It seems plausible that there is a roughly optimal human diet, a range within which one will age modestly more slowly than is the case when falling outside it. The work on fasting mimicking is quite solid, for example. What does one eat when not in a period of fasting mimicking, however? On this topic, the science tends to get drowned out by the marketing, ever a human failing. Given a more coordinated scientific community, it could be possible to produce data that is compelling, however, a reasonable and defensible answer to the question. Just don't expect that to turn up any time soon, or for it to settle the diet wars when it does.
Examining a range of nutrition research from studies in laboratory animals to epidemiological research in human populations provides a clearer picture of the best diet for a longer, healthier life. Researchers recently described the "longevity diet," a multi-pillar approach based on studies of various aspects of diet, from food composition and calorie intake to the length and frequency of fasting periods. The researchers reviewed hundreds of studies on nutrition, diseases, and longevity in laboratory animals and humans and combined them with their own studies on nutrients and aging.
The work also included a review of different forms of fasting, including a short-term diet that mimics the body's fasting response, intermittent fasting (frequent and short-term) and periodic fasting (two or more days of fasting or fasting-mimicking diets more than twice a month). In addition to examining lifespan data from epidemiological studies, the team linked these studies to specific dietary factors affecting several longevity-regulating genetic pathways shared by animals and humans that also affect markers for disease risk. These include levels of insulin, C-reactive protein, insulin-like growth factor 1, and cholesterol.
The authors report that the key characteristics of the optimal diet appear to be moderate to high carbohydrate intake from non-refined sources, low but sufficient protein from largely plant-based sources, and enough plant-based fats to provide about 30 percent of energy needs. Ideally, the day's meals would all occur within a window of 11-12 hours, allowing for a daily period of fasting. Additionally, a 5-day cycle of a fasting or fasting-mimicking diet every 3-4 months may also help reduce insulin resistance, blood pressure, and other risk factors for individuals with increased disease risks.
The next step in researching the longevity diet will be a 500-person study taking place in southern Italy. In addition to the general characteristics, the longevity diet should be adapted to individuals based on sex, age, health status, and genetics. For instance, people over age 65 may need to increase protein in order to counter frailty and loss of lean body mass.