Most aren't aware enough to even ask it.
And is brings attention to the larger problem of us taking mutliple different medications, supplements and drinks that could push the amount of any one additive into the ridiculously excessive category.
More isn't necessarily better.
The body has a "recipe" for the chemical reactions that keep us healthy.
Just like one egg added to a bread recipe would make a nice loaf of bread, adding 17000 eggs to the recipe would not lead to a nice loaf of bread.
One problem everyone recognizes on the internet is that there is information overload.
Taking nutritional supplements as an example, many sites tout supplements as important to treat or prevent "this" or "that".
But they very often don't give the "whole truth".
[Some even have a conflict of interest in that they sell the supplements.]
That is why I like to turn to a "reputable site" for questions like this.
Three of them include Medline Plus (run by the National Institute of Health), the Mayo Clinic, and Web MD.
[Now I am suspicious by nature, and even am suspicious about the above sites, but in the main I think they have good information with oversight by teams of knowlegeable doctors.]
Here is what the Medline Plus web site says:
"Are there safety concerns?
Vitamin B12 is LIKELY SAFE for most people when taken by mouth or when the prescription-only, injectable product is used correctly. In some people, vitamin B12 might cause diarrhea, blood clots, itching, serious allergic reactions, and other side effects.
Vitamin B12 also appears to be safe when used on the skin for psoriasis. Mild itching has been reported in one person who used a specific avocado oil plus vitamin B12 cream for psoriasis.
Special precautions & warnings:
Pregnancy and breast-feeding: Vitamin B12 is LIKELY SAFE for pregnant or breast-feeding women when taken by mouth in the amounts recommended. The recommended amount for pregnant women is 2.6 mcg per day. Breast-feeding women should take no more than 2.8 mcg per day. Donít take larger amounts. The safety of larger amounts is unknown.
High numbers of red blood cells (polycythemia vera): The treatment of vitamin B12 deficiency can unmask the symptoms of polycythemia vera.
Abnormal red blood cells (megaloblastic anemia): Megaloblastic anemia is sometimes corrected by treatment with vitamin B12. But this can have very serious side effects. Donít attempt vitamin B12 therapy without close supervision by your healthcare provider.
Leberís disease, a hereditary eye disease: Do not take vitamin B12 if you have this disease. It can seriously harm the optic nerve, which might lead to blindness.
Allergy or sensitivity to cobalt or cobalamin: Do not use vitamin B12 if you have this condition.
Are there interactions with medications?
Do not take this combination.
Vitamin B12 is important for producing new blood cells. Chloramphenicol might decrease new blood cells. Taking chloramphenicol for a long time might decrease the effects of vitamin B12 on new blood cells. But most people only take chloramphenicol for a short time, so this interaction isn't a big problem.
Are there interactions with herbs and supplements?
Folic acid, particularly in large doses, can cover up vitamin B12 deficiency, and cause serious health effects. Be sure that your healthcare provider checks your vitamin B12 levels before you start taking folic acid.
Potassium supplements can reduce absorption of vitamin B12 in some people and might contribute to vitamin B12 deficiency.
Early research suggests that vitamin C supplements can destroy dietary vitamin B12.
It isn't known whether this interaction is important, but to stay on the safe side, take vitamin C supplements at least 2 hours after meals.
Are there interactions with foods?
Heavy drinking for at least a two-week period can decrease vitamin B12 absorption from the gastrointestinal tract."
The Mayo Clinic site adds the following concerns:
"Use cautiously in patients with cardiovascular concerns
. After coronary stenting, an intravenous loading dose of folic acid, vitamin B6, and vitamin B12 followed by oral administration daily has been shown to increase rates of restenosis (reoccurrence of narrowing of a blood vessel). Due to the potential for harm, this combination of vitamins should not be recommended for patients receiving coronary stents.
Use cautiously in patients with elevated blood pressure
, as high blood pressure following intravenous administration of hydrocobalamin has been reported.
Use cautiously in patients taking the following agents, as they have been associated with reduced absorption or reduced serum levels of vitamin B12: ACE inhibitors, acetylsalicylic acid (aspirin), antibiotics, anticonvulsants, bile acid sequestrants, colchicine, H2 blockers, metformin, neomycin, nicotine, nitrous oxide, oral contraceptives, para-aminosalicylic acid, potassium chloride, proton pump inhibitors (PPIs), and zidovudine (AZT, Combivirģ, Retrovirģ). Additionally, vitamin C may cause the degradation of vitamin B12 in multivitamin supplements, and chloramphenicol may inhibit the biosynthesis of vitamin B12."
After reading all the above, I wouldn't take both your multivitamin and the 5 Hour Energy Drink.
But then again I wouldn't take the 5 Hour Energy drink anyway, because as is explaind in another currently running TT thread http://tt.tennis-warehouse.com/showthread.php?t=453146
, the amount of caffeine in 5 Hour energy is enough to raise concerns that it could lead to enough of a hyper-exited state to actually lose focus - tennis demands steely nerves in tight situations. (It's not like being a blitzing linebacker).
But it is a free country - it will be up to you to decide what to do.
Still, I am interested in what YOU decide after reading this and several other responses here, and consulting with your doctor.