Cocoa flavanols

Blending certain ingredients in fruit smoothies can influence whether your body is getting a nutritional boost, finds a new study. Smoothies can be a tasty and convenient way to get the important fruits and vegetables you need for a healthy diet. But is a banana and blueberry smoothie the best combo? Researchers at the University of California, Davis, suggest that blending certain ingredients in smoothies can influence whether your body is getting a nutritional boost. The study, published today in the Royal Society of Chemistry's journal Food and Function, used smoothies to test how various levels of polyphenol oxidase, an enzyme in many fruits and vegetables, affects the levels of flavanols in food to be absorbed by the body. Flavanols are a group of bioactive compounds that are good for your heart and cognitive health and are naturally found in apples, pears, blueberries, blackberries, grapes and cocoa -- common smoothie ingredients. "We sought to understand, on a very practical level, how a common food and food preparation like a banana-based smoothie could affect the availability of flavanols to be absorbed after intake," said lead author Javier Ottaviani, director of the Core Laboratory of Mars Edge, which is part of Mars, Inc., and an adjunct researcher with the UC Davis Department of Nutrition. Slice an apple or peel a banana and the fruit will quickly turn brown. That happens because of polyphenol oxidase, or PPO, an enzyme naturally present in those foods. The browning occurs when the food containing that enzyme is exposed to air, cut or bruised. The researchers wanted to know whether consuming freshly prepared smoothies made with different PPO-containing fruits impacted the amount of flavanols available to the body. Bananas versus berries The researchers had participants drink a smoothie made with banana, which has naturally high PPO activity, and a smoothie made with mixed berries, which have naturally low PPO activity. Participants also took a flavanol capsule as a control. Blood and urine samples were analyzed to measure how much flavanols were present in the body after ingesting the smoothie samples and capsule. The researchers found that those who drank the banana smoothie had 84% lower levels of flavanols in their body compared to the control. "We were really surprised to see how quickly adding a single banana decreased the level of flavanols in the smoothie and the levels of flavanol absorbed in the body," Ottaviani said. "This highlights how food preparation and combinations can affect the absorption of dietary compounds in foods." Last year, the Academy of Nutrition and Dietetics issued a dietary recommendation, advising people to consume 400 to 600 milligrams of flavanols daily for cardiometabolic health. Ottaviani said for people who are trying to consume those flavanols, they should consider preparing smoothies by combining flavanol-rich fruits like berries with other ingredients that also have a low PPO activity like pineapple, oranges, mango or yogurt. He also said bananas remain a great fruit to be eaten or consumed in smoothies. For those who want to consume smoothies with bananas, or other high PPO activity fruits and vegetables such as beet greens, the suggestion is to not combine them with flavanol-rich fruits such as berries, grapes and cocoa. The findings of this study could spur future research into how other foods are prepared and the effects on flavanols, for example, Ottaviani said tea is a major dietary source of flavanols and depending on how it is prepared, a different amount of flavanols would be available for absorption. "This is certainly an area that deserves more attention in the field of polyphenols and bioactive compounds in general," said Ottaviani. Jodi Ensunsa, Reedmond Fong, Jennifer Kimball and Alan Crozier, all affiliated with the UC Davis Department of Nutrition and researchers affiliated with the UC Davis Department of Internal Medicine, University of Reading, King Saud University and Mars, Inc. contributed to the research. The study was funded by a research grant from Mars, Inc., which collaborates with researchers to study potential benefits of cocoa flavanols for human health.

Procyanidins are a class of polyphenols (plant metabolites) that are abundantly found in nature. The B-type procyanidins are one of the most commonly consumed catechin oligomers in the human diet. Previous studies have shown both the long-term and single-dose advantages of B-type procyanidins on human metabolism, circulation, and the nervous system. Now researchers review the hormetic effects of B-type procyanidins exerted on the primary target organ, the gut, via activation of the central nervous system. B-type procyanidins, made of catechin oligomers, are a class of polyphenols found abundantly in foods like cocoa, apples, grape seeds, and red wine. Several studies have established the benefits of these micronutrients in reducing the risk of cardiovascular diseases and strokes. B-type procyanidins are also successful in controlling hypertension, dyslipidemia, and glucose intolerance. Studies attest to the physiological benefits of their intake on the central nervous system (CNS), namely an improvement in cognitive functions. These physiological changes follow a pattern of hormesis -- a phenomenon in which peak benefits of a substance are achieved at mid-range doses, becoming progressively lesser at lower and higher doses. The dose-response relationship of most bioactive compounds follows a monotonic pattern, in which a higher dose shows a greater response. However, in some exceptional cases, a U-shaped dose-response curve is seen. This U-shaped curve signifies hormesis -- an adaptive response, in which a low dose of usually a harmful compound induces resistance in the body to its higher doses. This means that exposure to low levels of a harmful trigger can induce the activation of stress-resistant pathways, leading to greater repair and regeneration capabilities. In case of B-type procyanidins, several in vitro studies support their hormetic effects, but these results have not been demonstrated in vivo. To address this knowledge gap, researchers from Shibaura Institute of Technology (SIT), Japan, led by Professor Naomi Osakabe from the Department of Bioscience and Engineering, reviewed the data from intervention trials supporting hormetic responses of B-type procyanidin ingestion. The team, comprising Taiki Fushimi and Yasuyuki Fujii from the Graduate School of Engineering and Science (SIT), also conducted in vivo experiments to understand possible connections between B-type procyanidin hormetic responses and CNS neurotransmitter receptor activation. Their article was made available online on June 15, 2022 and has been published in volume 9 of Frontiers of Nutrition on September 7, 2022. The researchers noted that a single oral administration of an optimal dose of cocoa flavanol temporarily increased the blood pressure and heart rate in rats. But the hemodynamics did not change when the dose was increased or decreased. Administration of B-type procyanidin monomer and various oligomers produced similar results. According to Professor Osakabe, "These results are consistent with those of intervention studies following a single intake of food rich in B-type procyanidin, and support the U-shaped dose-response theory, or hormesis, of polyphenols." To observe whether the sympathetic nervous system (SNS) is involved in the hemodynamic changes induced by B-type procyanidins, the team administered adrenaline blockers in test rats. This successfully decreased the temporary increase in heart rate induced by the optimal dose of cocoa flavanol. A different kind of blocker -- a1 blocker -- inhibited the transient rise in blood pressure. This suggested that the SNS, which controls the action of adrenaline blockers, is responsible for the hemodynamic and metabolic changes induced by a single oral dose of B-type procyanidin. The researchers next ascertained why optimal doses, and not high doses, are responsible for the thermogenic and metabolic responses. They co-administered a high dose of cocoa flavanol and yohimbine (an α2 blocker) and noted a temporary but distinct increase in blood pressure in test animals. Similar observations were made with the use of B-type procyanidin oligomer and yohimbine. Professor Osakabe surmises, "Since α2 blockers are associated with the down-regulation of the SNS, the reduced metabolic and thermogenic outputs at a high dose of B-type procyanidins seen in our study may have induced α2 auto-receptor activation. Thus, SNS deactivation may be induced by a high dose of B-type procyanidins." Previous studies have proven the role of the gut-brain axis in controlling hormetic stress-related responses. The activation of the hypothalamus-pituitary-adrenal (HPA) axis by optimal stress has a strong influence on memory, cognition, and stress tolerance. This article highlights how HPA activation occurs after a single dose of B-type procyanidin, suggesting that stimulation with an oral dose of B-type procyanidin might be a stressor for mammals and cause SNS activation. Hormesis and its triggering biochemical pathways deliver protection against various pathological and aging processes, enhancing our general health and making us resilient to future stress. Though the exact relation between B-type procyanidins and the CNS needs more research, the health benefits of B-type procyanidin-rich foods remains undisputed.