The Absorption of Vitamin B&lt;sub&gt;12&lt;/sub&gt; in the Elderly

De, Hyams

doi:10.1159/000244833

Cited by 13 publications

(4 citation statements)

References 15 publications

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Section: Age and Absorptionmentioning

confidence: 99%

“…Based on studies of fecal excretion, urinary excretion, serum levels and the hepatic uptake of vitamin B 12 , several investigators have concluded that the absorption of this vitamin is unaffected by age (26–28). Hymans (28) used fecal excretion and hepatic uptake methods to compare vitamin B 12 absorption in young men (28 to 50 years old) and aged men (73 to 90 years old). Results of this study indicated that the stomach of aged persons can produce sufficient intrinsic factor to provide for normal absorption of vitamin B 12 , and that the aged ileum can efficiently absorb the vitamin B 12 ‐intrinsic factor complex.…”

Section: Age and Absorptionmentioning

confidence: 99%

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Effect of Age on Intestinal Absorption: Implications for Drug Absorption in the Elderly

Bender¹

1968

J American Geriatrics Society

110

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Studies dealing with the influence of increasing age on intestinal absorption are reviewed. Interest in these studies has resulted from statements that increasing age is accompanied by a delay and a reduction in drug absorption. There are, however, no data to support this conclusion. Nevertheless, data from studies of the absorption of sugars, fats and vitamins in subjects of different ages may be relevant to the problem of drug absorption, as are the other changes in gastrointestinal function that occur with advancing age. In the elderly there is a reduction in gastric pH which, in the case of some drugs, affects the solubility and thus will influence the rate of absorption. Furthermore, there is a reduction in intestinal blood flow, which would tend to delay or reduce drug absorption. Possibly there is a reduction in the number of absorbing cells in the intestine, with a consequent loss of absorbing surface in the aged; this may explain the reported reduction in passive diffusion in the aged. A modification of special transport mechanisms is suggested by the fact that the absorption of galactose, 3-methyl glucose, calcium, and thiamine is reduced with increasing age. All of these factors tend to imply that drug absorption in the elderly is reduced. Fortunately perhaps, the reduction in absorption is accompanied by decreased metabolism and decreased excretion. Thus, limited absorption from the intestine is balanced by delayed elimination of drugs.Drug activity is modified by increasing age (1, 2), the modification usually being attributed to decreased metabolism and excretion, reduced homeostatic capacity, and a decrease in the number of active cells (receptor sites) (3, 4). There are also conjectures that drug absorption may be impaired or delayed in the elderly (5, 6), but with the exception of a study by Gwilt et al. (7), no data are yet available which permit comparison of the absorption of drugs among adults of different ages. In view of the lack of data regarding drug absorption according to age, studies concerning the effect of age on the absorption of other substances are reviewed here.For the past twenty years, interest in the effect of increasing age on intesti-

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Section: Age and Absorptionmentioning

confidence: 99%

Section: Age and Absorptionmentioning

confidence: 99%

Effect of Age on Intestinal Absorption: Implications for Drug Absorption in the Elderly

Bender¹

1968

J American Geriatrics Society

110

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“…How ever, Chinn etal. (1956) found no significant difference in the rate or the extent of protein digestion and absorption in old age and the findings of impaired absorption of vitamin B12 have not been con firmed by subsequent work (Swenseid et al, 1954;Chow et al, 1956;Tauber et al, 1957;Hyams, 1964).…”

Section: Introductionmentioning

confidence: 90%

Thiamine Absorption in Old Age

Thomson¹

1966

Geront clin

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“…On the other hand, there were other reports, in which no decrease in absorption of Bit could be found in the aged (4-6). Hyams reported a sufficient secretion of IF in the gastric juice in the aged (7). The serum level of B12 was found to be low in the aged by others (8)(9)(10)(11)(12)(13).…”

mentioning

confidence: 89%

Effects of aging on intracellular transport of vitamin B12(B12) in rat enterocytes.

Toyoshima

Inada

Kameyama

1983

Journal of Nutritional Science and Vitaminology, J Nutr Sci Vit

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SummaryTo elucidate the effect of aging on the vitamin B12 (B12) transport in enterocytes, young and old (3-4 months and over 1 .5 years, respectively) female rats were studied. Two units of rat intrinsic factor (IF), saturated with 57Co-labeled cyanocobalamin were orally adminis tered, and the amount of B12 absorbed into each subcellular fraction of enterocytes was assayed. Concentration of endogenous B12 in each subcellular fraction was also studied. Absorption of radioactive B12 in the lysosomal fraction was maximum between 2 and 4hr in each age group . In the older rats, the amount absorbed was lower than in the young rats . The older rats showed a significantly lower value of endogenous B12 in the mitochondria. It has already been reported by us that there exist two B12 binders in enterocytes: lysosomal and microsomal binders. The con centrations of lysosomal and microsomal binders as well as B12 uptake in the mitochondria were significantly lower in the older rats than in the young rats. These data might help to explain the lower B12 absorption in the lysosomal fraction and lower B12 contents in the mitochondrial fraction.

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The Absorption of Vitamin B<sub>12</sub> in the Elderly

Cited by 13 publications

References 15 publications

Effect of Age on Intestinal Absorption: Implications for Drug Absorption in the Elderly

Effect of Age on Intestinal Absorption: Implications for Drug Absorption in the Elderly

Thiamine Absorption in Old Age

Effects of aging on intracellular transport of vitamin B12(B12) in rat enterocytes.

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