Health Professionals Newsletter

Welcome to the tenth newsletter from the United Kingdom Tea Council. This service will keep you up to date with current tea4health activities and events and inform you of the latest published research. We'll keep you updated on a quarterly basis with news and views from across the tea industry.

Research Update

Reducing the risk of stroke in male smokers - tea may help
Following an extensive study, Finnish researchers have concluded that drinking more than 2 cups of tea a day (340ml) may reduce the risk of stroke in male smokers.

Information from the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study was used to examine the associations between tea (and coffee) drinking and risk of stroke in male smokers. This randomised, double-blind, placebo-control trial was originally designed to determine whether supplements of _-tocopherol and/or _-carotene could reduce the incidence of cancer in men who smoked 5 or more cigarettes per day. At baseline a sub-set of 26,556 men (93% of the original cohort), mean age 57.6 years, were asked about their tea (and coffee) drinking habits - including the average number of cups consumed per day/week during the previous year and the usual cup size. These cup sizes were then converted to 'average' cup sizes of tea of 170ml. About 64% of the men never drunk tea and researchers did not determine the type of tea consumed as they pointed out that Finnish men rarely drink any tea other than black tea - there was no information on whether tea was taken with or without milk. The men were followed up after an average of 13.6 years and the study collected 360,187 person-years of follow-up data. During that time 3365 men suffered a stroke.

Drinking two or more cups of tea per day, compared to drinking no tea, decreased the risk of one particular sub-type of stroke, cerebral infarction, by 21%. This association was independent of age, supplementation group and cardiovascular risk factors (number of cigarettes smoked, Body Mass Index, systolic and diastolic blood pressure, serum total cholesterol, history of diabetes and coronary heart disease, physical activity and alcohol intake). There was no association between tea drinking and the risk of intracerebral or subarachnoid haemorrhage.

These findings are consistent with studies carried out in Dutch men and Japanese men and women, although the latter investigated the effects of green tea rather than black tea.

The researchers believe the antioxidant properties of the phenolic compounds in tea may be responsible for the beneficial effects. For example, in vitro and in vivo studies have found that these compounds prevent the oxidation of Low Density Lipoprotein (LDL) cholesterol. Oxidation of LDL particles promotes the formation of atherosclerotic lesions leading to an increased risk of cardiovascular disease. Furthermore another study found that black tea reduced platelet activation and C-reactive protein in healthy men; high levels of C reactive protein have been associated with an increased risk of ischemic stroke. However further studies are required to determine the exact protective mechanisms.

This study has particular strengths due to its prospective design; the statistical power as a result of the large number of stroke cases; and the extensive amount of information on cardiovascular risk factors allowing for adjustment of potential confounders. One limitation is that tea consumption was only measured once, at baseline, and this may not accurately reflect the actual level of tea consumption throughout the study period.

Nevertheless this large study among a smoking population provides good evidence that drinking more than 2 cups of tea per day may reduce the risk of cerebral infarction in male smokers. It remains to be seen whether these results are reproducible in women and in non-smoking populations and indeed whether the increased level of tea drinking by UK populations would provide additional protection from other types of stroke.
Larsson, S., Mannisto, S., Virtanen, M. J., Kontto, J., Albanes, D. and Virtamo, J. (2008) Coffee and tea consumption and risk of stroke subtypes in male smokers. Stroke 39: 1681-1687.

Drinking tea delays the onset of Parkinson's disease
A small Israeli study of patients with Parkinson's disease (PD) has found that those who drink more than 3 cups of tea per day delay the age of developing PD by more than 7 years.

This retrospective study recruited patients with a clinical diagnosis of PD from the Movement Disorders Unit in Tel Aviv Sourasky Medical Centre. Consecutive patients were identified through the researchers' computerised database. Of the 300 originally recruited, 283 agreed to participate. After exclusions a total of 278 patients completed the study. To minimise bias the patients were not told about the purpose of the study.

PD motor symptoms onset were defined as the year in which any motor disturbances that could later be attributed to PD were first noticed by the patient, a family relative or a caregiver as recorded in the medical file. Information about tea consumption was gathered, including the number of cups per day (caffeine-free and herbal teas were not counted towards tea consumption), the duration of tea drinking prior to PD symptom onset and the age of starting tea drinking and stopping (if appropriate). Data was obtained from a first degree relative for subjects with dementia.

Tea drinking was categorised into 3 groups: none, <2, 2-3 and > 3 cups per day - details about volume, tea type, brewing method and whether milk was added were not sought.

The average age of the study population was 68.4 years and the mean age at motor symptom onset was 58.1 years. As a result the average duration of the disease was 10.3 years.

Around 64% of the participants were, or had been, tea drinkers, although the vast majority continued to drink tea before and after the development of PD. There was a significant delay in the age of onset of motor symptoms by 7.7 years in patients who drank more than 3 cups of tea per day.

The possible mechanism for this association was not investigated but the authors anticipated caffeine might have an effect. However coffee consumption was also investigated in this study and no protective effect was found. The higher caffeine levels in coffee compared to tea would suggest that factors other than caffeine are having a beneficial effect. One suggestion is that it may be the free-radical scavenging phenolic compounds in tea exerting a neuroprotective effect.

This is the first study to investigate the effect of tea drinking on the age of onset of PD motor symptoms. Although a small study, these results are highly encouraging and warrant further research to confirm whether there is a causative relationship as well as determining whether different tea types have similar effects.
Kandinov, B., Giladi, N. and Korczyn, A. (2008) Smoking and tea consumption delay onset of Parkinson's disease. Parkinsonism Relat Disord. Apr 21 (Epub Ahead of print) 1-6.

Other News

Caffeine containing drinks may reduce the risk of breast cancer in postmenopausal women
A large, long-term, prospective cohort study of nurses in the US has concluded that drinking caffeine containing drinks, including tea and coffee, may help to reduce the risk of breast cancer in postmenopausal women.

Drinking tea and coffee has been suggested to both increase and decrease the risk of breast cancer. These drinks, as well as cocoa, contain caffeine which in animal studies has been found to stimulate and suppress mammary tumours. Coffee and tea are also rich in various compounds that in test tube and animal studies have shown anti-cancer properties. However, population studies examining the effect of tea, coffee and caffeine on breast cancer risk have generated inconsistent results.

To investigate the effects of caffeinated and decaffeinated tea and coffee consumption on breast cancer risk in a large population of women with long follow up and repeated measures of intake, data from the Nurses' Health Study cohort was examined.

The Nurses' Health Study cohort was established in 1976 to look at risk factors for cancer and lifestyle. 121,700 female nurses, between 30 - 55 years, answered a postal questionnaire on lifestyle and cancer risk. For the current study 85,987 women completed a food frequency questionnaire in 1980 which included questions on the consumption of tea, coffee with caffeine, cola and other carbonated beverages with caffeine, and chocolate. This same questionnaire was repeated a further 6 times until 2002. Decaffeinated coffee was added to the dietary questionnaire from 1984 to 1998.

Questions focused on whether consumption had greatly increased or decreased in the past 10 years. Participants were asked how often on average they had consumed tea or coffee over the past year: these were then categorised into 5 groups - never, less than 1 cup per month, 1 cup/ month to 4.9 cups/ week, 5 cups/ week to 1.9 cups a day, 2-3.9 cups per day and 4 or more cups per day. Assumptions regarding the caffeine content of tea and coffee were made: 47mg per 225ml cup of tea and 137mg per 225ml cup of coffee. Calculations were then made regarding total caffeine intake from tea, coffee and other caffeine-containing foods and drinks.

Participants were followed up for 22 years, and during that time 6,553 cases of breast cancer were documented. After exclusions, 5,272 cases of invasive breast cancer were reported among 85,987 subjects.

There was no significant association between tea or coffee consumption, both long- and short-term, and risk of breast cancer during the 22 year follow up period. However when overall caffeine intake was examined, a high total caffeine consumption was associated with a lower risk of breast cancer in postmenopausal women - particularly those with oestrogen-receptor positive and progesterone-receptor positive breast cancer. This would suggest a possible mechanistic role involving steroid hormones although further research is required to examine this relationship.

This large study has demonstrated that tea drinking neither decreases nor increases the risk of breast cancer in women but a high caffeine intake may be protective for post menopausal women with receptor positive breast cancer.
Ganmaa, D., Willett, W. C., Li, T. Y., Feskanich, D., van Dam, R. M., Lopez-Garcia, E., Hunter, D. J., and Holmes, M. D. (2008) Coffee, tea, caffeine and the risk of breast cancer: A 22 year follow-up. Int. J. Cancer 122: 2071-2076







Health Professionals Newsletter Welcome to the tenth newsletter from the United Kingdom Tea Council. This service will keep you up to date with current tea4health activities and events and inform you of the latest published research. We'll keep you updated on a quarterly basis with news and views from across the tea industry. Research Update Reducing the risk of stroke in male smokers - tea may help Following an extensive study, Finnish researchers have concluded that drinking more than 2 cups of tea a day (340ml) may reduce the risk of stroke in male smokers. Information from the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study was used to examine the associations between tea (and coffee) drinking and risk of stroke in male smokers. This randomised, double-blind, placebo-control trial was originally designed to determine whether supplements of _-tocopherol and/or _-carotene could reduce the incidence of cancer in men who smoked 5 or more cigarettes per day. At baseline a sub-set of 26,556 men (93% of the original cohort), mean age 57.6 years, were asked about their tea (and coffee) drinking habits - including the average number of cups consumed per day/week during the previous year and the usual cup size. These cup sizes were then converted to 'average' cup sizes of tea of 170ml. About 64% of the men never drunk tea and researchers did not determine the type of tea consumed as they pointed out that Finnish men rarely drink any tea other than black tea - there was no information on whether tea was taken with or without milk. The men were followed up after an average of 13.6 years and the study collected 360,187 person-years of follow-up data. During that time 3365 men suffered a stroke. Drinking two or more cups of tea per day, compared to drinking no tea, decreased the risk of one particular sub-type of stroke, cerebral infarction, by 21%. This association was independent of age, supplementation group and cardiovascular risk factors (number of cigarettes smoked, Body Mass Index, systolic and diastolic blood pressure, serum total cholesterol, history of diabetes and coronary heart disease, physical activity and alcohol intake). There was no association between tea drinking and the risk of intracerebral or subarachnoid haemorrhage. These findings are consistent with studies carried out in Dutch men and Japanese men and women, although the latter investigated the effects of green tea rather than black tea. The researchers believe the antioxidant properties of the phenolic compounds in tea may be responsible for the beneficial effects. For example, in vitro and in vivo studies have found that these compounds prevent the oxidation of Low Density Lipoprotein (LDL) cholesterol. Oxidation of LDL particles promotes the formation of atherosclerotic lesions leading to an increased risk of cardiovascular disease. Furthermore another study found that black tea reduced platelet activation and C-reactive protein in healthy men; high levels of C reactive protein have been associated with an increased risk of ischemic stroke. However further studies are required to determine the exact protective mechanisms. This study has particular strengths due to its prospective design; the statistical power as a result of the large number of stroke cases; and the extensive amount of information on cardiovascular risk factors allowing for adjustment of potential confounders. One limitation is that tea consumption was only measured once, at baseline, and this may not accurately reflect the actual level of tea consumption throughout the study period. Nevertheless this large study among a smoking population provides good evidence that drinking more than 2 cups of tea per day may reduce the risk of cerebral infarction in male smokers. It remains to be seen whether these results are reproducible in women and in non-smoking populations and indeed whether the increased level of tea drinking by UK populations would provide additional protection from other types of stroke. Larsson, S., Mannisto, S., Virtanen, M. J., Kontto, J., Albanes, D. and Virtamo, J. (2008) Coffee and tea consumption and risk of stroke subtypes in male smokers. Stroke 39: 1681-1687. Drinking tea delays the onset of Parkinson's disease A small Israeli study of patients with Parkinson's disease (PD) has found that those who drink more than 3 cups of tea per day delay the age of developing PD by more than 7 years. This retrospective study recruited patients with a clinical diagnosis of PD from the Movement Disorders Unit in Tel Aviv Sourasky Medical Centre. Consecutive patients were identified through the researchers' computerised database. Of the 300 originally recruited, 283 agreed to participate. After exclusions a total of 278 patients completed the study. To minimise bias the patients were not told about the purpose of the study. PD motor symptoms onset were defined as the year in which any motor disturbances that could later be attributed to PD were first noticed by the patient, a family relative or a caregiver as recorded in the medical file. Information about tea consumption was gathered, including the number of cups per day (caffeine-free and herbal teas were not counted towards tea consumption), the duration of tea drinking prior to PD symptom onset and the age of starting tea drinking and stopping (if appropriate). Data was obtained from a first degree relative for subjects with dementia. Tea drinking was categorised into 3 groups: none, <2, 2-3 and > 3 cups per day - details about volume, tea type, brewing method and whether milk was added were not sought. The average age of the study population was 68.4 years and the mean age at motor symptom onset was 58.1 years. As a result the average duration of the disease was 10.3 years. Around 64% of the participants were, or had been, tea drinkers, although the vast majority continued to drink tea before and after the development of PD. There was a significant delay in the age of onset of motor symptoms by 7.7 years in patients who drank more than 3 cups of tea per day. The possible mechanism for this association was not investigated but the authors anticipated caffeine might have an effect. However coffee consumption was also investigated in this study and no protective effect was found. The higher caffeine levels in coffee compared to tea would suggest that factors other than caffeine are having a beneficial effect. One suggestion is that it may be the free-radical scavenging phenolic compounds in tea exerting a neuroprotective effect. This is the first study to investigate the effect of tea drinking on the age of onset of PD motor symptoms. Although a small study, these results are highly encouraging and warrant further research to confirm whether there is a causative relationship as well as determining whether different tea types have similar effects. Kandinov, B., Giladi, N. and Korczyn, A. (2008) Smoking and tea consumption delay onset of Parkinson's disease. Parkinsonism Relat Disord. Apr 21 (Epub Ahead of print) 1-6. Other News Caffeine containing drinks may reduce the risk of breast cancer in postmenopausal women A large, long-term, prospective cohort study of nurses in the US has concluded that drinking caffeine containing drinks, including tea and coffee, may help to reduce the risk of breast cancer in postmenopausal women. Drinking tea and coffee has been suggested to both increase and decrease the risk of breast cancer. These drinks, as well as cocoa, contain caffeine which in animal studies has been found to stimulate and suppress mammary tumours. Coffee and tea are also rich in various compounds that in test tube and animal studies have shown anti-cancer properties. However, population studies examining the effect of tea, coffee and caffeine on breast cancer risk have generated inconsistent results. To investigate the effects of caffeinated and decaffeinated tea and coffee consumption on breast cancer risk in a large population of women with long follow up and repeated measures of intake, data from the Nurses' Health Study cohort was examined. The Nurses' Health Study cohort was established in 1976 to look at risk factors for cancer and lifestyle. 121,700 female nurses, between 30 - 55 years, answered a postal questionnaire on lifestyle and cancer risk. For the current study 85,987 women completed a food frequency questionnaire in 1980 which included questions on the consumption of tea, coffee with caffeine, cola and other carbonated beverages with caffeine, and chocolate. This same questionnaire was repeated a further 6 times until 2002. Decaffeinated coffee was added to the dietary questionnaire from 1984 to 1998. Questions focused on whether consumption had greatly increased or decreased in the past 10 years. Participants were asked how often on average they had consumed tea or coffee over the past year: these were then categorised into 5 groups - never, less than 1 cup per month, 1 cup/ month to 4.9 cups/ week, 5 cups/ week to 1.9 cups a day, 2-3.9 cups per day and 4 or more cups per day. Assumptions regarding the caffeine content of tea and coffee were made: 47mg per 225ml cup of tea and 137mg per 225ml cup of coffee. Calculations were then made regarding total caffeine intake from tea, coffee and other caffeine-containing foods and drinks. Participants were followed up for 22 years, and during that time 6,553 cases of breast cancer were documented. After exclusions, 5,272 cases of invasive breast cancer were reported among 85,987 subjects. There was no significant association between tea or coffee consumption, both long- and short-term, and risk of breast cancer during the 22 year follow up period. However when overall caffeine intake was examined, a high total caffeine consumption was associated with a lower risk of breast cancer in postmenopausal women - particularly those with oestrogen-receptor positive and progesterone-receptor positive breast cancer. This would suggest a possible mechanistic role involving steroid hormones although further research is required to examine this relationship. This large study has demonstrated that tea drinking neither decreases nor increases the risk of breast cancer in women but a high caffeine intake may be protective for post menopausal women with receptor positive breast cancer. Ganmaa, D., Willett, W. C., Li, T. Y., Feskanich, D., van Dam, R. M., Lopez-Garcia, E., Hunter, D. J., and Holmes, M. D. (2008) Coffee, tea, caffeine and the risk of breast cancer: A 22 year follow-up. Int. J. Cancer 122: 2071-2076
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