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Chocolate is officially “good for you”, according to The Guardian. We can now apparently rejoice at the thought that munching our Easter eggs will make us less likely to have a stroke or heart attack. The Daily Telegraph says that eating a bar a day could cut the risks by as much as 39%.

The news is based on research that followed 19,000 people over eight years. Looking at the participants’ chocolate intake at the start of the study, researchers found that higher intake of chocolate was associated with reduced risk of heart attack or stroke. However, the strength of this association was reduced when the influence of the participants’ blood pressure was taken into account. Equally, it cannot be concluded that chocolate had influenced the participants’ blood pressure it was only measured once, at the start of the study. It is also important to note that those in the highest consumption category consumed only 7.5g a day, which is far less than a whole bar of chocolate.

Overall, the question remains as to whether chocolate has any cardiovascular health benefits. The important thing to remember is that, regardless of any potential benefits, chocolate is high in fat and calories and should be enjoyed only in moderation. A diet high in fat and calories is known to increase the risk of obesity, heart disease and stroke, rather than decreasing it.

 

Where did the story come from?

This research was conducted by Dr Brian Buijsse and colleagues of the German Institute of Human Nutrition. The study was given financial support by the German Federal Ministry of Science, the European Union and the German Cancer Aid. The study was published in the peer-reviewed European Heart Journal.

In general, the newspaper reports have not provided a balanced summary of the findings and limitations of this research, which can give no firm conclusions on the health benefits of eating chocolate.

 

What kind of research was this?

This was a cohort study designed to investigate the link between eating chocolate and development of high blood pressure, stroke and heart disease over an eight-year follow-up period.

A cohort study is normally a good way of observing whether a risk factor is linked to an outcome across an extended period of follow-up. However, the researchers must ensure that their cohort of participants is sufficiently large (as it was in this study) and that they account for other factors that could possibly influence their outcomes (confounders) when analysing their results. There can be particular problems with assessing dietary factors through a cohort study, namely that it is often difficult to get an accurate quantification of a person’s consumption of a particular food, and dietary habits are liable to change over time.

The preferred method for studying the effects of a substance like chocolate would be a randomised controlled trial, in which people were assigned to consume chocolate or no chocolate. However, this is likely to be unfeasible due to the large number of people and long duration of follow-up that would be needed to study cardiovascular outcomes like stroke risk. Ideally, the participants would also restrict their chocolate intake to only that which is assigned by the researchers. This seems unlikely to happen over a long study period.

If chocolate does contain compounds that reduce the risk of cardiovascular disease, these specific substances could be extracted and tested against a placebo in randomised controlled trials.

 

What did the research involve?

This study used participants drawn from another study called the European Prospective Investigation into Cancer (EPIC). This research gathered data on 19,357 members of the general population, aged between 35 and 65, who took part in enrolment examinations between 1994 and 1998. All were free of cardiovascular disease and were not taking blood pressure medications. The examinations included completing a food frequency questionnaire, an interview about their medical history, lifestyle and socio-demographic details, and measurement of blood pressure and body mass index (BMI).

Chocolate consumption was assessed by how frequently a 50g bar of chocolate was consumed and how many bars of chocolate participants ate each day. In addition, 8% of the sample (1,568 people) participated in a 24-hour dietary recall assessment.

Follow-up assessments were carried out by postal questionnaire sent every two to three years. By 2004-6 (average 8.1 years), the researchers had four complete rounds of follow-up, with an average 90% response rate across all questionnaires. Self-reports of heart attack, stroke or associated symptoms were confirmed by reviewing medical records and death certificates and contacting treating physicians.

In this subsequent study, the researchers analysed the relationship between chocolate intake and cardiovascular outcomes in models adjusted for different groups of possible confounding factors. These factors included total energy intake, age, gender, alcohol intake, employment status, BMI, waist circumference, smoking, physical activity, education, diabetes, and intake of fruit, vegetables, red meat, processed meat, dairy, coffee, tea and cereal fibre.

 

What were the basic results?

In total, 92.3% of the sample reported chocolate consumption at the start of the study. Various factors were associated with increased chocolate intake, such as female sex and lower intake of fruit, vegetables, dairy and alcohol. At the start of the study, reporting higher chocolate consumption was also associated with lower blood pressure (1.0mmHg average difference between the highest and lowest consumption categories). Of those who took part in the 24-hour food recall, 57% ate milk chocolate, 24% dark, 2% white and 17% did not specify chocolate type consumed.

There were 166 cases of heart attack and 136 cases of stroke during the eight-year follow-up. After adjusting for age, sex, lifestyle, BMI, diabetes and other dietary factors, those in the highest category of chocolate consumption (7.5g a day) had a 39% decreased risk of the combined outcome of heart attack or stroke compared to the lowest consumers (1.7g a day) (relative risk 0.61, 95% confidence interval 0.44 to 0.87).

Separate analysis for stroke and heart attack risk revealed significant risk reduction for stroke but not heart attack. However, adjusting for the influence of blood pressure at the start of the study reduced the strength of both associations.

 

How did the researchers interpret the results?

The researchers concluded that “chocolate consumption appears to lower cardiovascular risk, in part through reducing blood pressure”. They say the association appears stronger for stroke than for heart attack.

 

Conclusion

There are a number of important limitations that must be considered when interpreting these results:

• In this type of study, confounding factors, other than the one being assessed (chocolate consumption in this case), may contribute to the differences between the groups. Although this study took into account a number of potential confounders, it is possible that additional confounders were not measured or were inaccurately quantified. For example, lifestyle and other dietary measures were only assessed in a single measurement at the start of the study and may not reflect the participants’ histories or behaviour during follow-up.
• Although the researchers used a standard food frequency questionnaire and a 24-hour food recall questionnaire in a small sample of participants, there may still be inaccuracies in people’s recollection of their diets. Diet, including chocolate consumption, is likely to vary over a lifetime and a single assessment is unlikely to capture a person’s lifelong habits. It is also difficult to take into account the chocolate that may be included in the diet in the form of biscuits, baked goods and other sources.
• The level of chocolate consumption (estimated based on the 8% of the sample who carried out the 24-hour dietary recall) was low. For instance, those in the highest category reportedly consumed only 7.5g of chocolate a day and those in the lowest category only 1.7g. This is considerably less than the mass of the average chocolate bar, and the difference between the two groups is reported to be the equivalent of less than one small square of a 100g bar. It is unclear where the idea of a “healthy bar a day” in newspapers has come from.
• Associations between chocolate and stroke or heart attack were reduced in strength when the researchers adjusted for the influence of blood pressure at the start of the study. Although the research reports that the reduced risk of heart attack and stroke may be due to the effect that chocolate has on reducing blood pressure, chocolate consumption and blood pressure were both measured at the same time in this study. This means that it cannot tell whether chocolate could have contributed to the slightly lower blood pressure at the start of the study, or whether the higher consumption group maintained lower blood pressure during follow-up.
• The researchers note that other studies on chocolate have had mixed findings, with some showing a reduction in cardiovascular disease with increasing chocolate consumption and others showing no association or only weak associations. A systematic review of all relevant studies would give a clearer picture of whether an association exists.
• As the researchers rightly say, the findings would need confirmation in randomised controlled trials. There may be some practical difficulties with this due to the long follow-up needed for measuring cardiovascular outcomes and the large participant numbers required. However, if certain compounds in chocolate (such as flavonoids) are thought to be responsible for potential cardiovascular benefits, it may be more feasible for these to be extracted and tested in randomised controlled trials.

Overall, the limitations of this study mean that it cannot conclusively prove that chocolate was directly responsible for the reduction in heart attacks and strokes. The assumption that running to the shops to eat a bar a day will stop us getting a heart attack or stroke is tantalising but fanciful. However, chocolate can be enjoyed in moderation as part of a healthy, balanced diet.

High blood pressure and diabetes are both clearly associated with increased risk of cardiovascular diseases, and being overweight or obese is associated with both these risk factors. Therefore, eating a diet high in fat and calories is likely to increase, rather than decrease, your risk of these diseases.

Links To The Headlines

It’s official: Chocolate is good for you. The Guardian, March 30 2010

Chocolate ‘can cut blood pressure and help heart’. BBC News, March 30 2010

A chocolate bar a day ‘can cut the risk of heart disease and stroke’. The Daily Telegraph, March 30 2010

One piece of chocolate a day could save your heart. Daily Express, March 30 2010

Links To Science

Buijsse B, Weikert C, Drogan D et al. Chocolate consumption in relation to blood pressure and risk of cardiovascular disease in German adults. European Heart Journal, [published online] March 30, 2010

Press release: Those Easter eggs may be good for you! Study shows chocolate reduces blood pressure and risk of heart disease

"A revolutionary treatment for gout could result in a new form of therapy for a range of other medical conditions – such as diabetes and obesity", The Independent reported. It said tests in mice found that implanting a small plastic capsule, which contained genetically engineered cells, under the skin could reduce the symptoms of gout and potentially other metabolic diseases, such as diabetes or obesity.

This study has shown that it is possible to use a cell-based system that uses certain biological mechanisms to regulate levels of uric acid in mice. This is a fascinating development, but further research will be needed to see whether this system can be safely tested in humans.

The system developed in this study works specifically for uric acid, but it is possible that a similar approach could be used to control other compounds in the body. However, each compound will need its own system for monitoring and controlling its levels, and some compounds may be more difficult to control than others. Therefore, although diabetes seems to be a potential target for a similar approach, it is not yet clear if this will be possible.

 

Where did the story come from?

Dr Christian Kemmer and colleagues from ETH Zurich and other research centres in Switzerland and France carried out this research. The study was funded by the Swiss National Science Foundation and the EC. The research paper was published in the peer-reviewed scientific journal Nature Biotechnology.

The Independent correctly reported that this study was in mice and focused on uric acid metabolism. Although it may be possible to adapt this technique to treat conditions such as diabetes, the technique is in its early stages and has not yet been adapted for dealing with glucose, or for animal models of diabetes. Therefore, The Independent’s headline that the “Capsule offers hope to diabetes sufferers” seems premature.

 

What kind of research was this?

This aim of this research was to work towards creating a device that could maintain a steady level of uric acid in the blood, based on natural biological mechanisms. Uric acid is a chemical formed when proteins are broken down in the body. It is removed from the body in urine. Too much uric acid in the body can cause a condition called gout, where uric acid crystals form in the joints and cause pain.

Our bodies have many mechanisms for keeping chemicals such as uric acid at optimal levels. If these mechanisms go wrong, it can lead to imbalances in these chemicals and potentially disease. This study was carried out to show that it was possible to create a biologically based system that can sense and correct imbalances in uric acid in the blood stream. If such a device were possible, the researchers hoped that the same principle could be applied to correct imbalances in other compounds, such as glucose levels in diabetics.

This type of research in animals is essential for the development of new treatments as such early research could not be carried out in humans. The technique will need to be refined in animals and shown to be effective and safe for any of the different conditions that it might be used for, before it could be tried in humans with these conditions. As the body controls the levels of different compounds in the body in different ways, the technique would need to be adapted for each new compound and may not be as effective for all compounds.

 

What did the research involve?

The researchers first developed a system that could sense and respond to increases in uric acid in the blood. This system was based on a bacterial protein (called HucR), which, in the absence of uric acid, can switch off certain genes by binding to their DNA. When uric acid is present, the protein binds to the uric acid instead, releasing the DNA and allowing the gene to become active.

The HucR protein was adapted so that it would regulate the activity of a specific gene that produces urate oxidase, a protein that breaks down uric acid. The theory was that when uric acid levels were low, the HucR protein would bind to the urate oxidase gene and stop it from being active; when uric acid levels were high, the HucR protein would “release” the gene, allowing it to start producing urate oxidase to break down the excess uric acid. This effect needed to be reversible, so that once uric acid levels returned to normal, the HucR would bind to the urate oxidase gene again and stop it being active.

The researchers tested their system in human cells grown in the laboratory. They also genetically engineered the cells to produce a protein that transports uric acid into the cells, to make them more sensitive to the chemical.

Once the system had been demonstrated as working in cells in the laboratory, the testing progressed to mice that lacked their own urate oxidase. These mice developed high levels of uric acid in their blood and uric acid crystals formed in their joints and kidneys, causing symptoms similar to gout in humans.

The genetically engineered human cells were implanted into these mice. The researchers looked at what happed to the levels of uric acid in the blood and urine, and the uric acid crystals in their kidneys. They also compared these levels with levels in mice treated with allopurinol (a treatment used for gout that lowers the levels of uric acid) and in control mice implanted with cells that had not been genetically engineered to regulate uric acid.

 

What were the basic results?

The researchers found that, in mice with high uric acid levels implanted with the genetically engineered cells, uric acid levels in the blood and urine were reduced to the same levels as mice treated with allopurinol. These levels were lower than the levels in control mice that were not implanted with engineered cells or treated with allopurinol.

The levels of uric acid seen in the blood in the mice was 5 milligrams per decilitre (mg/dl), lower than the 6 mg/dl needed for uric acid crystals to dissolve in humans. The mice treated with the genetically engineered cells also developed fewer uric acid crystals in their kidneys than the control mice.

 

How did the researchers interpret the results?

The researchers concluded that they have developed a cell-based implant system that can “provide self-sufficient and reversible control of uric acid levels in the bloodstream”. This can prevent the build-up of uric acid but also maintain normal baseline levels of uric acid. They say the system may be suited for treating and preventing conditions associated with high levels of uric acid in the body, such as gout. They also say that the basic principle of this system could motivate the development of similar systems to regulate other chemicals in the body.

 

Conclusion

This study has shown that components of biological systems can be used to make a synthetic cell-based system for controlling uric acid levels in the blood stream in mice. This is a fascinating development and further research will determine whether the system can be used in humans. The technique is likely to require further testing of its efficacy and safety in animals before it could be tested for treating gout in humans.

The system developed here is specifically aimed at uric acid, but it is possible that a similar approach could be used to control other compounds in the body. However, each compound will need its own system for monitoring and controlling its levels, and some compounds may be more difficult to control than others. Therefore, although diabetes seems to be a possible target for a similar approach, it is not yet clear if this will be possible.

Links To The Headlines

Capsule offers hope to diabetes sufferers. The Independent, March 29 2010

Links To Science

Kemmer C, Gitzinger M, Daoud-El Baba M, et al. Self-sufficient control of urate homeostasis in mice by a synthetic circuit. Nature Biotechnology 2010

“Acupuncture can help cure patients of a fear of the dentist’s drill,” according to The Daily Telegraph. It says that research shows that just one five-minute session of acupuncture can reduce anxiety and enable people who have previously avoided the dentist to have treatment.

This study looked at 20 people whose fear of the dentist had previously hampered or prevented the completion of their dental treatment. It found that their pretreatment level of anxiety reduced after acupuncture and they were all able to receive their dental treatment. However, this study did not compare people receiving acupuncture with people receiving no anxiety treatment. This means we cannot rule out the possibility that their fear naturally reduced over time. Also, the dental procedures performed in this study were minor (cleaning or examination), and this study cannot tell us whether acupuncture would provide anxiety relief for major procedures such as drilling.

Overall, the study suggests that further investigation into the use of brief acupuncture sessions for reducing dental anxiety is warranted, but larger, blinded, randomised controlled studies will be needed to confirm acupuncture’s effects.

 

Where did the story come from?

Dr Palle Rosted and colleagues from Weston Park Hospital in Sheffield and other centres in the UK and Denmark carried out this research. No specific sources of funding were reported for the study. The study was published in the peer-reviewed journal Acupuncture Medicine.

The Daily Telegraph, BBC News and Metro have covered this story. They report the research accurately, and The Daily Telegraph and BBC News have importantly noted that larger studies will be needed to confirm the findings. It is not possible to say whether acupuncture can “help cure patients of a fear of the dentist’s drill”, as is suggested in The Daily Telegraph, as the patients did not receive any drilling during their treatment.

 

What kind of research was this?

This was a case series looking at the use of acupuncture to relieve anxiety in people who were afraid of receiving dental treatment.

This type of study does not include a control group of people not receiving acupuncture to compare against. This makes it difficult to determine whether any reduction in fear seen in the treated individuals would have occurred naturally over time. As no other anxiety treatment was compared, it is also not possible to say whether acupuncture would be any better than other approaches, such as hypnotism.

A further limitation of this research is that such a small number of cases may not be representative of the many members of the general population who have some degree of anxiety about dental treatment. Equally, it may be too small to give a good idea of the different levels of anxiety for which such a treatment may be more or less effective.

 

What did the research involve?

The study looked at whether acupuncture reduced anxiety in 20 people who were afraid of receiving dental treatment, as rated by the patients themselves and the dentists.

To be eligible for inclusion, patients had to have previously shown signs of severe anxiety about receiving dental treatment that had made treatment impossible or difficult. They also had to show moderate-to-severe anxiety on a standard self-reported questionnaire measure called the Beck Anxiety Inventory (BAI). A higher score on this scale indicates greater anxiety, with a maximum score of 63.

The patients reported having had dental anxiety for between 2 and 30 years, with an average of about 10 years. The study reports that in 14 patients, planned dental treatment had previously been cancelled due to their dental anxiety. In addition, six patients had required sedatives such as diazepam or midazolam in order to undergo dental treatment in the past, and another three had required a general anaesthetic. The exact types of dental treatment associated with these instances were not reported.

Eight dentists reported on twenty patients that received acupuncture over eighteen months. These dentists had been trained in using acupuncture to treat dental anxiety. They carried out the acupuncture five minutes before starting treatment, applying needles to two points on the top of the head that reportedly have a relaxing effect. The needles were inserted and rotated anticlockwise and clockwise for five seconds, and then left in place during the dental treatment. During dental treatment patients received minor procedures, mainly dental examination (13 patients) or cleaning of the teeth (7 patients). The dentists also used their standard procedures for easing patient anxiety.

The patients’ anxiety levels were assessed using the BAI questionnaire before the acupuncture treatment and after the acupuncture and dental treatment. The dentists rated their patients’ anxiety on a scale of zero to five, where zero indicated no anxiety and five severe anxiety. The patients also used this scale to rate their anxiety in the 24 hours before their treatment, when they entered the clinic, and during their past and current treatments. The study did not blind the patients or the dentists to the anxiety treatment received.

 

What were the basic results?

The patients were less anxious in the 24 hours before their current treatment than they had been in the past, with an average (median) score of three for current treatment compared with a score of four during previous treatment.

Before acupuncture the patients reported moderate-to-severe anxiety (average BAI questionnaire score of 26.5). After acupuncture and dental treatment, the patients’ anxiety had reduced significantly, and they only showed mild anxiety (average BAI score of 11.5). They also rated their anxiety as lower during current treatment than in past treatments (average score of two for current treatment compared with four for previous treatment on a scale from zero to five). The dentists also rated their patients as less anxious in the current treatment than in past treatments (average score of four for previous treatment and two for current treatment).

Twelve of the twenty patients (60%) were reported to have responded positively to acupuncture treatment, based on the BAI scale. Current dental treatment could be completed by all twenty patients, of whom only six had previously been successfully treated without acupuncture. There were no serious side effects of the acupuncture, although two patients reported sleepiness.

 

How did the researchers interpret the results?

The researchers conclude that “acupuncture prior to dental treatment has a beneficial effect on the level of anxiety in patients with dental anxiety”. They say that the technique is easy to learn and inexpensive, but that any recommendations regarding its use “should not be made until a controlled trial has been performed”.

 

Conclusion

There are a number of points to note when interpreting this study:

• As there was no control group we cannot tell whether the reduction in the patients’ anxiety levels was because their fears naturally subsided over time or due to the acupuncture. The dentists also used their standard techniques for anxious patients, and these could have contributed to the results seen.
• The study was small, and could only include people who agreed to have acupuncture. It is not clear how many people had been asked to take part but declined, or the reasons why people may have declined. The small study size and lack of information on those who declined means results of the study may not be representative of the average individual who is afraid of the dentist. For example, some people who are afraid of dental treatment may have a fear of needles, which could reasonably be extended to a fear of acupuncture needles.
• The individuals in this study were only receiving minor dental procedures (cleaning or examination). The study cannot tell us what effect acupuncture could have on anxiety relating to more major dental treatment, such as fillings or the use of the drill.
• It is not possible to say what effect the treatment would have on children who are afraid of the dentist as only adults were included.
• The study cannot tell us whether acupuncture would have been any better than other possible approaches to reducing fear, such as a brief counselling session or hypnosis, or the dentists’ standard anxiety relief techniques.
• The study was not blinded, therefore it is not clear how much of the effect was due to the acupuncture itself and how much was due to the fact that the patients knew they were receiving acupuncture aimed at reducing their anxiety. This also applies to the dentists’ ratings of patient anxiety.

Overall, the study suggests that using a brief acupuncture session for reducing anxiety in people afraid of the dentist could be worth further investigation, but larger, blinded, randomised controlled studies will be needed to confirm its effects.

Links To The Headlines

Acupuncture ‘can cure patients of a fear of the dentist. The Daily Telegraph, March 30 2010

Acupuncture ‘can treat dental phobia’. BBC News, March 30 2010

Links To Science

Rosted P, Bundgaard M, Gordon S, Lynge Pedersen AM. Acupuncture in the management of anxiety related to dental treatment: a case series. Acupuncture in Medicine 2010;28:3-5