 How can we remain young at heart? The capacity of our blood vessels to repair themselves is dependent on endothelial progenitor cells that emerge from stem cells in our bone marrow to patch up any holes in our endothelium, the innermost lining of our blood vessels that keeps our blood flowing smoothly. Lower levels of circulating endothelial progenitor cells in the blood correlates with arterial diseases like erectile dysfunction. Other numbers, on the other hand, are correlated with significantly reduced risk of death from cardiovascular causes. Before we explore how to boost our levels, let's first establish cause and effect. A randomized, double-blind placebo-controlled trial was performed in men and women with peripheral vascular disease, a circulation disorder characterized by the narrowing of blood vessels outside of the heart or brain. The artery-supplying blood to their legs were so ravaged by disease that they could only walk about a minute before the muscles in their legs cried out in pain from lack of oxygen. For each study participant, one leg was randomly selected to be injected with cells from their own bone marrow, and the other was injected with their own peripheral blood as a control. Not only was pain-free walking time significantly extended in the marrow-injected leg, they were less likely to subsequently lose it. Severe limoschemia, lack of oxygen, from peripheral vascular disease carries a 10-40% amputation rate within six months. In the control group, 14% were forced to undergo a major amputation compared to zero in the bone marrow group. Given these remarkable benefits, the link between higher numbers of endothelial progenitor cells and lower risk of dying from cardiovascular disease may indeed be causal. Short of sticking a large bore needle into your hip, how else can we cultivate and release more endothelial progenitor cells into our system? Smoking cessation is one of the most important and effective lifestyle changes to increase the number and function of active endothelial progenitor cells. Cutting down isn't enough. There are 20 cigarettes in a pack. If you only smoke about one a day, wouldn't you think you'd only have like one-twentieth the risk of cardiovascular disease compared to smoking the whole pack? Based on a meta-analysis of more than 100 studies, smoking only about one cigarette a day costs around 10 times the risk of cardiovascular disease you'd expect by that logic compared to smoking a pack a day. There is no safe level of smoking when it comes to heart attack and stroke risk. Human exposure to secondhand smoke can deteriorate or circulate endothelial progenitor cell count, so even just being around smokers is risky. Randomized controlled trials show exercise training can actually boost endothelial progenitor cell circulation. In a study of middle-aged and older sedentary men, for example, three months of moderate aerobic exercise, mostly walking with some participants starting to jog a bit as their fitness improved led to a doubling of endothelial progenitor cells in their bloodstream. Regular aerobic exercise could be considered a first-line strategy for helping to prevent and treat arterial aging. What about diet? A randomized controlled trial showed that reducing saturated fat, mostly in the form of butter, significantly elevated endothelial progenitor cell numbers, consistent with a study on baboon showing that even a few weeks of a high-clustral, high-fat diet could cause dramatic premature epithelial cell senescence. Individual foods that have been showed to increase circulating endothelial progenitor cells include berries, onions, and green tea. And a diet centered completely around whole plant foods not only showed a boost in endothelial progenitors, but an improvement in endothelial function along with a drop in LDL cholesterol.