B12, I'm vegetarian, and have been for most of my life. I am allergic to fish.
I do eat Marmite
and I do like and eat nutritional yeast.
It's the one vitamin that vegetarians and especially vegans really cannot get otherwise.
Vitamin C is a necessity, it facilitates the uptake of iron for starters. In our climate, even eating kale, etc., daily, it's hard to get enough from our naturally grown in season foods. It is very easily lost with cooking too.
I'm a fair skinned, freckled, green eyed Scot with a lot of red (well I did, the red's mostly gone white) in my hair.
I do really, really notice a difference in myself when I take Vitamin D.
In our climate, frequently overcast and the bright yellow ball rarely in evidence, it's sensible.
I had a blood test that came back and my exceptionally low level of Vitamin D was sufficiently concerning that my Doctor phoned me and said that there was a prescription waiting for me to pick up from the Chemist.
I buy my own now, I reckon the NHS has enough to pay for without having to cover the cost of my vitamins too.
When I don't take glucosamine for a few weeks my joints genuinely stiffen up. I am very aware of my damaged joints (rheumatoid arthritis) and I notice changes in their flexibility. If I take glucosamine they don't go red hot and swollen unless I've put a lot of effort on them.
Vitamin E is an immune system boost. The capsules are also a really good additive in home made creams, lipsyls and the like too
I'm a post menopausal female and I really don't want osteoporosis, or dental decay, but I don't eat meat (so no bone broth) and I can't drink milk. I am lactose intolerant.
I do have a healthy diet, five at every meal is commonplace, and I do eat tofu made with accessible calcium. I do eat a wide variety of nuts too. It still needs the other minerals.
I think that last bit matters. I am who I am. Who are you ? what stage of life are you ? and how good is your diet/health ?
It's not rocket science, figure it out and make sure you're taking what is most likely to be lacking.
We do live a lot longer than even our own parents generation. Our life expectancy is very good, much better to have a healthy long life than one blighted by simply sorted lack.
M