Functional chocolate is now marketed on multiple platforms, from its innate flavanol content to specific disease-reduction claims. Mark J Tallon, PhD, takes a bite out of the latest cocoa research
The Theobroma cocoa plant is the source of one of the earliest functional ingredients known to the healthy-foods market. With consumption dating back to the Mayans and Aztecs, cocoa powder and chocolate (a mixture of cocoa, cocoa butter, sugar, etc) are enticing new consumers on issues outside of taste. Chocolate is gaining recognition as a rich source of fibre, proteins and vitamins including A, E and folic acid.1,2 However, the compound capturing the most attention is the flavonoids (monomers known as procyanidins such as epicatechin).3,4
From the commercialisation of sterol-fortified chocolate that lowers cholesterol, to specially manufactured flavanol-dense chocolate that maintains blood-pressure health, research is racing to catch up with the marketing. Immune and cognitive health, improved insulin sensitivity, and antioxidant status are some of the other research areas developing within this category.
Chocolate and cocoa are rich sources of polyphenols. In vitro data have shown that extracts can cause a selection of biological responses, such as nitric-oxide induced arterial vasodilation, which may affect blood pressure.
One study often quoted by chocolate manufacturers is a meta-analysis carried out by the University Hospital Cologne.5 This study assessed five randomised controlled studies of cocoa administration involving a total of 173 subjects with a median duration of two weeks. After the cocoa diets, the pooled mean systolic and diastolic blood pressures were -4.7mm Hg and -2.8mm Hg lower, respectively, compared with the cocoa-free controls. The authors concluded that these randomised dietary studies indicate that consumption of foods rich in cocoa may reduce blood pressure.
However, the positive here is not always the case. Dr Karin Ried from the University of Adelaide recently found that 70 per cent cocoa chocolate containing 750mg polyphenols did not exhibit a blood pressure-lowering effect.6 There are a few issues with this trial that may have caused the negative result. Firstly, the chocolate was poorly characterised with type, ratio and concentration of the specific monomers within the polyphenol dose not presented. Secondly, due to the poor concentration of polyphenols, subjects were required to consume 50g dark chocolate every day and 20 per cent considered it an unacceptable long-term treatment option while 50 per cent found it difficult to eat. In any application of chocolate as a health intervention, the practicability of chocolate intake as a long-term treatment option must be considered.
Like other organs in the body, the brain is susceptible to oxidation and associated damage from inflammation that can lead to neurodegeneration. Research from epidemiological studies has indicated that dietary flavonoids may prevent neurodegenerative diseases.7 A study from the UK explored the effect of flavanols on cognitive function following ingestion of flavanol-rich cocoa (five days of 150mg cocoa flavanols).8 Although no significant effect on behaviour or function tasks were evident, a pilot study with a single acute dose (450mg flavanols) of flavanol-rich cocoa increased the cerebral blood flow to gray matter. The authors suggested the results indicated applications with cocoa flavanols for treatment of vascular impairment, including dementia and strokes, and thus for maintaining cardiovascular health. Additionally, the dose is key to the effect from flavanols and high doses may be required to affect cognitive performance. Chocolate bars in Grandma's stocking!
In 2008, a rodent study assessed the impact of a high-dose (equivalent to 1.7g/day in a 70kg human or 527mg procyanidins) cocoa extract (Acticoa, Barry Callebaut) from between 15 and 27 months of age.9 The trial assessed the supplementation on age-related cognitive deficits, urinary-free dopamine levels, lifespan and cognitive performances. These results suggest that Acticoa powder may be beneficial in retarding age-related brain impairments, including cognitive deficits (memory) in normal ageing and perhaps neurodegenerative diseases.
Inflammation has been linked to many disease states, as well as affecting general well being. One specific area of health is its relationship with cardiovascular-disease risk. Because of the epidemiological link between flavonoid intake and the prevention of coronary heart disease (CHD), researchers from Barcelona, Spain, investigated the chronic effects of cocoa consumption on atherosclerosis (considered a low-grade inflammatory disease) biomarkers in high-risk patients.10 A four-week placebo-controlled intervention trial was conducted with 40g cocoa powder, which demonstrated a reduction in inflammatory markers (VLA-4, CD40 and CD36) in the cocoa group over the placebo subjects. Additionally, serum concentrations of the soluble endothelium-derived adhesion molecules P-selectin and intercellular adhesion molecule-1 were significantly lower in the cocoa intervention.
These results are positive and suggest that the intake of cocoa polyphenols may modulate inflammatory mediators in patients at high risk of cardiovascular disease. However, although these anti-inflammatory effects may contribute to the overall benefits of cocoa consumption against atherosclerosis, long-term intervention trials looking at specific disease outcomes are required before we can conclude on the health relationship for disease reduction.
Of all the environments that cause skin damage, UV radiation from the sun contributes 80 per cent, and is the most important factor in premature skin ageing. In a trial published this year, researchers evaluated the photoprotective potential of chocolate consumption, comparing a conventional dark chocolate to a specially produced chocolate with preserved high flavanol (HF) levels.11
Thirty subjects each were randomly assigned to either a HF (n=15) or low flavanol (LF) (n=15) chocolate group, which consumed a 20g portion of chocolate daily. The minimal erythema dose (MED; the minimum amount of UVB that produces redness 24 hours after exposure) was assessed at baseline and after 12 weeks.
In the HF chocolate group, the mean MED more than doubled after 12 weeks of chocolate consumption, while in the LF chocolate group the MED remained without significant change. This study demonstrated that consumption of a chocolate rich in flavanols results in photoprotection and can thus be effective at protecting human skin from harmful UV effects. The take-home message is that the flavanol content is key to the health impact of chocolate. This trial is an exciting breakthrough, and future trials will need to focus on visual skin measurements such as skin-texture changes and wrinkling, which can be converted to useful and supportive health claims.
The future is tasty
The functional-chocolate market and its new research are slowly influencing the conventional perception of chocolate as being unhealthy. A quick search of Pubmed demonstrates publications have increased 170 per cent in the last decade (Jan 1999-2000 v Jan 2008-2009). This dramatic acceleration in chocolate research is set to continue over the next five years, yet with the challenges from the European health-claims system, cocoa extracts for the EU may be the growth area, with the US becoming more dominant for chocolate-specific health claims. Only time will tell.
Mark J Tallon, PhD, is founder of NutriSciences Ltd, a consultancy firm specialising in health-claim substantiation, product development and technical writing.
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