Anthocyanins are responsible for the deep blue, purple and red colours of many fruits and vegetables, such as these blood oranges.J.P. Moczulski/The Globe and Mail
Chances are, you’ve heard that berries, especially blueberries, benefit brain health.
Many studies have linked blueberries, which are rich in anthocyanins, to healthy brain aging.
Turns out, anthocyanins may do more than protect cognitive health.
According to a major new review of research, higher intakes of anthocyanins can also keep your heart healthy as you age.
What’s more, the amounts associated with these benefits are surprisingly achievable through diet.
Here’s what to know about the latest research, plus which foods, berries and beyond deliver plenty of anthocyanins.
What are anthocyanins?
Anthocyanins are a subclass of phytochemicals that belong to the flavonoid family, a large group of thousands of compounds found in fruits, vegetables, nuts, cocoa, red wine and tea.
Anthocyanins are responsible for the deep blue, purple and red colours of many fruits and vegetables, including blueberries, blackberries, raspberries, strawberries, cherries, red grapes, pomegranate seeds, black currants, blood oranges, red cabbage, purple sweet potatoes, radishes and eggplant.
They do more than give plants their colourful hues, though.
Anthocyanins have antioxidant and anti-inflammatory properties that are thought to support healthy blood vessels, the heart and the brain as we age.
About the new research
For the meta-analysis, published this month in the American Journal of Clinical Nutrition, researchers set out to examine whether higher intakes of anthocyanins improved cardiometabolic health and reduced the risk of developing cardiovascular disease in healthy, disease-free adults.
(A meta-analysis combines the findings from many studies and uses the pooled data to come to new conclusions; it provides stronger evidence than the findings from a single study.)
While previous research has suggested that anthocyanins protect against cardiovascular disease and Type 2 diabetes, many of these studies included both healthy people and those who already had cardiometabolic disease.
Since people with health conditions are more likely to experience greater improvements, earlier results from anthocyanins may not apply to healthy individuals.
The researchers reviewed a total of 83 studies – observational studies and randomized controlled trials – conducted in healthy participants.
When they pooled and analyzed data from 18 observational studies, which tracked participants for up to 24 years, they found consistent protective effects with higher anthocyanin intakes.
Compared to lower anthocyanin intakes, those with higher intakes had a 26 per cent lower risk of developing cardiovascular disease, an 18 per cent reduced risk of heart attack and an 11 per cent lower risk of Type 2 diabetes.
The team also reviewed 65 randomized controlled trials and found strong evidence that consuming at least 50 mg of anthocyanins a day improved endothelial function. The endothelium is the single layer of cells that line the inside of blood vessels; it regulates blood vessel contraction and relaxation. The main symptom of endothelial dysfunction in the coronary arteries include chest pain or tightness, which can worsen during physical activity; fatigue and shortness of breath can also occur.
Specifically, anthocyanins improved flow-mediated dilation, a measure of how well the endothelium helps blood vessels relax and expand in response to increased blood flow. This improvement was seen both immediately after consuming anthocyanin-rich foods and weeks after regular consumption.
Impaired flow-mediated dilation indicates early dysfunction of the endothelium; it’s an independent predictor of future cardiovascular events.
Anthocyanin consumption was also associated with significantly lower fasting insulin levels, suggesting improved insulin sensitivity.
Strengths, caveats
The study’s greatest strength is its focus on healthy participants. It provides compelling evidence that anthocyanins may help prevent cardiometabolic disease through their beneficial effects on vascular function.
As well, combining observational studies that tracked clinical outcomes – such as cardiovascular disease, Type 2 diabetes and randomized controlled trials that measured changes in cardiometabolic biomarkers – provides stronger evidence than either type of study alone.
One limitation is the fact that the observed reduced risks of cardiovascular disease and diabetes come from observational studies, which cannot prove cause and effect.
Another caveat is that anthocyanin-rich foods also contain other flavonoids and phytochemicals which may also contribute to their cardiometabolic benefits.
Benefits with very achievable anthocyanin intakes
In the current study, the strongest and most consistent anthocyanin benefit observed in healthy people was improved vascular health.
The good news is that the daily amount of anthocyanins linked to improved endothelial function is well within reach.
For example, roughly one half-cup of blueberries, blackberries, cranberries or black currants, or about one cup of sweet cherries, can provide around 50 mg or more of anthocyanins.
Keep in mind the anthocyanin content of fruits and vegetables can vary considerably depending on the variety, growing region, ripeness, storage and processing.
Anthocyanins – part of a heart healthy diet
The new results add to growing evidence that anthocyanin-rich foods deserve a place on your regular menu.
But don’t lose sight of the bigger picture. When it comes to heart health, your overall dietary pattern matters more than any single food or nutrient.
Add colourful anthocyanin-rich foods to an overall healthy dietary pattern, whether it’s a Mediterranean-style diet, the DASH diet, the MIND diet or a flexitarian approach to eating.
That’s where the strongest evidence lies for healthy aging and long-term cardiovascular health.
Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan.