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. 2022 Jul 6;116(1):74-85.
doi: 10.1093/ajcn/nqac065.

Vitamin B-12 malabsorption and renal function are critical considerations in studies of folate and vitamin B-12 interactions in cognitive performance: NHANES 2011-2014

Marsha E Samson  1   2 , Lorraine F Yeung  1 , Charles E Rose  1 , Yan Ping Qi  1 , Christopher A Taylor  3 , Krista S Crider  1
Affiliations

Vitamin B-12 malabsorption and renal function are critical considerations in studies of folate and vitamin B-12 interactions in cognitive performance: NHANES 2011-2014

Marsha E Samson et al. Am J Clin Nutr. .

Abstract

Background: Cognitive health is a public health concern among older adults. Dietary supplement (SUP) use is common and concerns have been raised about high folic acid intake among those with vitamin B-12 deficiency and exacerbation of poor cognitive performance (PCP).

Objectives: We evaluated SUP use, usual folic acid intake, and blood folate and vitamin B-12 concentrations in relation to cognitive performance.

Methods: We used NHANES 2011-2014 data on adults aged ≥60 y (n = 2867) and estimated total usual folic acid intake from diet and supplements, vitamin B-12 intake from SUPs, blood folates, vitamin B-12 concentrations, vitamin B-12 insufficiency (≤258 pmol/L), high folate (serum folate ≥59 nmol/L or RBC folate ≥1609 nmol/L), and PCP (<34 on the Digit Symbol Substitution Test). We assessed folate distributions adjusted for multiple variables, including renal function.

Results: Compared with persons without PCP, adults with PCP were less likely to use supplements containing folic acid (mean ± SEE: 34.4% ± 2.4%) or vitamin B-12 (mean ± SEE: 47.5% ± 1.6%). Among vitamin B-12-insufficient adults, 18.0% ± 1.6% (mean ± SEE) reported taking a vitamin B-12 supplement. Among participants with high folate and insufficient vitamin B-12 concentrations, 34.3% ± 11.5% (mean ± SEE) reported taking vitamin B-12-containing supplements. Persons with high folate and normal vitamin B-12 concentrations had lower odds of PCP [aOR (adjusted odds ratio): 0.61; 95% CI: 0.45, 0.83] than persons with normal folate and vitamin B-12. Persons with high folate and normal methylmalonic acid (MMA) had lower odds of PCP (OR: 0.56; 95% CI: 0.40, 0.78) than those with normal folate and MMA concentrations. After adjustment for renal function, elevated risk of PCP was attenuated among persons with high folate and MMA. Concurrent high folate and insufficient vitamin B-12 concentrations were not associated with PCP.

Conclusions: Differential associations between vitamin B-12 and MMA highlight the need to consider renal function in studies of high folate and low vitamin B-12 status. Consumption of vitamin B-12 supplements concurrent with low vitamin B-12 status may indicate vitamin B-12 malabsorption.

Keywords: folic acid; kidney dysfunction; malabsorption; older adults; poor cognitive performance; supplements; vitamin B-12.

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Conflict of interest statement

The authors’ responsibilities were as follows—KSC: initiated the project; KSC and LFY: designed the research and had primary responsibility for the final content; MES, CER, and YPQ: conducted the research and analyzed the data; MES: wrote the initial draft of the paper; KSC, LFY, CER, YPQ, and CAT: contributed to revisions; and all authors: read and approved the final manuscript. The authors report no conflicts of interest.

Figures

FIGURE 1
FIGURE 1
Participant flowchart NHANES 2011–2014. MEC, mobile examination center.
See this image and copyright information in PMC

Comment in

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