Thursday, February 5, 2015

Health Benefits of Chocolate - Cognitive Decline/Dementia Benefits


Dark chocolate improves attention

Larry Stevens eats a piece of high-cacao content chocolate every afternoon, which is in part because he has developed a taste for the unsweetened dark chocolate. It's also because research shows that it lowers blood pressure and his new study reveals that it improves attention, which is especially important when hitting that midday slump.

"Chocolate is indeed a stimulant and it activates the brain in a really special way," said Stevens, a professor of psychological sciences at NAU. "It can increase brain characteristics of attention, and it also significantly affects blood pressure levels."

The study, published in the journal NeuroRegulation and sponsored by the Hershey Company, is the first to examine the acute effects of chocolate on attentional characteristics of the brain and the first-ever study of chocolate consumption performed using electroencephalography, or EEG technology. EEG studies take images of the brain while it is performing a cognitive task and measure the brain activity.

Historically, chocolate has been recognized as a vasodilator, meaning that it widens blood vessels and lowers blood pressure in the long run, but chocolate also contains some powerful stimulants. Stevens said his team wanted to investigate if people who consume chocolate would see an immediate stimulant effect.

Stevens and his colleagues in the Department of Psychological Sciences performed the EEG study with 122 participants between the ages of 18 and 25 years old. The researchers examined the EEG levels and blood pressure effects of consuming a 60 percent cacao confection compared with five control conditions.

Michelle Montopoli, an NAU alumna and student at the time of the study, led the EEG testing phase which included measuring serving sizes of the samples based on participant weight and packaging them so the participants were blind to what they were tasting. Constance Smith, professor of psychological sciences, assisted with the physiological analyses.

The results for the participants who consumed the 60 percent cacao chocolate showed that the brain was more alert and attentive after consumption. Their blood pressure also increased for a short time.

"A lot of us in the afternoon get a little fuzzy and can't pay attention, particularly students, so we could have a higher cacao content chocolate bar and it would increase attention," Stevens said. He added that a regular chocolate bar with high sugar and milk content won't be as good, it's the high-cacao content chocolate that can be found from most manufacturers that will have these effects.

The most interesting results came from one of the control conditions, a 60 percent cacao chocolate which included L-theanine, an amino acid found in green tea that acts as a relaxant. This combination hasn't been introduced to the market yet, so you won't find it on the candy aisle. But it is of interest to Hershey and the researchers.

"L-theanine is a really fascinating product that lowers blood pressure and produces what we call alpha waves in the brain that are very calm and peaceful," Stevens said. "We thought that if chocolate acutely elevates blood pressure, and L-theanine lowers blood pressure, then maybe the L-theanine would counteract the short-term hypertensive effects of chocolate."

For participants who consumed the high-cacao content chocolate with L-theanine, researchers recorded an immediate drop in blood pressure. "It's remarkable. The potential here is for a heart healthy chocolate confection that contains a high level of cacao with L-theanine that is good for your heart, lowers blood pressure and helps you pay attention," Stevens said.

Stevens hopes the results of this study will encourage manufacturers to investigate further and consider the health benefits of developing a chocolate bar made with high-cacao content and L-theanine.

"People don't generally eat chocolate and think it's going to be healthy for them," Stevens said. He added that there is a possibility the millions of hypertension patients in the country could eat a bar of this heart healthy chocolate every afternoon and their blood pressure would drop into the normal range, and they would be more alert and attentive.
Mounting evidence demonstrates improved cognitive function from cocoa flavanol consumption

It is normal for cognitive function to slightly deteriorate with age. Memory capacity begins to worsen, along with processing speed and the ability to form long-term memories. Finding a way to defer the onset of these issues becomes increasingly important as life expectancy gets longer and global populations age.

This study, conducted by researchers from Italy's University of L'Aquila and Mars, Incorporated, reinforces the results of several recent cognitive studies--throwing more light on the important role diet plays in maintaining cognitive health. Dr. Giovambattista Desideri, lead author on the paper, said, "The results of this study are encouraging--they support the idea that diet, and specifically a diet rich in cocoa flavanols, can play an important role in maintaining cognitive health as we age."

This study was the second installment in a two-part investigation by this team into the effects cocoa flavanols have on the brain. The first study, published in the journal Hypertension in 2012, found cognitive and cardiometabolic benefits of habitual cocoa flavanol consumption in older adults who had been diagnosed with mild cognitive impairment (MCI). Despite these findings, the question of the benefits of cocoa flavanols on cognitive function among individuals without MCI remained uncertain.

This second study just published in the AJCN looked to address this question. Enrolling men and women aged 61-85 years with no evidence of cognitive dysfunction, the participants in this controlled, randomized, double-blind study were assigned to one of three flavanol groups, consuming a drink containing either high (993 mg), intermediate (520 mg) or low (48 mg) amounts of cocoa flavanols every day for eight weeks. The nutritionally matched drinks were specially prepared. The high- and intermediate-flavanol cocoa drinks were produced using Mars' patented Cocoapro® process, while the low-flavanol drink was made with a highly processed, alkalized cocoa powder. Other than the inclusion of the test drink, normal diets and regular lifestyle were maintained throughout the study.

At the start of the study and again after eight weeks, cognitive function was assessed using a battery of tests that examined memory, retention, recall, as well as executive function. Among those individuals who regularly consumed either the high- or intermediate-flavanol drinks, there were significant improvements in overall cognitive function after only eight weeks. As cognitive function was normal for this aged population, this study shows that even cognitively healthy individuals can quickly benefit from the regular inclusion of cocoa flavanols in their diets.

In addition to evaluating cognitive function, the researchers also monitored insulin resistance, blood pressure and other metabolic markers. Excitingly, there was also evidence of improvements in these cardiometabolic outcomes. In the high- and intermediate-flavanol groups, both systolic and diastolic blood pressures were reduced and insulin resistance was significantly improved. In contrast, only a modest improvement in diastolic blood pressure was observed in the low-flavanol group, with no significant improvements in either systolic blood pressure or insulin resistance among the consumers of the low-flavanol drink.

It is not yet fully understood how cocoa flavanols bring about improvements in cognitive function, but the study's authors suggest that the improvements in insulin resistance and blood pressure could be revealing. "Earlier studies suggest a central role for insulin resistance in brain aging," said Desideri. "These results could therefore provide some insight into a possible mechanism of action for the cognitive improvements we have observed."

Over the past decade, there has been significant evidence indicating that consuming cocoa flavanols improves vascular function. Dr. Catherine Kwik-Uribe, human health and nutrition director at Mars, Incorporated, and co-author on this latest study, said, "Since the brain is a heavily vascularized tissue, we might also be looking at vascular improvements as underlying the observed improvements in cognitive function."

Dr. Kwik-Uribe went on to speak about Mars' flavanol research program that has spanned over two decades: "The amount of research showing the beneficial effects of cocoa flavanol consumption is growing and Mars is proud to be a partner in important research like this that highlights the positive role cocoa flavanols may play in supporting healthy aging."

Dr. Desideri and his team are already thinking about the next steps: "It is clear from our latest research and other recent studies that cocoa flavanols have profound effects on the body, and specifically the brain," said Desideri. "Now we'd like to know how they work and how long the effects last. If these further studies confirm the findings that brain health can be improved by consuming dietary flavanols, it may have the potential to affect the daily lives of millions of people world-wide."

Chocolate may help keep brain healthy

Drinking two cups of hot chocolate a day may help older people keep their brains healthy and their thinking skills sharp, according to a study published in the August 7, 2013, online issue of Neurology®, the medical journal of the American Academy of Neurology.

The study involved 60 people with an average age of 73 who did not have dementia. The participants drank two cups of hot cocoa per day for 30 days and did not consume any other chocolate during the study. They were given tests of memory and thinking skills. They also had ultrasounds tests to measure the amount of blood flow to the brain during the tests.

"We're learning more about blood flow in the brain and its effect on thinking skills," said study author Farzaneh A. Sorond, MD, PhD, of Harvard Medical School in Boston and a member of the American Academy of Neurology. "As different areas of the brain need more energy to complete their tasks, they also need greater blood flow. This relationship, called neurovascular coupling, may play an important role in diseases such as Alzheimer's."

Of the 60 participants, 18 had impaired blood flow at the start of the study. Those people had an 8.3-percent improvement in the blood flow to the working areas of the brain by the end of the study, while there was no improvement for those who started out with regular blood flow.

The people with impaired blood flow also improved their times on a test of working memory, with scores dropping from 167 seconds at the beginning of the study to 116 seconds at the end. There was no change in times for people with regular blood flow.

A total of 24 of the participants also had MRI scans of the brain to look for tiny areas of brain damage. The scans found that people with impaired blood flow were also more likely to have these areas of brain damage.

Half of the study participants received hot cocoa that was rich in the antioxidant flavanol, while the other half received flavanol-poor hot cocoa. There were no differences between the two groups in the results.

"More work is needed to prove a link between cocoa, blood flow problems and cognitive decline," said Paul B. Rosenberg, MD, of Johns Hopkins School of Medicine in Baltimore, who wrote an editorial accompanying the study. "But this is an important first step that could guide future studies."

Dietary cocoa flavanols reverse age-related memory decline

Dietary cocoa flavanols -- naturally occurring bioactives found in cocoa -- reversed age-related memory decline in healthy older adults, according to a study led by Columbia University Medical Center (CUMC) scientists. The study, published today in the advance online issue of Nature Neuroscience, provides the first direct evidence that one component of age-related memory decline in humans is caused by changes in a specific region of the brain and that this form of memory decline can be improved by a dietary intervention.

The researchers point out that the product used in the study is not the same as chocolate, and they caution against an increase in chocolate consumption in an attempt to gain this effect.

As people age, they typically show some decline in cognitive abilities, including learning and remembering such things as the names of new acquaintances or where one parked the car or placed one's keys. This normal age-related memory decline starts in early adulthood but usually does not have any noticeable impact on quality of life until people reach their fifties or sixties. Age-related memory decline is different from the often-devastating memory impairment that occurs with Alzheimer's, in which a disease process damages and destroys neurons in various parts of the brain, including the memory circuits.

Previous work, including by the laboratory of senior author Scott A. Small, MD, had shown that changes in a specific part of the brain -- the dentate gyrus -- are associated with age-related memory decline. Until now, however, the evidence in humans showed only a correlational link, not a causal one. To see if the dentate gyrus is the source of age-related memory decline in humans, Dr. Small and his colleagues tested whether compounds called cocoa flavanols can improve the function of this brain region and improve memory. Flavanols extracted from cocoa beans had previously been found to improve neuronal connections in the dentate gyrus of mice.

A cocoa flavanol-containing test drink prepared specifically for research purposes was produced by the food company Mars, Incorporated, which also partly supported the research, using a proprietary process to extract flavanols from cocoa beans. Most methods of processing cocoa remove many of the flavanols found in the raw plant.

In the CUMC study, 37 healthy volunteers, ages 50 to 69, were randomized to receive either a high-flavanol diet (900 mg of flavanols a day) or a low-flavanol diet (10 mg of flavanols a day) for three months. Brain imaging and memory tests were administered to each participant before and after the study. The brain imaging measured blood volume in the dentate gyrus, a measure of metabolism, and the memory test involved a 20-minute pattern-recognition exercise designed to evaluate a type of memory controlled by the dentate gyrus.

"When we imaged our research subjects' brains, we found noticeable improvements in the function of the dentate gyrus in those who consumed the high-cocoa-flavanol drink," said lead author Adam M. Brickman, PhD, associate professor of neuropsychology at the Taub Institute.

The high-flavanol group also performed significantly better on the memory test. "If a participant had the memory of a typical 60-year-old at the beginning of the study, after three months that person on average had the memory of a typical 30- or 40-year-old," said Dr. Small. He cautioned, however, that the findings need to be replicated in a larger study -- which he and his team plan to do.

Flavanols are also found naturally in tea leaves and in certain fruits and vegetables, but the overall amounts, as well as the specific forms and mixtures, vary widely.

The precise formulation used in the CUMC study has also been shown to improve cardiovascular health. Brigham and Women's Hospital in Boston recently announced an NIH-funded study of 18,000 men and women to see whether flavanols can help prevent heart attacks and strokes.
The researchers point out that the product used in the study is not the same as chocolate, and they caution against an increase in chocolate consumption in an attempt to gain this effect.

Besides flavanols, exercise has been shown in previous studies, including those of Dr. Small, to improve memory and dentate gyrus function in younger people. In the current study, the researchers were unable to assess whether exercise had an effect on memory or on dentate gyrus activity. "Since we didn't reach the intended VO2max (maximal oxygen uptake) target," said Dr. Small, "we couldn't evaluate whether exercise was beneficial in this context. This is not to say that exercise is not beneficial for cognition. It may be that older people need more intense exercise to reach VO2max levels that have therapeutic effects."

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