Wednesday Feb 17, 2016 (foodconsumer.org) -- A new study published recently in American Journal of Clinical Nutrition suggests eating fish or taking marine-derived omega-3 fatty acid supplements like DHA may help prevent mild cognitive impairment and cognitive decline in healthy individuals and patients with dementia, Alzheimer's disease, or Parkinson disease.

The study analyzed data from 21 studies on the neuroprotective effect of eating fish, polyunsaturated fatty acids (PUFAs) and omega-3 PUFAs against dementia, Alzheimer's disease and Parkinson disease and found consumption of fish and n–3 (ω-3) PUFAs was protective against the diseases and related symptoms.

Specifically, researchers found one serving of fish per week was associated with 5% and 7% reduced risk for dementia and Alzheimer's disease, respectively, during the follow-up, which lasted 2.1 years to 21 years..  

An analysis of pooled data showed the relative risk for mild cognitive impairment and Parkinson disease were 29% and 10% lower for those who had intake of eight-grams of PUFA per day.  It is not clear if these PUFA are omega-6, or omega 3 or both types of long chain polyunsaturated fatty acids.

More significant protective effects against dementia and Alzheimer’s disease came from docosahexaenoic acid, a type of omega-3 fatty acid found in fish and marine algae.  To be exact, each additional 0.1 grams of DHA per day was associated with 14% and 37% reduced risk for dementia and Alzheimer's disease, respectively.

Yu Zhang, Jingnan Chen, Jieni Qiu, Yingjun Li, Jianbing Wang, and Jingjing Jiao, Intakes of fish and polyunsaturated fatty acids and mild-to-severe cognitive impairment risks: a dose-response meta-analysis of 21 cohort studies, Am J Clin Nutr February 2016, vol. 103 no. 2 330-340