HYDERABAD: More than one-third of adults assessed showed signs of mild cognitive impairment (MCI), with the condition associated with lower levels of vitamins D, B2, B6 and B9, according to a study.
Researchers from the ICMR-National Institute of Nutrition (NIN), Hyderabad, and Kamineni Academy of Medical Sciences and Research Centre found MCI in 36.4% of 184 participants aged 55 to 85 years. The participants were assessed between January 2024 and March 2025 using the Montreal Cognitive Assessment (MoCA), along with blood tests for micronutrients and neuronal biomarkers.
Those with MCI had significantly lower levels of vitamins D, B1, B2, B6, B9 and B12 than participants without the condition. Vitamin D deficiency was found in 72% of the MCI group, compared with 48% of the non-MCI group. For vitamin B2, the figures were 63% and 37%, while vitamin B9 deficiency was recorded in 11% and 2%, respectively.
The differences were particularly marked for vitamins D, B2, B6 and B9. Median vitamin D levels were 16.2 ng/mL among participants with MCI, compared with 20.9 ng/mL among those without it. Vitamin B2 levels were 203 nmol/L and 243 nmol/L, respectively, while B6 levels were 29.6 nmol/L and 38.6 nmol/L.
The study also found that deficiencies tended to occur together. Nearly 39% of participants with MCI had more than two deficiencies among the six vitamins studied — D, B1, B2, B6, B9 and B12 — compared with 19% of those without MCI.
Higher levels of vitamins D, B6 and B9 were associated with better MoCA scores. After adjusting for age, sex, education, BMI, HbA1c, systolic blood pressure and neuronal markers, higher concentrations of all six vitamins were associated with a lower predicted probability of MCI, with the strongest associations seen for vitamins D and B6.
For vitamin D, the predicted probability of MCI fell from 0.94 at the 10th percentile of concentration to 0.20 at the 90th percentile. For B6, it declined from 0.92 to 0.04. The researchers cautioned that confidence intervals were wider at higher concentrations because fewer participants fell within those ranges.
The study began with 1,020 volunteers. After exclusions for factors including multivitamin use, chronic diseases, recent infections, hospitalisation and psychiatric disorders, as well as non-participation in blood collection, 184 participants remained for analysis — 116 men and 68 women.
MCI is an intermediate stage between normal cognitive ageing and dementia and can affect memory, attention, language and other cognitive functions.
While early identification could help in understanding and addressing factors linked to cognitive decline, the researchers stressed that the cross-sectional study cannot establish that vitamin deficiencies cause MCI. Further research is needed to determine whether improving micronutrient status can influence cognitive outcomes.
Study snapshot
36.4% of the 184 older adults assessed had mild cognitive impairment (MCI)
Those with MCI had lower levels of vitamins D, B1, B2, B6, B9 and B12
Nearly 39% of those with MCI had deficiencies in more than two vitamins, compared with 19% without MCI.
Higher levels of vitamins D, B6 and B9 were associated with better cognitive scores.
The strongest associations with lower MCI probability were seen for vitamins D and B6.
The study found an association, not proof that vitamin deficiencies cause MCI