High cholesterol concentration is a major risk factor for cardiovascular disease (CVD), and consumption of fish has been associated with a lower CVD risk in several studies. The beneficial health effects of consuming fish have traditionally been ascribed to the long-chain PUFA (LC-PUFA) EPA (C20:5n-3) and DHA (C22:6n-3), although consumption of fish oils or concentrates with high EPA and DHA contents does not affect the cholesterol concentration in humans and lowers the cholesterol concentration in rats and mice only when given in very high doses. Fish oils contain a plethora of fatty acids besides EPA and DHA, and in recent years, increased focus has been on the long-chain MUFA (LC-MUFA) cetoleic acid (C22:1n-11). Cetoleic acid is found in high amounts in oils from certain fish species such as herring, which has relatively low contents of both EPA and DHA. The investigators have recently summarised and meta-analysed the available literature that investigates the effects of diets containing fish oils or fish oil concentrates that have a high content of cetoleic acid but low or no content of EPA and DHA on cholesterol concentration in rodents, showing that cetoleic acid-rich fish oils and concentrates prevent high cholesterol concentration.

Inclusion Criteria:

• BMI over 25 kg/m2
• Stable body weight last 3 months

Exclusion Criteria:

• Allergies towards fish, milk, egg, gluten
• Tobacco use (cigarettes or snus)
• Diseases affecting the heart, intestinal function, kidney function or insulin secretion
• Use of medications targeting cholesterol -or glucose metabolism
• Use of dietary supplements
• Pregnant or breastfeeding
• Following a strict diet
• Had bariatric surgery or using medications for weight loss
• Recent or planned surgical procedures
• High intake of fish/seafood