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Stronger Evidence Brewing for Vascular Benefits of Tea

Stronger Evidence Brewing for Vascular Benefits of Tea

Tea is the second most widely consumed drink in the world. There have been numerous studies of the relationship between tea consumption and vascular disease. Although most such studies have found a negative correlation between these two,1-4 some have shown no association,5 and 1 study has even suggested that increasing tea consumption is associated with greater risk of coronary artery disease.6

FINDINGS FROM A FRENCH STUDY
Evidence from a recent French study bolsters the case for an association between tea drinking and reduced risk of vascular disease—at least in certain populations.7 The study assessed the relationship between tea consumption and common carotid artery intima-media thickness (CCA-IMT) and carotid plaques. It involved 6597 community-dwelling persons aged 65 years or older who were recruited from 3 French cities (Bordeaux, Dijon, and Montpellier) to participate in a study of vascular factors and the risk of dementia. Atherosclerotic plaques in the extracranial carotid arteries were measured with a standard protocol, and participants answered questions about their background, medical history, and personal habits, including consumption of various types of food and drink.

Increasing daily tea consumption was associated with a lower prevalence of carotid plaques in women, with prevalences of 44%, 42.5%, and 33.7% in women who drank no tea, 1 or 2 cups a day, and 3 or more cups a day, respectively (P = .0001). The association was independent of age, education, and other dietary factors.

The results were also unchanged after adjustments for systolic blood pressure, use of antihypertensive medications, low-density lipoprotein cholesterol level, high-density lipoprotein cholesterol level, and use of lipid-lowering therapy. No association was found between tea consumption and carotid plaques in men or between tea consumption and CCA-IMT in either men or women.

PART 2: SIMILAR RESULTS IN A DIFFERENT COHORT
The authors of the French study found similar results when they examined participants in another, younger population sample. In 1123 persons recruited for the Aging Vascular Study (EVA study), the frequency of carotid plaques was 18.8% in women who drank no tea, 18.5% in women who drank 1 to 2 cups of tea a day, and 8.9% in women who drank 3 or more cups of tea a day. Again, there was no association of tea consumption with carotid plaques in men or with CCA-IMT in persons of either sex.

The reason no association was found between tea consumption and carotid plaques in men in either study population was not clear. However, the authors noted that previous research suggests a similar trend: 3 of the studies that did not show any significant association between tea consumption and atherosclerosis were performed in men only.8-10

Because this latest French study7 involved a large number of participants, because its results remained robust even after adjustment for numerous potential cofounders, and because it found the same trend in an independent cohort, it strengthens the argument for an inverse association between tea drinking and atherosclerosis or vascular events. There is now good evidence that at least in elderly women, drinking tea may reduce the risk of carotid atherosclerosis.

References

REFERENCES:
1. Keli SO, Hertog MG, Feskens EJ, Kromhout D. Dietary flavonoids, antioxidant vitamins, and incidence of stroke: the Zutphen study. Arch Intern Med. 1996;156:637-642.
2. Peters U, Poole C, Arab L. Does tea affect cardiovascular disease? A meta-analysis. Am J Epidemiol. 2001; 154:495-503.
3. Gardner EJ, Ruxton CH, Leeds AR. Black tea—helpful or harmful? A review of the evidence. Eur J Clin Nutr. 2007;61:3-18.
4. Geleijnse JM, Launer LJ, Van der Kuip DA, et al. Inverse association of tea and flavonoid intakes with incident myocardial infarction: the Rotterdam Study. Am J Clin Nutr. 2002;75: 880-886.
5. Sesso HD, Paffenbarger RS Jr, Oguma Y, Lee IM. Lack of association between tea and cardiovascular disease in college alumni. Int J Epidemiol. 2003; 32:527-533.
6. Woodward M, Tunstall-Pedoe H. Coffee and tea consumption in the Scottish Heart Health Study follow up: conflicting relations with coronary risk factors, coronary disease, and all-cause mortality. J Epidemiol Community Health. 1999;53:481-487.
7. Debette S, Courbon D, Leone N, et al. Tea consumption is inversely associated with carotid plaques in women. Arterioscler Thromb Vasc Biol. 2008;28:353-359.
8. Rimm EB, Katan MB, Ascherio A, et al. Relation between intake of flavonoids and risk for coronary heart disease in male health professionals. Ann Intern Med. 1996;125:384-389.
9. Hirvonen T, Virtamo J, Korhonen P, et al. Intake of flavonoids, carotenoids, vitamins C and E, and risk of stroke in male smokers. Stroke. 2000;31: 2301-2306.
10. Hertog MG, Sweetnam PM, Fehily AM, et al. Antioxidant flavonols and ischemic heart disease in a Welsh population of men: the Caerphilly Study. Am J Clin Nutr. 1997;65: 1489-1494.
 
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