As you are aware from my previous posts I champion vegetable and fruit consumption. These treasures are abundant in taste, texture, vitamins, mineral and fibre…..but they are also full of bioflavonoids, or flavanoids (members of the polyphenol family). Flavonoids are bioactive plant compounds which have gained increasing amount of publicity over the last few years. Scientists have been looking into the health benefits of these plant compounds and quite a lot of interesting data has been coming to light.
A yet to be published review article(1) looked at polyphenols (mainly found in grapes) and their role in health and found that these compounds may help to reduce the risk of heart disease. The authors of the study state that “Consumption of grape and grape extracts and/or grape products such as red wine may be beneficial in preventing the development of chronic degenerative diseases such as cardiovascular disease“. Grape seeds, grape skin and grape juice contain many different polyphenols including; resveratrol, anthocyanins and flavonoids – you may be familiar with these names as they are widely available as supplements. In conclusion to this review the authors say “supplementation with grape seed, grape skin or red wine products may be a useful adjunct to consider for a dietary approach in the prevention of cardiovascular diseases, although additional research is required to support such a strategy“
Flavonoids act as antioxidants in the body, helping to prevent cell damage and protection against disease by mopping-up destructive unstable oxygen molecules known as ‘free radicals’ (I have mentioned antioxidants and their role in health previously a number of times). Polypheonols also seem to have other protective effects on the heart and blood vessels. They seem to prevent blood clotting, abnormal heart beat and blood vessel narrowing. As yet scientists are not exactly sure of how these plant compounds act, however they do seem to positively change the way our genes function.
Another recently published study(2) looked at the association between a variety of flavonoids and the risk of cardiovascular disease and stroke. The scientists studied 1950 Finish men aged between 42-60 who were free from prior heart disease or stroke. Participants were followed for an average of 15 years and during this time over 100 strokes and 150 cardiovascular disease deaths occurred. Data analysis revealed that men who consumed the highest amounts of flavonoids had a greatly reduced risk of stroke and there was also a reduced risk of death from cardiovascular disease. The results are unsurprising as fruit and vegetables are the major sources of flavonoids and there is plenty of data to show that these foods protect us from all kinds of diseases including stroke and heart disease. The interesting point comes from the fact that the analysis took into account various vitamin intakes suggesting that the flavonoids themselves make a real impact on health.
Yet another study published just this month (3) highlights the health benefits of flavonoids, this time their potential role in weight maintenance and prevention of weight gain. The researchers of this study looked at the association between flavonoids and BMI (body mass index, a measure of overweight) over a 14 year period in 4280 men and women aged between 55-69 years. The results showed that women with the highest intake of flavonoids experienced a significantly lower increase in BMI over the study period. Again, this is not surprising. Individuals who eat a lot of vegetables and fruits tend not to fluctuate in weight and stay leaner.
Now onto two pieces of research (4,5) which I am particularly fond of as they involve dark chocolate! Readers of my blog will know my penchant for dark chocolate. Dark chocolate containing 85%+ cocoa solids is something I truly adore and really savour the moment of one bitter square slowly melting over my tongue! Drinking black cocoa is also something I enjoy. The health benefits of cocoa have been publicised over the last few years and evidence that cocoa may help in the prevention of many conditions, such as cancer and heart disease, is mounting. Cocoa is packed with great minerals such as magnesium and is also ‘choc’ full of flavonoids.
A very recent study(4) suggests that cocoa consumption may be good for the heart (great news since I would have trouble giving it up!). The researchers investigated the short-term effects of eating either solid dark chocolate or drinking liquid cocoa on blood vessel function and blood pressure. The small study included 45 adults who were overweight but healthy (and not obese) who were, on average, 53 years old. In the first stage of the trial the participants consumed a bar of dark chocolate containing 22g of cocoa powder or a cocoa-free bar. In the second stage the participants drank sugar-free cocoa containing 22g cocoa powder, cocoa containing sugar or a placebo containing no cocoa.
Eating dark chocolate and drinking sugar-free cocoa improved blood vessel function compared to placebo and blood pressure decreased in individuals who ate the dark chocolate bar or drank the sugar-free cocoa, compared to those who consumed the placebo. The researchers conclude by saying “The acute [short term] ingestion of both solid dark chocolate and liquid cocoa improved endothelial [lining of the blood vessels] function and lowered blood pressure in overweight adults. Sugar content may attenuate [reduce] these effects, and sugar-free preparations may augment [improve] them”
The other small study(5) found that flavonoid rich cocoa was associated with a significant increase in blood flow to the brain, as measured via a special sort of ultrasound (Transcranial dopler ultrasound). The authors suggest that their data could indicate a promising role for regular cocoa consumption in the treatment and prevention of stroke and dementia.
These studies were very small and preliminary but I found them interesting!! I would like to add that this is not a plug to justify regular chocolate binges (although it does help me to feel better about my dark chocolate habit)! The cocoa used in these studies, and other studies that link cocoa to health benefits such as lowered risk of heart disease, was high flavanol cocoa and only a very small amount was used daily. Sugary, sweet milk chocolate won’t provide the health benefits discussed (sorry to be the bearer of sad news!).
Flavonoids and polyphenols in general are found abundantly in fruits and vegetables, which are so important for our health. Vegetables and fruit should form the core of a healthy diet and getting a good variety will give the body many of the nutrients that are needed for optimal health. Flavonoid supplements are now available, though the evidence for their use is still in the early stages. If you feel your diet is lacking in vegetables and fruits you may want to consider a supplement to top-up and cover the shortfall, but remember supplements are not a replacement for a healthy diet.
(1)http://www.elsevier.com/wps/find/authored_newsitem.cws_home/companynews05_01042 Mounting evidence shows health benefits of grape polyphenols. Philadelphia October 28. Due to be published in the November issue of Nutrition Research
(2)Mursu J et al. 2008. Flavonoid intake and the risk of ischaemic stroke and CVD mortality in middle-aged Finnish men: the Kuopio Ischaemic Heart Disease Risk Factor Study. BJN. 100:890-895
(3)Hughes L et al. 2008. Higher dietary flavone, flavonol, and catechin intakes are associated with less of an increase in BMI over time in women: a longitudinal analysis from the Netherlands Cohort Study. Am J Clin Nutr. 88:1341-1352
(4)Faridi Z et al. 2008. Acute dark chocolate and cocoa ingestion and endothelial function:a randomised controlled crossover trial. Am J Clin Nutr. 88:58-63
(5) Sorond FA et al. 2008. Cerebral blood flow response to flavanol-rich cocoa in healthy elderly humans. Neuropsychiatric Disease and Treatment. 4:433-440
Written by Ani Kowal