While there isn’t a straightforward rulebook for longevity, there are key lessons from the people who live in blue zones that can help you create and stick with new habits to age healthfully. One of those lessons resides in the food culture of an 80-mile-long peninsula in Central America, named a blue zone in the early 2000s. 

The residents of Nicoya, Costa Rica—known for its coastal views south of the Nicaraguan border—have routinely enjoyed three foods together for at least 6,000 years old, Dan Buettner, the Blue Zones LLC founder shares in his recent docuseries Live to 100 on Netflix. 

“Without a doubt one of the reasons people in Nicoya are living a long time is because they are eating this diet of beans, squash, and corn,” Buettner says in the film. “They call it the three sisters.” 

These plant-based foods are economical and practical sources of protein that have served Nicoya’s residents into old age. Contrary to the Western diet where meat is the primary source of protein, beans, corn, and squash provide protein at a low cost and without the cholesterol and saturated fat of red meat.

 “They are spending a fraction of what we do on meat and dairy, and they are getting all the protein they need,” Buettner says in the film. “It just goes to show you do not need to be wealthy to eat healthy.” 

Here are the health benefits of the “three sisters.” 

1. Corn  

In Nicoya, families have traditionally made tortillas by soaking corn kernels in  wood ash. 

“The traditional processing of corn boosts the nutritional value,” Buettner says in the film. 

The tortillas are high in complex carbohydrates, integral for maintaining energy. Corn by itself is also rich in fiber, so it will digest slowly and keep you satiated. 

The good news is even if you don’t make homemade tortillas, you can enjoy corn in other ways or add it to salsas, salads or vegetable chilis. 

2. Beans 

Black beans contain antioxidants, which strengthen the immune system, Buettner says in the film. They also provide a substantial source of protein for muscle growth and fiber for managing blood sugar. 

Buettner champions a daily dose of beans in his book, The Blue Zones American Kitchen: 100 Recipes to Live to 100, and they’re featured in many of its recipes. 

“[Beans] reign supreme in the blue zones and are the cornerstone of every longevity diet in the world,” he writes in his book.  

Beans are also more accessible than other sources of protein—you can get them for less than $2 a pound, he previously told Fortune. 

Whether in soup or tacos or by themselves, beans are another easy addition to your recipe collection. 

3. Squash

Squash is rich in vitamins A, B, and C, as well as magnesium and potassium, which are critical for bone, blood, and heart health, according to the Cleveland Clinic. Their antioxidants also help reduce oxidative stress, which can cause cell damage and disease. 

Adding seasonal squash to your next dish can be a great way to start incorporating it into your diet. Fall varieties include butternut, acorn, and spaghetti squash. Consider roasting them as a side or filling them with other vegetables and grains, like quinoa and tomatoes. 

The blue zone way of eating  is not a strict diet, but a lesson in how combining flavorful, inexpensive whole, plant-based foods can be tasty and contribute to your longevity. 

“Find the ingredients you love, and if you can learn how to combine them to make something delicious, you’re on your way to eating to 100,” he previously told Fortune.