ApoB is thought to be the best blood biomarker to assess heart disease risk. This is because high levels of ApoB are associated with an increased risk of atherosclerosis (the build-up of plaque in your arteries that can impair blood flow). When left unaddressed, plaque build-up affects health if it occurs in the heart or brain and can lead to heart attack or stroke when compounded over time.
Heart disease is currently the leading cause of death in the United States and is estimated to contribute to over 650,000 deaths in the US alone every year. Therefore, ApoB levels are correlated with longevity and healthspan.