Klinisk Biokemi i Norden Nr 3, vol. 27, 2015 - page 40

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Klinisk Biokemi i Norden · 3 2015
Doktorgradsavhandling
Essential omega-3 fatty acids in health and disease.
Association with total mortality and use of biomarkers
in clinical practice
Morten Lindberg
Central Laboratory, Vestfold Hospital Trust, Tønsberg, Norway
Department of Laboratory Medicine, Children’s and Women’s Health,
Norwegian University of Science and Technology, Trondheim, Norway
Morten Lindberg disputerte 31.
oktober 2014 for PhD graden ved
Norges teknisk-naturvitenska-
pelige universitet i Trondheim.
Avhandlingens tittel: Essential
Omega-3 Fatty Acids in Health
and Disease. Association with
Total Mortality and Use of Bio-
markers in Clinical Practice. Veiledere: Kristian S.
Bjerve og Arne
Åsberg
Essential fatty acids
Fat has always been an important source of energy.
In 1929 it was demonstrated that rats fed a diet
extremely low in fat developed scaly dermatitis,
caudal necrosis, weight loss and early death. These
symptoms were prevented or reversed when the fatty
acid part from lard (rich in omega-6 fatty acids) was
added to the diet. In the fifties and sixties, similar
symptoms were described in infants and children
who received milk substitutes containing little or no
fat and in adults dependent on prolonged parenteral
nutrition. In adults, the symptoms were resolved by
the administration of Intralipid, a soybean-oil based
intravenous fat emulsion developed in Sweden by
Dr. Arvid Wretlind. By this time, essential fatty acid
deficiency was recognized mainly as a deficiency in
linoleic acid and its relatives in the omega-6 fatty
acid family. It lead to a shift in dietary intakes of
fat where saturated and monounsaturated fat were
substituted by polyunsaturated fats and oils mainly
based on soybean production. During the following
decades, it became evident that the increased intake
of omega-6 fatty acids was not solely beneficial. In the
mid-eighties, the importance of omega-3 fatty acids
for the normal development of the retina and brain
was first described in rhesus monkeys. Later, clini-
cal symptoms ascribed to omega-3 deficiency were
reported and their importance in human physiology
established. Essential fatty acid deficiency per se is
restricted to patients on total parenteral nutrition
or patients having severe malabsorption syndromes.
However, in the following years, a number of physio-
logical functions were attributed to fatty acids and
their metabolites.
Fatty acids in health and disease
In addition to the symptoms of essential fatty acid
deficiency, both omega-3 and omega-6 fatty acids
have been shown to modulate many diseases. More
than 40 years ago Bang and Dyerberg described the
plasma lipid and lipoprotein pattern in Greenland
Eskimos and introduced a hypothesis to account for
the low incidence of coronary heart disease in a popu-
lation consuming a high-fat, high-cholesterol diet.
In the following years, the qualitative difference of
plasma fatty acid composition was compared between
Greenland Eskimos and Caucasian Danes living in
Denmark. It became clear that the main difference
was an increased concentration of long-chain n-3
polyunsaturated fatty acids in the diet and plasma
of Greenland Eskimos. With their observation, Bang
and Dyerberg opened a new field of research. Since
their first publication in 1971, thousands of scientific
reports have contributed to our understanding of how
long-chain n-3 fatty acids may modulate a diversity
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