The identification of foods that have heart healthy benefits is a growing pursuit by food science laboratories as industry, and government, endeavours to stem the rising figures for cardiovascular disease.
Heart disease made up 16.7 million, or a considerable 29.2 per cent, of total global deaths in 2003, claims the UN-backed World Health Organisation (WHO).
A large body of epidemiologic evidence supports the concept that diets rich in fruit and vegetables could prevent, or delay, the onset of certain chronic diseases, including heart disease.
But the precise mechanisms behind the power of these foods has remained elusive.
Data that suggests a casual link between fruit and vegetables and their flavonoid content has been a point of departure for scientists investigating the mechanisms.
In terms of cardiovascular health, one class of flavonoids, the flavanols - that include cacao, tea, and grapefruit - are attracting increasing attention because of their antioxidant properties and increased nitric oxide bioavailability.
A recent small study, published in this month's American Journal of Clinical Nutrition , suggests that consumption of dark chocolate could improve glucose metabolism and decreases blood pressure.
Researchers at the University of L'Aquila in Italy studied 15 healthy young adults with typical Italian diets, supplemented daily with 100 g dark chocolate or 90 g white chocolate, each of which provided 480 kcal.
The polyphenol contents of the dark and white chocolate were assumed to be 500 and 0 mg, respectively.
Divided into two groups participants each ingested one of the types of chocolate for 15 days, ingested no chocolate for a subsequent 7 days, and then ingested the other chocolate for an additional 15 days.
Assessing insulin resistance, insulin sensitivity and blood pressure the authors found that the dark chocolate was associated with improved insulin resistance and sensitivity and decreased systolic blood pressure, whereas white chocolate had no effect.
The editorial of the American Journal of Clinical Nutrition, that published the findings this month, notes the concentration of flavanols in any chocolate depends on both the flavanol content of the cacao plant, and the procedures used for transforming the cocoa into chocolate.
"But although Grassi et al indicated that 100 g of the chocolate they used contains 500 mg polyphenols, they did not report how they determined this quantity,"
The accurate assessment of the flavanol content is pertinent to interpreting its biological effects.
Mounting evidence on the potential health benefits of chocolate could help beat off stagnant sales in an increasingly crowded marketplace.
Eating their way through about 10 kilos of chocolate a year, the British are Europe's number one chocolate consumer followed by Germany and France with 8.3 and 5.8 kilos respectively.
But, according to Datamonitor, the pace of growth is slated to slow down, kicking off in 2004 when overall chocolate volume sales rose by less than 1 per cent to 605 million kg.
"This trend is likely to continue to the end of the decade," say the researchers.
They anticipate that the major players on the UK market - Cadbury Schweppes, Masterfoods and Nestle - will increasingly turn to formulations for sugar free products, complete with a health twist, in order to achieve price premiums and claw back shrinking sales.