A vegan couple from Sydney's eastern suburbs fed their infant daughter such a strict diet of items like oats and rice milk she developed rickets meaning her bones could fracture from "normal handling".

The extreme diet and full extent of neglect the mum, 32, and dad, 34, inflicted on their infant daughter can be revealed for the first time after they pleaded guilty in court to failing to provide for a child, causing serious injury.

The girl, who along with her two older brothers, aged six and four, are in government care, weighed just 4.9kg at 19 months of age - a mere 2.3kg more than her birth weight.

Her harrowing plight only came to the attention of police and doctors after the girl, who was also not vaccinated, was taken to hospital in March this year after suffering a seizure.

One paramedic described her as "quite floppy" and "moving like a newborn".

During her one month stay in hospital, which included two days in intensive care, the severely underweight one-and-a-half year old was not seen to crawl or talk.

Hospital staff initially respected the parents' wishes to keep their daughter on a vegan diet.

However the mum even at first objected to her daughter being given soy because of her concerns about "hormones" in the formula, only agreeing to it after speaking to a dietitian.

Astoundingly, seven days into their daughter's hospital stay the mother and father exchanged text messages which showed "an unwillingness to accept that the vitamin D deficiency, fractures and stunted growth" in their daughter was a result of malnutrition.

When police spoke to the dad at hospital he told them he didn't realise she had only doubled in weight over 19 months.

"(He) thought she was a girl and different to boys - she was petite," court documents say.

In addition to not being immunised, the girl had no follow-up check-ups after she was born and did not have a birth certificate or Medicare number.

The mum told a hospital dietitian her family was vegan and her daughter would typically have one cup of oats with rice milk and half a banana for breakfast. She said she would give her a piece of toast with jam or peanut butter for lunch. And for dinner she said her daughter would be offered tofu, rice or potatoes. But she said the girl was a "fussy eater" so she might just have oats again.

The girl and her two brothers are in government care. Picture: Monique Harmer
The girl and her two brothers are in government care. Picture: Monique Harmer

The girl was breastfed once a day and might have a mouthful of fruit or "two sultanas" as a snack.

She lied and said her daughter had meat and dairy "intermittently", according to agreed facts tendered to court.

Shockingly, specialists found that the girl's bones didn't look like they had developed since birth.

She had severe deficiencies in nutrients like calcium, phosphate, vitamin B12, vitamin A, zinc and iron. Her levels of vitamin D were "undetectable".

The girl had fractures in her forearms and ribs and her bones were so frail experts believed they could have been caused by "normal handling".

This was due to her having rickets, a preventable condition caused by vitamin D deficiency which results in soft, weak bones, stunted growth and bowed legs.

Her teeth had not yet come through and the dentist had not seen such a delay before.

A dietitian said the little girl had been given a "restricted range of foods even within a vegan diet".

Practising dietitian Julie Gilbert also yesterday slammed the girl's diet as "extreme".

"Even though people don't want to have meat, or fish, or chicken in their diet they still need to have a protein source and a little bit of peanut butter is not going to be enough," she said.

"The whole diet is very short on energy.

"This is an extreme form of veganism and they are failing to actually realise nutritional requirements must still be met.

"If you are wanting your child to be vegan, you definitely need to sit down and discuss it with a dietitian. The requirements are very different and you need to make sure your child is meeting those requirements for optimum growth and development."

In just six months when the girl was in hospital and then foster care she put on 6kg. Two months ago she was seen to crawl and stand. But it is "imperative" she continue therapy and is monitored to help with developmental delays.

The mum and dad, who had charges of reckless grievous bodily harm withdrawn, will be sentenced in Downing Centre District Court on January 16.


The Sydney couple can’t be identified. Picture: Monique Harmer
The Sydney couple can’t be identified. Picture: Monique Harmer