RE: [pronut-hiv] Intake level for vitamin B6 for people living withHIV/AIDS (5)

["George M. Carter" <fiar@verizon.net>]

--Vivica Kraak wrote:
     snip....
     Your  point  is  well taken that research supports that most PLWHAs
     can benefit  from  a  supplemental  daily  MVI  at reasonable doses, in addition to  a nutrient-dense and diverse diet adequate in calories, protein and micronutrients to  sustain  increased  nutritional  demands during active infection and symptomatic HIV disease.

   This  IS  the centrally important point of this debate!! And I hope we
   can  actually  think about strategizing about how to get that MVI as a
   standard  of  care  for  PLWHAs.  But  of course, I am always happy to
   challenge the experts!

    [ But  you  need about high-level doses of micronutrients where the data are very clear about adverse effects - even for water-soluble vitamins like B6.  I don't believe  that  either  you  or  Dr.  Kaiser  could come up with any literature review beyond what an 11-member expert committee has concluded that chronically  high doses of vitamin B6 (e.g., 240 mg/d) may actually cause neuropathy.]

   I  beg  to differ here tho! The citation you provided did NOT actually
   say  that.  Only  that they rather arbitrarily placed the limit at 100
   mg.  Indeed,  I have found some abstracts below that suggest a cut off
   of 300-500 mg may be more reasonable as a level for chronic use.
   Of course this is IN ADULTS over 140 pounds (60 kg). And one must bear
   in  mind  possible  cross  reactions  (e.g., levodopa) or when used to
   offset toxicities (isoniazid) A review paper also largely supports this:
   [1]http://www.crnusa.org/safetypdfs/011CRNSafetyvitaminB6.pdf
   And  overall,  let  me make one thing perfectly clear: I'd say a multi
   that  had 25-100 mg of B6 would be perfectly fine. I am NOT advocating
   that  260  mg  be a consensus dosage, tho I hope to hear more from Dr.
   Kaiser.
   I'm  not  going  to base MY treatment decisions on what one panel says
   (and  in  my  case,  I'm  living  with  Hepatitis  C).  Nor would I be
   concerned  about  using  this  amount  of  B6. Again, it's also in the
   context   of   other  B  vitamins,  etc.,  not  just  as  an  isolated
   micronutrient,  which I think doesn't make as much sense, unless for a
   specific  intervention.  Partly  because  as one study noted (Ann Nutr
   Metab.  2001;45(6):255-8),  use of 25 mg pyridoxine alone over 10 days
   reduced  folate levels (but not B12); a good multi will have plenty of
   folate to balance this.
   And  let  me  say  to  you  all:  thanks!  While  I may come off a bit
   adversarial (OK, I am!)--it is the kind of impetus that gets me off my
   butt  and looking at the research! So it is all very edifying--and the
   bottom  line  is: what is going to the best, most helpful intervention
   for  people  living  with  HIV/AIDS....and  how  can  we  be sure that
   everyone has access to a good, appropriately potent multi?
   George M. Carter
   **
   0.5 g of course is 500 mg.
   Toussaint  C.  Pyridoxine-responsive  PH1:  treatment. J Nephrol. 1998
   Mar-Apr;11 Suppl 1:49-50.
   Departement     medico-chirurgical     de    Nephrologie,    Cliniques
   Universitaires de Bruxelles, Hopital Erasme, Belgium.
   Owing to the rarity of PH, the efficacy of pyridoxine therapy has only
   been  tested in very small series of patients. From two recent reports
   including  18  patients,  50%  of  patients  would  be unresponsive to
   pyridoxine whereas oxaluria would be normalized in 20% of patients and
   somewhat  reduced-but  not  to normal level-in the remaining 30%. In a
   few  aneodotical  cases  pyridoxine  administration  was  reported  to
   improve  kidney  function  in patients with renal failure secondary to
   hyperoxaluria. It is reminded that megadoses of pyridoxine (0.5 to 6 g
   daily) may induce severe sensory neuropathy.
   **
   The data below may constitute the dataset used by the panel. And here,
   you  will  note,  that  the evidence for neurotoxicity with pyridoxine
   occurred only in some women after over a year of use of a range of 500
   mg to over 5 GRAMS per day!
   Bernstein  AL.  Vitamin  B6  in  clinical neurology. Ann N Y Acad Sci.
   1990;585:250-60.
   Department  of  Neurology,  Kaiser Permanente Medical Center, Hayward,
   California 94545.
   Many  conditions in clinical neurology may be responsive to pyridoxine
   as a therapeutic agent. The current difficulty is in trying to isolate
   the conditions that are most likely to respond. Treating seizures is a
   major  part  of  a neurologic practice. Our current therapeutic agents
   are  only  partially  successful and limited by multiple side effects.
   One  problem  is  that patients often have to take these agents for an
   entire  lifetime,  further raising the risk of toxicity. If pyridoxine
   supplementation   can   improve   the   efficacy   of  currently  used
   medications,  it will be gladly accepted into our therapeutic arsenal.
   Headache,  chronic  pain, and depression all appear to run together in
   many  of our patients. The observations that serotonin deficiency is a
   common  thread  between  them  and that pyridoxine can raise serotonin
   levels  open  a  wide range of therapeutic options. Small studies have
   been  carried out with mixed success. Comparison with amitriptyline in
   the  treatment  of  headache  appears  to  show  about equal efficacy,
   although  side  effects would be expected to be more of a problem with
   the  amitriptyline.  Behavioral  disorders  are  relatively common and
   continue  to  be a major problem, disrupting the lives of the patients
   and  their  families.  Current  treatments  are not acceptable to most
   people  because  of the risk of side effects with long-term usage. If,
   as Dr. Feingold suggests, many of these problems are caused by "toxic"
   exposures    to    chemicals    that   are   pyridoxine   antagonists,
   supplementation   at   early   ages   may   reduce  the  incidence  of
   hyperactivity  and  aggressive  behavior.  This raises the question of
   safety.  Is pyridoxine safe for long-term use in large segments of the
   population,  including  children?  The studies on children with Down's
   syndrome  and  autism,  utilizing  much higher doses than are used for
   other  therapeutic  purposes,  seem  to  indicate  relative  safety if
   carefully  monitored.  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. In children there is not enough data to make
   any sort of suggestion. Because the major neurologic complication is a
   peripheral  neuropathy  and  the  causes of this condition are myriad,
   pyridoxine  may  cause neuropathy only in patients with a pre-existing
   susceptibility to this condition.
   **
   This  study again suggests use of at least 300-500 mg per day in order
   for neurotoxicity to result.
   Bassler  KH.  Use and abuse of high dosages of vitamin B6. Int J Vitam
   Nutr Res Suppl. 1989;30:120-6.
   Concepts of vitamin B6 megatherapy are classified in three categories:
   1.  megatherapy  with  well-known  mechanism of action; 2. megatherapy
   with  hypothetical or unknown, but nevertheless plausible mechanism of
   action;  3.  megatherapy on the basis of pure speculation. Examples of
   all three categories are shown. The dosages applied extend from 100 mg
   up  to  several  grams; the duration of treatment varies from weeks to
   several  years. After long-term intake of high doses toxic effects can
   occur  in  the  form of peripheral sensory neuropathy, in two reported
   cases combined with a subepidermal vesicular dermatosis. The threshold
   above which toxic effects can occur appears to be somewhat between 300
   and  500 mg/day; however, systematic investigations in this dose range
   have never been performed. Furthermore, there appears to be an inverse
   relationship  between  the  dose  and the time up to the occurrence of
   toxic  symptoms. The danger consists less in controlled application by
   a  physician  as far as he is aware of the clinical picture of sensory
   neuropathy. Doses in excess of 500 mg are rarely necessary in specific
   indications.  Unlike  this situation, self-medication by laymen on the
   basis  of  promises  in  obscure  health  magazines is much more risky
   because  the  dose  is  frequently  raised more and more up to several
   grams per day when the expected effect does not occur.

References

   1. 3D"http://www.crnusa.org/safetypdfs/011CRNSafetyvitaminB6.pdf";