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

Last week I wrote about garlic in relation to lowering blood pressure.  Today I wanted to mention potassium and blood pressure.

Firstly I wanted to write a little more about the problem of high blood pressure (hypertension) in the Western world.  For purposes of illustration I am using statistics(1) for England derived from the 2005 Health Survey for England.  However, the trend is general for the UK and beyond.  High blood pressure is not great news!  It increases the risk of heart disease and stroke and is also linked to dementia and eye problems such as age related macular degeneration.

Hypertension is defined as a systolic blood pressure of 140mmHg or over, or a diastolic blood pressure of 90mmHg or over (see last week for definitions and explanations of diastolic and systolic).  The target for the general population is to have a blood pressure below 140 (systolic)/85 (diastolic).

In England 2005:
*The average systolic blood pressure was 134mmHG for men and 128mmHG for women
*35% of men and 28% of women had hypertension or were being treated for hypertension
*59% of men and 44% of women with hypertension were not receiving treatment
*Of the individuals who were being treated for high blood pressure over 50% remained hypertensive (with a high blood pressure)
 

Blood pressure levels increased with age.
*In men aged 16-24 the average systolic blood pressure was 128mmHg compared to 141mmHg in men aged 75 and over
*In women aged 16-24 the average systolic blood pressure was 117mm Hg compared to 144mmHg in those aged 75 and over. 
*Only 1% of women aged 16 to 24 are hypertensive, compared to 42% aged 55 to 64 and around 67% aged 65 to 74.

As the statistics show, high blood pressure is a very real problem, especially as we get over the age of 40.  Thankfully there is plenty we can do to keep our blood pressure in check and lower it if necessary.  Last week I discussed garlic supplementation and today I am looking at potassium.  The British Heart Foundation(1) have a booklet on blood pressure with more detailed information on why blood pressure maintenance is important, the causes of high blood pressure and detailed advice on how to reduce it.  The booklet can be downloaded from their website.

Back to potassium.  A recent review(2) has found that boosting dietary intake levels of potassium may help to lower the risk of developing high blood pressure and may also decrease blood pressure in individuals already suffering from hypertension. 

Vegetables and fruits are great sources of potassium.  The authors of the study point out that a healthy intake of potassium is thought to be one reason why vegetarians and isolated populations have a very low incidence of heart disease.  In areas were diets are low in sodium and high in vegetables and fruits (representing high potassium levels), hypertension affects only 1% of the population. In contrast, the authors note that in industrialized societies, where people consume diets high in processed foods and large amounts of dietary sodium 1 in 3 persons have hypertension.

In addition to potassium the review study looked at calcium and magnesium, minerals which are also important in controlling blood pressure.  The authors conclude that “A high intake of these minerals [potassium, calcium and magnesium] through increased consumption of fruits and vegetables may improve blood pressure levels and reduce coronary heart disease and stroke”

An increase in vegetables and fruits is fantastic general dietary advice.  These super foods are full of essential vitamins, minerals and other phytonutrients (bioactive plant chemicals) as well as fibre and are vital to our health, not just blood pressure.  Getting a minimum of five portions a day is recommended (recently the National Cancer Institute has recommended 5-9 portions a day and the Danish campaign aims at a minimum of 6 a day!).  Potassium supplements are available and limited trial data exists to support their usefulness in lowering blood pressure, however, potassium supplements should not be used as a replacement for fruit, vegetables and a healthy diet.

(1)British Heart Foundation http://www.heartstats.org/homepage.asp, http://www.bhf.org.uk/

(2)Houston MC & Harper KJ.  2008.  Potassium, magnesium and calcium:their role in both the cause and treatment of hypertension.  10:3-11

Written by Ani Kowal

One of my close friends is pregnant (I am very excited)!  We were chatting about pregnancy health and the topic of preeclampsia came up.  Recently a study(1) was published which suggests that increasing the amount of fibre eaten during early pregnancy may help to reduce the risk of preeclampsia developing later.  I thought now was as good time as any to look into this complex topic further!

Preeclampsia is a serious condition also known as: pregnancy-induced hypertension (PIH); proteinuric gestational hypertension; and toxaemia of pregnancy.  It is a form of high blood pressure (hypertension) that develops in conjunction with water retention (oedema) and/or excess protein in the urine (proteinuria).  Around 3% of all pregnant women suffer from preeclampsia each year and this condition is the principal cause of maternal death in the UK.  Around 10 mothers and 1000 babies die each year as a result of the effects of preeclampsia and the condition is also the most common reason for elective (often early) delivery.  Usually preeclampsia occurs between the 20th week of Pregnancy and the end of the first week postpartum.  The earlier it presents in pregnancy the more threatening it can become.

As I began my research last week I thought this post would be relatively short.  Going back to my 2001 MSc lecture notes there was not a whole lot of dietary/nutrition related evidence to work with.  However, as I began to search through recent medical databases I was pleased and enthralled with the emergence of new information.  The definitive causes of preeclampsia are not known and there are many theories.  Nutritional factors, however, do seem to be at play. 

Keep body weight in check:
Maternal overweight and obesity places women at risk.  A BMI (body mass index) greater than 25 is seen as a risk.  To work out your BMI divide your weight in kg / by your height in metres² (height x height) or use an online BMI calculator e.g. the NHS calculator.  A recent study(2) also shows that gaining a lot of weight during pregnancy may be a risk factor.  This study looked at 34,143 women age 18-34 who were already overweight at the start of their pregnancies.  Gaining more than 15lb during pregnancy was a significant risk factor for the development of preeclampsia and gaining more than 25lb increased the risk further.  The lowest risk of adverse outcomes was for women who gained 6-14lb.

Dietary fibre:
The study(1) mentioned in my opening paragraph was carried out because evidence already exists for the beneficial effects of fibre in reducing hypertension (high blood pressure).  1538 pregnant women were involved in the study and their dietary intake was assessed 3 months before and during early pregnancy.  Women with the highest dietary fibre intake (more than 21g/day) had a significantly reduced risk of preeclampsia when compared to women with the lowest dietary fibre intake (less than 12g/day).  These are important findings, as I have mentioned in previous blog posts the average intake of fibre in the UK is low (around only 12g/day).  The recommended daily intake is currently set at 18g/day in the UK, however for optimal health many experts regard at least 25g/day as necessary. 

This most recent study adds weight to earlier evidence(3) which also found that fibre was associated with a significantly reduced risk of preeclampsia.  The researchers also found that potassium intake was a significant protective factor (I will be discussing potassium intake a blood pressure further on Thursday).  This evidence was interesting as it mentioned specific foodstuffs, with fruits and vegetables being associated with a reduced risk of preeclampsia development (unsurprisingly since vegetables and fruits are great sources of fibre and potassium).

Fruits, Vegetables and Antioxidant Vitamins:
You may be sick of my constant mentioning of vegetables and fruits?!  Well, they really are vitally important to health and I will be writing about them as often as possible!  As indicated above these super foods provide the body with fibre and are fantastic sources of potassium.  In addition to this they are packed full of vitamins, minerals and flavonoids (bioactive plant compounds).  Many of these plant nutrients act as antioxidants in the body.

Antioxidants protect our cells from the damaging effects of highly reactive molecules called free radicals (which cause oxidative stress in the body).  There is mounting evidence that these destructive molecules, together with lowered antioxidant defences, play a significant role in the development of preeclampsia.  The body does produce its own antioxidants but also relies on vitamins, mineral and phytochemicals (including flavonoids) from the diet, especially from colourful vegetables and fruits, for additional valuable supplies.

Dietary antioxidants and supplemental vitamin C and E(4,5), lycopene(6), selenium(7,8) and  multivitamins(9) all appear to have some protective role to play against the development of preeclampsia, although the evidence for supplements is not yet conclusive and further large trials are needed.  The evidence to date certainly seems to suggest an important role for fruit and vegetable consumption during pregnancy, a variety of colourful vegetables and fruits will provide a whole array of vital nutrients to the body.  Selenium is not as widely available in the UK diet, although Brazil nuts are a terrific source. 

In addition to diet you may wish to discuss taking a pregnancy safe multi-vitamin and mineral supplement with your GP, midwife or health professional.

Omega 3 Essential Fatty Acids:
Recent evidence suggests that women with preeclampsia have reduced levels of essential omega 3 fatty acids in their blood(9,10).  Omega 3 fatty acids are vital for the efficient functioning of the immune system.  A lack, or imbalance, of these fatty acids is associated with inflammation in the body.  Inflammatory chemicals (cytokines) have been implicated in the development of and risk for preeclampsia.  Omega 3 fatty acids are essential for optimal foetal development (and are especially important in brain and immune development) and it is important to ensure a regular supply during pregnancy.  I have spoken about these fats extensively in previous posts.  Good dietary sources are oily fish (salmon, trout, mackerel, sardines) and flaxseeds or walnuts for vegetarians/vegans.  Many people in the UK do not eat these foods regularly.  Speaking to your GP or midwife about an omega 3 supplement, a fish oil (providing about 250mg EPA and 250mg DHA per day) or flaxseed oil may be prudent to ensure adequate levels throughout pregnancy and beyond.

At the moment the evidence is preliminary and needs backing up by large, well designed trials and further research.  Personally, I feel that the take home message is that being a normal weight (BMI 19-24), being physically active and having a healthy, nourishing diet rich in fruits, vegetables and essential fats may be protective.....great advice for good health for all of us then!

(1) Qiu et al.  2008.  Dietary fibre intake in early pregnancy and risk of subsequent preeclampsia.  American Journal of Hypertension.  21:903-909 [EPub doi:10.1038/ajh.2008.209 17 July]
(2) Langford A et al.  2008.  Does Gestational Weight Gain Affect the Risk of Adverse Maternal and Infant Outcomes in Overweight Women?  Matern Child Health J.  [Epub ahead of print]
(3) Frederick, I. O., et al.  Dietary fiber, potassium, magnesium and calcium in relation to the risk of preeclampsia.  J Reprod Med.  50(5):332-344, 2005.
(4)Chappell LC et al.  1999.  Effects of antioxidants on the occurrence of preeclampsia in women at increased risk: a randomised trial.  The Lancet.  354:810-816
(5)Chappell  LC et al.  2002.  Vitamin C and E supplementation in women at risk of preeclampsia is associated with changes in indicies of oxidative stress and placental function.  Am J Obstet Gynecol.  187:777-784
(6)Sharma JB et al.  2003.  Effect of lycopene on preeclampsia and intra-uterine growth retardation in primigravids.  Int J Gynaecol Obstet.  81:257-262
(7)Han L & Zhou SM.  1994.  Selenium supplement in the prevention of pregnancy induced hypertension.  Chin Med J.  107:870-871
(8)Rayman et al.  2003.  Low selenium status is associated with the occurrence of the pregnancy disease preeclampsia in women from the United Kingdom.  Am J Obstet Gynecol.  189:1343-1349
(9) Bodnar LM et al.  2006.  Periconceptional multivitamin use reduces the risk of preeclampsia.  Am J Epidemiol.  164:470-477
(10) C et al.  2006.  Erythrocyte omega-3 and omega-6 polyunsaturated fatty acids and preeclampsia risk in Peruvian women.  Arch Gynecol Obstet.  274:97-103
(11)Mehendale S et al.  2008.  Fatty acids, antioxidants, and oxidative stress in pre-eclampsia.  Int J Gynaecol Obstet.  100:134-238

Written by Ani Kowal

It makes food taste great and brings any dish to life with flavour.  I love garlic!  Garlic is a type of vegetable, there are two species: Allium sativum  (cultivated garlic) and Allium ursinum  (wild bear's garlic), both of which belong to the Amaryllis (Amaryllidaceae) family.

A plethora of health benefits are attributed to garlic with studies showing that it seems to have positive effects for the heart and circulatory system, immune system and digestive system.  It also seems to be anti-parasitic, anti-viral, anti-fungal and anti-bacterial.  The lists go on and on!

Today I wanted to look at garlic supplementation in relation to lowering blood pressure.  Until very recently research on garlic supplementation and blood pressure had been inconclusive.  However, the latest, most comprehensive review(1) of scientific evidence “suggests that garlic preparations are superior to placebo in reducing blood pressure in individuals with hypertension [high blood pressure]”.  The review of scientific literature was undertaken by researchers at The University of Adelaide, South Australia.  The scientists looked at studies that were published between 1955 and 2007, and only included ‘high quality’ research (randomised controlled trials with true placebo groups).  A significant association was found between blood pressure at the start of intervention with garlic supplements and the levels of blood pressure reduction.

The garlic was effective at lowering both the systolic and diastolic blood pressure.  Systolic blood pressure, represented by the top number in a blood pressure reading, is the measure of the phase of the heartbeat when the heart contracts and pumps blood into the arteries.  Diastolic blood pressure, represented by the bottom number in a blood pressure reading, is the measure of the phase of the heartbeat when the heart muscle relaxes and allows the chambers to fill with blood. 

The review found that, on average, garlic reduced systolic blood pressure by 4.6 mmHg.  The scientists also looked at studies that were conducted with people with a high blood pressure (hypertension), in these studies the garlic had a more pronounced effect with a reduction of systolic blood pressure by an average of 8.4 mmHg and diastolic blood pressure by 7.3 mmHg. The higher a person's blood pressure was at the beginning of the study, the more it was reduced by taking garlic supplements.

These results are very similar to those of widely used hypertension drugs such as beta blockers, which reduce systolic blood pressure by around 5 mmHg, and ACE (angiotensin converting enzyme) inhibitors, which produce around an 8 mmHg drop in systolic blood pressure.

In the population as a whole, the authors of the study note that a reduction of systolic blood pressure by around 4-5 points and diastolic blood pressure by 2-3 points could cut the risk of heart disease and heart disease-related death by up to 20 percent.  The scientists also note that more research is needed to determine whether garlic supplementation might have long-term effects on heart disease risk. 

In most of the studies reviewed in this paper the participants given garlic took it in powdered form as a standardized supplement at a dose of 600 mg - 900 mg daily for 12-23 weeks. The garlic supplements provided around 3.6 mg - 5.4 mg of allicilin which is the active ingredient in garlic.  A fresh clove of garlic contains around 5 mg - 9 mg of allicin (and tastes wonderful!), so whether you eat garlic regularly or choose to take a supplement it may well be helpful for your blood pressure or for your health in general!

As high blood pressure is a (silent but) major risk factor for heart attack I wanted to mention the British Heart Foundation campaign which aims to alert us to the more visible symptoms of a heart attack.  As part of the campaign there will be a two minute TV  promotion at 9.17pm on ITV1 this Sunday (10th August) during a break in the  ‘Midsomer Murders’ programme.  The charity is calling the event ‘Watch Your Own Heart Attack’.  More information can be found on their website or by clicking on this link.

(1)Ried K et al.  2008.  Effect of garlic on blood pressure: A systematic review and meta-analysis.  BMC Cardiovascular Disorder.  8:13(16 June), [E-pub doi:10.1186/1471-2261-8-13]

Written by Ani Kowal