A bunch of companies are popping up that let you curate your own personalized vitamin regimen (Care/of and Vitamin Packs, for example). Do I think they’re necessary? Probably not, if you already eat a balanced diet with a variety of fruits, vegetables, whole grains, nuts, and legumes. You absorb vitamins better through food anyway.
That said, many of these services appear to be backed by credible medical organizations and provide smart nutrients, like vitamin D and probiotics. On the other hand, some of them may also recommend certain supplements that may not have the kind of clinical research backing them that others do.
Bottom line: If you’re concerned about nutritional deficiencies, a vitamin pack delivered to your door could be useful and convenient. But for a truly personalized vitamin regimen, it’s wise to get tested by your doctor to see which nutrients you’re lacking. And, of course, check in with your doc before taking any supplement, to make sure it’s safe for you.