Flavanols are a distinct subgroup of plant compounds known as flavonoids. These natural substances are widely found in various fruits, vegetables, and other plant-based foods and beverages. Flavanols possess a unique chemical structure, characterized by a hydroxyl group located at position 3 of their C ring, which differentiates them from other flavonoid types.
Flavanol-Rich Foods
Many everyday foods offer a notable supply of flavanols, making them accessible through a balanced diet. Dark chocolate and cocoa are particularly rich sources, containing flavanol monomers such as epicatechin and catechin, along with their oligomeric forms known as procyanidins. Epicatechin constitutes a significant portion of the catechins found in cocoa beans.
Teas, including both green and black varieties, also provide a considerable amount of flavanols like catechins and epicatechins, with epigallocatechin gallate (EGCG) being a prominent compound in green tea. Apples contain various flavanols. Berries, such as blueberries, strawberries, blackberries, cherries, and raspberries, are abundant in different types of flavonoids, including flavanols.
Grapes are another source of these beneficial compounds, especially catechins, found in Vitis vinifera grapes and red wine. Other plant-based foods like bananas, peaches, pears, onions, kale, and parsley also contribute to dietary flavanol intake. The specific flavanol content in foods can vary depending on the plant cultivar, growing conditions, and how it is processed or prepared.
Impact on Cardiovascular Health
Flavanols contribute to cardiovascular well-being through several mechanisms, primarily by supporting the function of blood vessels. They have been shown to improve endothelial function, the inner lining of blood vessels. This improvement often leads to vasodilation, where blood vessels relax and widen, allowing for better blood flow throughout the body.
The beneficial effect on vasodilation is largely attributed to flavanols’ ability to increase the bioavailability of nitric oxide (NO). Nitric oxide signals blood vessels to relax, enhancing circulation. Studies involving flavanol-rich cocoa have demonstrated reductions in both systolic and diastolic blood pressure. For instance, overweight adults consuming flavanol-rich dark chocolate saw systolic blood pressure decrease by 3.2 mmHg, while a monthly intake of 900 mg of total flavanols from cocoa drinks resulted in average reductions of 4.4 mmHg systolic and 3.9 mmHg diastolic.
Beyond blood pressure regulation, flavanols also influence platelet function. Flavanol-rich cocoa can inhibit platelet activation, which may reduce the risk of unwanted blood clot formation. Additionally, flavanol consumption has been linked to improvements in insulin sensitivity, a factor that plays a role in overall cardiometabolic health.
Influence on Cognitive Function
Flavanols influence brain health and cognitive processes. These compounds, particularly epicatechin, are capable of crossing the blood-brain barrier, allowing them to directly interact with brain tissue. Epicatechin has been detected in the brain following oral consumption, suggesting its direct involvement in neurological pathways.
One of the primary ways flavanols support cognitive function is by enhancing cerebral blood flow (CBF). They increase blood circulation within the brain, especially in the grey matter. This improved blood flow ensures that brain cells receive adequate oxygen and nutrients, beneficial for cognitive processes. The effect of increased cerebral blood flow from flavanol intake has been observed to be more pronounced in healthy elderly individuals.
Flavanols also exhibit neuroprotective properties, safeguarding brain cells from damage. They help reduce neuroinflammation and protect neurons from harm caused by neurotoxins. These compounds interact with cellular signaling pathways to promote the survival of neurons and enhance synaptic plasticity, the ability of synapses to strengthen or weaken.
The consumption of flavanols has been associated with improvements in various aspects of cognition, including memory and learning. They can promote angiogenesis and neurogenesis, particularly in the hippocampus, a brain region for memory formation. Chronic consumption of cocoa flavanols, at specific dosages and durations, has been linked to improvements in processing speed, executive function, and working memory in individuals experiencing mild cognitive impairment.
Obtaining Flavanols Through Diet and Supplements
Obtaining flavanols through whole foods is recommended, as these sources provide a complex mixture of beneficial plant compounds and other nutrients that work synergistically. While flavanol supplements are available, the bioavailability of compounds from whole foods can be enhanced by the food matrix. However, the concentration of flavanols in natural foods can vary significantly due to plant species, growing conditions, and storage methods.
Food processing techniques can significantly impact flavanol content. Dutch-processing, or alkalization, of cocoa powder involves treating cocoa with an alkali. This process reduces acidity, alters flavor, and darkens color, but also substantially reduces flavanol content. Natural, non-alkalized cocoa powders contain high levels of flavanols, averaging around 34.6 mg per gram.
In contrast, heavily Dutch-processed cocoa powders can have significantly lower flavanol levels, sometimes as little as 3.9 mg per gram. This processing can also lead to the epimerization of flavanols into less bioavailable forms. Therefore, choosing natural cocoa powder over alkalized versions can help maximize flavanol intake from chocolate products.
While there is no standardized recommended daily intake for flavanols, research studies often explore intakes within a specific range. For instance, the Academy of Nutrition and Dietetics suggests a daily flavanol intake of 400 to 600 milligrams from diverse food sources to support cardiometabolic health. This recommendation emphasizes obtaining flavanols from a variety of nutrient-dense foods rather than solely relying on supplements, which may not offer the same benefits as whole foods.