"Not enough people know what Lyme disease is and the dangers of being bitten by an insect," Hadid told judges Gordon Ramsay and Christina Tosi while tearing up. "[The prize] can help with finding a cure. It can help so much."
"I'm the only one in, of my siblings, my mom and my family, that hasn't been affected by Lyme disease," she said in the emotional interview. "It's been really hard for me because I'm the only one that doesn't really understand it."
"What's been hardest for me is just trying to find a way to be their hope and kind of be a strength for them even with the disease that I can't understand fully because I haven't been through it," she added.
Hadid celebrated her "MasterChef" victory by sharing a photo of herself with her winnings. "Call me MasterChef Hadid! All the lymies out there @LymeAlliance this one's for you! Thank you@MasterChefonFox," she tweeted.
Hadid is the eldest child of Foster and real estate developer Mohamed Hadid, who were married from 1994 to 2000.
"I have always had and continue to have the utmost respect and love for Yolanda, which is why it is so frustrating to see headlines questioning her chronic debilitating illness," David Foster said while defending the 52-year-old reality star in December.
Hadid is known for her modeling work with Guess, and walked in her first Victoria's Secret Fashion Show in November.
She is presently dating Zayn Malik, and was spotted apartment hunting with the former One Direction singer this month.
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