Cranberries + Heart Health
According to the U.S. Centers for Disease Control and Prevention, heart disease is the leading cause of death in the United States for both men and women. More than a quarter of all deaths each year in both males and females are due to heart disease.
There are many research studies that help explain how cranberries may help maintain heart health. The following information describes studies in cell cultures, animals, and humans. Human studies provide the best scientific evidence; however, all studies provide information that helps researchers and health professionals determine the role of cranberries play in a heart healthy diet.
Cranberries and Cholesterol
Reducing LDL cholesterol and triglycerides and increasing HDL cholesterol are important steps in managing risk of heart disease. The following studies describe how cranberries, as part of a heart healthy diet, may help maintain healthy cholesterol levels.
A cell culture study by Chu and colleagues (1) showed that when a cranberry extract was added to liver cells, the liver cells developed more receptors that bind LDL cholesterol. Having more LDL receptors means LDL cholesterol is cleared from the blood more efficiently. Researchers do not yet know if this same effect happens in human who consume cranberry products.
Many researchers have shown in cell culture studies that cranberries inhibit LDL oxidation. Oxidized LDL is more likely to stick to artery walls compared to non-oxidized LDL cholesterol. Wilson and colleagues have published multiple studies (2,3) using cranberry extracts and cranberry juice to reduce oxidation of LDL cholesterol. There are many antioxidant compounds in cranberries that can explain this effect.
An animal study by Reed (4) tested the effects of cranberry juice powder on blood cholesterol levels. Total cholesterol levels dropped the most in the animals (pigs) with the highest baseline cholesterol levels. This is the case with many dietary interventions for high cholesterol; the higher the initial level, the greater the reduction in total cholesterol. Eating cranberries as part of a healthy diet that is rich in fruits, vegetables, whole grains and other plant-based foods like nuts and legumes may help maintain healthy cholesterol levels.
A 28-day human study by Caron and colleagues (5) showed that subjects who drank a low calorie cranberry juice (compared to a non-cranberry placebo beverage) experienced significant reductions in total cholesterol and LDL cholesterol. No significant changes occurred in triglycerides or HDL cholesterol.
Cranberries and Blood Pressure
Maintaining healthy blood pressure levels can help reduce risk of stroke, one form of heart disease. Sodium and potassium are two minerals related to blood pressure control. A high sodium diet may increase blood pressure while a high potassium diet may reduce blood pressure.
Cranberries, as part of heart healthy diet, may help maintain healthy blood pressure levels. Cranberries are not only naturally low in sodium, but they also contain potassium. Choosing foods like cranberries that contain more potassium than sodium is one way to help maintain healthy blood pressure levels.
Cranberries and Endothelial Cell Health
Endothelial cells line the arteries throughout the human body. When endothelial cells are damaged by oxidative stress or inflammation, scar tissue builds up in the damaged area. Over time, cholesterol sticks to the scar tissue. This is what causes blockages in the major arteries leading to the heart.
An endothelial cell culture study by Youdim and colleagues (6) showed that antioxidant compounds found in cranberries (like anthocyanins and hydroxycinnamic acids) protect the cells from oxidative damage. Youdim and colleagues were also able to show that cranberry anthocyanins, compounds in cranberries that give them their vibrant red color, are able to suppress inflammation, another occurrence that can damage endothelial cells and lead to scar tissue development.
An animal study by Maher and colleagues (7) showed that when rats were intravenously given cranberry juice or saline, the cranberry treatment decreased blood pressure. As part of this same study, they conducted an arterial cell study to test the effects of cranberry juice on nitric oxide formation in the arterial endothelial cells. When endothelial cells produce nitric oxide, arteries relax, thereby reducing blood pressure. This cell study showed that cranberry juice caused the endothelial cells to produce nitric oxide, which helps explains how cranberries may help promote healthy blood pressure levels.
(1) Chu FY, Liu RH. Cranberries inhibit LDL oxidation and induce LDL receptor expression in hepatocytes. Life Sci. 2005;77:1892-1901.
(2) Wilson T, Porcari JP, Harbin D. Cranberry extract inhibits low density lipoprotein oxidation. Life Sci. 1998;62:381-386.
(3) Wilson T, Porcari JP, Maher MA. Cranberry juice inhibits metal and non-metal initiated oxidation of human low density lipoproteins in vitro. J Nutraceut Function Med Food. 1999;2:5-14.
(4) Reed J. Cranberry flavonoids, atherosclerosis, and cardiovascular health. Crit Rev Food Sci Nutr. 2002;42(Supp):301-316.
(5) Caron AD, Kautza BC, Wilson T. Cholesterol lowering effect of low calorie cranberry juice in humans. FASEB J. 2005;19:A1009-1010.
(6) Youdim KA, McDonald J, Kalt W, Joseph JA. Potential role of dietary flavonoids in reducing microvascular endothelium vulnerability to oxidative and inflammatory insults. J Nutr Biochem. 2002;13:282-288.
(7) Maher MA, Mataczynski H, Stefaniak HM, Wilson T. Cranberry juice induces nitric oxide-dependent vasodilation in vitro and its infusion transiently reduces blood pressure in anesthetized rats. J Med Food. 2000;3:141-147.