Effects of fish proteins and lipids on health in young European families: The diet test period ended

By: Inga Thorsdottir, Unit for Nutrition Research, University Hospital and University of Iceland

June 21. 2005

Preliminary analyses show that fish consumers seem to loose weight and their blood pressure decrease more than control group.


The SEAFOODplus Project 1.2 YOUNG is designed as a cross-European intervention where more than 300 young overweight adults are given qualified instructions to follow four different diets. The aim is to be able to differentiate between the effects of fish protein and fish lipids on metabolic syndrome risk factors, bone health and weight regulation. The project YOUNG includes also an epidemiological study on possible protective effects of fish oil on postpartum depression. This is tested by statistical calculations on data collected in Denmark.

An evaluation of available literature came to the conclusion that eating fish as a main course in one meal per week could lower prevalence of coronary heart disease, the main cause of death in industrialized countries, by 15% (He et al., 2004). Omega-3 fatty acids have been shown to have several physiological effects protecting against coronary heart disease and its precursor, the metabolic syndrome. They protect against arrhythmia, reduce platelet aggregation, and thereby have an anti-thrombotic effect, and they lower triglycerides in blood (Singleton et al., 2000, Chan et al., 2003).

Much less is known about the effects of fish protein. There are, however, several indications, from e.g. studies on animals, about fish proteinís health effects. Fish proteins have been suggested to prevent from insulin resistance in high-fat fed obese rats (Lavigne et al., 2001), to improve glucose-insulin metabolism and dyslipidemia (Moei et al., 1999), and diminish development of high blood pressure and hypercholesterolemia (Yahia et al., 2003, Trembley et al., 2003).

Studies in SEAFOODplus

The intervention studies of the SEAFOODplus project YOUNG aims at clearing the picture of health effects of fish protein vs. fish fat.

The diet test periods or the interventions are just finished in all the participating countries, which are Iceland, Ireland, Spain and Denmark, and working with the chemical analysis and directly measured data is starting. The basic diets were similar in composition, but designed with the following variables:

  • Diet 1 included lean fish
  • Diet 2 fat fish
  • Diet 3 meat and no fish, but omega-3 fatty acids capsules
  • Diet 4 meat and no fish, no n-3 fatty acids, but placebo capsules were given.

Many health variables were measured in every subject; such as body weight and appetite, and the metabolic syndrome risk factors measured as blood lipids, glucose, insulin and blood pressure, as well as effects on inflammation markers and bone health parameters. The data so far calculated are direct measurements on 98 Icelandic participants or about one third of the total number of participants. See table below.

The table shows strong average results of the diets given. It is too early to say anything about the difference between the effects of fish oil vs. fish protein, but the fish consumers did seem to loose more weight and decrease more in blood pressure.

Preliminary results of eight week diets in the SEAFOODplus project YOUNG.
Inga Thorsdottir and her team

Other partners in young: Mairead Kiely, Alfredo Martinez, Narcissa Bandarra, Sjurdur Olsen



Chan DC, Watts GF, Mori TA, Barret HR, Redgrave TG, Beilin LJ. Randomized controlled trial of the effect of n-3 fatty acid supplementation on the metabolism of apolipoprotein B-100 and chylomicron remnants in men with visceral obesity. Am J Clin Nutr 2003;77:300-307.

He K, Song Y, Daviglus ML, Liu K, Van Horn L, Dyer AR, Greenland P. Accumulated evidence on fish consumption and coronary heart disease mortality: a meta-analysis of cohort studies. Circulation.


Lavigne C, Tremblay F, Asselin G, Jacques H, Marette A. Prevention of skeletal muscle insulin resistance by dietary cod protein in high fat-fed rats. Am J Physiol Endocrinol Metab 2001;281:E62-E71.

Moei TA, Bao DQ, Burke V, Puddey IB, Watts GF, Beilin LJ. Dietary fish as a major component of a weight-loss diet:effect on serum lipids, glucose, and insulin metabolism in overweight hypertensive subjects. Am J Clin Nutr 1999;70:817-25.

Singleton CB, Walker BD, Campbell TJ. N-3 polyunsaturated fatty acids and cardiac mortality. Aust NZ J Med 2000;30:246-251.

Tremblay F, Lavigne C, Jacques H, Marette A. Dietary cod protein restores insulin-induced activation of phosphatidylinosol 3-kinase/Akt and GLUT4 translocation to the T-tubules in skeletal muscle of high-fat-fed obese rats. Diabetes 2003;52:29-37.

Yahia DA, Madanni S, Prost E, Prost J, Bouchenak M, Belleville J. Tissue antioxidant status differs in spontaneously hypertensive rats fed fish protein or casein. J Nutr 2003;133:479-482.