Fish oil - A claim we have heard for years has been challenged by a new study published in 2026. 🧠

"Fish oil protects your brain (in older adults)."

A claim we have heard for years has been challenged by a new study published in 2026. 🧠

Liao et al. (J Prev Alzheimer’s Dis, 2026) followed 819 older adults from ADNI for 5 years. The result was surprising: cognitive decline was faster in the group taking omega-3 supplements.

📉 MMSE: −0.27 points per year
📈 ADAS-Cog13: +0.82 points per year
📈 CDR-SB: +0.21 points per year
(All p<0.001)

This difference is equivalent to 7.8%–15% of the annual progression of Alzheimer’s disease.

THE SURPRISING PART ⤵️
The acceleration was NOT mediated by amyloid, tau, or gray matter.
The only change: glucose metabolism in regions vulnerable to AD — in other words, synaptic energy production slows down. This mechanism explains 30.8% of the MMSE decline and 40.8% of the ADAS-Cog increase.

WHY?
DHA is the most readily oxidized fatty acid in brain mitochondria. The same “flexibility” underlies its anti-inflammatory effects
— but also makes it the most susceptible to lipid peroxidation.

The result: mitochondrial dysfunction → energy deficit → cognitive decline.

⚖️ NUANCES
The study does not say “omega-3 is bad for everyone”:
• It was conducted in an older cohort (≥55)
• Most participants used fish oil (susceptible to oxidation)
• Observational — not an RCT
• It does not call dietary fish consumption into question

🩺 WHAT SHOULD YOU DO?
1️⃣ Stop taking supplements automatically without a reason
2️⃣ Look at your diet first (2 servings of oily fish per week)
3️⃣ Consider having your baseline omega-3 level measured
4️⃣ If you take supplements, pay attention to product quality
5️⃣ Reassess high-dose and long-term use with your physician

⚠️ Do not stop taking omega-3 recommended by your physician on your own.
Prescribed treatments are planned based on an individualized
risk–benefit assessment.

📥  CLICK HERE for all references and the article summary

Assoc. Prof. Dr. Alişan Burak Yaşar · Psychiatrist
Source: Liao ZB et al., J Prev Alzheimer’s Dis 13:100569 (2026)