As any parent of young children knows, the science of packing a healthy, satisfying lunch can be a difficult undertaking.

There are not only picky eaters to please, but numerous restrictions depending on a child's school, because of food allergies.

While many parents can accept the peanut butter sandwich no longer has a place in a child's lunch bag, some parents think the dietary restrictions are often taken too far.

Toronto's R. H. McGregor Elementary School, for example, has recently asked parents of students in one class not to send Granny Smith or Red Delicious apples for snacks, because of one student's allergy.

"Our son, for example, is a picky eater," says Danny Regu, whose seven-year-old son is in Grade 2 at R. H. McGregor, "and an apple is pretty much the only fruit he is going to eat."

Regu says his son and other kids understand allergies, and that they are not to share food. He says banning apples may be going too far.

'Impossible to pack a decent lunch'

"I mean there's countless allergies out there, and if every parent starts calling the school and starts asking the school to ban everything their child is allergic to, it's going to be impossible to pack a decent lunch."

Officially, the Toronto District School Board says students can bring whatever they want for lunch or snacks.

"Even if there is an anaphylactic reaction, we cannot ban a product," TDSB spokesperson Ryan Bird told CBC News.

"What we do do," he said, "is strongly encourage parents not to bring that in, because it comes down to student safety. Our parents understand that."

And when promoting a healthy and balanced diet is part of the curriculum across Canada, many experts say food restrictions only make nutritious eating more difficult.

Food allergies a growing concern

Melissa Murray, a registered dietitian and diabetes educator at Toronto's St. Joseph's Health Centre, says having gone through school where nuts were restricted in part because of her own allergies, she understands the need for caution.

But when a child's allergies are less severe, Murray says taking away food options can often make healthy eating harder.

"Food restrictions are best when done on a case-to-case basis in a school, depending on the severity of the allergies in the children attending.

"Allergenic foods are typically nutritious, however, the safety of children comes first and nutrition can always be obtained from other foods."

Melissa Murray is a registered dietitian and diabetes educator at Toronto's St. Joseph's Health Centre. Having gone through school where nuts were restricted in part because of her own allergies, she understands the need for caution.

Beatrice Povolo is the director of advocacy with Food Allergies Canada.

She says food allergies are a growing concern in Canada, in terms of the number of people affected: 2.5 million Canadians, including 300,000 school-aged children.

Povolo says there is not a one size fits all solution to keeping kids safe.

"Given that children can be allergic to many different things, not just nuts and peanuts," she said, "it really needs to be looked at at the classroom level, school level, as well as the individual child, and working together with the parents and teacher to figure out what the best strategy would be for that specific situation."

'My job is to teach my child to advocate for himself'

And the open conversation between parents and a school Povolo speaks about has been taken to another level by some proactive parents.

Allison Venditti's five-year-old son,Aldon, is in senior kindergarten at Essex Public School. Venditti has worked at length with the school to cater to her son's multiple food allergies, including eggs, soy and tree nuts. She says none of his allergies is airborne, so parents can pack whatever they like in his playmates' lunch bags.

"If I was to come into a school and say, by the way, you can't bring eggs or peanuts or peas or soy ... you know, soy is in probably 90 per cent of processed foods. It's unrealistic for me to ask that."

Venditti's son has his own place mat, the tables are cleaned after lunch and snacks, students practise hand-washing, and a teacher watches closely to make sure there is no sharing. She says kids will do anything to keep their friends safe, and asking for food to be restricted is not the best solution for her son.

"There are so many different names for these things, that they might not be able to do it even if they tried. I'm not going to put my trust in what other people are hoping to get right. My job is to teach my child to advocate for himself, and he recognizes he eats only what certain people give him to eat."

And Venditti says she does not criticize other parents who might ask for foods to be restricted.

"I try to be as sympathetic as I can ... No parent is going out of their way to make life more difficult for other parents, but they will go out of their way to keep their child safe."