The Nicoya Diet: Corn, Beans and Squash — The Three Sisters of Longevity
The Nicoya diet is built around three staple crops — corn, beans and squash — known as the three sisters, which together provide complete protein, fibre and essential nutrients that support the remarkable longevity seen in this Costa Rica Blue Zone. This traditional way of eating emphasises whole, minimally processed plant foods prepared simply, with meat and dairy playing only minor roles. Research on the region's centenarians shows their dietary pattern is a key factor in Nicoya longevity.
What is the Nicoya diet?
The Nicoya diet refers to the traditional eating pattern of the Nicoya Peninsula in northwestern Costa Rica, one of the world's five Blue Zones where people routinely live past 90 in good health. It centres on corn tortillas, black beans, squash, tropical fruits, rice and occasional eggs or small portions of meat, all prepared with minimal added fat or sugar. The diet is naturally high in fibre, complex carbohydrates and plant-based protein, and low in processed foods.
Why are corn, beans and squash called the three sisters?
Corn, beans and squash are called the three sisters because they are traditionally planted together in a mutually beneficial system: corn provides a stalk for beans to climb, beans fix nitrogen in the soil, and squash leaves shade the ground to retain moisture and suppress weeds. Nutritionally, they complement each other perfectly — corn and beans together form a complete protein, while squash adds beta-carotene, vitamin C and fibre. This agricultural and nutritional synergy has sustained Nicoyan communities for generations.
How does the three sisters combination support healthy ageing?
The three sisters combination supports healthy ageing by delivering a steady supply of complex carbohydrates, plant protein, fibre and antioxidants that help regulate blood sugar, support gut health and reduce inflammation. Corn provides energy and B vitamins; beans contribute iron, folate, magnesium and resistant starch; squash supplies carotenoids that convert to vitamin A. Together they create a nutrient-dense foundation linked to lower rates of heart disease, diabetes and cognitive decline in Nicoya's older adults.
What does a typical day of eating look like in Nicoya?
A typical Nicoyan day starts with gallo pinto — rice and black beans cooked with onions, peppers and coriander — often served with corn tortillas and a side of fresh fruit. Lunch might feature a bean stew with squash, vegetables and a small portion of chicken or cheese, accompanied by tortillas. Dinner is lighter: perhaps a vegetable soup with corn dumplings or beans with squash. Snacks are whole fruits like papaya, mango or marañón (cashew fruit). Meals are eaten slowly, often with family.
Is the Nicoya diet plant-based?
The Nicoya diet is predominantly plant-based but not strictly vegetarian; animal foods appear in small amounts as condiments or occasional additions rather than main dishes. Eggs, fresh cheese, chicken and pork are used sparingly, while beans, corn, squash, rice, fruits and vegetables make up the bulk of daily calories. This plant-forward pattern aligns with findings from the Adventist Health Study and other longevity research showing that diets rich in legumes and whole grains correlate with longer healthspans.
How do Nicoyans prepare corn for maximum nutrition?
Nicoyans traditionally nixtamalise corn — soaking and cooking dried maize in an alkaline solution (usually lime water) before grinding it into masa for tortillas. This ancient process increases the bioavailability of niacin (vitamin B3), improves protein quality, boosts calcium content and reduces mycotoxins. The resulting tortillas are a nutrient-rich staple eaten at nearly every meal. You'll find traditional dried beans and whole-grain corn products in our pantry range at The Blue Zone Food Store.
What role do beans play in Nicoya longevity?
Beans are the primary protein source in the Nicoya diet, eaten daily in forms ranging from gallo pinto to hearty stews. Black beans are most common, providing fibre, resistant starch, folate, iron and polyphenols that support cardiovascular and metabolic health. Population studies in the region associate higher legume intake with lower mortality risk. Soaking beans before cooking — a standard Nicoyan practice — reduces antinutrients and improves digestibility.
Which squash varieties are used in the Nicoya Peninsula?
The Nicoya Peninsula uses several squash varieties including ayote (a large, sweet-fleshed winter squash similar to butternut), chayote (a pear-shaped, mild-flavoured squash eaten skin and all), and calabaza (a generic term for various pumpkin-like squashes). These are added to bean pots, simmered in soups, or simply roasted. Their deep orange flesh signals high carotenoid content, which research links to reduced oxidative stress and better immune function in older adults.
Can you follow the Nicoya diet outside Costa Rica?
Yes, you can follow the Nicoya diet principles anywhere by centring meals on the three sisters: choose nixtamalised corn tortillas or masa harina, cook dried black beans from scratch, and incorporate winter squash like butternut or kabocha. Add plenty of seasonal vegetables, tropical or local fruits, brown rice, and use herbs like coriander, oregano and garlic for flavour. Limit meat to small portions a few times a week, and avoid ultra-processed foods. The Blue Zone Food Store stocks many of these staples for UK shoppers.
How does the Nicoya diet compare to other Blue Zone diets?
All Blue Zone diets share core principles — plant-forward, legume-rich, whole-food based — but each reflects local agriculture. The table below highlights key similarities and differences.
| Blue Zone | Staple Carbohydrate | Primary Legume | Key Fat Source | Distinctive Feature |
|---|---|---|---|---|
| Nicoya, Costa Rica | Corn (nixtamalised) | Black beans | Small amounts of pork fat, cheese | Three sisters agriculture; high calcium water |
| Okinawa, Japan | Purple sweet potato | Soy (tofu, miso) | Minimal; some pork for flavour | Hara hachi bu (80% rule); turmeric tea |
| Sardinia, Italy | Barley, sourdough bread | Fava beans, chickpeas | Sheep/goat cheese, olive oil | Cannonau wine; pastoral lifestyle |
| Ikaria, Greece | Potatoes, whole-grain bread | Lentils, chickpeas | Olive oil | Herbal teas; midday naps; fasting periods |
| Loma Linda, USA | Whole grains, oats | All legumes, nuts | Nuts, avocado, olive oil | Vegetarian/vegan Adventist community |
What lifestyle factors accompany the Nicoya diet?
Diet alone doesn't explain Nicoya longevity. Centenarians there also benefit from strong family networks, daily physical activity through walking and farm work, a sense of purpose (plan de vida), regular sun exposure for vitamin D, and hard water naturally rich in calcium and magnesium. They eat their largest meal at midday, fast overnight for 12+ hours, and maintain social rituals around food. These factors work synergistically with the three sisters diet to promote healthy ageing.
Where can you find authentic Nicoya diet ingredients in the UK?
Look for masa harina (nixtamalised corn flour) at Latin American grocers or online, dried black beans at any supermarket or wholefood shop, and butternut or kabocha squash in season at greengrocers. Specialty shops may stock ayote or chayote. For convenience, The Blue Zone Food Store offers a curated selection of traditional dried beans, whole grains and pantry staples aligned with Blue Zone eating patterns.
Ready to bring the three sisters to your table? Start with a simple pot of black beans, warm corn tortillas and roasted squash — then build from there. Your journey to eating like a Nicoyan centenarian begins with one meal.
Frequently asked questions
What is the Nicoya diet?
The Nicoya diet is the traditional eating pattern of Costa Rica's Nicoya Peninsula, a Blue Zone where people live exceptionally long lives. It centres on corn, beans and squash — the 'three sisters' — plus rice, tropical fruits, and small amounts of animal foods.
Why are corn, beans and squash called the three sisters?
They're called the three sisters because they're traditionally grown together in a mutually beneficial planting system: corn supports climbing beans, beans fix soil nitrogen, and squash shades the ground. Nutritionally, corn and beans form a complete protein while squash adds vitamins and fibre.
Is the Nicoya diet vegetarian?
The Nicoya diet is predominantly plant-based but not strictly vegetarian. Meat, eggs and cheese appear in small amounts as flavourings or occasional additions, while beans, corn, squash, rice and vegetables provide the vast majority of calories.
What is nixtamalisation and why does it matter?
Nixtamalisation is the traditional process of soaking and cooking corn in an alkaline solution (lime water) before grinding it into masa. It increases niacin bioavailability, improves protein quality, adds calcium and reduces toxins — making corn tortillas far more nutritious.
Can I follow the Nicoya diet in the UK?
Yes. Use masa harina for tortillas, cook dried black beans from scratch, add butternut or kabocha squash, eat plenty of seasonal vegetables and fruit, choose brown rice, and keep meat portions small. Many UK wholefood shops and online stores stock these ingredients.