People with higher levels of C-reactive protein in their blood have a 2.22 times greater chance of dying from coronary heart disease over 15 years, even after accounting for social isolation. This...

We analyzed the available evidence and found that people with higher levels of C-reactive protein in their blood have about 2.22 times greater chance of dying from coronary heart disease over 15 years, even when social isolation is taken into account [1]. This suggests that elevated C-reactive protein is linked to a higher risk of death from heart disease, independent of how socially connected someone is. C-reactive protein is a marker of inflammation in the body — it’s a protein the liver makes when there’s ongoing low-grade inflammation, which can happen due to things like infection, stress, or metabolic changes. Higher levels over time may reflect underlying processes that affect heart health, but we don’t know exactly why. The same evidence shows that while C-reactive protein is tied to heart disease death, it does not appear to explain the connection between social isolation and heart disease death. In other words, social isolation may increase risk through other pathways — like changes in behavior, stress hormones, or sleep — that aren’t captured by this one marker. What we’ve found so far leans toward C-reactive protein being a useful signal of increased risk, but not a full explanation for how social isolation affects the heart. There’s no evidence in our review that contradicts this. If you’re concerned about heart health, checking C-reactive protein levels might give some insight into inflammation, but it’s not the whole story. Managing stress, staying active, and maintaining social connections may still matter — even if they don’t show up in a blood test.