high homosystien is red alert for cancer and heart disease. taking b12 and folic can really lower homosystiene levels. i managed to wrangle some blood tests from gp and they all came back normal apart from the folic acid which was very very low. so i was given some folic acid from gp. but when i actually started to read my results properly like comparing the "range" that is acceptable i was always very very borderline so i supplement myself with vitamins. not a lot but with b12 with added folic. i also try to eat a lot better as if you can its good to eat food that your body craves vitamins from.
some people suffer from pernicious anemia which means they cannot produce intrinsic factor that helps to utilise b12 which people years ago died from. its good to do some research and get some advice. i think this multi vitamin is a good choice but suspect you could get it all much cheaper. amazon do some good ones from germany that are a lot cheaper than uk ones and very good.
I had B12, folic acid and B2 deficiency for years. I used to get angular cheilitis, depression and anxiety, not to mention digestive problems. I cannot tell you how much better I feel now. I take a supplement made by New U:
https://nuunutrition.com/products/vitamin-b12
and they are AMAZING! Methylcobalamin is a much better form of B12 than cyanocobalamin. It is less toxic and easier to assimilate. Even people with no intrinsic factor can absorb B12 through a process known as "passive absorption." They have to take a large dose as only 1-2% max is absorbed this way. My problem wasn't lack of intrinsic factor but a largely vegetarian diet and a lot of ignorance on my part.