ten years ago i was obsessed with b12. for a very long time, b12 deficiency has been the main nutritional differential dx for ms.
as a long term vegan, i was a prime candidate for b12 deficiency. i had a test on file for which serum b12 was not detectable (for that one, i'd made a point of not messing up the results with supplements). however, at the time of my diagnosis, i could take b12 all i wanted and things did not turn around. it was only when i implemented a more diverse nutritional regimen that i had real improvements.
the past decade has taught me, in detail, to consider a wider array of essential nutrients where chronic illness is concerned.
b12 assessment is as problematic as the rest. there are many more essential nutrients to consider. while it's certainly worth looking at,
b12 is not a prime suspect where multiple childbirths are concerned.
http://jn.nutrition.org/content/133/5/1732S.full
"An adequate supply of nutrients is probably the single most important environmental factor affecting pregnancy outcome. Women with early or closely spaced pregnancies are at increased risk of entering a reproductive cycle with reduced reserves.
Maternal nutrient depletion may contribute to the increased incidence of preterm births and fetal growth retardation among these women as well as the
increased risk of maternal mortality and morbidity. In the past, it was assumed that the fetus functioned as a parasite and withdrew its nutritional needs from maternal tissues. Studies in both animals and humans demonstrate, however, that
if the maternal nutrient supply is inadequate, the delicate balance between maternal and fetal needs is disturbed and a state of biological competition exists. Furthermore, maternal nutritional status at conception influences how nutrients are partitioned between the mother and fetal dyad.
In severe deficiencies maternal nutrition is given preference; in a marginal state the fetal compartment is favored. Although the studies of nutrient partitioning have focused on energy and protein, the
partitioning of micronutrients may also be influenced by the maternal nutritional status.".
Cobalamin status during normal pregnancy and postpartum: a longitudinal study comprising 406 Danish women
https://www.ncbi.nlm.nih.gov/pubmed/16548919
"Results: P-cobalamin showed a gradual, significant decline during pregnancy (P < 0.0001) followed by a significant increase postpartum (P < 0.0001); at 18, 32, 39 wk gestation and 8 wk postpartum median values were 225, 172, 161 and 319 pmol/L, respectively."
pretty bad during pregnancy but not terrible post partum. i like to be above 370 pmol/L personally.
this is from an unpublished master's thesis. i would have enjoyed the chance to check out the full text vs just the abstract. excerpt:
https://ourarchive.otago.ac.nz/handle/10523/6311
"The mean maternal dietary zinc intake was 11.2 mg/day, with 69% (n=36) consuming below the EAR of 10 mg/day. The average serum zinc concentration was 9.8 μmol/L, and 2% of women had serum zinc concentrations below 7.65 μmol/L, while 35% were below 10.7 μmol/L. None of the variables examined were significantly associated with serum zinc concentrations."
these postpartum/lactation numbers for serum zinc *are* bad. at my local hospital, levels below 11.5 umol/l are considered deficient, never mind 'suboptimal'. i can choose another area lab and they'll be using 8.6 umol/l as their lower cutoff so i can be deficient or not depending where i have my sample analyzed. i aim for levels in the high teens, ideally very close to 18 umol/l for serum zinc. that's based on multiple studies of serum zinc levels in healthy controls.
from an earlier, related published work:
Zinc supplementation during lactation: effects on maternal status and milk zinc concentrations.
http://ajcn.nutrition.org/content/61/5/1030.short
"Overall mean zinc intakes were 13.0 +/- 3.4 mg/d for the NZS group and 25.7 +/- 3.9 mg/d (including supplement) for the ZS group. Plasma zinc concentrations of the ZS group were significantly higher than those of the NZS group (P = 0.05). ... The mean dietary zinc intake observed in the nonsupplemented group was adequate to maintain normal maternal zinc status and milk zinc concentrations through > or = 7 mo lactation."
when i have time, i'll have to get into the full text on that to see what plasma levels were achieved postpartum given that higher mean intake of zinc without supplementation. interesting!