Omega-6 - experts lowering the requirement from 1% to 0.3% ...

Metabolism. 2008 May;57(5):698-707.

Fish oil prevents essential fatty acid deficiency and enhances growth:
clinical and biochemical implications.

Strijbosch RA, Lee S, Arsenault DA, Andersson C, Gura KM, Bistrian BR,
Puder M.
Department of Surgery and the Vascular Biology Program, Children's
Hospital Boston, Harvard Medical School, Boston, MA 02115, USA.

Fish oil, a rich source of omega-3 fatty acids, has never been used as
the sole source of lipid in clinical practice for fear of development
of essential fatty acid deficiency, as it lacks the believed requisite
levels of linoleic acid, an omega-6 fatty acid. The objectives of this
study were to establish biochemical standards for fish oil as the sole
fat and to test the hypothesis that fish oil contains adequate amounts
of omega-6 fatty acids to prevent essential fatty acid deficiency.
Forty mice were divided into 2 groups that were either pair fed or
allowed to eat ad libitum. In each group, 4 subgroups of 5 mice were
fed 1%, 5%, and 10% fish oil diets by weight or a control soybean diet
for 9 weeks. Blood was collected at 4 time points, and fatty acid
analysis was performed. Food intake and weight status were monitored.
All groups but the pair-fed 1% fish oil group gained weight, and the
5% fish oil group showed the highest caloric efficiency in both pair-
fed and ad libitum groups. Fatty acid profiles for the 1% fish oil
group displayed clear essential fatty acid deficiency, 5% fish oil
appeared marginal, and 10% and soybean oil diets were found to prevent
essential fatty acid deficiency. Fish oil enhances growth through
higher caloric efficiency. We established a total omega-6 fatty acid
requirement of between 0.30% and 0.56% of dietary energy,
approximately half of the conventionally believed 1% as linoleic acid.
This can presumably be attributed to the fact that fish oil contains
not only a small amount of linoleic acid, but also arachidonic acid,
which has greater efficiency to meet omega-6 fatty acid requirements.

PMID: 18442636
.

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