A University of Eastern Finland study has found that eating more fatty fish can increase good cholesterol levels.

The study was published in the journal PLOS ONE and found participants who increased their fish fatty consumption to three or four fish meals per week had more large HDL (high-density lipoprotein) also known as "good cholesterol" particles in their blood than those who did not eat fish so frequently.

For the study, 131 participants with "impaired glucose metabolism and features of the metabolic syndrome" were divided into three groups, the first asked to eat wholegrain products and bilberries as well as three to four weekly servings of fatty fish, the second asked to eat whole grains in addition to their regular eating habits, and the third, a control group, asked to eliminate whole grains and limit their intake of berries and fish.

A total of 106 participants completed the trial.

Daily fish intake in the three groups worked out to be 67g, 42g and 16g respectively.

Participants who experienced the most positive changes were those eating three to four fish meals per week, and the greater the increase in fish intake, the greater the increase in concentration of large HDL.

Fish consumed for the study included fatty options such as rainbow trout, salmon, vendace and herring. The fish were prepared without additional butter or cream.

Cholesterol is generally divided into "good" and "bad," with good cholesterol capable of removing bad cholesterol from arteries in addition to lowering risk of cardiovascular disease.

Bad cholesterol contributes to increased risk of this disease.

"People shouldn't fool themselves into thinking that if their standard lipid levels are OK, there's no need to think about the diet, as things are a lot more complicated than that.

Soft vegetable fats and fish are something to prefer in any case," postdoctoral researcher Maria Lankinen says.

Researchers also emphasize the importance of maintaining a heart-healthy diet that's low in red meat and high in fish and other foods that lower bad cholesterol, such as olive oil, whole grains and nuts.