Manganese tolerance test

The manganese tolerance test measures the plasma uptake of pharmacological doses of manganese. This test is analogous to the plasma tolerance test for zinc, which was described in 1973 (15) and has subsequently been used extensively in this (16) and other laboratories as a qualitative indicator of absorption (17,18). 

In manganese tolerance tests, blood samples are collected at fasting and at regular time intervals following administration of an oral manganese load. In this study, results of tolerance tests with manganese alone were subsequently compared with plasma responses in the same subjects when the manganese dose was accompanied by various dietary components. 

In order to determine the independent effect of cellulose on manganese bioavailability, manganese tolerance tests were administered with 15 g of alpha cellulose (Sigma Co., Inc., St. Louis, MO) to six human subjects. The cellulose was given in gelatin capsules in addition to a 40 mg dose of manganese as MnCl. and 200 ml of deionized water. As seen in Figure 4, the addition of cellulose to... 

In a series of manganese tolerance tests, three dietary components —cellulose, pectin, and phytate—were found to reduce plasma uptake of manganese. Although the amount of manganese administered (40-50 mg) in these tolerance tests was much larger than that typically consumed (0.9 to 7.0 mg per day) (55,56), the results were similar to those obtained in bioavailability studies with other trace elements. Thus it appears that diets high In fiber and phytates also reduce the bloavailabllity of manganese. 

The influence of three dietary factors - pectin, cellulose and phytates - on plasma uptake of manganese (Mn) was studied in adults administered Mn tolerance tests. Plasma samples were collected at hourly intervals following administration of various doses of several Mn salts. It was found that a 40 to 50 mg dose of elemental Mn was necessary to produce consistent plasma responses and that manganese chloride (MnCl ) was better absorbed than the sulfate or acetate form. In fasting subjects, plasma Mn was 0.64, 1.29, 1.12, 0.95, and 0.75 ug/L at hours 0, 1,... 

The manganese load in the tolerance tests was administered in capsule form along with 200 ml of deionized distilled water. 

Human and animal studies indicate that inorganic manganese compounds have a very low acute toxicity by any route of exposure. The toxicity values for a given Mn compound are shown in Table 20 to depend on the species of test animal as well as the route of exposure. Manganese concentrations as high as 2000 ppm were found to be tolerated by test animals over a six-month period without any ill effects (208). 

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