Postmenopausal women have a high prevalence of hypertension (high blood pressure) and often develop arterial stiffness (hardening of the arteries), resulting in increased cardiovascular disease risk. Medications are available to help treat risk factors, but many patients prefer natural therapies. The results of a recent clinical trial suggest that eating blueberries daily may reduce blood pressure and arterial stiffness. The study was published in The Journal of the Academy of Nutrition and Dietetics, and publicized in The New York Times on January 14, 2015.
Q: What is in blueberries that may reduce blood pressure and arterial stiffness?
A: Blueberries contain powerful natural compounds call flavonoids which include anthocyanin. These substances act as antioxidants (which reduce cell damage) and antioxidants can increase the production of nitric oxide in the blood vessel. One of nitric oxide’s main jobs is increasing blood flow by dilating blood vessels thus lowering blood pressure. Anthocyanin gives blueberries and other berries such as cranberries and strawberries their bright color.
Q: How was this study conducted? What amount of blueberries was consumed per day as part of this study?
A: At the start of the study 48 postmenopausal women with pre or mild high blood pressure were randomly placed in one of two groups. Group 1 was given 22 grams of freeze dried blueberry powder to take daily for 8 weeks and group 2 was given 22 grams of a powder without blueberry content. This is equivalent to 1 cup of blueberries per day. The women had their blood pressure, artery stiffness, and certain blood markers measured. During the eight weeks the women carried on with their normal exercise and diet.
Q: Why did the study focus particular on postmenopausal women with high blood pressure and arterial stiffness?
A: High blood pressure is an important risk factor for developing heart disease. After menopause, the risk of high blood pressure increases in women. Arterial stiffness and the narrowing of blood vessels are both related to the development of high blood pressure.
Q: What specifically did the results show?
A: At the end of the study, women who were taking the blueberry-containing powder had a 5.1 percent lowering of systolic blood pressure, which is the top number in the blood pressure reading. They also had a decrease of 6.3 percent in diastolic blood pressure, or the bottom number measuring the pressure. Additionally, the women taking the blueberry-containing powder had a 6.5 percent decrease in their arterial stiffness and measurement of nitric oxide in their blood increased by 68.5 percent. As we discussed earlier, both of these changes can lower blood pressure.
Q: Are there other foods that may decrease cardiovascular risks, and other ways for women to improve their cardiovascular health?
A: Diet can play an important role in decreasing a woman’s risk of heart disease. Start with small changes, get used to the change and then build on it. Easy things to remember include avoiding fried fast food and processed foods containing vegetable shortening. When preparing meals, choose a variety of oils (extra virgin olive oil, canola, peanut) and foods containing natural fats (nuts, seeds, avocado, olives, soy, fish). Make simple changes for a healthier choice such as low-fat or non-fat dairy products. Always remember to include a variety of plant foods such as unrefined vegetables, fruits and wholegrain cereals in your meal plan. Try to add legumes (like baked beans, soybeans, lentils and tofu) instead of white potatoes and rice with dinner. At work, have a handful of a variety of raw unsalted nuts available, especially walnuts and almonds. Eat oily fish at least once per week. Trim all visible fat from meat and remove poultry skin and eat only the meat. Avoid added salt at the table. Check the sodium content of foods and choose the lowest sodium products. Physical activity is important for women of every age. Exercise does not need to strenuous, does not require expensive equipment, does not mean you must belong to a gym! Try getting at least 30-minutes of moderate intensity physical activity as many days of the week as you can. Exercise can be broken up into shorter intervals such as three 10-minute sessions most days of the week and you will still be decreasing your risk of heart disease. The most important thing is to MOVE! All activities count even walking while talking on the phone, gardening, housekeeping, going up and down stairs, playing with the children. The more you move the healthier your heart will be.
Source: Yale University