umijoshi wrote:Why would it? You're not taking anything away, you're only adding.
It all depends on what you consider health effects, and I would suggest the OP keep reading the articles and decide for themselves, as it really does seem to be up for debate. But there has been studies that have shown that compounds in milk bind to some compounds in tea that some consider to be healthy compounds, and studies suggest that this binding process removes our bodies ability to utilize those compounds from the tea.
Again I am far from versed in the science on this, I have just read general synopsis's of the articles. I honestly haven't cared too much about it, because I like to appreciate many things in as pure a form as possible, and don't like mixing items into my teas, or coffee, etc.