radicals (reactive oxygen species) in our vascular system, helping to reduce oxidative stress, which in turn helps maintain healthy nitric oxide levels. Quercetin was also found to increase nitric oxide bioavailability and stimulate enzyme processes that increase nitric oxide production.*
Quercetin-induced autophagy, where the body eliminates dead or damaged cells, also helps to support cellular endothelial health and resiliency and, in turn, healthy nitric oxide production.*
As Quercetin is the most abundant flavonol in the human diet from fruits and vegetables, there is speculation that we may have evolved to utilize Quercetin in ways that help maintain circulatory health.*
In one Quercetin supplement study looking at the effects of 730 mg of Quercetin/day for 28 days on adults, Quercetin was found support healthy blood pressure.*
But much like studies on diets rich in fruits and vegetables, Quercetin did not impact blood pressure in adults with normal blood pressure. In summary, Quercetin may promote healthy circulatory balance.*
When lipids like cholesterol and triglycerides are high in the blood, they can accumulate in the vascular wall, which can lead to an harmful chain reaction of free radicals, oxidative stress, and cellular damage.
Genetics, diet, lifestyle, and exercise can all impact lipid metabolism and, in turn, healthy vascular wall function.
In animal studies, Quercetin was found the help maintain healthy cholesterol levels in the blood even when fed a high-fat diet and slightly lowered total cholesterol levels in animals fed a regular diet.*
Quercetin was also found to help certain types of white blood cells (THP-1-derived macrophage cells) increase the outflow of cholesterol.*
Oxidized cholesterol plays a significant role in the buildup of plaque in the vascular system. Furthermore, oxidized cholesterol can also promote clotting and damaging immune processes through its interactions with platelets, endothelium cells, and white blood cells.
As a potent antioxidant Quercetin, and other antioxidant flavonoids from fruit and vegetables were found to inhibit the oxidation of cholesterol.*
Bromelain may promote circulatory health by aiding processes that dissolve fibrin and by inhibiting the synthesis of fibrin, a protein involved in blood clotting.*
Beyond the Bullet Points
Dig deeper into the literature evolving around quercetin and bromelain and cardiovascular health.
de Whalley, C. V., Rankin, S. M., Hoult, J. R. S., Jessup, W., & Leake, D. S. (1990). Flavonoids inhibit the oxidative modification of low density lipoproteins by macrophages.Biochemical pharmacology,39(11), 1743-1750. Link
Edwards, R. L., Lyon, T., Litwin, S. E., Rabovsky, A., Symons, J. D., & Jalili, T. (2007). Quercetin reduces blood pressure in hypertensive subjects.The Journal of nutrition,137(11), 2405-2411. Link
Garelnabi, M., Mahini, H., & Wilson, T. (2014). Quercetin intake with exercise modulates lipoprotein metabolism and reduces atherosclerosis plaque formation.Journal of the International Society of Sports Nutrition,11(1), 22. Link
Hegele, R. A. (2009). Plasma lipoproteins: genetic influences and clinical implications.Nature Reviews Genetics,10(2), 109-121. Link
Khoo, N. K., White, C. R., Pozzo-Miller, L., Zhou, F., Constance, C., Inoue, T., ... & Parks, D. A. (2010). Dietary flavonoid quercetin stimulates vasorelaxation in aortic vessels.Free Radical Biology and Medicine,49(3), 339-347. Link
Kwatra, B. (2019). A review on potential properties and therapeutic applications of bromelain.World J. Pharm. Pharm. Sci,8(11), 488-500. Link
Larson, A. J., Symons, J. D., & Jalili, T. (2010). Quercetin: A treatment for hypertension?—A review of efficacy and mechanisms.Pharmaceuticals,3(1), 237-250. Link
Muselin, F., Cristina, R. T., Dumitrescu, E., Doma, A. O., Radulov, I., Berbecea, A. A., ... & Horablaga, N. M. (2022). Quercetin Beneficial Role in the Homeostatic Variation of Certain Trace Elements in Dyslipidemic Mice.Evidence-Based Complementary and Alternative Medicine,2022. Link
Papakyriakopoulou, P., Velidakis, N., Khattab, E., Valsami, G., Korakianitis, I., & Kadoglou, N. P. (2022). Potential pharmaceutical applications of quercetin in cardiovascular diseases.Pharmaceuticals,15(8), 1019. Link
Soppert, J., Lehrke, M., Marx, N., Jankowski, J., & Noels, H. (2020). Lipoproteins and lipids in cardiovascular disease: from mechanistic insights to therapeutic targeting.Advanced drug delivery reviews,159, 4-33. Link