*Strengths and Limitations*

To our knowledge, this is one of the first studies examining the type of oil consumed in relation to successful aging of older adults, using two different population-based studies. From the epidemiological perspective, using samples from different populations is useful in order to minimize the effect of several types of bias and to multiply the external validity of the findings. In addition, the reported results could be of significant importance for public health policymakers, since a basic principle of empowerment and health promotion is the awareness of people of the effect of harmful behaviors, such as diet related behaviors. This study also has several limitations. The dietary habits, as well as all other participants' characteristics, were measured once, thus a measurement error may exist and there is always a bias in self-reported questionnaires. Nutrient intake (e.g., type of consumed fat) was calculated through food composition tables using the information retrieved through the FFQs; thus, inaccurate recall of food intake, or a tendency towards social desirability resulting in individuals over-reporting healthy food intake and underreporting unhealthy food intake cannot be ruled out. Moreover, the type of consumed olive oil was not reported; however, the effect of olive oil—regardless of the specific type—consumption on human health is established [36]. Finally, all participants included in this study are from Mediterranean region so extrapolation to other populations and geographical regions may be limited.
