LAUSR

According to the letter published by Dr. Lu-Lu Zhai and collaborators [1], we can comments as follows. This study considered three areas of Chile that have different average temperature ranges and are located in different latitudes (Antofagasta 23.6524° S 70.3954° W; Santiago 33.4569° S 70.6483° W; Concepción 36.827° S 73.0498° W). The study was conducted in late fall through early spring. During May to September 2018, cloudiness in Santiago (in the plain, 570 m above sea level) was 47–58%, minimum temperatures 7 °C maximum 23 °C, cloudiness in Antofagasta (on the coast) was 73–84%, minimum temperatures 13 °C maximum 24 °C and cloudiness in Concepción (at the coast) was 40–60, minimum temperatures 6 °C maximum 16 °C. These two conditions make the population wear warm clothing with little exposure to the sun. However, the exact sun exposure time was not determined in this study. The intensity of UV rays varies according to the season, in our case samples were taken between the end of autumn and the beginning of spring. Despite these conditions, the deficit results were extraordinarily high, even in the city of Antofagasta, a result that a priori we did not expect. The Cosinor modeling [2] is an exciting way of correcting the measurement of vitamin D. However, we do not have values of this vitamin for the spring and summer periods, so we cannot estimate the variability by seasonality. Nevertheless, this is a piece of advice that we will apply in our future studies. Liver function was not determined due to the nature of the study, although we do have serum samples available for such determinations. Even so, we tend to think that it is difficult to find differences between these populations of healthy children, whose liver function should be expected. Indeed, the best way to determine the consumption of vitamin D-contributing foods is a frequency of consumption questionnaire adjusted for these foods; however, due to the exploratory objective of this study, only a few specific foods and dietary behaviors related in general to the plasma micronutrients proposed in the original design, without a particular emphasis on vitamin D, were asked, according to the consumption data described in the 2010 National Food Consumption Survey (ENCA) [3]. In this age range, only dairy products seem to be necessary. Precisely because of what Dr. Zhai pointed out and the exploratory nature of this study, analyses of this type were not carried out. The idea of this study was to detect these deficiencies to subsequently be able to focus our future research on those micronutrient deficiencies.