the concern would be the b6.
Vitamin B6 (pyridoxine) causes neuropathy at intakes of 1000 mg per day or more, which is about 800 times the daily intake from foods. There have also been occasional reports of toxicity at intakes of 100-300 mg per day.
n=2 case studies of neuropathy with supp in the B25/B50 range
Studies involving large population groups with carpal tunnel syndrome, all adults, using 100-150 mg/day have shown minimal or no toxicity in five- to 10-year studies. Women self-medicating for PMS taking 500 to 5000 mg/day have shown peripheral neuropathy within one to three years. It would appear from this retrospective analysis that pyridoxine is safe at doses of 100 mg/day or less in adults.
http://www.pubmedcentral.nih.gov/articl ... id=1949298
Vitamin B6 at less than 200 mg daily is not likely to cause any adverse effects, but patients should be monitored for changes in symptoms, particularly when high doses are taken over long periods.
other than that, i have not found any studies looking at b6 toxicity from dietary intakes. i'm going to hazard that most studies using supplements or use histories are talking about synthetic supplements...
How can I tell if my B vitamin is good?
A good example of "junk" nutritional supplements is B vitamins. Most people do not know that most B vitamins are made from petrochemicals! For your best health, take a whole-nutrient B vitamin and avoid synthetics.
"Whole food" vitamins are those that have been carefully processed and unaltered in any way that would change the molecular structure or biochemical combinations and actions of the vitamin complexes.
Chemically, natural and synthetic vitamins are identical. The same ingredients are contained within the molecules but they are arranged in a different fashion. When a beam of polarized light passes through a natural vitamin it will always bend to the right, due to the molecular rotation of the natural substance. The letter "d" seen on some supplement labels represents dextro or "right." This indicates that the vitamin is the natural form.
As a beam of polarized light passes through a synthetic vitamin it splits into two parts, one part bending to the right and the other to the left. The synthetic supplements may be represented by the letters "dl" preceding the vitamin name. The "d" for dextro and the "l" for levo or left. This demonstrates that the molecular rotation of the synthetic is not identical to the natural form. The biological activity of synthetic vitamins can be 50% to 70% less than nutrients in natural, whole food supplements.
B vitamins are not generally referred to in conjunction with these letters but the difference in molecular structure between synthetic and a truly natural substance applies to them as well as any other nutrient.
Whole food supplements and some "natural" supplements will give foods as sources for the nutrients they contain. If a supplement is synthetic it will usually show the following as sources:
B complex – no source listed
B1 – thiamine mononitrate or thiamine hydrochloride
B2 – riboflavin
B5 – calcium D-pantothenate
B6 – pyridoxine hydrochloride
B12 – cobalamin
Folic Acid – pteroylglutamic acid
Biotin – d-Biotin
whole food b-complex examples:
http://www.organic-pharmacy.com/rightfo ... ngredients
http://www.naturallydirect.net/whole-fo ... omplex.htm