Women who drink three cups of tea a day “are less likely to have heart attacks and strokes,” the Daily Express reports. The newspaper adds, however, that “strangely, no added benefit of tea drinking was found among women who only had one or two cups a day or for men”.
The story is based on a French study that looked at how the thickness of ’plaques’ in the carotid artery were related to the amount of tea that men and women drank. Plaques are build-ups of fat and cholesterol in the blood vessels (known as atherosclerosis). They have been linked to an increased risk of heart attack and stroke. The women who drank three cups of tea or more a day were seen to have fewer plaques in their arteries. However, because of its design, this study cannot prove that tea consumption was the cause of less plaque build-up in the arteries; a randomised controlled trial would be the best way to show this.
On the strength of this study alone, it would be better to suggest to women (and men) that they should drink tea because they enjoy it, rather than in any hope that it may reduce their risk of heart disease or stroke.
Stéphanie Debette and colleagues of the University Hospital of Lille and Broussais Hospital, Paris, France carried out this research. The Fondation pour la Recherche Médicale funded the preparation and initiation of the study. Various other institutions and foundations also provided support. It was published in Arteriosclerosis, Thrombosis and Vascular Biology , a peer-reviewed medical journal.
This was a cross-sectional analysis of data collected at the start of the Three-City (3C) Study, a large cohort study of the French population. The 3C study attempted to clarify the relationship between tea consumption, thickness of the carotid artery and plaque build up.
In the 3C study, 9,693 people aged 65 years or older were recruited from the cities of Dijon, Bordeaux and Montpellier between March 1999 and March 2001. Of these people, 6,635 (excluding those aged over 85) had an ultrasound examination to determine their carotid artery thickness. The participants were also interviewed by a nurse and data was collected on past medical history (including cardiovascular disease and medications), lifestyle factors, education, average daily consumption of tea and coffee (divided into none, one to two cups, or three or more cups), and average weekly consumption of various foods. The study also recorded blood pressure, body mass index (BMI), blood sugar levels and blood cholesterol levels.
Of the people with ultrasound scans, 6,597 also provided data on their tea consumption and these were included in the final analysis. The researchers carried out statistical tests to see whether there was any link between the three tea-drinking categories and thickness of the carotid arteries. The researchers adjusted for possible confounding factors, including age, smoking, BMI, diabetes, cholesterol, alcohol consumption and diet.
EVA, a matching study, was carried out following these results to investigate whether similar associations were found in a younger population group aged between 51 and 79.
When the researchers looked at the association between level of tea consumption and the other variables tested, they found that tea consumption was inversely associated (i.e. when one increases the other decreases) with age, blood pressure, BMI, diabetes and smoking in women. It was inversely associated with alcohol consumption in men, and with coffee and meat consumption in both. In both men and women, tea consumption was positively associated (an increase in both variables at the same time) with consumption of fish, fruit and vegetables and a higher education level. It was also positively associated with hormone replacement therapy (HRT) in women.
The researchers found that drinking three or more cups of tea reduced the risk of finding plaques on the carotid arteries in women, even after adjustment for potential confounding factors. However, there was no link between tea consumption and thickness of the artery wall. In men, there was no link between tea consumption and carotid plaques or thickness of the artery wall.
In the EVA study of younger men and women, there was no link between tea consumption and carotid plaques or thickness of the artery wall in either sex.
The researchers conclude that, in their large French sample, carotid plaques occurred less frequently in women who drank three or more cups of tea per day. However, this association was not seen in men.
This is a large population study and, reportedly, the first to examine the link between tea consumption and atherosclerosis. However, interpretations from the results should be made with care.