The findings of previous experiments suggested that polyunsaturated fatty acids(PUFAs) has been linked to anti-hyperlipidemia, and reducing the risk of cardiovascular disease.This is a randomized double-blind trial, aims to study the effect of PUFAs on blood lipids and human metabolism. Firstly, the investigators will investigate the efficacy of mixed plant oil(echium oil, camelina oil, safflower oil) and pure echium oil on improving the levels of blood lipids. Secondly, next generation sequencing (NGS), ultra-high performance liquid chromatography-tandem mass spectrometric (UPLC-MS/MS) and gas chromatography-mass spectrometry detection will be conducted to explore the role of PUFAs on gut microbiota as well as metabolites. Thirdly, single nucleotide polymorphism will be genotyped by Time-of-flight mass spectrometry to find the gene-environment interaction effect.

Inclusion Criteria:

• Aged between 30-60 years of age
• Marginal elevated blood lipids or hyperlipidemia[Total cholesterol≥5.2 mmol/L(200 mg/dl) or triglyceride≥1.70 mmol/L(150mg/dl) or low density lipoprotein cholesterol≥3.4 mmol/L(130 mg/dl)]

Exclusion Criteria:

• Pregnancy；
• Known cardiovascular disease, diabetes, hypertension and any other chronic disease；
• Known gastrointestinal disease, such as Irritable Bowel Syndrome(IBS), functional bowel disease and so on；
• Acute or chronic inflammatory conditions;
• Liver or kidney dysfunction;
• An unwillingness to discontinue nutritional supplements；
• Use of lipid-lowering, antiinflammatory, antidepressant, or blood pressure medication;
• Evidence of drug or alcohol abuse；
• Take antibiotics or probiotics in the last three months.

The all details of groups assignment are arranged and controlled by the research designers. The color, shape, and external packaging of the n-3 polyunsaturated fatty acid and placebo are consistent (faint yellow to yellow oil in transparent soft capsules). Each bottle of capsules will be marked with the name (or identify number) of the participants by research designers. Thus, the grouping of participants is blind to the rest of the researchers (like outcomes assessors).