A few months ago, the results of the PURE study (Prospective Urban Rural Epidemiology) were published and made a lot of noise in the media. The main message that has been conveyed on social media is that we should replace carbohydrates with fats in our diet. Some went even further by saying that bacon is a good choice or that it would be better to follow the ketogenic diet. But what did the study really say?
The PURE study is a large-scale research involving 135 335 individuals aged between 35 and 70 years old, originating from 18 countries, and who were followed for a period of 7 years. The researchers concluded that a high carbohydrate intake was associated with an increased risk of mortality, whereas a high fat intake was associated with a decreased risk of mortality.
According to the results obtained, the researchers recommended that the daily intake of fat should be about 35% of total calories and that the daily intake of carbohydrates should be about 45% of total calories. However, these recommendations are not really different from current Canadian guidelines, which recommend that carbohydrate make up 45% to 65% of total daily calories and that fat make up 20% to 35% of total daily calories. It should be noted that the carbohydrates and fat intakes measured in the PURE study are extremely far from those advocated by the ketogenic diet (more than 80% of daily calories from fat). The researchers did state that the results of this study do not support the implementation of a very low carbohydrate diet.
It should also be noted that we cannot base nutrition recommendations on the results of a single study. In addition, researchers did not consider the quality of the diet, i.e. the variety and type of foods eaten, their nutritional value and the extent of their transformation. For example, they put on the same level refined sugars from sweets and sugary drinks as sugars from carbohydrates coming from whole grains and fruits. They also did not consider the participants’ fiber and trans fat intake. Yet we know that ultra-processed foods do not have the same impact on health as fresh foods. Finally, to be able to evaluate the participants’ diets, they asked them to complete a food frequency questionnaire. In other words, participants were asked how often they ate certain types of food. However, participants completed the questionnaire only at the beginning of the study. It was therefore assumed that they fed identically for 7 years.
In conclusion, with further inspection, the results of the PURE study are not as extraordinary as the media has tried to make us believe. The impact of food on health is a complex science, and a single nutrient cannot be responsible for health problems alone. Carbohydrates, fats and proteins are all essential to life and perform various functions in the body. For example, carbohydrates are the main source of energy for the muscles and the brain and promote the balance of intestinal flora. Proteins allow the construction and repair of muscles and promote satiety. Fats promote the absorption of certain vitamins and the production of hormones. So, should you replace sugar with fat in your diet? This depends on various factors such as the quality of your diet, your health state, your physical activity level, your genetic makeup, your tastes, etc. If you eat a lot of refined sugars, then maybe yes. But in that case, it would be better to increase your intake of good fats such as nuts, avocado and olive oil.