Times have changed. It used to be that an apple a day kept the doctor away.
But three recent studies indicate this mantra could be changed to “a blueberry-avocado-cocoa-bean-smoothie a day” keeps the doctor away—if the doctor is a cardiologist.
The new heart benefits of blueberries were outlined in the Journal of the Academy of Nutrition and Dietetics by Florida State University researchers led by Sarah Johnson, assistant director of the Center for Advancing Exercise and Nutrition Research on Aging.
Over a mere eight weeks, 48 postmenopausal women with pre- and stage-one hypertension were randomly given either 22 grams of freeze-dried blueberry powder— equal to one cup of fresh blueberries—or 22 grams of a placebo powder. They continued dieting and exercising as usual.
At the study’s start, patients’ blood pressure was taken and their arterial stiffness was measured. Certain blood biomarkers were also ascertained.
By the end of the study, patients who consumed blueberry powder, on average, experienced a 7 mmHg (5.1 percent) decrease in systolic blood pressure and a 5 mmHg (6.3 percent) reduction in diastolic blood pressure. They also experienced an average reduction of 97 cm/second (6.5 percent) in arterial stiffness.
The researchers discovered that nitric oxide, a biomarker for in blood vessel widening, increased by 68.5 percent. The nitric oxide likely caused the reductions in blood pressure.
Earlier studies showed blueberries lowered blood pressure, but they involved much larger and more untenable daily quantities of blueberry powder, from 50 to 250 grams (or 11 daily cups of fresh blueberries).
Next the group will study other doses, longer consumption periods and different populations of patients.
Meanwhile, an avocado a day benefits your heart in another way: it may help lower bad cholesterol, according to a recent study in the Journal of the American Heart Association. In particular, the study found that adding an avocado a day to a moderate-fat, cholesterol-lowering diet—compared with a moderate-fat diet without an avocado—offers heightened LDL (low-density lipoproteins, or bad cholesterol) lowering benefits.
Professor of nutrition Penny Kris-Etherton and her team actually tested three commonly adopted anti-cholesterol diets: a lower-fat diet of 24 percent fat, and two moderate fat diets of 34 percent fat. The moderate fat diets were similar, although one incorporated one avocado daily, while the other incorporated an equivalent amount of high oleic acid oils.
The avocados used were Hass avocados, which are smaller, bumpier and darker than Florida avocados.
The 45 participants were overweight adults aged 21 to 70. All three diets significantly lowered LDL and total cholesterol. However, a greater reduction in LDL and total cholesterol occurred among those on the avocado diet, compared with the other two.
LDL was reduced by 13.5 mg/dL on the avocado diet. LDL was reduced by 8.3 mg/dL on the moderate-fat diet, and by 7.4 mg/dL on the low-fat diet.
Everyone involved followed each diet for five weeks, with a two-week break in between each diet. Blood samples were taken at the start and finish of each period. The order of the diets was randomly assigned.
The study was conducted, unsurprisingly, by Mars, Inc. and a team from the University of L’Aquila. Led by Giovambattista Desideri, it was the second of two studies. The first, published in a 2012 issue of Hypertension, found both cognitive and cardio-metabolic benefits from habitual cocoa flavanol consumption in older people with mild cognitive impairment (MCI).
The new study, which was controlled, randomized and double-blind, attempted to address the same questions in people without MCI. Men and women 61 to 85 years old drank one of three different amounts of flavanols from cocoa: high (993 mg), intermediate (520 mg), or low (48 mg) daily for eight weeks. The high- and intermediate-flavanol cocoa drinks were made using a process devised by Mars; the low-flavanol drink was made with an alkalized cocoa powder. The participants otherwise continued with their normal diets.
Among those drinking the high- and intermediate-flavanol drinks, there were significant improvements in cognitive function after eight weeks. Importantly, there was evidence that accompanying improvements in heart cardiometabolic levels may have been responsible. In the high- and intermediate-flavanol groups, both systolic and diastolic blood pressures dropped, and insulin resistance was improved. By contrast, there was only a small improvement in diastolic blood pressure in the low-flavanol group, and no significant improvements in either systolic blood pressure or insulin resistance among those drinking the low-flavanol drink.
There are variable levels of flavanols in chocolate, as opposed to cocoa beans, so no one is recommending that people rush out to buy out the local candy store. The study’s product is not commercially available. Further testing is being done.