Dear Sally
<It has come to my attention that the lipid composition of farm raised fish
may contain significant amounts of saturated fat. As a registered dietitian,
I am concerned about the lipid content of farm raised fish. I would
appreciate any information(brief) you have.>
There is a large literature, predominately in research journals, on lipid
content and lipid compositional of fish, wild and farmed. I append a
bibliography in respect of farmed fish culled from my own notes. I would not
try to claim it is comprehensive. It is not easy to summarise this complex
literature, but some generalisations can be made. Typically farmed fish have
higher lipid contents than their counterparts caught from the wild. The
fatty acid composition of the lipids varies both between and within farmed
or wild, and is influenced by the diet of the fish. A portion of the fatty
acids are saturated, but the fraction of PUFA's is not markedly different
between wild and farmed fish. I don't think you can classify fish lipids
from whatever source as 'saturated'. Since fat content of farmed fish is
markedly higher than that of the wild counterpart a consumer wild take in
more PUFA's from a given weight of farmed fish than from the wild
counterpart. I have already referred to fatty acid composition of the fat
being influenced by diet, but fish are capable of metabolising fats in the
diet to increase the proportion of PUFA's in their lipids even when their
diet is low in them.
The beneficial effects of fish lipids in the control of cardiovascular
disease is well documented in the nutrition literature, but I note an
increasing interest in the effects of PUFA's on neurological development in
the foetus and in infants. In refining the mechanisms of the effects of PUFA
's in human nutrition, attention is being given to the balance between n-3
and n-6 unsaturated acids, and some of the listed references reflect this
interest.
I am not aware of a comprehensive review of a comparison of lipid
compositions of wid and farmed fish, but I can strongly recommend to you,
and anyone interested in fish lipids and human nutrition, the first paper
listed, Arts et al, 2001. Though it is not primarily about farmed fish there
are some mentions of aquacultured products and it forms an excellent basis
for evaluating the literature on fish lipids and human nutrition.
Peter Howgate
-------------------------------------------------
Arts, M.T., Ackman, R.G. & Holub, B.J. (2001). Essential fatty acids in
aquatic ecosystems; a crucial link between diet and human health and
evolution. Canadian Journal of Fisheries and Aquatic Sciences, 58, 122-137.
Aursand, M., Bleivik, B., Rainuzzo, J.R., Jørgensen, L. & Mohr, V. (1994).
Lipid distribution and composition of commercially farmed Atlantic salmon
(Salmo salar). Journal of the Science of Food and Agriculture, 64, 239-248
Bell, J.G., McEvoy, J., Webster, J.L., McGhee, F., Millar, R.M. & Sargent,
J.R. (1998). Flesh lipid and carotenoid composition of Scottish farmed
Atlantic salmon (Salmo salar). Journal of Agricultural and Food Chemistry,
46, 119-127
Bjerkeng, B., Refstie, S., Fjalestad, K.T., Storebakken, T., Rødbotten, M. &
Roem, A.J. (1997). Quality parameters of the flesh of Atlantic salmon (Salmo
salar) as affected by dietary fat content and full-fat soybean meal as a
partial substitute for fish meal in the diet. Aquaculture, 157, 297-309
Brannan, R.G. & Erickson, M.C. (1996). Sensory assessment of frozen stored
channel catfish in relation to lipid oxidation. Journal of Aquatic Food
Product Technology, 5, 67-80
Cronin, D.A., Powell, R. & Gormley, R. (1991). An examination of the n-3 and
n-6 polyunsaturated fatty acid status of wild and farmed Atlantic salmon
(Salmo salar). Irish Journal of Food Science and Technology, 15, 53-62.
Erickson, M.C. (1992). Lipid and tocopherol composition of two varieties of
Tilapia . Journal of Aquatic Food Product Technology, 1, 91-109
Erickson, M.C. (1993). Compositional parameters and their relationship to
oxidative stability of channel catfish Journal of Agricultural and Food
Chemistry, 41, 1213-1218
Fowler, K.P., Karahadian, C., Greenberg, N.J. & Harrell, R.M. (1994).
Composition and quality of aquacultured hybrid striped bass fillets as
affected by dietary fatty acids. Journal of Food Science, 59, 70-75, 90.
George, R. & Bhopal, R. (1995). Fat composition of free living and farmed
sea species: implications for human diet and sea-farming techniques. British
Food Journal, 97, 19-22.
Greene, D.H.S. & Selivonchick, D.P. (1990). Effects of dietary vegetable,
animal and marine lipids on muscle lipid and hematology of rainbow trout
(Salmo gairdneri). Aquaculture, 89, 165-182
Guillou, A., Soucy, P., Khalil, M. & Adambounou, L. (1995). Effects of
dietary vegetable and marine lipid on growth, muscle fatty acid composition
and organoleptic quality of flesh of brook charr. Aquaculture, 136, 351-362
Higgs, D.A., Skura, B.J., Dosanjh, B.S., Yan, D., Powrie, W.D. & Donaldson,
E.M. Comparing farmed and wild coho salmon. (1989 ). Canadian Aquaculture,
5, 51-53.
Johansson, L., Kiessling, A., Åsgård, T & Berglund, L. (1995). Effects of
ration level in rainbow trout, Oncorhyncus mykiss (Walbaum), on sensory
characteristics, lipid content and fatty acid composition. Aquaculture
Nutrition, 1, 59-66.
Kennish, J.M., Chambers, K.A., Whipple, W.J., Sharp-Dahl, J.L. & Rice, S.D.
(1992). Differences in lipid, fatty acid composition and cholesterol levels
among tissues and among stocks for pen-reared chinook salmon (Onchorynchus
tshawytscha) fed on a commercial diet. Seafood Science and Technology.
Proceedings of the International Conference Seafood 2000, 13-16 May, 1990,
Halifax, Canada, E.G. Bligh, (ed), Fishing News Books, Oxford, 46-57.
Kennish, J.M., Sharp-Dahl, J.L., Chambers, K.A., Thrower, F. & Rice, S.D.
(1992). The effect of a herring diet on lipid composition, fatty acid
composition, and cholesterol levels in the muscle tissue of pen-reared
chinook salmon (Oncorhynchus tschawytscha). Aquaculture, 108, 309-322.
Kiessling, A., Johansson, L. & Storebakken, T. (1989). Effects of reduced
feed ration levels on fat content and fatty acid composition in white and
red muscle from rainbow trout. Aquaculture, 79, 169-175.
O'Leary, C.D. & Matthews, A.D. (1990). Lipid class distribution and fatty
acid composition of wild and farmed prawn, Penaeus monodon. Aquaculture, 89,
65-81
Otwell, W.S. & Rickards, W.L. (1981). Cultured and wild American eels,
Anguilla rostrata: fat content and fatty acid composition. Aquaculture, 26,
67-76.
Sargent, J.R., & Tacon, A.G.(1999). Development of farmed fish: a
nutritionally necessary alternative to meat. Proceedings of the Nutrition
Society, 58(2), 377-83.
Skonberg, D.I. Rasco, B.A. & Dong, F.M. (1994). Fatty acid composition of
salmonid muscle changes in response to a high oleic acid diet. Journal of
Nutrition, 124, 1628-1638.
Stéphan, G., Guillaume, J. & Lamour, F. (1995). Lipid peroxidation in turbot
(Scophthalmus maximus) tissue: effect of dietary vitamin E and dietary n-6
or n-3 polyunsaturated fatty acids. Aquaculture, 130, 251-268
Steffens, W. (1998). Effects of variation in essential fatty acids in fish
feeds on nutritive value of freshwater fish for humans. Aquaculture, 151,
97-119.
Tucker, B.W. (1992). Aquatic products and human nutrition. Journal of
Aquatic Food Product Technology, 1, 5-8.
Turley, E. & Strain, J.J. (1993). Fish oils, eicosanoid biosynthesis and
cardiovascular disease: an overview. International Journal of Food Sciences
and Nutrition, 44, 145-152.
Webster, C.D., Tiu, L.G., Tidwell, J.H., van Wyk, P. & Howeton, R.D. (1995).
Effects of dietary protein and lipid levels on growth and body composition
of sunshine bass (Morone chrysops x M. saxitilis) reared in cages.
Aquaculture, 131, 291-301.
van Vliet, T. & Katan, M.B. (1990). Lower ratio of n-3 to n-6 fatty acids in
cultured than in wild fish. American Journal of Clinical Nutrition, 51, 1-2.
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