Biomedical Engineering Reference
In-Depth Information
cholesterol, or increase in plasma cholesterol level and liver weight. HMG-
CoA reductase activity was 7.7-times more elevated in the sterol chitosan
group, than in the sterol group. No signii cant dif erence was observed in
results obtained at 1, 3 or 6 weeks. It was concluded that chitosan at 7.5 %
was able to adequately maintain cholesterol homeostasis in rats despite a
greatly increased intake of cholesterol.
When discussing the role of chitosan as cholesterol lowering nutriceuti-
cal, and considering possible mechanisms for its action, one should keep
in mind that animal studies might not be predictive of results in humans
because of the presence of chitinases in the digestive systems of many ani-
mals, as a point of dif erence from humans [264]. Chitosan was i rst shown
to reduce serum cholesterol in humans in 1993, when adult males, fed chi-
tosan-containing biscuits for 2 weeks (3 g/day for week 1. 6 g/day for week
2), experienced a signii cant decrease of 6 % in total cholesterol [251].
h e
subjects also demonstrated a 10 % increase in HDL cholesterol. However,
in a 28 day study in overweight subjects, given a daily dose of approxi-
mately 0.6 g/day of chitosan, no reduction in total cholesterol was detected
[265]. h e failure to i nd any reduction in cholesterol in this study was due
to the small quantity of chitosan used. Two studies have reported serum
cholesterol reductions with chitosan treatment. A double blind study
involving 51 obese women consuming 1.2 g of microcrystalline chitosan
for 8 weeks demonstrated signii cant reductions in LDL, although not total
serum cholesterol [266]. Eighty-four female subjects with mild to moder-
ate hypercholesterolemia, receiving 1.2 g of chitosan per day, experienced
a signii cant decrease in total serum cholesterol [267]. h e results of the
animal studies and human trials provide convincing evidence that chitosan
is ef ective in lowering total and LDL cholesterol. Chitosan appears to be
active in humans at rather low doses, with as little as 1.2 g per day, produc-
ing signii cant reductions in serum cholesterol.
Chitosan is widely promoted and available as dietary supplement to aid
weight loss and lower blood cholesterol levels, since chitosan could theo-
retically bind ingested fats and oils directly and/or prevent lipid absorption
indirectly, via removal of bile acids and other acttions.
Numerous clinical trials have been conducted to validate the claim. Jull,
et al.
, reviewed published results of i t een such studies which lasted for
4-24 weeks, including a total of 1219 participants [33].
Reviews suggest
that there is some evidence for chitosan being more ef ective than placebo
in the short-term treatment of overweight and obesity. However, many of
the included trials had been of poor quality.
Results obtained from high quality trials indicated that the ef ect of chito-
san on body weight was minimal and unlikely to be of clinical signii cance.
