There is a study that found having seven servings of refined grains (white bread, pasta/noodles, breakfast cereals, crackers, and bakery products, etc.) per day was associated with a 27 per cent greater risk for early death. 33 percent greater risk for heart disease and 47 per cent greater risk for stroke.
The Prospective Urban Rural Epidemiology (PURE) study has been examining diets from diverse populations in low-, middle- and high-income countries around the world. Over 16 years of analysis of 137,130 participants in 21 countries, including Canada, the researchers found the intake of refined grains and added sugars have greatly increased over the years
Since this was an observational study it has the disadvantage of not being able to establish causation. Although, their data was adjusted for several possible confounding factors such as obesity, wealth status, etc. there are almost certain, that other factors that were not defined in this study that could be at play. Eating a diet high in refined carbohydrates increases small, dense LDL particles which are very atherogenic.
Another study including over 400,000 people found that those with the highest refined sugar intake had a four-fold increase in heart attacks compared to those with the lowest intakes.
A diet high in refined carbohydrates is not good for health.