Polyphenols found in tea manifest anti-cancer effects, but their use is limited by poor bioavailability and disagreeable taste.

A new study in the Journal of Dairy Science® finds that when epigallocatechin gallate (EGCG), the major extractable polyphenol in green tea and the most biologically active, when diluted in skim milk or other milk complexes remains bioactive and continues to reduce colon cancer cell proliferation in culture at concentrations higher than 0.03 mg of EGCG/mL.

“These results support a new role for milk as an ideal platform for delivery of bioactive compounds and opens the door to a new generation of dairy products providing additional benefits to human health,” say authors Sanaz Haratifar and Milena Corredig, of the department of food science and department of human health and nutritional sciences of the University of Guelph in Canada. 

The majority of extractable polyphenols in tea are flavan-3-ols, commonly referred to as catechins. EGCG is the major catechin found in tea.

Tea polyphenols have been shown to inhibit tumor formation, reduce cancer cell proliferation, increase normal cell death (apoptosis), and/or suppress the formation of new blood vessels feeding tumors (angiogenesis).

For several reasons, tea catechins have poor bioavailability and the goal of the current study was to encapsulate EGCG in casein (milk protein) molecular aggregates, known as micelles, to maintain and enhance catechin bioavailability.

In one experiment, human colorectal cancer cells (HT-29) were grown for 24 hours in the presence of EGCG in water or dispersed in milk. The number of living cancer cells (cell viability) was measured, and it was shown that EGCG reduced cell viability in a dose-dependent fashion.

The study will appear in the February 2014 edition of Journal of Dairy Science.