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.
Background
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 protein’s 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.
