This study has been getting a lot of attention in the news because the authors claim that their findings directly contradict the current government sanctioned dietary guidelines that recommend a low fat diet. This was a cohort study, where people enrolled, underwent baseline measurements (physical measures and questionnaires to understand their socioeconomic groups and habitual diet intake) and were then followed up for ~7 years where any health events (from heart attack and strokes to death) were recorded.
Over 135,000 people from 18 countries were studied, with investigators dividing participants into ‘quintiles’ according to their dietary intakes. They also used statistical corrections to adjust for factors they felt could bias the analysis such as age, sex, education, smoking, and physical activity. The most notable findings were that ‘total mortality’ (the total number of people who died during the study) was significantly higher in the higher quintiles of carbohydrate intake (>70% energy from dietary carbs) vs the lower quintiles (45% energy from dietary carbs).
However, there was no association with carbohydrate intake and the incidence of cardiovascular disease and related health events.
By comparison, higher fat intake ( ~35% from energy from dietary fat) gave a significant decrease in total mortality relative to lower dietary fat intake (~10 % from energy from dietary fat). Total dietary fat intake was NOT associated with increased occurrence of cardiovascular diseases.
The authors conclude that current nutritional recommendations to follow a low fat diet may be incorrect. They acknowledge in the discussion section that there may be some methodological weaknesses in their work (use of a questionnaire to measure diet, lack of follow up diet analysis after baseline and residual confounding factors). They also note that the highest fat consumption (at 35%) and lowest carbohydrate consumption (at 45%) is still a long way from being a ‘ketogenic diet,” where around 80-90% of dietary calories come from fat. Instead of citing this study as the holy grail for support of the ketogenic diet, it seems as if the results can instead be interpreted as evidence for moderating carbohydrate intake.
Authored by Dr. Brianna Stubbs
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