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Chromium studies
Chromium supplements given to people with impaired glucose tolerance
or diabetes may lead to improved blood glucose, insulin and lipid
variables. Chromium has also been shown to improve lean body mass in
humans and swine. Studies on the effectiveness of chromium
supplementation in patients with glucose intolerance and type II
diabetes have produced conflicting results. Improvements have been noted
in glucose tolerance tests in adult diabetics (Glinsmann
and Mertz 1966, Mossop 1983) and glucose intolerant men and women (Martinez
1985, Anderson 1983, Anderson 1991). In a Finnish trial in 1990,
noninsulin-requiring diabetics supplemented with chromium had a
beneficial effect on insulin response at one hour but no improvement in
glucose tolerance tests (Uusitupa
1983). Chromium supplementation may also have a favorable impact on
triglycerices, LDL and HDL cholesterol. (Abraham
1991, Press 1990). In contrast to these findings, three trials have
shown no benefit of chromium with glucose tolerance, insulin levels or
blood lipid concentrations. (Sherman
1968, Offenbacher, 1985, Rabinowik, 1983). Unfortunately, variations
in chromium preparations and dosages, duration of therapy and the
heterogeneity of study populations make meaningful comparisons of the
trials difficult.
More recent human studies have shown favorable responses with
chromium supplementation. Diets supplemented with chromium picolinate
(200 ug/day) were compared to a placebo in 48 patients with type I
diabetes and 114 patients with type II diabetes. In approximately 70% of
patients supplemented with chromium, there was a reduced need for
insulin or oral hypoglycemic medications (Ravina
1995). The most promising study to date was carried out in China
involving 180 patients with type II diabetes. This randomized,
placebo-controlled trial showed significant improvements in lipids and
HbA1C levels at 2 and 4 months of supplementation with chromium. The
response appeared to be dose related with the most benefit achieved in
the group supplemented with 1000 ug/day, an amount which is higher than
the upper limit of the ESADDI (Anderson
1997).
These studies strengthen the association of insufficient dietary
chromium and risk factors for maturity-onset diabetes and cardiovascular
diseases (Anderson
1992, 1993). Chromium affects the glucose/insulin interaction in
subjects with hypoglycemia, hyperglycemia, diabetes and hyperlipemia
with no detectable effects on control subjects. Chromium has been
observed to improve insulin binding, insulin receptor number, insulin
internalization, beta-cell sensitivity and insulin receptor-related
enzymes with overall increases in insulin sensitivity. It is suggested
that chromium, by down-regulating beta-cell activity, may increase
glucagon secretion. Such an effect might play a role in the documented
therapeutic activity of supplemental chromium in reactive hypoglycemia
and might also be of benefit to dieters (McCartny
1996).
