West... that first study was done in 1987, long before zinc monomethionine was commonly available for humans. It was not evaluated at all in that study.
Zinc Picoloinate is also a good form, however, picolinic acid cannot be
tolerated by some patients...namely bipolars.
Zinc is absorbed throughout the GI tract...beginning in the stomach.
There are many sites in fact.
http://www.inchem.org/documents/jecf...no/v17je33.htm
Quote:
Zinc, as contained in food and drink, is absorbed through the gut
mucosa which is the normal route of entry into the body. It is
absorbed at several sites in the gastrointestinal tract. The initial
site of absorption is the stomach and occurs within 15 minutes after
ingestion; however, the major site is the second portion of duodenum.
Absorption also occurs in other segments of both the small and large
intestine (Henkin & Aamodt, 1975; Methfessel & Spencer, 1973a,b).
The exact mechanism by which zinc is transported across the
gastrointestinal mucosa and serosa is not known. The formation of a
low molecular weight organic zinc chelate is thought to be the initial
event, possibly a tetrahedral quadradentate ligand formed from a small
organic molecule and the zinc, and it is this complex which is
absorbed from the gastrointestinal tract (Suso & Edwards, 1971a,b).
Studies on rats suggest that metallothionein, a low molecular weight
cytoplasmic metalloprotein, plays a key role in zinc haemostasis
(Richards & Cousins, 1976; Hall et al., 1979). It has been shown in
rats that there is a direct correlation between the dietary zinc
intake and the binding of zinc of intestinal mucosal metallothionein
(Hall et al., 1979). The absorption of zinc can be affected by many
substances. Both phytate and soy protein inhibit the formation of the
zinc-protein complex and as a result diminish the absorption of zinc
(Davis, 1972; O'Dell & Savage, 1960; Reinhold et al., 1973). Other
substances which adversely affect zinc absorption include cotton-seed,
peanut, safflower, calcium, phosphate, food and zinc itself (Davis,
1972; Heth et al., 1966; Nielsen et al., 1966a,b; Pecoud et al., 1975;
Schelling et al., 1973; Smith et al., 1962). The body burden of zinc
can be diminished either by reductions in the amount of zinc absorbed
as seen in several types of malabsorptive processes or by increases in
the removal of zinc from the body. The latter is evidenced by
increases in excretion seen in intrinsic kidney disease, reduced
plasma metal binding which is congenital in origin and inborn errors
of metabolism (Slavik et al., 1973a,b). The absorption of zinc has
been shown to be enhanced by the presence of histidine, cysteine,
methionine and ethylenediamine tetracetic acid. These are thought to
act by promoting the formation of the low molecular weight organic
zinc complex (Giroux, 1972; Nielsen, 1966a,b). The diminution of zinc
absorption can be species dependent, since in the rat a low protein
diet is associated with a reduction in zinc absorption, while the
reverse is the case with humans. Feeding studies with rats showed
that for absorbed zinc the faeces constitutes the major route of
elimination. Only minor amounts are eliminated in the urine.
Administration of large amounts of zinc did not result in elevated
tissue levels of zinc (Heller & Burke, 1927; Drinker et al., 1927a,b),
since increasing the level of zinc in the diet results in decreased
absorption.
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This quoted PubMed abstract says:
Quote:
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Amino acids, such as histidine and methionine, and other low-molecular-weight ions, such as EDTA and organic acids (e.g., citrate), are known to have a positive effect on zinc absorption and have been used for zinc supplements.
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http://www.ncbi.nlm.nih.gov/entrez/q...=pubmed_docsum
Basically a chelate is better tolerated. That is true with other minerals.
They tend to be absorbed more efficiently with less side effects. Zinc can cause nausea/vomiting..so side effects are important.
I am not a fan of "bulk nutrition" sites... these are body building sites, and not written by professionals.
While the case against picolinic acid is weak...there are references to high intakes and negative effects for some patients:
Quote:
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In theory, picolinic acid, a component often found with chromium, may alter the metabolism of certain chemicals in the brain. If these chemicals are altered, the doses of some drugs used to treat conditions such as depression or Parkinson's disease may need to be changed.
|
from
http://www.intelihealth.com/IH/ihtIH...l?d=dmtContent
The amount in 200mcg(microgram) of chromium picolinate (which is usually cited as a common source of picolinic acid is much smaller than the 25 milligram amount of a standard zinc picolinate tablet. So since the newer zinc does not have this potential, and still shows good reports in most recent studies, I prefer recommending it.
People are still free to use the picolinate version if they choose. The chelates in general are better than the old "sulfate" form.
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All truths are easy to understand once they are discovered; the point is to discover them.-- Galileo Galilei
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Weezie looking at petunias 8.25.2017
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