This thesis explores how sodium intake, protein consumption, and body composition impact health, shedding light on the U-shaped relationship between sodium intake and mortality. Both very low and very high sodium intakes increase the risk of death, and this research investigates why.
It uncovers that sodium’s role in the body goes beyond its effect on blood pressure. Sodium levels in the blood are closely linked to extracellular fluid volume (ECFV), a key aspect of hydration and salt balance, independent of blood pressure. While these findings deepen our understanding of sodium’s physiological effects, more research is needed to use blood sodium levels as personalized health markers. Emerging tools, such as new ECFV measurements, may help tailor health advice in the future.
The thesis also reveals that the increased mortality risk linked to low sodium intake is not due to sodium alone. It is strongly tied to low protein intake, which often signals poor nutritional health, whereas concomitant high protein intake is linked to lower mortality rates. Surprisingly, 10% of people, especially older adults, consume less protein than recommended. Lastly, the research highlights that individuals with low muscle mass and low protein intake face the highest mortality risks. Body composition, particularly muscle mass, predicts mortality risks better than BMI.
These findings advocate for personalized dietary advice that considers the combined effects of sodium, protein, and body composition to improve health and reduce mortality risks, and moving beyond the “one-size-fits-all” nutrition recommendations.
