There is evidence that B12 function cannot be restored to healthy levels by adding small amounts of animal products into the diet.
van Dusseldorp et al. (1999, Netherlands) investigated whether moderate consumption of animal products is sufficient for achieving normal B12 function in 73 adolescents who had been strict macrobiotics (MAC) until 6 years old and then switched to a lacto-ovo-vegetarian (LOV) or non-vegetarian (NV) diet. 94 people who had never been macrobiotic or vegetarian served as controls. Dairy supplied an average of ~1 µg B12/day for the MACs. They also ate fish, red meat, or chicken 2-3 times/week.
|Table 1. van Dusseldorp et al.van Dusseldorp, 1999 (1999, Netherlands)|
|sMMA > .41 µmol/l||HCY > 12.8 µmol/l|
|A,B,C,D – Statistically significant difference between groups with same letters|
Thus, moderate animal product consumption was not enough to restore normal B12 status for 21% of these children, based on MMA levels.
van Dusseldorp M, Schneede J, Refsum H, Ueland PM, Thomas CM, de Boer E, van Staveren WA. Risk of persistent cobalamin deficiency in adolescents fed a macrobiotic diet in early life. J Clin Nutr. 1999 Apr;69(4):664-71.