For more than 60 years, Canada's Food Guide has been the definitive word on how to follow a healthy diet. It's a product of evolving scientific and nutritional research, and also factors in the types of food available, what kinds of food people buy, lifestyle changes, how much they eat, and how their food is prepared.

But now, it's ready for an update.

So why is the Food Guide being revised?

The last Canada Food Guide was issued in 1992. Since then, we have, as a nation, become fatter. So it comes as no surprise that the 1992 guide's serving size suggestions may need to be overhauled. The science of nutrition has also made big advances in the last 13 years. There are also many more vegetarians now than there were in '92.

And then there's the very makeup of Canada and its food supply. Increasing immigration has helped to launch a host of new kinds of food into the dietary mainstream. The current guide, for instance, includes pictures of broccoli and bananas. But what about okra, chickpeas, and collard greens?

The next Food Guide may also be plural. Health Canada's office of nutrition policy and promotion is considering issuing different guides for different ethnic groups to reflect their widely varying diets.

And in a nod to cyber-consumers and critics who say the current Food Guide is too confusing or just plain boring, the next guide will feature better graphics, better explanations of terminology, and it will be available in an interactive format. Enter your gender, age, weight, and the amount of exercise you get, and you'll get a more personalized recommendation of the kind of diet you should follow.

How has the Food Guide changed over the years?

Subsequent editions of the guide (there were updates in 1944, 1949, 1961, 1977, 1982, and 1992) added pictures, updated and broadened the shopping lists, and reflected the current thinking on nutritional requirements. Six main food groups became five (in 1944) and eventually four (1977). The 1949 guide, acknowledging that Canada's post-war population was eating more, suggested that "more" was not necessarily "better." The "Food Rules" became a "Food Guide." The suggestion to "Use Liver Frequently" morphed into "Eat Liver Occasionally." And by 1977, the suggestion to eat a serving of potatoes a day was deleted.

The 1977 revision was also notable for grouping the four main food groups around a wheel. In 1982, the guide shifted its dietary advice in an attempt to reduce chronic diseases that were hitting Canadians in ever-rising numbers. A message to limit fat, sugar, salt and alcohol was added.

In 1992, the Food Guide's design changed again – this time to a rainbow. The biggest of the rainbow's rays are reserved for grain products and vegetables and fruit ("eat more often") while the smaller rays are for milk products and meat and alternatives ("choose lower fat products").

How does Canada's Food Guide compare to other countries' guides?

Canada's Food Guide has its rainbow – the U.S. a pyramid. The old pyramid put fats, oils and sweets at the pointed top (the smallest part of the pyramid) and breads, cereals, rice and pasta at the bottom. But that was replaced by a new guide of interactive pyramid that didn't have any one group at the top.

China's, the Philippines', and South Korea's food guides have also adopted pyramid or pagoda shapes, while most of Europe has opted for a variation of wheels, pie charts or plates. Canada's rainbow is, it appears, unique in the world of food guides.

A comparison of various countries' dietary guides published by the American Dietetic Association showed broad similarities among the major food groupings from culture to culture. But look closer, and many differences are quick to appear. Germany's food guide, for example, has a grouping just for fluids; some guides split fruits and vegetables into separate categories; some classify nuts as proteins while others put them in fats; while the Philippines guide has no group at all for milk or dairy products. Filipinos don't drink much milk.

So what happens next?

The review of Canada's Food Guide began in 2003 with input from dozens of industry and trade groups, health organizations, governments, universities, consumer groups and other agencies.

A survey of those stakeholders found almost half believed that key messages of the Food Guide were not reaching consumers – especially serving sizes and how the suggested ranges of the number of servings affected individual Canadians. A majority also felt the guide didn't reflect enough variety or ethnic foods.

Throughout 2004, Health Canada established working groups and advisory committees. They commissioned research that continued into 2005. Health Canada says stakeholders will get a chance to weigh in on proposed changes to the food guide by the fall of 2005. While that is happening, test groups of consumers will be asked for their thoughts.

The plan is for the new Canada Food Guide to be released in the spring of 2006.