- Eating a handful of wild blueberries every day may boost cognitive and cardiovascular health, according to a new study.
- The study reveals that blueberry anthocyanins are responsible for improving vascular and cerebral blood flow, which are some of the likely mechanisms behind healthy cognitive function.
- Anthocyanins are polyphenols, a family of plant compounds increasingly associated with health benefits.
A cup of wild blueberries is more than a tasty snack, according to new research from the Faculty of Life Sciences and Medicine at King’s College London in the UK. It can also stimulate the brain, lower blood pressure and contribute to better cardiovascular health.
The randomized, double-blind, placebo-controlled trial found that blueberry eaters had improved executive function, enhanced short-term memory, and faster reaction times.
Study participants who had a daily drink of 26 grams (g) of freeze-dried wild blueberry powder for 12 weeks saw a 3.59 millimeters of mercury (mmHG) reduction in systolic blood pressure and an improvement in blood vessel function compared to people consuming a placebo powder.
Participants who consumed blueberries were better at immediately remembering word lists and showed improvement
The study appears in the American Journal of Clinical Nutrition.
The study involved 61 healthy male and female participants from London, aged between 65 and 80. For 12 weeks, half of them drank a drink containing 26g of freeze-dried wild blueberry powder daily, while the other half consumed a placebo matching taste, appearance, macronutrients, fiber and vitamin C.
It is common for food studies to use powdered substances for precision measurements.
The 26g of blueberry powder the participants drank each day was equivalent to 178g of whole blueberries. This translates to somewhere between 75 and 80 blueberries, as they vary in size.
Lead researcher Dr. Ana Rodriguez-Mateos noted Medical News Today that blueberries don’t have to be wild, as “other studies have been done with other types of blueberries showing cognitive and vascular health benefits.”
Researchers believe that the beneficial effects of blueberries are due to their blue pigments called
“Anthocyanins are a class of polyphenols,” explained Michelle Routhenstein, a heart health dietitian not involved in this study.
“[T]there are about 8,000 different types of polyphenols that provide health benefits,” she added. “Some other types of foods that contain beneficial polyphenols include green tea, broccoli, pears, and spices like turmeric and cinnamon.”
Anthocyanins are also present in strawberries, raspberries, red grapes and purple vegetables.
“There is evidence of the health benefits of other anthocyanin-rich foods, and there’s no reason to think they won’t work as well as blueberries, as long as the amount of anthocyanins provided with these food is sufficient and that the anthocyanins are bioaccessible and bioavailable.
– Dr. Ana Rodriguez-Mateos
Dr. Rodriguez-Mateos and co-author Dr. Claire Williams studied the cognitive and cardiovascular benefits of blueberries separately and found similar results.
As a result, Dr. Rodriguez-Mateos said, they “decided to simultaneously investigate effects on vascular and cognitive functions in a clinical study.”
They set out to measure cerebral blood flow since other research suggested it might be a mechanism behind the beneficial effects of polyphenols as well as increased vascular blood flow.
Moreover, recent insights into the gut microbiota and the gut-brain axis prompted them to explore this relationship as well.
The mechanism behind the beneficial effects of polyphenols is not yet fully understood.
One theory is that polyphenols “may act as signaling molecules, acting through several cellular signaling pathways, modulating nitric oxide bioavailability and different enzymes,” Dr. Rodriguez-Mateos said.
Researchers found an increase in anthocyanin metabolites in participants’ urine after the 12-week study period.
Dr. Rodriguez-Mateos is certain that “the mechanism of action in blood vessels is
Although the study found evidence that blueberries improved cerebral and vascular blood flow, it found no difference in arterial stiffness and blood lipids between people consuming the fruit and the placebo group.
Always, “[w]When blood flow is improved, heart and brain health is beneficial,” Routhenstein said.
Regarding the role of the gut microbiota, said Dr. Rodriguez-Mateos, “one hypothesis we proposed in our study is that polyphenols may act by increasing the abundance of beneficial butyrate-producing bacteria, and therefore the production of butyrate”.
She added that this needs to be confirmed in other studies.
According to the American Heart Association, better cardiovascular and cognitive health are promoted by eating a diet high in vegetables, fruits, whole grains, healthy proteins, minimally processed foods, and moderate oil.
Recent research has indicated that a Mediterranean diet may be the optimal diet for heart health.
Routhenstein mentioned the benefits of “green vegetables, especially spinach, Swiss chard and kale rich in nitrates, which can help dilate the arteries.”
“It helps improve blood circulation and improve vascular, cardiac and cognitive functions,” she noted.
There are many other foods linked to cognitive health, Routhenstein said. “Omega-3 fatty acids like wild salmon and sardines are linked to better cognition due to their richness
Besides, “[s]Some studies suggest that unsaturated fats, like omega-3 fatty acids, may also help reduce levels of beta-amyloid, a component in the development and progression of Alzheimer’s disease.
