What do people who live to 100 have in common?

The Blue Zones

The Blue Zones are five places where people were reported to reach very old age unusually often. They are Sardinia in Italy, Okinawa in Japan, Ikaria in Greece, Nicoya in Costa Rica, and the Seventh-day Adventist community of Loma Linda in California.

People there share four habits:

• a mostly plant-based diet, with meals that stop before they feel full
• movement built into daily life, such as walking, gardening and housework
• close family and social ties
• a sense of purpose that lasts into old age

Some of the age records have been questioned. In some regions birth records are poor. Pension fraud and clerical errors can also inflate the number of very old people.

The habits are still well supported. Much larger studies link the same kind of diet, physical activity and social ties to longer life.

The genes linked to long life

Certain gene variants are more common in people who reach 100. No single gene explains a long life.

FOXO3 has the most consistent results. Some versions of it are more common in long-lived people across many populations. FOXO3 works in the insulin and IGF-1 signaling pathway, which helps cells manage fuel, stress and repair.

APOE also comes up again and again. Its e2 form is linked to better odds of healthy aging. Its e4 form is linked to a higher risk of Alzheimer's disease and heart disease.

Variants in genes that handle blood fats and insulin signaling also come up often.

These variants change the odds in large groups of people. Many people who carry the favorable versions die at ordinary ages. Many people without them live very long lives.

A consumer DNA array tests about 0.02% of your DNA. It checks the well-known variants and misses most rare ones. Whole-genome sequencing covers about 3 billion positions, including rare variants.

Lifestyle explains more than genes

Twin and family studies suggest that genes explain less than half of the differences in how long people live. The rest comes from environment, behavior and chance.

Your DNA cannot tell you whether you will reach 100. It can show how you handle blood fats and blood sugar, and how you process certain medicines. It can also show which health checks may be worth starting earlier. See an example report.

Informational and educational, not a diagnosis. Bring anything of medical consequence to your physician.