Yes, vitamin B complex supplements can cause diarrhea and other side effects like weakness, headache, nausea, and tingling sensations in some people
Tiredness, stress, ill-health, poor or limited diet will all reduce this absorption further. For some people, taking a vitamin B12 supplement is one of the easiest ways to maintain healthy levels
They are generally safe and work well for those who are deficient
By enhancing oxygen transport, it promotes greater energy and vitality
Foods rich in vitamin B12 also contain high levels of histamine, which can trigger a reaction
Also, just to note, those with darker skin tones, need to really quite careful with things like salicylic peels as they can cause pigmentation