Blood Test Could Provide Snapshot of Overall Health

Cardiorespiratory fitness significantly influences various bodily systems, from metabolism to brain function. Currently, there is no standardized method to quantitatively assess cardiorespiratory fitness, even though it provides a comprehensive view of a person’s health. Now, a new study has found that levels of circulating proteins could be effective biomarkers for cardiorespiratory fitness, a crucial but previously difficult-to-quantify component of an individual’s overall health.

In the study published in Nature Medicine, investigators at Northwestern University Feinberg School of Medicine (Chicago, IL, USA) used statistical models to identify circulating proteins that most significantly affect overall health across over 14,000 participants. The researchers developed a cardiorespiratory fitness score based on an individual's levels of certain circulating proteins, which are linked to inflammation, neuronal survival and growth, and oxidative stress, among other factors. This scoring system was then validated using data from 20,000 individuals in the UK Biobank, revealing that a favorable score correlates with a lower risk of all-cause mortality.

The team further tested the validity of their scoring system by analyzing the circulating proteins of over 600 individuals before and after they participated in a 20-week exercise program. The study found that improvements in participants' cardiorespiratory fitness scores were associated with the beneficial impacts of exercise on their cardiorespiratory systems. These results establish a foundation for a scoring system that could potentially assess holistic health through a simple blood test, offering insights into the relationship between fitness and health. Building on this, the researchers plan to extend this protein scoring method to additional areas of overall health.

“We know a lot about trajectories of health. Someone might be on a declining trajectory, but when we see patients at one time point, it’s really hard for us to extrapolate what a trajectory of someone’s health may be,” said Ravi Kalhan, MD, MS, professor of Medicine in the Division of Pulmonary and Critical Care, of Preventive Medicine in the Division of Epidemiology, and a co-author of the study. “If we could apply these single-time-point measurements using a blood test that reflects a greater, more difficult-to-ascertain factor of health, that really would be interesting.”

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Northwestern University Feinberg School of Medicine