Everyone is deficient in pretty much all vitamins.
They're also deficient in protein, fat and carbs.
That's why we eat. If people are missing something, unless they have a legitimate reason (allergic, etc), then it's cause they have a poor diet.
It's really not that difficult:
Drink normal 2% milk.
Drink water - stay hydrated.
Eat eggs (the whole thing).
Eat lots of flesh (meat, poultry, fish, etc) with a generous portion of vegetables (beans, peas, corn, carrots, etc - large variety basically). This can be through steak, sausages, hamburgers, etc.
Alternate with pizza/pasta every now and then.
Eat a variety of fruit.
Get some sun (for that vitamin D).
Spoil yourself every now and then.
Don't avoid fat - some vitamins are fat soluble only.
You can deal with this by eating food with healthy fat.
Fish and a variety of nuts do this well.
I know some women that eat little, avoid meat and are surprised that they are anemic and constantly exhausted.
Eating one leaf of lettuce a day with your 450 different pills is not "healthy".
Nothing wrong with taking supplementary pills - operative word being "supplementary". Supplementary to an already healthy diet.