The secret to a long life may lie in how rural Costa Ricans eat

This article provides insight into why elderly Costa Ricans have a mortality rate that is among the lowest in the world. Diet may play a key role. Yu et al. analyzed dietary data from nearly 3,000 Costa Ricans over age 60 who participated in the nationwide health survey, Costa Rican Longevity and Healthy Aging Study (CRELES). Publicly available from the National Archive of Computerized Data on Aging (NACDA), CRELES’ national scope, large sample size, and wealth of data on diet and health, enabled the authors to characterize and compare rural and urban elderly populations in the country, and examine diet and nutrition patterns underlying Costa Rican longevity.

CRELES was made up of a set of nationally representative longitudinal surveys of the health and lifecourse experiences of older Costa Ricans, conducted in a baseline wave with two follow-up waves between 2005 and 2009. It used a food frequency questionnaire to assess respondents’ diet, capturing over 75 percent of variance in macro- and micronutrient intake. The study also collected data on health history, socioeconomic status, living conditions, and health care utilization. Other health indicators included anthropometrics, observed mobility data, and biomarkers from blood and urine (such as cholesterol, glycosylated hemoglobin, C-reactive protein, and cortisol). Respondent deaths were also tracked and the conditions surrounding them were measured in surviving family interviews.

For their analysis, Yu et al. evaluated data from the 2,819 CRELES participants who provided dietary information in the baseline interview. They found significant differences between the traditional diets of rural versus urban seniors. Urban dwelling seniors ate more processed foods heavy in fat, calcium, and soybean oil. Elderly rural residents had a higher consumption of carbohydrates that had a lower glycemic index, fiber, and dietary iron, and they used more palm oil for cooking than elderly urban dwellers. Despite this higher intake of saturated palm oil, rural seniors had lower BMI and cholesterol, likely due to the protective effect of a higher consumption of beans and fiber, which the authors noted are associated with longer leukocyte DNA telomere length, a biomarker of biological aging. With their analysis, Yu et al. were able to provide evidence that a traditional rural diet rich in beans and fiber, even with palm oil, and low in other processed foods may contribute to the lower mortality observed among elderly rural Costa Ricans compared to their urban counterparts.