It sounds like Canada’s guide followed the same path that the US’s did: the original USDA food pyramid was influenced by lobbying and recommended lots of carbohydrates and milk. It also suffered from the fact that there was no attempt to have people follow the diet to see its effects before the USDA recommended it to the whole country. Over the past twenty years, the USDA has quietly been revising the recommendations (they make a big deal when they issue new recommendations and websites to distribute them, but they don’t say much about what actually changed each time).

My favorite example is that a doctor once recommended that I follow the DASH diet to lower my blood pressure. The DASH diet was a modified version of the 1990s food pyramid. A relatively recent study compared it with diets that get fewer calories from carbohydrates, and while all the diets they tried did lower blood pressure, the original DASH diet was the worst of the bunch ( https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3236092/ ).