Pantothenic acid high intakes

Relatively Httie is known about the bioavailabiUty of pantothenic acid in human beings, and only approximately 50% of pantothenic acid present in the diet is actually absorbed (10). Liver, adrenal glands, kidneys, brain, and testes contain high concentrations of pantothenic acid. In healthy adults, the total amount of pantothenic acid present in whole blood is estimated to be 1 mg/L. A significant (2—7 mg/d) difference is observed among different age-group individuals with respect to pantothenic acid intake and urinary excretion, indicating differences in the rate of metaboHsm of pantothenic acid. 

Fenech, M., Baghurst, P., Luderer, W., Turner, J., Record, S., Ceppi, M., and Bonassi, S. (2005). Low intake of calcium, folate, nicotinic acid, vitamin E, retinol, beta-carotene and high intake of pantothenic acid, biotin and riboflavin are significantly associated with increased genome instability—Results from a dietary intake and micronucleus index survey in South Australia. Carcinogenesis 26, 991-999. 

Biotin uptake into enterocytes is by a sodium-dependent carrier, which also transports pantothenic acid (Section 12.2) and lipoic acid, but is inhibited by biocytin and dethiobiotin. The carrier is found in both the small intestine and the colon, so both biotin and pantothenic acid synthesized by intestinal bacteria can be absorbed (Chatterjee etal., 1999 Ramaswamy, 1999 Said, 1999 Prasad and Ganapathy, 2000). Even at relatively high intakes (up to 80 /rmol), biotin is more-or-less completely absorbed (Zempleni and Mock, 1999b). 

There are no reports of adverse effects. With the exception of occasional mild diarrhea, with oral pantothenic acid m doses as high as 20g/day. In the absence of evidence of toxicity, a tolerable upper intake level cannot be derived for pantothenic acid. 

About 6 to 8 mg/day has been established as the desirable pantothenic acid intake for adult human beings. Adolescent individuals (over 12 years) and pregnant and nursing women have a particularly high requirement for pantothenic acid (the recommended daily allowance is 10 to 15 mg). The normal diet contains 6 to 12 mg pantothenic acid per day, so that severe deficiency symptoms are rarely seen and are difficult to produce experimentally (2,4,8). 

In mice, it was found that usual dietary pantothenate levels did not affect the rate of absorption of a standard pantothenate dose, i.e., there was no evidence for feedback adaptation of the absorption pathway to low or high intakes, and it is assumed that the same is true in other species, including humans. However, there is some evidence from rat studies that the extent of secretion of enzymes degrading CoA into the gut lumen may partially limit the availability of pantothenic acid from CoA. 

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