Blueberries are well recognized as a very healthy fruit and some have even labeled them a “super-food.” However, it is less well known that the leaves of the blueberry bush actually contain more antioxidants than the berries, giving them a greater ability to counteract free radicals and perhaps a more therapeutic value for certain diseases. As far back as the late 1920s, blueberry leaf extract was investigated for its impact on diabetes and blood sugar levels; more modern studies indicate it may also be helpful for liver disease and high blood pressure. Consult with an herbalist before embarking on a supplementation regimen of blueberry leaves.
High Blood Pressure
High blood pressure, hypertension, is referred to as the “silent killer” because it frequently doesn’t cause overt symptoms but can precipitate deadly heart attacks and strokes. As a general guideline, your blood pressure is considered high if greater than 140 systolic pressure while your heart beats and/or greater than 85 diastolic pressure while your heart relaxes, according to the “Textbook for Functional Medicine." Blood pressure can vary greatly throughout the day, with dietary factors and emotional and physical stressors having an effect. Thus, a diagnosis of hypertension should not be given based on a single blood pressure reading. Overt symptoms of hypertension include headaches, numbness and tingling in the limbs, racing heartbeat and vague feelings of anxiety.
Properties of Blueberry Leaves
Blueberry leaves are rich in antioxidants such as phenolics and phytochemicals, including chlorogenic acid, myricetin and epicatechin. These powerful antioxidants and plant compounds possess broad spectrum anti-diabetic properties, such as the ability to reduce sugar production in your liver and sugar uptake in your intestines, slow down the metabolism of carbohydrates, moderate blood insulin levels and protect the insulin producing islet cells in your pancreas, according to the “Natural Standard Herb & Supplement Reference: Evidence-based Clinical Reviews.” Diabetes and high blood pressure are related and often occur together because of the tissue damage and inflammation resulting from high levels of glucose in your blood. As such, the leaves of blueberries seem to secondarily help with hypertension.
Blueberry Leaves and Hypertension
In a variety of animal studies investigating the effects of blueberry leaves on diabetes, researchers noticed that blood triglycerides and blood pressure often normalized as well. Researchers discovered that blueberry leaf extract strongly inhibited the effects of an angiotensin-converting enzyme and reduced hypertension in rats, according to a Japanese study published in a 2007 edition of the journal “Bioscience, Biotechnology and Biochemistry.” The researchers concluded that the results are promising for the use of blueberry leaf as a hypotensive remedy.
Recommendations
Blueberry leaves are consumed a variety of ways, including chewed raw or made into an herbal tea, but for therapeutic use it’s best to consider blueberry leaf extract because of its high concentration of antioxidants. Many of the beneficial plant compounds found in the leaves are also within the blueberries, grapes and green tea leaves, albeit in lower concentrations. If you have diabetes or high blood pressure, ask your doctor if blueberry leaf extract is safe and appropriate for you to try.
References
- “Textbook for Functional Medicine”; David S. Jones; 2005
- “Natural Standard Herb & Supplement Reference: Evidence-based Clinical Reviews”; Catherine E. Ulbricht, et al; 2005
- "Bioscience, Biotechnology and Biochemistry"; Effect of Vaccinium ashei reade Leaves on Angiotensin Converting Enzyme Activity in Vitro and on Systolic Blood Pressure of Spontaneously Hypertensive Rats in Vivo; H. Sakaida, et al.; September 2007
