Survey of n-3 and n-6 polyunsaturated fatty acids in fish and fish products.

Claudia Strobel,Gerhard Jahreis,Katrin Kuhnt

doi:10.1186/1476-511x-11-144

Claudia Strobel, Gerhard Jahreis + Show 1 more

Open Access

https://doi.org/10.1186/1476-511x-11-144

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Abstract

BackgroundThe imbalance of the n-3/n-6 ratio in the Western diet is characterised by a low intake of n-3 long-chain (LC) PUFA and a concurrent high intake of n-6 PUFA. Fish, in particular marine fish, is a unique source of n-3 LC PUFA. However, FA composition of consumed fish changed, due to the increasing usage of n-6 PUFA-rich vegetable oils in aquaculture feed and in fish processing (frying) which both lead to a further shift in n-6 PUFA to the detriment of n-3 LC PUFA.The aim of this study was to determine the ratio of n-3/n-6 including the contents of EPA and DHA in fish fillets and fish products from the German market (n=123). Furthermore, the study focussed on the FA content in farmed salmon compared to wild salmon as well as in processed Alaska pollock fillet, e.g., fish fingers.ResultsTotal fat and FA content in fish products varied considerably depending on fish species, feed management, and food processing. Mackerel, herring and trout fillets characteristically contained adequate dietary amounts of absolute EPA and DHA, due to their high fat contents. However, despite a lower fat content, tuna, pollock, and Alaska pollock can contribute considerable amounts of EPA and DHA to the human supply.Farmed salmon are an appropriate source of EPA and DHA owing to their higher fat content compared to wild salmon (12.3 vs. 2.1 wt %), however with elevated SFA, n-9 and n-6 FA contents representing the use of vegetable oils and oilseeds in aquaculture feed. The n-3/n-6 ratio was deteriorated (2.9 vs. 12.4) but still acceptable. Compared to pure fish fillets, breaded and pre-fried Alaska pollock fillet contained extraordinarily high fat and n-6 PUFA levels.ConclusionsSince fish species vary with respect to their n-3 LC PUFA contents, eating a variety of fish is advisable. High n-6 PUFA containing pre-fried fish support the imbalance of n-3/n-6 ratio in the Western diet. Thus, consumption of pure fish fillets is to be favoured. The lower n-3 PUFA portion in farmed fish can be offset by the higher fat content, however, with an unfavourable FA distribution compared to wild fellows.

Highlights

The imbalance of the n-3/n-6 ratio in the Western diet is characterised by a low intake of n-3 long-chain (LC) Polyunsaturated fatty acids (PUFA) and a concurrent high intake of n-6 PUFA
Fish and shellfish are considered to be nutritionally high-quality food as they are a major source of marinederived omega-3 long-chain polyunsaturated fatty acids (n-3 LC PUFA; C ≥ 20) for the human diet [1,2]
Since n-3 and n-6 PUFA compete for the same enzymes for desaturation and elongation and each class of PUFA has a different effect on human health, an appropriate ratio of both is crucial

Summary

Introduction

The imbalance of the n-3/n-6 ratio in the Western diet is characterised by a low intake of n-3 long-chain (LC) PUFA and a concurrent high intake of n-6 PUFA. N-3 LC PUFA together with their metabolites (eicosanoids) engaged in various physiological processes and are essential for normal growth and development [3] They play an important role in the prevention of cardiovascular and inflammatory diseases and have a. The current Western diet, involving a high consumption of meat and sausage products as well as an increased intake of vegetable oils (via excessive use in food processing), characterises high quantities of n-6 PUFA and a deficit in n-3 PUFA [12,13]. Current data reveals the n-6/ n-3 ratio in the Western diet as being between 8:1 and 17:1 [9,14] It follows that by decreasing n-6 PUFA and simultaneously increasing n-3 PUFA intake this ratio can be improved leading to positive effects for human health [8,11]

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