There are no comprehensive studies that I've seen but if you look through the literature on specific
vitamins you can piece together a picture that doesn't look good.
Vitamin neurotoxicity. Snodgrass SR. "Megadose vitamin therapy may cause injury that is confused
with disease symptoms. High vitamin intake is more hazardous to peripheral organs than to the
nervous system, because CNS vitamin entry is restricted. Vitamin administration into the brain or
CSF, recommended in certain disease states, is hazardous and best avoided. The lack of controlled
trials prevents us from defining the lowest human neurotoxic dose of any vitamin."
Safety of megavitamin therapy. Omaye ST. "The therapeutic use of such compounds (megavitamin intake)
is based on the spectacular effect of vitamins on deficiency diseases; however, evidence that the
ingestion of large amounts of vitamins beyond the "Recommended Daily Allowances" (RDA) is beneficial
is not within the basic concept of nutrition. Vitamins, like many substances, may be toxic when
taken in large quantities, especially the fat-soluble vitamins, and the concept of "more is better"
is a common misconception. Vitamin supplements can be suggested only in the unusual cases of
patients having inadequate intake, disturbed absorption (genetic or otherwise), or increased tissue
requirements. A well-balanced diet that includes a wide variety of foods from each of the four food
groups is adequate for the supply of vitamins, as well as other nutrients, in healthy people. This
paper will review some of the recent findings regarding vitamin toxicity and the mechanisms of
The problem is that there is very little information on the effects of even megadosage let alone
slightly elevated levels of the varoius vitamins over long periods. This means that you have to
infer effects. My inferences from my readings are that vitamin dosages significantly (more than
300% or more) above the daily suggested amounts are probably bad for some people and it takes more
However, bicycle racers tend to think that a vitamin "suppliment" is a necessity and develop a habit
of taking large doses of vitamins daily. This worries me and it especially bothers me to hear of
brittle bones which can be a sign of reduced iron in the bones. And that can come from EPO use even
though the patient is taking iron suppliments. This is a double edged sword because EPO generates
improperly formed red blood cells and robs the bone marrow of iron. These cells die much faster than
normal red blood cells and this can cause iron poisoning as the kidneys and liver strive to get rid
of it. Elevated levels of blood iron from suppliments can make this much worse. I seem to recall
reading a paper that suggested elevated Vitamin A also caused brittle bones.
Anyway, there are all sorts of possible problems with taking large vitamin doses and very many
of them would present difficulties in tracing it back to long term higher-than-normal dosages
There is a reason that vitamins are trace substances in the body. Leave them that way.
"Carl Sundquist" <[email protected]
> wrote in message
> "Tom Kunich" <[email protected]
> wrote in message
> > Heart problems and brittle bones are some of the side effects of overodsing on vitamins but it
> > usually takes large doses over a
> > time for the worst side effects. One of the things to be really careful with is iron. Don't take
> > any vitamins that contain iron
> > most varied diets already have more than enough iron for a man.
> Can you cite some studies on effects of ODing on vitamins? My mom is
> vitamin freak.