Study Finds Eating Raisins Regularly Helps Lower Blood Pressure

Posted on March 26, 2012

A study has found that eating raisins may help lower blood pressure. Research presented today at the American College of Cardiology's 61st Annual Scientific Session suggests that, among individuals with mild increases in blood pressure, the consumption of raisins 3 times a day may significantly lower blood pressure, especially when compared to eating other common snacks. Raisins are often cited as a food that can lower blood pressure and benefit heart health, but the researchers believe this is the first controlled study to scientifically support raisins' blood pressure-lowering effects, especially when compared to alternative snacks.

Harold Bays, MD, medical director and president of Louisville Metabolic and Atherosclerosis Research Center (L-MARC) and the study's lead investigator, says, "It is often stated as a known fact that raisins lower blood pressure. But we could not find much objective evidence in the medical literature to support such a claim. However, our study suggests if you have a choice between eating raisins or other snacks like crackers and chocolate chip cookies, you may be better off snacking on raisins at least with respect to blood pressure."

Dr. Bays and his team conducted a randomized controlled clinical trial to compare the blood pressure effect of eating raisins versus other snacks in 46 men and women with prehypertension. Participants were randomly assigned to snack on raisins or prepackaged commercial snacks that did not contain raisins, other fruits or vegetables but had the same number of calories per serving three times a day for 12 weeks. The study controlled for individual differences in nutrition and physical activity.

Data analyses found that compared to other snacks, raisins significantly reduced systolic blood pressure at weeks 4, 8, and 12, ranging from -4.8 to -7.2% or -6.0 to -10.2 mmHg (p values <0.05). Within group analysis demonstrated that raisins significantly reduced mean diastolic blood pressure at all study visits, with changes ranging from -2.4 to - 5.2 mmHg (p values < 0.05). Pre-packaged snacks (including crackers and cookies) did not significantly reduce systolic or diastolic blood pressure at any study visit.

The study did not identify how raisins can lower blood pressure, but they are high in potassium, and have fiber, polyphenols, phenolic acid, tannins and antioxidants.

Dr. Bays says, "Raisins are packed with potassium, which is known to lower blood pressure. They are also a good source of antioxidant dietary fiber that may favorably alter the biochemistry of blood vessels, causing them to be less stiff, which in turn, may reduce blood pressure."

Dr. Bays cautions that this was a single site study and larger trials are needed to confirm the blood pressure-regulating effect of raisins.