Other References

1. Cui, A., Xiao, P., Ma, Y., Fan, Z., Zhou, F., Zheng, J., & Zhang, L. (2022). Prevalence, trend, and predictor analyses of vitamin D deficiency in the US population, 2001-2018. Frontiers in nutrition, 9, 965376. https://doi.org/10.3389/fnut.2022.965376
2. https://www.nutritionaloutlook.com/view/americans-confident-in-dietary-supplement-effectiveness-and-quality-in-2020-including-during-covid-19-pandemic-crn-surveys-show?utm_source=chatgpt.com