Edit: Based on jimrandomh’s claim below I think that I should clarify that by “needless supplementation” I mean any supplementation done when it has not been demonstrated (eg with blood work at a clinic) that you have a deficiency of that particular mineral.
Bayes disagrees with you.
If you know that most people in your country (the United States for example) are deficient in vitamin D then prior to having blood work done, and absent any other evidence you have collected that suggests you are an exception, you should expect to be deficient in vitamin D.
Bayes disagrees with you.
If you know that most people in your country (the United States for example) are deficient in vitamin D then prior to having blood work done, and absent any other evidence you have collected that suggests you are an exception, you should expect to be deficient in vitamin D.