Can berry pigments help your heart? Explore research on blood vessels, blood pressure and why more anthocyanins do not prove greater protection.
Research into the pigments in berries and certain grapes points to possible benefits for blood vessels. Understanding what those findings mean takes more than comparing the deepest shades in the fruit bowl.
Choosing blueberries for breakfast is straightforward. Working out whether their purple pigments will protect your heart is rather more complicated.
Research into anthocyanins and heart health offers encouraging findings, particularly around how blood vessels function, but it cannot yet turn the colour of your shopping basket into a reliable measure of cardiovascular protection.
A review of 37 studies published in Nutrients, examining grapes and blueberries, draws attention to potential benefits involving blood pressure, inflammation and oxidative stress. There is enough here to warrant interest. The difficulty comes when a finding about a compound, or a change in a cardiovascular measurement, becomes a promise about the food on your plate.
Six times the pigment needs some explanation
Take red-fleshed grapes. BOOMBITES says an analysis by the University of Murcia found its grapes contained six times more anthocyanins than a traditional black-skinned table grape tested for comparison. The pigments were present in both the skin and flesh.
That is a specific claim about the composition of fruit. The comparison does not demonstrate six times the cardiovascular benefit, establish that these grapes prevent disease or tell shoppers how they perform against every other variety.
The distinction matters because a number can sound more informative than it really is. Measuring a pigment answers one question; establishing what eating that fruit does for a person’s health requires different evidence.
Anthocyanins themselves belong to the polyphenol family of plant compounds. They give foods including blueberries, blackberries, red cabbage and certain grapes their dark red, black and purple shades, and are studied for their antioxidant properties and possible cardiovascular effects.
Yet grapes and blueberries contain several compounds of scientific interest. When researchers study the fruit, any observed benefit cannot automatically be assigned to anthocyanins alone. Equally, sharing a pigment does not mean different foods will produce the same result.
What blood vessel function can reveal
One of the more useful areas of investigation is endothelial function: how well blood vessels relax and regulate blood flow. It gives researchers something specific to examine beyond the broad description of a food as rich in antioxidants.
GP Dr Nisa Aslam, who has a special interest in nutrition and heart health and co-authored the review, explains:
“In addition, further research studies have found anthocyanins to be particularly useful in helping the endothelial function, which is how well blood vessels relax and regulate blood flow. Better endothelial function generally means healthier arteries and lower cardiovascular risk.”
This is a reason to take the research seriously. Blood vessel function is relevant to cardiovascular health, and understanding how food may influence it is worthwhile.
It also leaves an important question open. An improvement in this measure does not, by itself, demonstrate that people who eat a particular fruit will have fewer heart attacks or strokes. Those are different outcomes, and readers need to know which a study actually investigated.
What the other findings add
Professor José Abellán-Alemán, a review co-author and director of the Cardiovascular Risk Chair at the Catholic University of Murcia, highlights studies reporting improvements in blood pressure and reductions in oxidative stress.
Oxidative stress involves unstable molecules that can damage cells. The review authors also point to research suggesting anthocyanins may reduce markers of inflammation, another area relevant to vascular health.
These findings help explain the interest in anthocyanin-containing foods. How much weight to give them depends on the research behind them: who took part, what they consumed, how long they were studied and how consistently the results agreed.
The total of 37 studies cannot answer those questions on its own. Nor does it supply a dependable estimate of the benefit an individual might expect from a portion of blueberries. A study count is useful context; it is no substitute for examining what was tested.
A practical place for colourful food
Ahead of World Heart Day on 29 September, the everyday message remains a varied diet and an active lifestyle. Colourful fruit and vegetables can fit comfortably into that pattern, with blueberries, blackberries, red cabbage and grapes offering different ways to include anthocyanin-containing foods.
The research provides a reason to understand those foods more closely. It offers much less certainty about ranking them by pigment content or predicting the effect of a particular serving on an individual’s heart.
There is no need to make the fruit bowl competitive.
