Re: High Folic Acid Intake Unlikely to Worsen B12 Deficiency

[Guest guest]

The analytical determination of vitamin B12 levels doesn't translate B12

deficiency and it is masked by high levels of folic acid. I am not sure if the

analytical procedure itself or the metabolism of vitamin B12 (I have to check

references). MMA and homocystein are more accurate determination of vitamin B12

deficiency than vitamin B12 levels alone.

Previous findings have shown that the rate of missed diagnosis ranging from 10

to 26 percent when diagnosis is based on low serum vitamin B12 levels alone.

Levels of 300pg/mL of vitamin B12 translate already a depletion of hepatic

reserves (although those levels are considered normal), neurological symptoms

appear before the reserves are depleted, the levels of vitamin B12 translate

total vitamin B12 and not the metabolic active form. Although the conventional

reference interval for serum vitamin B12 is 150-800 pg/mL I rather see all of my

patients, with >400pg/mL than low levels.

Increased levels of B12 > 1000pg/L can be seen when there is an alteration of

gut flora or in patients with GI tract cancers.

This reference shows an interesting algorithm to diagnosis vitamin B12

deficiency

http://www.aafp.org/afp/2003/0301/p979.html

Catia Borges

>

> High intake of folic acid from fortified food and supplements is not likely

> to worsen the biochemical abnormalities linked to B12 deficiency, according

> to the results of a cross-sectional

>

study<http://www.ajcn.org/content/early/2011/06/08/ajcn.111.014621.abstract?sid=\

62758011-3d86-4f8d-ba7b-7d88f47cb2aa>reported

> online June 8 in the

> *American Journal of Clinical Nutrition*.

>

> " In elderly individuals with low serum vitamin B12 (B12), those who have

> high serum folate have been reported to have greater abnormalities in

> biomarkers for B12 deficiency: low hemoglobin (Hgb), and elevated total

> homocysteine (tHcy) and methylmalonic acid (MMA), suggesting that folate

> exacerbates B12-related metabolic abnormalities, " write L. Mills, MD,

> MS., senior investigator in the Division of Epidemiology, Statistics and

> Prevention Research at the Eunice Kennedy Shriver National Institute of

> Child Health and Human Development, National Institutes of Health, and

> colleagues. " We determined whether high serum folate in individuals with low

> serum B12 increases the deleterious effects of low B12 on biomarkers of B12

> cellular function. "

>

> The study sample consisted of 2507 university students who were questioned

> about medical history and use of folic acid and B12 supplements and who gave

> blood samples for testing of serum and red cell folate, hemoglobin, plasma

> homocysteine, and MMA, holotranscobalamin (holoTC), and ferritin in serum.

>

> Approximately 5% of the students sampled had low levels of B12 (< 148 pM),

> and these were subdivided based on folate concentration into group 1 (high

> folate level; > 30 nM) and group 2 (low/normal folate level; ≤ 30 nM). Group

> 1 had significantly higher mean intakes of folic acid and B12 from

> supplements and fortified food than did group 2.

>

> Compared with participants in group 2, those in group 1 did not have greater

> abnormalities in any specific test result of B12 cellular function. In fact,

> they had significantly higher holoTC and red cell folate levels,

> significantly lower total homocysteine levels, and nonsignificantly lower (*

> P* = .057) MMA concentrations than group 2. Hemoglobin and ferritin levels

> were not significantly different between the groups.

>

> " Our findings are reassuring for people who have low vitamin B12 levels, "

> Dr. Mills said in a news release. " We found no evidence that folate could

> worsen their health problems. Consuming higher amounts of folate does not

> seem to interfere with the body's use of vitamin B12 in otherwise healthy

> individuals. "

>

> Limitations of this study include lack of food intake data and a relatively

> small number of participants (mostly women) in the low B12-high folate

> group.

>

> " In our study, we carefully checked for people who had intestinal surgery or

> disorders that disrupt the absorption of B12, to be sure that they did not

> bias our analysis, " Dr. Mills said. " High folate does not appear to increase

> the risk of anemia among healthy people with low B12 levels. " Dr. Mills

> said.

>

> *This study was funded by the Intramural Research Program of the National

> Institutes of Health, Eunice Kennedy Shriver National Institute of Child

> Health and Human Development. The study authors have disclosed no relevant

> financial relationships.*

>

> *Am J Clin Nutr*. Published online June 8, 2011.

>

Abstract<http://www.ajcn.org/content/early/2011/06/08/ajcn.111.014621.abstract?s\

id=62758011-3d86-4f8d-ba7b-7d88f47cb2aa>

>

>

> --

> Ortiz, MS, RD

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