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Addition of milk prevents vascular protective effects of tea.
Eur Heart J 2007; 28(2):219-23EH

Abstract

AIMS

Experimental and clinical studies indicate that tea exerts protection against cardiovascular diseases. However, a question of much debate is whether addition of milk modifies the biological activities of tea. We studied the vascular effects of tea, with or without milk, in humans and elucidated the impact of individual milk proteins in cell culture experiments, with isolated rat aortic rings and by HPLC analysis.

METHODS AND RESULTS

A total of 16 healthy female volunteers consumed either 500 mL of freshly brewed black tea, black tea with 10% skimmed milk, or boiled water as control. Flow-mediated dilation (FMD) was measured by high-resolution vascular ultrasound before and 2 h after consumption. Black tea significantly improved FMD in humans compared with water, whereas addition of milk completely blunted the effects of tea. To support these findings, similar experiments were performed in isolated rat aortic rings and endothelial cells. Tea induced vasorelaxation in rat aortic rings and increased the activity of endothelial nitric oxide synthase by phosphorylation of the enzyme in endothelial cells. All effects were completely inhibited by the addition of milk to tea. Of the various kinds of milk proteins, the caseins accounted for these inhibiting effects of milk, probably by formation of complexes with tea catechins.

CONCLUSION

Milk counteracts the favourable health effects of tea on vascular function. This finding indicates the need for particular awareness in the interpretation and design of studies comprising nutritional flavonoids.

Authors+Show Affiliations

Medizinische Klinik mit Schwerpunkt Kardiologie und Angiologie, Charité-Universitätsmedizin Berlin, CCM, Charitéplatz 1, D-10117 Berlin, Germany.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

17213230

Citation

Lorenz, Mario, et al. "Addition of Milk Prevents Vascular Protective Effects of Tea." European Heart Journal, vol. 28, no. 2, 2007, pp. 219-23.
Lorenz M, Jochmann N, von Krosigk A, et al. Addition of milk prevents vascular protective effects of tea. Eur Heart J. 2007;28(2):219-23.
Lorenz, M., Jochmann, N., von Krosigk, A., Martus, P., Baumann, G., Stangl, K., & Stangl, V. (2007). Addition of milk prevents vascular protective effects of tea. European Heart Journal, 28(2), pp. 219-23.
Lorenz M, et al. Addition of Milk Prevents Vascular Protective Effects of Tea. Eur Heart J. 2007;28(2):219-23. PubMed PMID: 17213230.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Addition of milk prevents vascular protective effects of tea. AU - Lorenz,Mario, AU - Jochmann,Nicoline, AU - von Krosigk,Amélie, AU - Martus,Peter, AU - Baumann,Gert, AU - Stangl,Karl, AU - Stangl,Verena, Y1 - 2007/01/09/ PY - 2007/1/11/pubmed PY - 2007/11/9/medline PY - 2007/1/11/entrez SP - 219 EP - 23 JF - European heart journal JO - Eur. Heart J. VL - 28 IS - 2 N2 - AIMS: Experimental and clinical studies indicate that tea exerts protection against cardiovascular diseases. However, a question of much debate is whether addition of milk modifies the biological activities of tea. We studied the vascular effects of tea, with or without milk, in humans and elucidated the impact of individual milk proteins in cell culture experiments, with isolated rat aortic rings and by HPLC analysis. METHODS AND RESULTS: A total of 16 healthy female volunteers consumed either 500 mL of freshly brewed black tea, black tea with 10% skimmed milk, or boiled water as control. Flow-mediated dilation (FMD) was measured by high-resolution vascular ultrasound before and 2 h after consumption. Black tea significantly improved FMD in humans compared with water, whereas addition of milk completely blunted the effects of tea. To support these findings, similar experiments were performed in isolated rat aortic rings and endothelial cells. Tea induced vasorelaxation in rat aortic rings and increased the activity of endothelial nitric oxide synthase by phosphorylation of the enzyme in endothelial cells. All effects were completely inhibited by the addition of milk to tea. Of the various kinds of milk proteins, the caseins accounted for these inhibiting effects of milk, probably by formation of complexes with tea catechins. CONCLUSION: Milk counteracts the favourable health effects of tea on vascular function. This finding indicates the need for particular awareness in the interpretation and design of studies comprising nutritional flavonoids. SN - 0195-668X UR - https://www.unboundmedicine.com/medline/citation/17213230/Addition_of_milk_prevents_vascular_protective_effects_of_tea_ L2 - https://academic.oup.com/eurheartj/article-lookup/doi/10.1093/eurheartj/ehl442 DB - PRIME DP - Unbound Medicine ER -