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Chromium Picolinate #4 “Nutrient of the Nineties”
Picolinic
acid (PA) is an amino acid metabolite produced in the liver and kidney of man
and other
mammals. Detectable amounts are found in com-mon foods such as cow’s milk and
brewer’s yeast. An a\lid chelating agent, PA binds spontaneously to transition
metals such as chromium, zinc, and iron, and plays a physiological role in trace
mineral absorption. A recent study shows that the 24- hour urine of young men
(not using any picolinate-based supplements) contains about 20 mg of the glycine
conjugate of picolinic acid (corresponding to 14 mg PA); this implies that the
daily throughput of PA - from endogenous synthesis and absorption from food - is
at least 14 mg. In contrast, a daily dose of Chromium Picolinate providing 200
micrograms of chromium yields only 1.4 mg of picolinic acid - not more than
one-tenth the daily amount that the body synthesizes or absorbs from natural
foods.
In animal studies, picolinic acid is
well tolerated.Nakajima has reported that a daily dose of750 mg/ kg is required
to produce chronic toxicity in fats. At very high concentrations of2.5-3 mM in
tissue culture, picolinic acid has been shown to alter cell structure and
function owing to chelation of iron. These concentrations are several orders of magnitude higher
than could be achieved in vivo by supplementation with reasonable amounts of
mineral picolinates; these findings therefore have no relevance to an evaluation
of the safety of mineral picolinates as nutritional supplements.
The
nutritional trivalent form of chromium (Cr+3) is noted for its low toxicity
particularly when administered orally. The lowest ID5o reported for
intravenously administered Cr+3 in fats is 10 mg/kg - most researchers report a
higher figure. With respect to oral supplementation, an acute ID5o has not been
established, as it hasn't proved possible to kill a testanimal. For example,
after an oral bolus of 10-15 grarns Cr+3 as chromic chloride (5 orders of
magnitude greater than the nutritional amount) dogs experienced transient
vomiting and diarrhea, but no other adverse effects were noted. Mice or rats
receiving 2-5 ppm Cr+3 in the diet throughout life were not harmed and appeared
to be more resistant to infection; chromium lactate fed at up to 100 ppm had no
adverse effect on fats.
In light of the natural status
and minimal toxicity of its constituents, the lack of toxicity or side effects
noted for CrPA is not surprising. In acute toxicity tests, fats tolerated the
highest solubilized oral bolus that could feasibly be administered
(corresponding to 2.2 g/kg). When fed CrPA throughout life inamounts up to 5 ppm
Cr+3 in the diet, rats showed no adverse effects and survived significantly
longer than controls; at 1 ppm, the median lifespan of Long-Evans fats was
increased by 36%.
Well Tolerated in Clinical
Studies In clinicaI studies with chromium picolinate, noadverse effects have
been noted; these studies, todate, have used daily amounts of 200 or 400 mcg
chromium. In light of the fact that millions of people are now using the
supplement, the virtual absence of reported side effects is quite encouraging.
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