The Study
Lactase non-persistence is directed by DNA variation-dependent epigenetic aging
This study found that people who can't digest milk as adults tend to have certain changes in their DNA's 'tags' that turn off the milk-digesting gene as they get older. But it didn't prove that those tags cause the problem—it just showed they're linked. It's like noticing that people who don't exercise also have more tiredness, but not proving that not exercising is the only reason they're tired.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Everyone makes milk-digesting enzyme as babies, but most stop as they grow up. A tiny genetic difference decides whether your body keeps making it or turns it off over time.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 553 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — this explains why 65% of adults worldwide can't digest milk without discomfort, while others can drink it freely — it's not just genetics, but how genes control aging in your gut.
- 2People with the C allele (two copies) have 29x less milk-digesting enzyme than those with the T allele.
- 3Deleting a specific DNA region in mice cut adult enzyme levels by 3-8x.
- 4A nearby RNA molecule boosts enzyme production by 25% when active.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Nature structural & molecular biology
Year
2016
Authors
V. Labrie, Orion J. Buske, E. Oh, Richie Jeremian, Carolyn Ptak, G. Gasiunas, A. Maleckas, Rūta Petereit, A. Žvirblienė, K. Adamonis, Edita Kriukienė, K. Koncevicius, Juozas Gordevičius, Akhil Nair, Aiping Zhang, Sasha Ebrahimi, Gabriel Oh, V. Šikšnys, L. Kupčinskas, M. Brudno, A. Petronis
Related Content
Claims (6)
Most adults worldwide cannot digest lactose after infancy because their bodies stop producing the enzyme lactase, a trait inherited from human ancestors.
In adults, the level of DNA methylation at a specific genetic region near the lactase gene changes with age differently depending on whether a person can or cannot digest lactose, and these changes are linked to a 29-fold difference in lactase gene activity.
Deleting a specific non-coding region of the LCT gene in mice reduces lactase mRNA levels by 3 to 8 times in adult animals, and this reduction is stronger in adults than in infants, showing that this region is necessary for sustaining lactase production in mature intestinal cells.
The LCT intron 2 region is preserved across mammal species and becomes more methylated with age in both mice and humans, directly regulating the natural decline of lactase production after weaning, regardless of genetic variants that allow lactase persistence in some humans.
In adults, a specific genetic variation near the lactase gene leads to increasing DNA methylation over time, which reduces lactase production in individuals with the C allele but not in those with the T allele, resulting in lifelong lactase expression only in T allele carriers.
A specific RNA molecule called LOC100507600, which is produced near the lactase gene, is associated with higher levels of lactase mRNA in the human small intestine. Reducing this RNA molecule decreases lactase mRNA by 25% in intestinal cells.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.