Why? I'm very sensitive to supplements and usually notice effects immediately even on humble doses but B12 (I've tried 100%-20'000% RDA cyanocobalamin pills) doesn't feel doing anything I could notice. The combo of dish oil + B12 seems preventing menstrual pain in ladies though.
Typically negatives with overuse only exist with the supplements in my 1 minute glance. This is common amongst many different supplements actually. If you eat actual food you get full, so it prevents too much nutrition from being an issue. I don't think B12 is really something your body will reject, we are able to efficiently filter out any extra with minimal load on the kidneys & liver.
Cheap and effective B Complexes exist that use better forms of the various vitamins exist; only lazy manufacturers still use stuff like Cyanocobalmin. A good multivitamin should also be covering your B need as well, I ended up making a short list of good multis, and Life Extension 2-per-day Capsules ended up being the least expensive of ones that made the list... you pretty much have to go to Thorne and pay more to get better.
I am not an expert, experts may disagree for other reasons, but I do know my math and read the studies for my own benefit.
I like both, salmon especially. But I don't like the prices: fish prices vary wildly between countries and are too high for everyday consumption in many of them.
> Those two are both very oily, you can eat one or two servings a week and get enough omega-3
Now this becomes interesting. I thought one has to get a relevant dose of every nutrient every day.
It's very expensive to have a healthy diet, unless you only eat a small selection of foods.