 The Harvard Nurses' Health Study, involving more than 100,000 women, was started in 1976, and so, as you can imagine, is now the most definitive long-term study ever on older women's health. Since the study started, thousands of participants have died, and now, thanks to all that hard work, though 35 years later they published the Risk Factors for Mortality. And because it was a so-called competing risks analysis, it allows one to compare different risks to one another. The number one single cause of death? Heart disease. And so, no surprise that dietary cholesterol consumption was a significant risk factor for death. The second leading cause of death was smoking-related cancer deaths. According to the two, consuming the amount of cholesterol found in just a single egg a day appears to cut a woman's life short as much as smoking five cigarettes a day for 15 years. The most protective behavior they found was fiber consumption, eating just a cup of oatmeal worth of fiber a day appears to extend a woman's life as much as four hours of jogging a week. And of course there's no reason you can't do both. The one specific food most tied to longevity was nuts. You appear to also get four hours of weekly jogging benefit eating just two handful of nuts a week as well. Taking a step back though, it's worth noting that the intake of cholesterol, only found in animal foods, was associated with living a shorter life, and the intake of fiber, only found in plant foods, was associated with living a longer life.