Worldwide Interest in Vitamin D, Negative Effects on Kidneys, and Bone Density: Analysis of Google Trends Data

Background: Besides its role in calcium homeostasis and bone mineralization, vitamin D may also reduce the risk of cancer, cardiovascular and autoimmune diseases. Excessive vitamin D intake can lead to life-threatening hypercalcemia and toxicity, however. Here, we wanted to determine the relative search volume (RSV) of interest in vitamin D and its adverse biological effects (hypercalcemia, renal failure, kidney stones, bone density).Methods: We used data from Google Trends to assess changes in RSV trends across the world's regions. Data were extracted via the search terms "cholecalciferol", "ergocalciferol, "hypercalcemia", "acute renal failure", "kidney stones", and "bone density" from queries in English from 1 January 2004 to 1 October 2018 in the tool's related query database. Statistical analysis was performed using SPSS (R) 22.0 for Windows (IBM Inc., Armonk, NY, USA, 10504-1722).Results: There was a correlation between the RSV of cholecalciferol and ergocalciferol (Spearman's correlation) and the RSV of hypercalcemia, renal failure, kidney stones, and bone density. As measured by the change in RSV score, the trend for interest in kidney stones increased more rapidly than that for the other search terms. There was a positive correlation between the RSV score for cholecalciferol (or ergocalciferol) and renal failure and between the RSV score for cholecalciferol (or ergocalciferol) and kidney stones, whereas there was a negative correlation between cholecalciferol and hypercalcemia. The interest of ergocalciferol increased in parallel with the interest in bone density. The highest concentration of interest in cholecalciferol occurred in North America, Europe, India and Australia, whereas interest in ergocalciferol was greater in Central and South America, Spain, and Thailand. Interest in kidney stones was greater than cholecalciferol in North America, Brazil, India, and Australia, while interest in bone density was greater than cholecalciferol in North America, Brazil, Italy, Spain, South Africa, and Australia.Conclusions: In the pre-pandemic COVID-19 (COronaVIrus Disease 19) era, our preliminary results showed a positive correla-tion between global interest in cholecalciferol and kidney stones and renal failure, respectively. However, we found an unexpected negative correlation between global interest in cholecalciferol and hypercalcemia. Additionally, we found a positive correlation between global interest in ergocalciferol and bone density. These correlations can inform health interventions and education.