Holly, 39, hid her face as she gagged on the drink, which supposedly has great health benefits, helping people with having a healthy gut.
At the start of the segment, Holly said: “It is not that attractive, we’ve both tried it.
“Even now, just looking at it is making me feel a bit funny, but apparently it is very good for you.”
She added: “This is not for the faint hearted.”
As Liz tried to explain the details of the drink, Holly and Phil took a sip of the first one, as she squealed: “I don’t think I can do it, I don’t want to do it!”
She was then seen taking a sip and then hiding her face, as Phillip chimed in: ” It’s hard to get out of the straw to be honest.”
Holly said: “It tastes off, it tastes like something you take out of the fridge and think I’ve just ruined a perfectly good cup of tea with it.”
Liz then tried to speak about the kefir again, as Holly interrupted to ask: “How much of it do you have to drink, the whole thing?”
As she and Phillip joked about the drink, fans began to get annoyed as they told the pair off for being rude to their guest.
One fan posted: “Live now. Holly throws up over gone off milk.”
Another added: “Holly, let her speak!!”
A third chipped in: “You can really tell how much Holly and Phillip loved their Kefir Milk drinks!”
A fourth wrote: “Poor Liz Earle constantly interrupted or talked over when she’s trying to explain about Kefir by Phil & Holly. Starting to get annoying now.”
A fifth chipped in: “Kefir woman is not amused they don’t like it.”
This Morning continues tomorrow at 10am on ITV.