Effect of n−3 PUFA supplementation on cognitive function throughout the life span from infancy to old age: a systematic review and meta-analysis of randomized controlled trials1234

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ABSTRACT

Background:

n−3 PUFAs play an important role in cognitive function.

Objective:

The objective was to investigate the effect of n−3 PUFA supplements on cognitive development, function, and decline throughout the life span.

Design:

The study included randomized controlled trials and provided ≥3 mo of treatment. Potential studies were independently screened in duplicate, and study characteristics and outcomes were extracted. A meta-analysis was performed by using fixed- or random-effects models. The results are presented as standardized mean differences (SMDs) with 95% CIs.

Results:

Of the 3692 citations retrieved, 34 studies of a total of 12,999 participants (1031 infants, 1517 children, 3657 adults, and 6794 elderly individuals) were included. Compared with placebo, n−3 PUFA supplements significantly improved cognitive development in infants, including the Mental Development Index (SMD: 0.33; 95% CI: 0.15, 0.52), the Psychomotor Development Index (0.27; 95% CI: 0.09, 0.45), and language (0.27; 95% CI: 0.13, 0.42), motor (0.29; 95% CI: 0.14, 0.43), and cognitive (0.31; 95% CI: 0.16, 0.45) abilities. However, n−3 PUFAs did not promote cognitive function in terms of composite memory, executive function, and processing speed domains in children, adults, or the elderly, except for the attention domain. No association was found between n−3 PUFA intake and improvements in cognitive performance in terms of recognition, immediate and delayed word recall, digit span backward and forward tests, rapid visual information processing, verbal fluency, and simple and choice reaction times. In addition, n−3 PUFA supplements were not associated with improvements in cognitive decline or with any effects on Alzheimer disease in elderly people.

Conclusions:

n−3 PUFA supplements may significantly improve cognitive development in infants but do not improve cognitive performance in children, adults, or the elderly. n−3 PUFA intake, especially that of DHA supplements, may benefit cognitive development during infancy.

Keywords

cognitive function
infancy
life span
meta-analysis
n–3 polyunsaturated fatty acid

Cited by (0)

1

From the Chronic Disease Research Institute, Department of Nutrition, School of Public Health, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.

2

Supported by the National Natural Science Foundation of China (grant no. 31201307) and Zhejiang Provincial Natural Science Foundation of China (grant no. LY14C200008).

3

Supplemental Methods, Supplemental Tables 1–10, and Supplemental Figures 1–13 are available from the “Supplemental data” link in the online posting of the article and from the same link in the online table of contents at http://ajcn.nutrition.org.

4

Address correspondence to S Zhu, Chronic Disease Research Institute, Department of Nutrition, School of Public Health, School of Medicine, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China. E-mail: [email protected].

5

Abbreviations used: AD, Alzheimer disease; ADAS-Cog, Cognitive Subscale of the Alzheimer Disease Assessment Scale; LCPUFA, long-chain PUFA; MDI, Mental Development Index; MMSE, Mini-Mental State Examination; PDI, Psychomotor Development Index; RCT, randomized controlled trial; SMD, standardized mean difference.