of this video, I have long maintained that taking vitamin supplements simply isn't necessary.

They're certainly no substitute for a balanced diet.

specifically for the folic acid and calcium. Probably good thing since my younger daughter is allergic to dairy (even today at 28), and I could not ingest dairy products with her while pg or nursing.

Really unfortunate because folate enrich grains and flour to prevent birth defects.

by vitamin deficiencies).

I think there is the ever-present risk of confusing correlation and cause. First of all, most studies don't show any such relationship; only a few do. Secondly, people who have existing health problems may be more likely to choose to take vitamin supplements, and also be more vulnerable to a variety of conditions. Thirdly, there may be health hazards, not in the use of vitamin supplements as such, but in treating them as a substitute for other health measures, ranging from eating a balanced diet to seeking medical attention for symptoms.