Vitamin B12
B12 gets its own category for one good reason: it is found almost entirely in animal foods, so vegans and most vegetarians really do need to supplement it. Beyond that group, older adults absorb it less well too. It is one of the more genuinely necessary supplements for the people who need it, and a non-issue for everyone else. High-strength sublingual and spray forms are popular for absorption.
Common questions
Who should take B12?
Anyone on a vegan or largely vegetarian diet, and often older adults, who absorb it less efficiently. If you eat meat, fish, eggs and dairy regularly, you are probably getting enough already.
Tablets, sprays or sublingual?
All work. Sprays and under-the-tongue tablets are popular for people worried about absorption, but a standard tablet is fine for most. Consistency matters more than the format.