One of the most basic health principles (and, sadly, the one people most often ignore) is eating a diet of whole, nutritious foods rather than unhealthy processed foods. Keep in mind that processed and junk foods are loaded with grains, sugar, and unhealthy calories that increase your insulin levels, which not only accelerates the aging process but also increases your risk of obesity and chronic disease.
I also highly advise against consuming genetically engineered (GE) foods. Not only are GE foods less nutritious than organically-grown foods, but they also pose many health risks. In fact, most processed foods today contain GE ingredients – regardless of the fact that these GE components have not undergone long-term safety studies.
The best diet I would recommend for optimal health and longevity is one that's focused on whole, unprocessed foods – preferably organic vegetables, grass-fed meats, raw dairy, and nuts – acquired from healthy, sustainable, local sources. I also recommend consuming a good portion of your food raw, as well as adding naturally fermented foods to meals.
By implementing these basic diet changes, you can make a big leap toward longevity and optimal health.
For more useful tips in healthy eating, I advise you to follow the Mercola Nutrition Plan, which will guide you in choosing the right foods that will suit your unique biological makeup. The Mercola Nutrition Plan addresses your unique biochemical needs based on your specific genetics, allowing you to cure your health problems at the foundational level and giving you a more permanent solution for regaining your health.