Juice what the doctor ordered

Scientists have discovered the ideal fruit blend that could lower the risk of heart disease.

The team of French researchers discovered that a combination of grape, apple, blueberry, strawberry and lingonberry, mixed with a touch of lesser known fruits acerola, a cherry-like fruit from a shrub found in the West Indies, and aronia, also known as chokeberries and found in the wetlands of north-east Amercia, brought together the ideal combination of different polyphenols. More than half of the blend came from grape juice with the remaining 37 per cent made up of the other fruits.

Their research is published tomorrow (Thursday 5 May) in the latest edition of the Royal Society of Chemistry journal, Food and Function.

Although the relationship between polyphenol content and health is controversial as claims have been difficult to prove scientifically, the scientists proved that the various fruit and berry juices had different abilities to elicit relaxation of the coronary artery rings.

This is vital to a healthy lifestyle as abnormal or restricted blood flow to the heart can lead to heart damage because cells that are deprived of oxygen and nutrients die. Dead muscle cells in the heart cannot be replaced with new, healthy cells meaning connective tissue fills the space. This process - fibrosis - results in muscle loss and a weakening of the heart.

The scientists, from the University of Strasbourg, noted that numerous studies have shown polyphenol-rich sources such as red wine and green tea were potent inducers of endothelium-dependant relaxations in arteries but wanted to assess how well fruit blends compared to previous health "superfoods". They tried various combinations of 13 different fruit juices or purees, which had similar levels of polyphenols, antioxidant capacity and vitamin C content, before a survey of 80 consumers settled on the best in terms of flavour.

The team also discovered that potential health benefits of the blends depended more on the type of polyphenols contained in each fruit than the quantity of polyphenol content. 

Co-author Dr Cyril Auger said: "Among the various fruits investigated, the most active ones were predominantly berries including cranberry, lingonberry, aronia, blackcurrant and blueberry. These berries are characterised by the presence of high levels of anthocyanins, which are pigments responsible for the blue-red colours of fruits.

"The fact that several berries including raspberry, blackberry, boysenberry and elderberry had little biological activity despite having a high level of polyphenols indicates that the qualitative composition of the polyphenolic content is important for the biological activity."

The authors concluded: "Our data indicates that blends of fruit products can be developed to combine a high level of vasorelaxant activity and an enjoyable taste. The possibility that the regular intake of such active fruit juices may improve the endothelial function and hence vascular health still remains to be determined."

The Perfect Blend for a healthy heart:

• Acerola (4%)
• Apple (10%)
• Grape (63%)
• Lingonberry (5%)
• Aronia (4%)
• Blueberry (10%) 
• Strawberry (10%)
   

_{Notes for editors:}

_{The industrial partner that supplied the fruit juice and purees informed the authors that the percentages listed are the values they actually use for the production of the juice, so they have therefore been rounded-up.
Vasorelaxation refers to the widening of blood vessels resulting from relaxation of smooth muscle cells within the vessel walls, particularly in the large arteries, smaller arterioles and large veins.
The endothelium is the thin layer of cells that line the interior surface of blood vessels, forming an interface between circulating blood in the lumen and the rest of the vessel wall. Endothelial cells line the entire circulatory system, from the heart to the smallest capillary.}

References

Fruit juice-induced endothelium-dependent relaxations in
isolated porcine coronary arteries: evaluation of different
fruit juices and purees and optimization of a red fruit juice
blend
C Auger et al, Food Funct., 2011
DOI: 10.1039/c1fo10040h