Dietary recommendations to the general public can be unclear. They often don’t take into account nutrient and or drug interactions. For example, the long-held view that saturated fat should be reduced has been challenged by recent studies suggesting that saturated fat intake is not associated with cardiovascular mortality. There are many other examples.
A new study led by Carlos Celis-Morales of Universidad Católica del Maule, Talca, Chile, attempted to gain a clearer picture of diet and mortality using the UK Biobank cohort to examine the associations between macronutrients and their components and all cause mortality and cardiovascular disease (CVD); to conduct non-linear isocaloric replacement analyses; and to develop a dietary risk matrix to illustrate how conditional advice can be given.
Total fat intake was not significantly associated with all cause mortality. All the remaining macronutrients, except for MUFA, PUFA, and SFA, had non-linear associations with mortality. Risk of death was lowest among participants who consumed 5-20% energy from sugar.
The association of sugar with CVD risk seems to be stronger in participants with lower energy intake. Although the association of saturated fat with all cause mortality differed between individuals with high and low carbohydrate intake, no differences were observed for incident CVD.
Replacing starch with sugar was associated with lower all cause mortality up to 25% energy from sugar but was linearly associated with a higher risk of CVD.
The limitations of the study should not be ignored, however as the dietary information used in this study was provided by around half of UK Biobank participants, selection bias is possible. Also, food source (eg, whole grain versus refined carbohydrate sources) might modify the associations between macronutrient intake and outcomes.
“This study found that many of the associations between macronutrient intakes and health (mortality and CVD risk) are non-linear. Thus, dietary advice should be based on current intake. Moreover, components of carbohydrates also displayed differential associations with health outcomes, indicating that dietary guidelines on carbohydrate intake should also take account of the divergent associations of sugar and starch,” concluded the authors.