Is Ortho-Core the best overall Multivitamin?
No. IMO, the level of B vitamins is way overdone and potentially dangerous long term. 800mcg of Folic Acid and 100mg of Vitamin B6? No thanks. I would not want to be ingesting over 200 mcg (max) and 2mg (max) per day. Not to mention the other Bs are very high as well. I just would not feel safe taking this supplement. There's just no excuse for that level of B vitamins.
Those levels are at the upper end of, but not above, the well-established safe intake ranges. While I wouldn't feel quite comfortable taking such a high amount of folic acid and B6 too, there is certainly some rationale for taking even those amounts, such as individual genetic polymorphisms (extensively reviewed here by Ames et al.) and health conditions potentially hindering the absorption or increasing the metabolic demand for B vitamins (potential anti-gylcation benefits of megadoses of P5P would be another reason, but they have to be weighted against the risk of neurotoxicity).
Of course, from the non-toxicity and absence of an UL for many B vitamins doesn't follow that it is a good idea to megadose them. For many polymorphisms mentioned in the Ames paper, doses one order of magnitude above the RDA are actually sufficient to compensate for the decreased coenzyme binding affinity. Given that most B complex supplements generally provide 50 mg of B1, B2, B6, niacin(amide) and panthothenate, and are available for at least 50 years and taken by millions of people worldwide, 50 mg can be taken as a resonably conservative, pragmatic UL, particularly with regard to B6 and its potential for neurotoxicity.
Given the lingering doubts about cancer-promoting effects of high-dose folic acid and the considerable genetic variation in the dihydrofolate reductase enzyme activity, which can lead to build-up unmetabolized folic acid in the plasma in some poeple, it would seem reasonable to limit folic acid to 400 mcg, or reduced folate (which is actually less bioavailable) to 800 mcg.
When it comes to B12, megadoses are generally a good idea because active absorption is strictly limited by the notoriously unreliable intrinsic factor and absorption by passive diffusion is in the range of 0.5-2% of given dose. Given that 500 mcg are commonly taken long-term by vegans or poeple lacking intrinsic factor, this amount again can be taken as a pragmatic UL.
With biotin there is a similar wide range in supplemental doses as with B12 but it is a much less critical nutrient. Although it seems completely non-toxic and some supplements contain high milligram doses, there is a rather dubious epidemiologic association between increased biotin intake and DNA instability (as mentioned here by Krillin) in one study that should provide enough reason to avoid such megadoses. On the other hand, there is some recent evidence from a study with transgenic mice that chronic alcohol consumption may lead to functional biotin (and possibly panthothenate) deficiency by significantly downregulating the expression of the "multivitamin" (biotin, pantothenate and lipoate, that is) transport protein SMVT. Given this study and that the RDA for pantothenate is much higher than for B1/2/6, I'd set the pragmatic UL to 100 mg, a level often found in B complex supplement. For biotin, the DV of 300 mcg contained in many multivitamins is actually 10 times the current RDA and this amount can be taken as the pragmatic UL.
Using the common approach in toxicology to divide the no observed adverse effect level (NOAEL) by two in order to provide an additional safety margin, I would devise the "ideal" B-vitamin supplement as follows:
Vitamin B1 (thiamin): 25 mg
Vitamin B2 (riboflavin): 25 mg
Vitamin B3 (niacin or niacinamide): 25 mg
Vitamin B6 (pyridoxine or P5P*): 25 mg
Folate (MTHF or natural folate): 400 mcg
Vitamin B12 (cyano- or methylcobalamin**): 250 mcg
Biotin: 150 mcg
Pantothenic acid: 50 mg
Optionally:
Lipoic acid: 50 mg or R-lipoic acid: 25 mg
CoQ10: 50 mg
*preferentially P5P or a mixture of both forms.
**preferentially methylcobalamin
Edited by timar, 15 September 2014 - 10:39 AM.