A longevity expert has urged people to eat "at least" three types of food a day to live longer. The advice is based on the diets of people living in Blue Zones - areas of the world with lower levels of chronic disease and longer life expectancy, the Mirror reported. 

The five original Blue Zones identified by the researchers are Okinawa in Japan, Sardinia in Italy, the Nicoya Peninsula in Costa Rica, Ikaria in Greece and Loma Linda in California. While the diets in each zone differ, there are some similarities that experts believe contribute to the longevity of the population. This includes eating "wholesome, nutrient- and fiber-rich foods," such as plants, legumes and healthy fats, while minimizing sugar intake and processed foods.

In an excerpt from Dan Buettner's recipe book "The Blue Zones Kitchen," shared on the BlueZones.com website, he explains the way long-timers eat.

"None of the Blue Zones centenarians I've met have tried to live to 100," he says. "No one has said at age 50, 'You know what, I'm going to put myself on this longevity diet and live another 50 years! They don't count calories, take vitamins, weigh protein grams, or even read labels. They don't restrict food intake - in fact, they all celebrate with food."

Among these guidelines is a list of 10 "super blue foods." Dan recommended eating "at least" three of these daily to ensure you're getting plenty of nutritious food:

Beans - all types: black beans, pinto beans, garbanzo beans, black-eyed peas, lentils

Green vegetables - spinach, kale, chard, beet tops, fennel tops

Sweet potatoes

Nuts - all types: almonds, peanuts, walnuts, sunflower seeds, Brazil nuts, cashews

Olive oil - green, extra virgin is usually best (note that olive oil breaks down quickly, so buy no more than a month's supply at a time)

Oats - Irish oats are best, slow cooked or sliced

Barley - in soups, as a hot cereal or ground for bread

Fruit - all types

Green or herbal teas

Turmeric - as a spice or tea.

"The results obtained here represent a long-term, statistical and scientifically sound study. We needed information that wasn't just anecdotal or based on interviews, kitchen visits or shared meals with individual centenarians," Buehner said. | BGNES