Longitudinal study finds higher omega-3 levels associated with reduced risk of early-onset dementia

Higher omega-3 blood levels are associated with reduced risk of early-onset dementia (EOD), a longitudinal prospective study demonstrates.¹ EOD is defined as a diagnosis before age 65, the study notes, adding that previous studies on dietary factors in dementia risk have focused on late-onset dementia.

The study, “Blood omega-3 is inversely related to risk of early-onset dementia,” was published in Clinical Nutrition in December 2025.

Study design

The researchers used data from the UK Biobank, analyzing omega-3 levels (total omega-3, DHA, and non-DHA omega-3) and EOD in 217,122 participants ages 40–64, with an average follow up period of 8.3 years.

The age range of the study population is a significant detail. “This is the first large-scale study to show that objectively measured omega-3 status is linked to lower risk of dementia diagnosed before age 65,” stated lead study author Aleix Sala‑Vila, PhD, in a January 15, 2026, press release from OmegaQuant.² “Most prior research has focused on older populations. Our findings strongly suggest that omega-3 intake earlier in midlife may play a meaningful role in brain health decades before dementia typically appears.”

The researchers also examined the interaction between the APOE-ε4 allele load (a significant risk factor for dementia) and omgega-3 levels.

Highlighted results

There were 325 cased of EOD identified in the participants.

• Compared with participants in first quintile (Q1) of omega-3 levels, participants in the fourth and fifth quintile (Q4 and Q5) demonstrated a statistically significant lower risk of EOD
• Participants in Q5 of DHA also demonstrated a lower risk of EOD compared with those in Q1
• A statistically significant lower risk of EOD was seen in Q3, Q4, and Q5 of non-DHA levels

No connection between omega-3 levels and APOE-ε4 allele were seen.

“This study expands the evidence of a beneficial association of omega-3 and LOD to EOD as well,” the researchers concluded. “These findings suggest that an increased intake of omega-3 fatty acids earlier in life may slow the development of EOD.” They also explained that more research, especially studies with diverse populations, would be needed to confirm the findings.

“These results reinforce the value of using blood biomarkers rather than self-reported diet when studying nutrition and brain health,” stated study co-author Nathan L. Tintle, PhD. “Because omega-3 levels can be safely and effectively increased through diet and supplementation, this represents a plausible, low-cost strategy that could help reduce the burden of early-onset dementia.”

“When a safe, accessible lifestyle factor is consistently associated with lower disease risk, it deserves serious consideration as part of a broader prevention strategy,” Sala-Vila added.

Other health conditions and omega-3 levels

Recently published studies have also examined the effects of omega-3 levels and risk of atrial fibrillation (AF) and of support for mental health. Both studies also involved data from the UK Biobank.

A meta-analysis from December 2025 found an inverse relationship between fish oil for omega-3 supplementation and AF.³ The average follow up in the study was 12.7 years on average and examined blood serum omega-3 metrics of DHA and total omega‐3s.

A study published in November 2025 found an inverse relationship between blood plasma levels of omega-3 fatty acids (which included DHA, non-DHA, and total omega-3) and passive suicidal ideation, history of self-harm, and future self-harm and omega-3 FAs levels.⁴ This study also noted the importance of omega-3s for neuronal cell membrane fluidity, neurotransmission, and brain function.

References

1. Sala-Vila, A.; Tintle, NL.; Westra, J.; Harris, WS. Blood omega-3 is inversely related to risk of early-onset dementia, Clinical Nutrition, 2026. 57, 106559. DOI: 10.1016/j.clnu.2025.106559.
2. OmegaQuant. Large-Scale Study Shows Higher Blood Omega-3 Levels Linked to Lower Risk of Early-Onset Dementia, January 15, 2026. https://omegaquant.com/large-scale-study-shows-higher-blood-omega-3-levels-linked-to-lower-risk-of-early-onset-dementia/ (Accessed 2026-01-16).
3. McEvoy, E. Meta-analysis finds higher blood omega-3 levels linked to lower atrial fibrillation risk, December 22, 2025. https://www.nutritionaloutlook.com/view/meta-analysis-finds-higher-blood-omega-3-levels-linked-to-lower-atrial-fibrillation-risk (Accessed 2026-01-16).
4. McEvoy, E. Higher omega-3 levels in plasma associated with reduced risk of self-harm, study shows, December 2, 2025. https://www.nutritionaloutlook.com/view/higher-omega-3-levels-in-plasma-associated-with-reduced-risk-of-self-harm-study-shows (Accessed 2026-01-16).