Written by Greg Arnold, DC, CSCS, and Chrystal Moulton-Walsh, Staff Writer. Of the 48 hypertensive postmenopausal women, those who consumed 22 grams of blueberry powder for 8 weeks had a 4.4 % decrease in systolic and a 3.75 % decrease in diastolic blood pressure compared to control.
According to the Centers for Disease Control and Prevention, about 70 million American adults (29%) have high blood pressure, but only about half (52%) have it under control. High blood pressure costs our healthcare system $46 billion each year which includes the cost of health care services, medications to treat high blood pressure, and missed days of work (1).
While 70% of those with high blood pressure use medication, for the 1 in 3 American adults who have “prehypertension” (2), with a blood pressure between 120/80 and 140/90 mmHg, blood pressure medication is not recommended but rather lifestyle modifications such as a change in diet (3, 4). Now a new study (5) suggests that adding blueberries to your diet may be one such dietary modification.
The study involved 48 postmenopausal women between the ages of 53 and 63 with prehypertension. They received either 22 grams of freeze-dried blueberry powder or 22 grams of a control powder (containing maltodextrin, fructose, blueberry flavoring, artificial coloring, silica dioxide, and citric acid) daily for 8 weeks. Participants were asked to consume 11g the test content in the morning and 11g in the evening mixed in a cup of water and flavored with either vanilla extract or Splenda according to individual preference. Before the study and at 4 weeks and 8 weeks, researchers measured blood pressure as well as artery stiffness by measuring the speed at which blood travels from the neck to the leg, called carotid-femoral pulse wave velocity, and from the arm to the ankle, called brachial-ankle pulse wave velocity. In addition, blood samples were obtained to measure for an inflammatory protein called C-reactive protein, nitric oxide (which relaxes blood vessels), and an antioxidant called superoxide dismutase.
While no significant differences were seen between the two groups after 4 weeks, significant differences were noted after 8 weeks:
Parameters Measured Blueberry Group Placebo Group p- value‡
Systolic blood pressure
(mmHg)
5.1% decrease
(138 to 131)**
0.7% increase
(138 to 139)
< 0.05
Diastolic blood pressure
(mmHg)
6.25% decrease
(80 to 75)**
2.5% increase
(78 to 80)
< 0.01
Brachial-ankle pulse wave velocity
(centimeters/second)
6.5% decrease
(1,498 to 1,401)**
0.05% increase
(1,470 to 1,477)
< 0.01
Superoxide dismutase
(micromoles/Liter)
58% increase
(0.21 to 0.50)**
53.1% increase
(0.23 to 0.49)**
< 0.01
‡ P-values correspond to significant differences found within a group. P-values listed correspond to percent changes noted with an asterisk (**); ** indicates significant difference from baseline values within the groupIn the case of SOD, both groups had significant within-group differences at p<0.01.
When attempting to explain why the placebo group experienced a comparable increase in superoxide dismutase (53.1%) as the blueberry group (58% increase), the researchers stated that they were unable to give a reason why this phenomenon occurred. However, when recounting the limitations of the study, researchers noted that they did not track dietary intake during and after the trial. Furthermore, when they compared data on nitric oxide and SOD within both groups, they found that nitric oxide increased independently of SOD indicating that blueberries directly influenced nitric oxide production.
The researchers also emphasized that the significant decreases noted in systolic blood pressure did not imply that blueberry powder is a replacement for blood pressure medications as “average systolic blood pressure levels remained in the prehypertensive range at the end of the treatment period”. But these results do remain significant because “they demonstrate that blood pressure can be favorably altered by the addition of a single dietary component.”
For the researchers, their study suggests that “regular consumption of blueberries over the long term could potentially delay the progression of hypertension and reduce cardiovascular risk in postmenopausal women.”
Source: Johnson, Sarah A., et al. “Daily blueberry consumption improves blood pressure and arterial stiffness in postmenopausal women with pre-and stage 1-hypertension: a randomized, double-blind, placebo-controlled clinical trial.” Journal of the Academy of Nutrition and Dietetics 115.3 (2015): 369-377.
© 2017 Elsevier B.V. or its licensors or contributors
Posted July 23, 2015.
Greg Arnold is a Chiropractic Physician practicing in Hauppauge, NY. You can contact Dr. Arnold directly by emailing him at PitchingDoc@msn.com or visiting his web site at www.PitchingDoc.com.
Chrystal Moulton BA, PMP, is a 2008 graduate of the University of Illinois at Chicago. She graduated with a bachelor’s in psychology with a focus on premedical studies and is a licensed project manager. She currently resides in Indianapolis, IN.
References:
- “High Blood Pressure Facts” posted on the CDC website
- Nwankwo T, Yoon SS, Burt V, Gu Q. Hypertension among adults in the US: National Health and Nutrition Examination Survey, 2011-2012. NCHS Data Brief, No. 133. Hyattsville, MD: National Center for Health Statistics, Centers for Disease Control and Prevention, US Dept of Health and Human Services, 2013.
- Chobanian AV, Bakris GL, Black HR, et al. Seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Hypertension. 2003;42(6):1206-1252
- Roger V, Go A, Lloyd-Jones D, et al. Heart disease and stroke statistics-2012 update: A report from the American Heart Association. Circulation. 2012;125(1):188-197
- Johnson SA. Daily blueberry consumption improves blood pressure and arterial stiffness in postmenopausal women with pre- and stage 1-hypertension: a randomized, double-blind, placebo-controlled clinical trial. J Acad Nutr Diet 2015 Mar;115(3):369-77. doi: 10.1016/j.jand.2014.11.001. Epub 2015 Jan 8
