A systematic review of the effects of increasing arachidonic acid intake on PUFA status, metabolism and health-related outcomes in humans.

Philip C Calder,Szimonetta Lohner,Ans Eilander,Bettina Schelkle,Cristina Campoy,Aliz Szommer,Ronald P Mensink,Bert J M Van De Heijning,Per-Olof Larsson,Mathilde Fleith,Stewart Forsyth

doi:10.1017/s0007114519000692

Abstract

We conducted a systematic review of randomised controlled trials (RCT) of increased intake of arachidonic acid (ARA) on fatty acid status and health outcomes in humans. We identified twenty-two articles from fourteen RCT. Most studies were conducted in adults. These used between 80 and 2000 mg ARA per d and were of 1-12 weeks duration. Supplementation with ARA doses as low as 80 mg/d increased the content of ARA in different blood fractions. Overall there seem to be few marked benefits for adults of increasing ARA intake from the typical usual intake of 100-200 mg/d to as much as 1000 mg/d; the few studies using higher doses (1500 or 2000 mg/d) also report little benefit. However, there may be an impact of ARA on cognitive and muscle function which could be particularly relevant in the ageing population. The studies reviewed here suggest no adverse effects in adults of increased ARA intake up to at least 1000-1500 mg/d on blood lipids, platelet aggregation and blood clotting, immune function, inflammation or urinary excretion of ARA metabolites. However, in many areas there are insufficient studies to make firm conclusions, and higher intakes of ARA are deserving of further study. Based on the RCT reviewed, there are not enough data to make any recommendations for specific health effects of ARA intake.

Highlights

Arachidonic acid (ARA) is the common name for all-cis5,8,11,14-eicosatetraenoic acid (Fig. 1), commonly abbreviated to 20 : 4ω-6 or 20 : 4n-6
Based upon a study with 2H-labelled linoleic acid (LA), Emken et al(4) reported that 1–2·2 % of LA is converted to other n-6 PUFA in healthy young adult males with about 0·5 % appearing as arachidonic acid (ARA)
A major role of cell membrane ARA is as a substrate for the synthesis of eicosanoids, which include prostaglandins, thromboxanes and leukotrienes

Summary

Introduction

Arachidonic acid (ARA) is the common name for all-cis5,8,11,14-eicosatetraenoic acid (Fig. 1), commonly abbreviated to 20 : 4ω-6 or 20 : 4n-6. ARA has been reported to contribute an average of 9·6, 6·6, 15·5, 9·5 and 16 % of total FA in plasma phosphatidylcholine, plasma cholesteryl esters (CE), erythrocytes, platelets and blood mononuclear cells in healthy British adults who were non-oily-fish consumers and were consuming typical diets(5). The resulting metabolites have many roles in inflammation and pain, regulation of the immune response, bone turnover, platelet aggregation and blood clotting, smooth muscle contraction and renal function(9–11) These well-known functions of ARA-derived metabolites suggest that ARA itself might impact a range of outcomes related to human health. The threshold of ADP required to induce platelet aggregation was decreased in all four subjects (by 40–90 %), which was interpreted as an enhanced potential for blood clotting This was considered to be a major health concern and most likely explains why there was no further interest in studies with ARA supplements in humans until the mid-1990s(13–17)

Methods

Results

Conclusion