The bottom line: In older adults from India, higher folate levels tracked with slower change on several biological aging measures, while higher homocysteine tracked with faster aging. The study followed participants over about 4.5 years, which makes it more informative than a one-time snapshot. It was still observational. It does not show that folate caused slower aging or that folic acid supplements can slow human aging.
Evidence at a glance
- Study type: Human longitudinal observational study.
- Population: Adults aged 60 and older in the nationally representative LASI-DAD cohort in India.
- Follow-up: Two measurement periods approximately 4.5 years apart.
- Main finding: Higher folate was associated with slower biological aging, while higher homocysteine was associated with faster aging.
- Main caution: Association does not establish causation, and results varied across aging measures.
What the researchers measured
The study examined folate, vitamin B12 and homocysteine, three blood markers connected to one-carbon metabolism. This network of chemical reactions helps cells make DNA, regulate methylation, maintain antioxidant defenses and carry out repair.
Folate and vitamin B12 help the pathway operate. Homocysteine is an amino acid that can rise when parts of the pathway are disrupted, although kidney function, genetics, medications, diet and other aspects of health can also influence it.
At the first visit, the analysis included 1,929 participants with the clinical measurements needed to calculate Phenotypic Age. A subset of 922 had DNA methylation data. The longitudinal Phenotypic Age analysis included 886 people who had complete measurements at both visits.
What biological age means here
Biological age is not a single property that can be measured directly. It is an estimate built from biomarkers associated with health, disease risk or the passage of time.
Phenotypic Age combines chronological age with routine blood measures linked to inflammation, immune function, metabolism, kidney health and other physiological systems. DNA methylation clocks use chemical tags attached to DNA. Those tags can affect how genes are regulated without changing the DNA sequence itself.
The study examined several methylation measures, including DNAm PhenoAge, GrimAge2, DunedinPACE and SystemsAge. These tools were designed for different purposes. Some are more closely related to mortality risk, while DunedinPACE is intended to estimate the current pace of aging. A change in one clock is not the same as a change in every dimension of aging, and it is not proof that a person will live longer.
What the study found
Across the longitudinal analysis, each doubling of homocysteine was associated with about 3.2 years more Phenotypic Age acceleration. Each doubling of folate was associated with about 1.1 years less acceleration on that measure.
People who moved into folate deficiency and those with persistently high homocysteine also showed less favorable aging trajectories. Folate had its strongest inverse associations with DunedinPACE and SystemsAge. Associations with DNAm PhenoAge and GrimAge2 were weaker or less consistent.
That uneven pattern matters. If every clock measured the same underlying process, results would be expected to align more closely. Instead, the findings reinforce that biological aging tools capture overlapping but distinct signals.
Why longitudinal evidence helps
A cross-sectional study compares people at one point in time. It can find that participants with higher folate have younger-looking biomarker profiles, but it cannot show whether folate changed first or whether healthier people simply had both better nutrition and more favorable aging measures.
Repeated measurements let researchers examine whether changes within the same people move together over time. That reduces some problems created by stable differences between participants. It still cannot remove all confounding. Changes in illness, kidney function, diet, medication use, body weight or socioeconomic circumstances could affect both the nutrient markers and the aging scores.
Why this is not a supplement result
The study did not randomly assign folic acid or compare supplements with a placebo. Blood folate reflects diet, food fortification, supplement use, absorption and metabolism. A higher level may also be a marker of broader dietary quality or health access.
Folate deficiency is a recognized medical problem, but treating a deficiency is different from taking extra folic acid to slow aging. More is not automatically better. Other population studies have reported nonlinear or conflicting relationships between folate and aging measures.
A causal test would require a sufficiently large randomized trial that defines folate status in advance, assigns a specific intervention, tracks harms and follows participants long enough to assess function and disease. Aging clocks could be useful secondary outcomes, but meaningful health outcomes would remain essential.
The Lifespan Brief assessment
This is useful human longitudinal evidence from a population that is underrepresented in aging research. The repeated measurements strengthen the finding that folate and homocysteine move with some biological aging trajectories.
The result is a carefully adjusted association, not evidence that supplements slow aging. It supports more research into one-carbon metabolism, nutritional deficiency and age-related physiology. It does not support treating a biological age score with over-the-counter folic acid.
Primary source
- Longitudinal associations of one-carbon metabolism biomarkers with biological and epigenetic aging in older adults in India, GeroScience, September 10, 2026.
This article is for general information and is not personal medical advice.