In the 1958 short film Mystery in the Kitchen, Mr. Jones has scurvy, and is limping slowly from his tractor. Daughter Marilyn is anemic, and has trouble concentrating in class. Son Walt suffers from rickets.

But the bowler-hat-wearing detective has solved the Jones family mystery. Poor diet and malnutrition are the cause, and Mrs. Jones is to blame, guilty of not serving enough milk, eggs and liver, which contain the nutrition her family needs.

"Canada's Food Rules?" the inspector says, looking straight at the camera. "Ignore them, and enjoy the worst of bad health!"

In the nearly 60 years since Mystery in the Kitchen was first broadcast – produced by what was then known as Canada's Department of National Health and Welfare Nutrition Division – the country's eating habits have changed dramatically. So, too, have the government's "food rules," known today as Canada's Food Guide.

Now, 75 years after its first publication, the government is preparing to release a new version of Canada's Food Guide – the first update since 2007 – expected to be made public early next year. For Health Canada, it has been a years-long process, and a monumental task.

The influence of the food guide is felt across the country, used by teachers, doctors and dietitians as the authority on healthy eating. The guide is available in a dozen languages and is the federal government's second-most-requested document.

It has also emerged one of the government's most controversial publications and the subject of fierce lobbying.

In updating the guide, Health Canada will have to address concerns from doctors and nutritionists who say it has not changed enough over its 75 years. Specifically, they argue it has done a poor job of adapting to changing health concerns, away from the malnutrition and wartime rationing the guide was originally intended to address, and toward more pressing, current concerns of obesity and diet-related chronic illness. At the same time, the department will have to balance those with concerns from the agriculture and food industry, which fear the effect a reduced presence on the guide might have on sales.

Recent signals from Health Canada have the former group encouraged. Last month, the department released its "guiding principles" – a mission statement that outlines the priorities. This document emphasizes a regular diet of "vegetables, fruit, whole grains and protein-rich foods – especially plant-based sources of protein," and explicitly warns against processed foods high in sodium, sugar and saturated fat.

It also appears to de-emphasize the necessity of animal meats and dairy – prompting at least one media report earlier this month to claim the new food guide "eliminates dairy as a food group." (Health Canada officials told The Globe and Mail no such decisions have been made.)

The Health Canada document also mentions a host of new food concerns – everything from environmental sustainability and animal welfare to the importance of eating local – illustrating just how much food culture has changed since Mystery in the Kitchen introduced Canadians to Mrs. Jones and her sickly family.

Even the iconic four food groups are up in the air. "There might still be food groups … there might not be food groups," said Hasan Hutchinson, director general of the Office of Nutrition Policy and Promotion at Health Canada. "We're still trying to establish what the policy will be."

Once thing is clear: The new guide is intended to represent major change.

"This is not tweaking, whatsoever," Dr. Hutchinson said.

The guide through the years

When Canada's Official Food Rules debuted in 1942, it was designed for a country at war. The goal was to keep the more than one million men and women in the armed services healthy and strong, with rules designed to maximize energy levels. A daily diet, for example, included a half pint of milk and "4 to 6 slices of Canada Approved Bread" each day. And these were just the daily minimums. "Use more if you can," the rules stressed.

"The guide itself was premised on military strength, industrial strength, building up soldiers," said Ian Mosby, a food historian. The guiding ideology, he said, was that "to be healthy, you have to eat more."

The rules were also meant for everyone else living with wartime rations and poverty. Leaflets encouraging Canadians to "check your war efficiency" emphasized tips for maximizing nutrition despite rationing.

The focus on increased consumption was strengthened two years later in the 1944 guide. "The basis of the rules shifted from 70% of the Dietary Standard as was the case in 1942 to a fully adequate figure,'" according to Health Canada. Milk requirements were boosted to one half to one pint a day, and vegetables from "one potato a day to at least one." Bread was to be served with butter.

By the mid-century, the thinking began to shift. Worldwide food shortages and an increasing understanding about the health effects of overeating led the 1949 guide to include a stern warning: "More," the guide stated, "is not necessarily better."

Throughout the latter half of the century, the rules continued to loosen. By 1961, the document was renamed from "rules" to "guide." With each subsequent version, the guide moved further and further away from recommendations on specific ingredients and more toward general "food groups," recognizing that a variety of foods could make up a healthy diet.

"Right now, it's a mess"

By the time the new guide is released, the current guide will have been in place for more than a decade.

In that time, the guide has become the target of substantial criticism for what many perceive as outdated advice based on old research.

One of the most common criticisms is that it simply prescribes too much food – too many calories for a healthy daily diet. The current model is focused on ensuring specific nutrient requirements are met – that people are getting enough zinc, vitamin A and so on, as opposed to encouraging a broad-based diet, said Yoni Freedhoff, an assistant professor of family medicine at the University of Ottawa.

"You can't tell a country to eat a whole hell of a lot more, and then when they do eat a whole hell of a lot more, wonder if you're not a part of the blame," he said.

He also pointed to other specific recommendations in the guide as outdated. Dr. Freedhoff is just one of many who have questioned the continued inclusion of dairy as a required food group. Others too doubt the wisdom of allowing fruit juice to count as a serving of fruits and vegetables.

Another frequent criticism of the food guide is that it does not adequately take into account the increasing diversity of Canadian palates.

Shortly after the food guide's first publication in 1942, the B.C. government conducted a study at a Vancouver-area elementary school that classified alarming numbers of the Chinese children as malnourished. They soon realized those children were not malnourished, but that the survey was based on the official food rules, which required milk and bread and other items not common to a Chinese diet.

Since then, Dr. Mosby said, the guide has done a better job – the 2007 version includes items such as pita, couscous and tofu – but it still has a long way to go to reflect the way many Canadians eat.

"It's very culturally specific," he said. "They try to define food in these groups in a way that sort of defines what Canadian food is and isn't – if you're missing one of these groups, not only are you malnourished, but you're also clearly not Canadian."

Others still say the guide's design is simply flawed.

"From a consumer perspective, the food guide is six pages long – it's long, it's cumbersome, it's not the best tool to put in your back pocket," said Sue Mah, a Toronto-based registered dietitian.

Critics say the idea of measuring food based on "serving size," is impractical and confusing. In the current food guide, one serving size of meat and alternatives is described as " 1/2 cup cooked fish, shellfish, poultry, lean meat; 3/4 cup cooked legumes; 3/4 cup tofu; 2 eggs; 2 tbsp peanut butter; or 1/4 cup shelled nuts and seeds."

Even his university-level students have trouble following the food guide, Dr. Mosby said. "I hope they do a good job of this [update], because right now it's a mess," he said.

Dr. Hutchinson acknowledges the design needs improvement. The serving sizes, he said, were "way too complex." And, because the current guide was meant for everyone from school-aged children to doctors and dietitians, "It tried to be everything to everyone."

The new guide, he said, will likely have different versions for different audiences.

Guiding principles

While the food guides of the past have been preoccupied with telling Canadians what to eat, it appears the new one will be equally focused on telling people what not to eat and also how to eat.

As part of its first guiding principle, Health Canada lists foods that Canadians should regularly eat: "vegetables, fruit, whole grains, and protein-rich food – especially plant-based sources of protein." Meat and dairy are not mentioned until the appendix, as examples of "protein-rich foods."

Dr. Hutchinson said these recommendations should not be taken as a signal that any one group will be eliminated from the final guide.

"Some of what's out there is taking it as saying: 'No animal products whatsoever,'" he said. "What we're talking about is going more plant-based, without necessarily eliminating animal products."

The second principle, which focuses on what not to eat, suggests limiting consumption of "processed or prepared foods" – a category that has not been mentioned in earlier guides.

"Saturated fat, sugar or too much salt – there is stronger evidence than ever that these are problematic," Dr. Hutchinson said.

The third principle, which focuses on how to eat, is perhaps attracting the most attention. This looks at overall food skills and knowledge, and encourages people to cook their own meals, and to eat together with family and friends whenever possible.

These arguments, including "preparing meals from scratch," and "eating slowly with enjoyment," echo the Brazilian dietary guidelines launched in 2014, a policy that has received acclaim worldwide for its simple-to-follow, common-sense messages.

Dr. Hutchinson said these are meant to address what he sees as the disconnect between general interest in food and practical knowledge about food. There is a massive interest in food in popular culture, on television and on social media, he said. Yet, "when you look at what's happening with food skills, we're not actually cooking as much, we seem to have lost that ability to pick up basic food and put healthy meals on the plates of our families."

The public consultation period closes next week. In the coming months, Dr. Hutchinson and his team will continue to finalize their plans for the guide. This means that the end result could still look very different from what has been released so far.

It will likely also receive intense scrutiny from the food industry. Unlike in previous food guides, Health Canada has committed this time not to meet privately with food-industry representatives as part of the process. Still, the public consultations are open to everyone, and already, groups such as the Dairy Farmers of Canada are making their feelings known. In a statement on their website addressing Health Canada, the group wrote, "milk and milk products are an important food category to keep."

Whatever the guide winds up looking like, it will not please everyone – inevitable, given the range of perspectives and evolving research surrounding nutrition and food.

"I don't know if we can ever have a perfect food guide," Dr. Freedhoff said. "It's a tough balancing job. I don't envy them."

Health Canada officials are promising significant changes with the new food guide. Already, documents released by the department show some emerging new themes.

The environment

Environmental sustainability will be a key consideration in the new guide. "The way our food is produced, processed, distributed, and consumed – including the losses and waste of food – can have environmental implications," Health Canada's guiding principles state. "In general, diets higher in plant-based foods and lower in animal-based foods are associated with a lesser environmental impact, when compared to current diets high in sodium, sugars and saturated fat."

Feedback given during public consultation also included interest in discussions of animal welfare, community gardening and encouragement of "buying locally grown foods."

Cultural diversity

Recent guides have tried to include culturally appropriate foods, but the new guide promises to go even further to address the changing face of this country, including representing Indigenous cultures and traditions.

"Traditional foods and the harvesting of traditional foods are intrinsically linked to identity and culture, and contribute to overall health."

Alternative diets

One issue raised repeatedly during public consultations was the applicability of the guide for vegetarians and vegans, and for those with allergies or intolerance of such things as gluten.

"Current food groups were considered … less useful to some because of their departure from the nutritional components, lack of applicability to all circumstances and needs such as for a vegan or vegetarian lifestyle or dietary restriction."

– Ann Hui

Source: Health Canada

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