Cover Image

PAPERBACK
$47.95



View/Hide Left Panel

subjects with serum B12 less than 150 pmol/L (200 pg/mL) had an elevated MMA concentration.

Studies of B12 intake and serum B12 concentration provide very limited information on the relationship of the two. In Finland, vegans consuming an uncooked (“living food”) diet were estimated to consume a mean of 1.8 µg/day of B12 (range 0 to 12.8 µg) (Rauma et al., 1995), but the accuracy of the dietary intake data is uncertain. The 16 vegans who ate seaweed (the main source of B12 reported) had B12 concentrations twice as high as those not eating seaweed (mean of 220 pmol/L [300 pg/mL] compared with 105 pmol/L [142 pg/mL]). On this diet 57 percent of the vegans had serum B12 concentrations less than 200 pmol/L (270 pg/mL). A study by Draper and colleagues (1993) provided dietary data on vegans that were not sufficient for drawing conclusions about diet-B12 relationships. Neither Garry and coworkers (1984) nor Sahyoun and colleagues (1988) separated data with regard to supplement use, so their data are not interpretable for setting EARs. A study of a macrobiotic population (Miller et al., 1991) revealed that more than half of the adults had low serum B12 concentrations and nearly onethird were excreting high amounts of MMA, but dietary information from the study was not sufficient for drawing conclusions. Moreover, studies need to be conducted in younger persons in whom B12 absorption is more likely to be normal.

B12EAR and RDA Summary, Ages 19 through 50 Years

On the basis of hematological evidence and serum B12 values, the EAR for B12 is estimated to be 2 µg/day for men and women ages 19 through 50 years. Sufficient data were not available to enable differences in requirements to be discerned for men and women in these age groups.

EAR for Men

19–30 years

2 µg/day of vitamin B12

 

31–50 years

2 µg/day of vitamin B12

EAR for Women

19–30 years

2 µg/day of vitamin B12

 

31–50 years

2 µg/day of vitamin B12

The RDA for B12 is set by assuming a coefficient of variation (CV) of 10 percent (see Chapter 1) because information is not available on the standard deviation of the requirement for B12; the RDA is defined as equal to the EAR plus twice the CV to cover the needs of



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement