Abstract Effects of feeding free chitosan to rats at graded levels up to 15 percent of the diet for eight weeks was investigated. Animals receiving diets containing 5 percent or less of chitosan grew well at comparable rates. Progressive growth reductions occurred when chitosan was increased to 10 and 15 percent of the diet and enlargement of liver and kidneys was observed only in animals receiving the highest level of dietary chitosan.

Liver moisture, protein, lipid, ash, and nucleic acids; blood hemoglobin and packed cell volume; and serum total protein, albumin, ceruloplasmin and transferrin were determined. Values for these components of liver and blood were altered significantly in the animals receiving the highest level of chitosan when compared to control animal. However, in animals receiving 5 percent or less of dietary chitosan none of these measures of tissue composition was different from controls, except for lever protein concentration of rats fed the 5 percent chitosan diet. Animal feeds containing coagulated by-products are not expected to contain over 0.2% chitosan in the total diet. No adverse effects have been observed at this level in rat feeding studies.

Therefore the tolerance level for dietary chitosan appears to be well above the levels expected to be in animal feeds containing by-products recovered from food processing wastes by coagulation with chitosan.

Comments This original work by Landes and Bough has particular significance in that the authors disclosed in 1976 that the lipid component of the livers from rats decreased after being fed increasing levels of chitosan. To quote the authors,

"Lipid concentration (in the liver) was decreased in animals receiving the 10 and 15 percent levels of dietary chitosan, with the decrease being significant for those receiving 15 percent of chitosan in the diet."

In the "Discussion" section, Landes and Bough make the following comment:

"Animals receiving the highest level of chitosan (15%) had reduced liver lipid concentration and in fact had very little or no depot fat."

It is also important to note that this work was published two years before the Furda Patent (Reference summary #9) was filed. A review of the Furda Patent application shows that the Landes and Bough paper was not cited as prior art.

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