The assisted dying advocate and bestselling author Wendy Mitchell, who spent years documenting her dementia, has died, her family has said.

Mitchell, 68, discussed her death in a letter published posthumously on her blog on Thursday.

“If you’re reading this, it means this has probably been posted by my daughters as I’ve sadly died,” she wrote. In the letter shared on her site Which Me Am I Today? Mitchell said she died after deciding to stop eating and drinking, and called for assisted dying to be legalised in the UK.

“In the end, I died simply by deciding not to eat or drink any more. The last cuppa tea ... my final hug in a mug, the hardest thing to let go of, much harder than the food I never craved … Dementia is a cruel disease that plays tricks on your very existence.

“I’ve always been a glass-half-full person, trying to turn the negatives of life around and creating positives, because that’s how I cope.”

The mother of two, from Yorkshire, was diagnosed with early onset dementia aged 58 in 2014. She was an ambassador at the Alzheimer’s Society and wrote two Sunday Times bestsellers, her 2018 memoir titled Somebody I Used to Know, and a guide to the disease called What I Wish People Knew About Dementia published in 2022.

The former NHS worker said: “Sorry to break the news to you this way, but if I hadn’t, my inbox would eventually have been full of emails asking if I’m OK, which would have been hard for my daughters to answer.”

Her final book One Last Thing: How to Live With the End in Mind covers assisted dying.

In her posthumous blogpost, Mitchell argued people should be able to chose between euthanasia and palliative care, and added that she had wanted to go to Dignitas in Switzerland, a non-profit clinic that provides “physician-assisted suicide”.

She said: “It’s amazing how such little value is placed on the act of dying. If assisted dying was available in this country, I would have chosen it in a heartbeat, but it isn’t.

“I didn’t want dementia to take me into the later stages; that stage where I’m reliant on others for my daily needs; others deciding for me when I shower or maybe insisting I had a bath, which I hate; or when and what I eat and drink. I was hoping to go [to Dignitas] at the beginning of the year.”

Mitchell’s daughters, Sarah and Gemma, announced her death on social media, telling followers she had “died peacefully”.