A nutritious diet might be the secret to longevity, according to one naturopathic doctor.Dr Ryan Shelton took to YouTube to share his “keys” to longevity. For those looking to prolong their life, the expert advised adding more vegetables to their diet, particularly beans and legumes.Dr Shelton said: “There are eight keys that researchers have found can increase longevity in humans.”One of the ways people may be able to prolong their lives is by upping their fruit and vegetable intake and enjoying a plant-based diet high in beans and legumes.For longevity, try enjoying a mostly plant-based dietPA IMAGESExamples of legumes are peanuts, alfalfa, lentils, beans, green beans, black-eyed peas, sugar snap peas, asparagus beans, soybeans and peas. According to MedicineNet, there are more than 40,000 varieties of beans in the world, although only a small percentage are produced for mass consumption. Common varieties include great northern beans, kidney beans, navy beans, pinto beans and black beans.Now, enjoying a plant-based diet does not mean giving up meat and other animal products entirely. It simply means prioritising plant-based foods.Harvard Medical School stated: “Plant-based or plant-forward eating patterns focus on foods primarily from plants. LATEST DEVELOPMENTS”This includes not only fruits and vegetables, but also nuts, seeds, oils, whole grains, legumes, and beans.”It doesn’t mean that you are vegetarian or vegan and never eat meat or dairy. Rather, you are proportionately choosing more of your foods from plant sources.”One example of a plant-based diet is the Mediterranean diet, which is often hailed as the healthiest diet out there.Those who follow the Mediterranean diet typically focus on plant-based foods, plus fish, poultry, eggs, cheese, and yoghurt a few times a week. Sweets and meat are enjoyed far less often.Harvard Medical School said: “The Mediterranean diet has been shown in both large population studies and randomised clinical trials to reduce risk of heart disease, metabolic syndrome, diabetes, certain cancers (specifically colon, breast, and prostate cancer), depression, and in older adults, a decreased risk of frailty, along with better mental and physical function.”The NIH’s National Institute on Aging offered some top tips on healthy meal planning. Mature people were advised to enjoy a variety of foods across the food groups, get enough protein, snack on chopped fruit and vegetables, enjoy foods fortified with vitamin B12, reduce their sodium intake and stay hydrated.READ MOREA doctor advised consuming plenty of beans and legumesGETTY IMAGESHow to increase longevityAvoid smokingEat a plant-based diet with plenty of beans and legumesEnjoy lots of moderate physical activityGet lots of sunlightPractise gardeningMaintain strong family connectionsBe in a community where there are empowered womenHave a strong sense of engagement