Now do the study for people whose diet is highly variable - sometimes I eat real healthy for weeks and sometimes it’s French fries and tater tots or pizza or other junk for dinner for weeks. I think the supplements help during my periods of poor dietary choices.
I used to have deficiencies in vitamin B and D and my doctor told me to take supplements for those. Levels have been good since.
I think it helps if you have deficiencies due to diet or genetics. But I also have years of data from bloodwork to back that up. I agree that taking them ‘just because’ is not a good idea. Getting your levels checked at your annual exam is easy. Talk to your doctor.