CHOCOLATE: A THERAPEUTIC AND NUTRACEUTICAL DELIVERY SYSTEM by Tim Ridgway
B
ased on the premise that most women like eating chocolate and the evidence that nutraceutical isoflavones are good for women’s health1, by putting nutraceutical isoflavones in a chocolate bar you could potentially have a winning guilt-free confectionary product, the ‘Venus Bar’. This is an example of how in the future chocolate manufacture and nutraceutical provision may combine. As it turns out, however, chocolate itself may be a lot more virtuous than previously thought; it may actually promote good health through its high content of plant polyphenols, in particular the flavanols, catechin and epicatechin. The bioactive ingredients of chocolate
Epidemiologic evidence has suggested that certain plant polyphenols, in particular the flavonoids, promote good health and help to prevent the onset of chronic diseases, including cardiovascular disease and cancer2. Amongst the flavonoids the flavanols have received specific attention for their potential to prevent cardiovascular disease and are present in wine, tea, and various fruits and berries. Chocolate also contains large amounts of flavanols and is now thought to have a potential cardioprotective role in the diet3. The flavanols in chocolate consist of the monomers epicatechin and catechin plus oligomeres of epicatechin and catechin which are known as procyanidins. Both flavanol monomers and oligomeres are thought to represent bioactive ingredients. Flavanols are distinct from other types of flavanoid as they tend not to appear as glycosides, but are present as aglycones or are esterified with gallic acid3. Bioavailability and metabolism
Following absorption from the gut, flavanols are methylated and glucuronidated with some sulphonication taking place in the liver. These metabolites may then represent the actual bioactive forms in the body. In addition colonic microflora can degrade the flavan ring structure to form simple phenolic and ring fission metabolites that may be physiologically active. Nevertheless, in studies following human cocoa
TIM RIDGWAY PhD is a science writer. email: tim.tridgway@wanadoo.co.uk
ingestion, catechin and epicatechin have actually been detected in human plasma as has the epicatechin dimer B2 (epicatechin-(4β-8)-epicatechin), showing a proportion of dietary flavanols to be bioavailable in unmodified form4. Mechanisms of action
Flavanols in chocolate are thought to offer cardioprotection by a variety of mechanisms including antioxidant action, the result of which is that LDL (low density lipoprotein) is protected from oxidation thus reducing the formation of atherosclerotic lesions. Other cellular mechanisms of action of flavanols include the reduction of inflammation, the reduction of platelet aggregation and an increase in the production of nitric oxide resulting in vasodilation3. The structural characteristic of flavanols that confirms their excellent antioxidant properties is the hydroxylation of the basic flavan structure, in particular the formation of 3?,4?-dihydroxy groups on the B-ring, ie. the formation of catechol structures5. Cocoa powder and cocoa extracts have been shown to exhibit greater antioxidant capacity than many other flavanoid-rich foods, including green and black tea, red wine, blueberry, garlic and strawberry3. Clinical trials
Over the past decade many clinical trials have been carried out to investigate the potential health benefits of chocolate; these works being recently reviewed by Cooper et al.6 Most of the clinical trials appeared to show a positive outcome for chocolate as a cardioprotective agent, although the fact that the scale of the trials was generally small should be taken into account before drawing any conclusions. As an example of a recent study, which used 39 healthy Japanese men, it was found that flavonoid-rich dark chocolate significantly improved coronary circulation as measured by noninvasive transthoracic Doppler echocardiography (TTDE)7. Dark, milk or white?
The flavanols in chocolate come from the cocoa liquor formed as a result of processing the cocoa beans. As white chocolate contains no cocoa liquor, it contains no flavanols and could thus be expected to have no cardioprotective properties; hence its use as a control when investigating the prospective benefits of flavanols in chocolate7.
european INDUSTRIAL PHARMACY • Issue 2 February 2009
13