Gwyneth Paltrow has branded her grandmother a "real c***".
The 38-year-old actress criticised Katharine Danner, the German-born mother of her mum Blythe Danner, claiming she tried to spark a family feud with her "mean" ways.
Discussing grandmothers with TV talk show host Chelsea Handler, Gwyneth said: "Mine was a realc***.
"She just hated my guts, basically, and she tried to poison my mother against me. She must not have been very happy and she must have had a lot of pain because she was as mean as hell."
Gwyneth also explained she took on her strict macrobiotic diet in order to encourage her father Bruce Paltrow, who died of cancer in 2002, to be more careful with his eating habits.
The Country Strong star - who has daughter Apple, six, and son Moses, five, with her husband Chris Martin - said: "The reason why I started eating healthy was because I was trying to get my dad to eat healthy when he was diagnosed with cancer.
"He was disgusted by all my health food, he was like, 'This is disgusting, this is like biting into cardboard, I hate this food.' I was trying to get him to cure his cancer by eating and I got into eating healthy too."
However, the actress abandoned the strict eating regime - which is mainly comprised of vegetables and fish and doesn't allow the consumption of any dairy or processed foods - when she got pregnant and allowed herself to eat whatever she wanted.
She added: "When I got pregnant with Apple, I could not eat any healthy food. It was like Baskin Robbins (ice cream) and French fries and I never looked back."
