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A hearty cup of tea?

A hearty cup of tea?

“People who drink several cups of tea or coffee a day could be at lower risk of heart disease,” according to reports.  Is suggested that drinking tea could cut the chances of a heart attack by up to a third.
The news is based on a Dutch study that followed 38,000 people for over 10 years, analysing their risk of stroke, cardiovascular disease and death.  When looking at the association between coffee consumption and events relating to heart disease, the study found that drinking moderate amounts of coffee (two to three cups a day) was better than a little or a lot.  With tea, drinking more than six cups a day was linked to the lowest risk.
There have been a number of contradictory research findings about the benefits and harms of caffeine.  For example, a separate Italian study recently found an increased risk of rheumatoid arthritis for women who drink tea.  The Dutch study’s limitations mean that it cannot prove that coffee and tea have a direct effect on heart attack risk.

The study was carried out in the Netherlands by researchers from the University Medical Center Utrecht and the National Institute for Public Health and Environment.  It was funded by the European Commission, the Dutch Cancer Society, the World Cancer Research Fund, the Netherlands Organisation for Health Research and Development and the Dutch Ministry of Public Health, Welfare and Sports and published in the peer-reviewed Journal of the American Heart Association.
The study can be considered in the wider context of better established evidence about reducing coronary heart disease risk. A senior cardiac nurse at the British Heart Foundation was quoted as follows:  “It's worth remembering that leading a healthy overall lifestyle is the thing that really matters when it comes to keeping your heart in top condition.  Having a cigarette with your coffee could completely cancel any benefits, while drinking lots of tea in front of the TV for hours on end without exercising is unlikely to offer your heart much protection at all."

The research

This large cohort study assessed the effects of tea and coffee consumption on health outcomes over a 13-year period, specifically any effects on cardiovascular health. The researchers have attempted to adjust their calculations to account for some potentially confounding factors (that may link the consumption of tea and coffee with adverse outcomes).  As with all observational studies, there is a concern over whether all possible confounding factors have been addressed or fully adjusted for.  The researchers have discussed some of the potential shortcomings of their study.

What was involved?

The researchers highlight the controversy that surrounds the benefits and harms of coffee consumption and note that the association between coffee and cardiovascular diseases remains controversial.  They also say that for tea consumption, a systematic review assessing the association with coronary heart disease and stroke is inconclusive, but in the European region, tea consumption appears beneficial in relation to myocardial infarction.
In this study, researchers investigated the relationship between tea and coffee consumption and cardiovascular disease in a large cohort of healthy Dutch men and women.  There were 37,514 participants, who were also participating in one of two other cohort studies and who were recruited from 1993 to 1997.  The first study enrolled women aged 50 to 69 who were participating in a breast screening programme and the second was in men and women aged 20 to 65.  The researchers excluded all those who had missing information about tea and coffee consumption or had cardiovascular disease at baseline (the start of the study).
At baseline, the participants completed a questionnaire asking about chronic diseases, presence of a variety of potential risk factors, demographics and their medical and lifestyle histories.  Their height, weight, hip-and-waist circumference and blood pressure were measured.  Physical activity was assessed according to a validated physical activity index.
Participants were also given a food frequency questionnaire that assessed their average daily consumption of 178 different foods during the previous year, including how many cups of coffee or tea they regularly drank during the past year and which types of coffee (regular, decaffeinated, other etc).  Tea and coffee consumption was then divided into six ranges (less than one cup per day, one to two, two to three, three to four, four to six, more than six cups per day).  Some of these categories were collapsed during analyses due to the small number of people within each group.
The researchers then noted the health outcomes of the participants up to 13 years after the baseline questionnaires, specifically any events or deaths from coronary heart disease (CHD) and stroke.  They also analysed the combined outcome of morbidity and mortality (events plus deaths) for stroke, CHD and death due to any cause.  Their study then assessed whether there was an association between the different levels of consumption of coffee and tea and the negative health outcomes, while taking into account a number of possible confounding factors.  The results were adjusted for age, gender, education, physical activity, smoking, waist circumference, menopausal status and HRT use, alcohol intake, total energy intake and intake of saturated fat, fibre, vitamin C and total fluid intake.

What were the basic results?

Over the course of follow-up, 1,950 cardiovascular events occurred (563 from stroke, and 1,387 from coronary heart disease (CHD)).  There were 1,405 deaths (including 70 from stroke and 123 from coronary heart disease).
The researchers found the lowest risk of CHD events to be linked with drinking more than two but less than three cups of caffeinated coffee per day.  The increased risk of stroke with more than six cups of coffee per day was no longer significant once the researchers had adjusted for confounding factors.  After taking into account these confounders, coffee consumption was not associated with death from stroke, death from any cause or death from coronary heart disease (although the researchers state that “although not significant, coffee slightly reduced the risk for CHD mortality”).
For tea, consumption of more than six cups per day was associated with the lowest risk of CHD events (HR 0.64, 95% CI 0.46 to 0.90, p=0.02).  The relationship between tea and stroke risk was not significant after adjusting for confounders.  There was a significant link between tea consumption and death from CHD, with the lowest risk of CHD death linked to two of the consumption ranges: one to three cups per day and more than three but less than six cups per day. After adjusting for confounding factors, there was no significant link between tea consumption and deaths from stroke or due to any cause.
The researchers say that “high tea consumption is associated with a reduced risk of CHD mortality”.  They note that their results suggest “a slight risk reduction for CHD mortality with moderate coffee consumption” and “strengthen the evidence on the lower risk of CHD with coffee and tea consumption”.
For coffee, the relationship with CHD events was “U-shaped”, i.e. higher risk with both very low and very high consumption.  For tea, there was a linear inverse association, reducing risk with increasing consumption.

Conclusion

This large cohort study with a long follow-up time has found an association between some levels of tea and coffee consumption and reduced risk of coronary heart disease events.  The study does highlight the following important limitations in the research, many of which are relevant because of the study design:
A relatively small number of people died during the course of follow-up (123 from CHD and 70 from stroke).  When considering these particular outcomes, the small numbers seen do not provide much statistical power to detect differences between the different consumption groups.
They had also relied on participants to recall their tea and coffee consumption over the course of a year at baseline.  There are two potential problems with this.  Recall may not be 100% accurate and collecting information on consumption only at baseline does not take into account very likely changes in consumption patterns over time.
Assumptions were made about the type of tea consumed (as this was not specified in the baseline questionnaires); i.e. that the majority of tea consumed was black tea.
Importantly, they note that they cannot exclude the possibility that some factors were commonly linked with the exposure (i.e. tea and coffee consumption) and with the outcome (CHD events).  In particular they say that coffee drinkers tend to smoke more and have less healthy lifestyles than tea drinkers and that this could explain higher risk of adverse outcomes in people consuming a lot of coffee.  While they have adjusted for some lifestyle factors, they acknowledge that they may not have done this fully.
While they acknowledge that adjustment for the presence of diabetes, high blood pressure and high cholesterol did not alter the associations, this may be because of the crude way they measured the presence of these diseases (through self-reporting at baseline).
Overall, the limitations and design of this study means that it adds more to the discussion about the benefits and harms of caffeine, but cannot be taken as proof that tea or coffee cause reductions in the risk of heart disease.  There are well-established ways of reducing the risk of heart disease, including healthy eating and physical activity, rather than relying on high tea consumption or moderate coffee intake.  The food standards agency makes particular recommendations about caffeine consumption for pregnant women (recommending no more than 200mg of caffeine per day, which is approximately two mugs of instant coffee or tea).

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1,400 'Pressure Stations' set up for "Know Your Numbers Week"

1,400 'Pressure Stations' set up to support the Blood Pressure Associations "Know Your Numbers Week"

One in three UK adults have high blood pressure, but Blood Pressure Association research found that almost three quarters of adults do not know their blood pressure.

Know your Numbers! is the Blood Pressure Association's flagship awareness campaign. It encourages adults across the UK to know their blood pressure numbers and take the necessary action to reach and maintain a healthy blood pressure.

The highlight is Know your Numbers! Week, the nation's largest annual blood pressure testing and awareness event. This takes place in the second week of September each year and provides free checks for around 250,000 adults across the UK. Since its launch in 2001, Know your Numbers! Week has ensured more than 1.5million people have had their blood pressure checked so that they know their blood pressure numbers in the same way as their height and weight.

Know your Numbers! Week involves hundreds of nationwide organisations signing up to provide free blood pressure tests and information at venues known as Pressure Stations. Pressure Stations are located throughout the community including pharmacies, workplaces, GP surgeries, hospitals, health clubs, leisure centres, shopping centres and supermarkets.

Know your Numbers! Week 2010 takes place fom the 13th to the 19th of September. Check with your local pharmacy and get yourself tested!

• High blood pressure is the main risk factor for stroke and a major risk factor for heart attack, heart failure and kidney disease. There is also increasing evidence that it is a risk factor for vascular dementia. ⁽¹⁾
• High blood pressure is a level consistently at or above140mmHg and/or 90mmHg. ⁽²⁾
• Approximately 16 million people in the UK have high blood pressure. ⁽³⁾
• 30 per cent of women and 32 per cent of men have high blood pressure. ⁽⁵⁾
• Up to the age of 64 there are higher rates of men with high blood pressure than women. ⁽⁵⁾
• People with high blood pressure are three times more likely to develop heart disease and stroke and twice as likely to die from these as people with a normal blood pressure. ⁽³⁾
• Approximately 62,000 unnecessary deaths from stroke and heart attacks occur due to poor blood pressure control ⁽⁴⁾
• High blood pressure rarely has any symptoms, the only way for people to know if they have the condition is to have their blood pressure measured
• Approximately one third of people with high blood pressuredo not know that they have it. ⁽⁵⁾
• More than 90 per cent of people with high blood pressure who are receiving treatment are not controlled to 140/90 mmHg. ⁽⁵⁾
• Most people with high blood pressure who need to take medications, will need to take two or more to ensure that their blood pressure is lowered down to a target of 140/85mmHg ⁽²⁾
• Among women, levels of high blood pressure increase as income decreases. ⁽⁵⁾
• The risks increase as blood pressure rises, whether you have high blood pressure or a normal blood pressure – between the age of 40 and 70, for every rise of 20mmHg systolic or every 10mmHg diastolic the risk of heart disease and stroke doubles; for the range 115/75 up to 185/115mmHg. ⁽⁶⁾

References

1. Forette F, Seux M, Staessen J. Prevention of dementia in randomised double-blind placebo controlled systolic hypertension in Europe (Syst-Eur) trial. The Lancet 1998;352:1346-51

2. Williams B et al.Guidelines for management of hypertension: report of the fourth working party of the British Hypertension Society, 2004 - BHS IV. The Journal of Human Hypertension 2004;18 :139-185 (available on the British Hypertension Society web site at www.bhsoc.org)

3.The Annual Report of the Chief Medical Officer of the Department of Health 2001 (www.doh.gov.uk)

4.He F, MacGregor G.Cost of poor blood pressure control in the UK : 62 000 unnecessary deaths per year. Journal of Human Hypertension 2003; 17: 455-457 (www.nature.com/jhh/)

5. Health Survey for England 2003. Department of Health publication available at www.dh.gov.uk

6. National Institutes of Health and National Heart, Lung and Blood Institute. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of high blood pressure 2003 (www.nhlbi.nih.gov/
guidelines/hypertension/

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New trials on existing medicine show potential to prevent heart failure

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Test could predict menopause

A number of newspapers have covered the story of a new blood test to predict when the menopause will occur which “could close the baby gap” by telling women how long they will remain fertile for.