The LIPGENE Human Dietary Intervention Study, multi-centre, trans -European, single-blinded, randomised, controlled trial with two principal aims. Firstly to determine the relative efficacy of reducing dietary SFA consumption, by altering quality of dietary fat and reducing the quantity of dietary fat, on metabolic and molecular risk factors of the metabolic syndrome. Secondly to determine if common genetic polymorphisms affect an individual's responsiveness to dietary therapy.

521 free-living subjects with the metabolic syndrome received one of four dietary treatments for 12 weeks: (1) High-fat (38% energy) SFA-rich diet; (2) High-fat (38% energy), MUFA-rich diet; (3) Isocaloric low-fat (28% energy), high-complex carbohydrate diet and (4) Isocaloric low-fat (28% energy), high-complex carbohydrate diet, with 1 g/d LC n-3 PUFA. A 3-day weighed food intake assessed dietary compliance pre-, mid- and post- intervention. An IVGTT, lipoprotein analysis, cytokine, adhesion molecule, coagulation factor and isoprostane levels were determined pre- and post-intervention. DNA, adipose and skeletal muscle biopsies, and PBMC were isolated to characterise nutrient sensitive molecular markers of insulin sensitivity.

Inclusion Criteria:

• Gender: males and females (not pregnant or lactating).
• Body Mass Index (BMI) 20-40 kg/m2
• Total cholesterol concentration equal to or < 8.0 mmol/l.
• Medications / nutritional supplements allowed, on condition that the subjects adhere to the same regimen during the intervention: anti-hypertensive medication (including beta-blockers), oral contraceptives, hormone replacement therapy, multi-vitamin supplements, other non-fatty acid based nutritional supplements (e.g. garlic, anti-oxidants, etc).
• Smokers and non-smokers.
• Regular consumers of alcohol, which is not excessive as defined by elevated liver enzymes (AST and ALT).
• Ethnicity: Intention to include white Europeans.

Exclusion Criteria:

• Diabetes or other endocrine disorders.
• Chronic inflammatory conditions.
• Kidney or liver dysfunction.
• Iron deficiency anaemia (haemoglobin < 12g/dl men, < 11g/dl women)
• Prescribed hypolipidaemic medication
• Prescribed anti-inflammatory medication
• Fatty acid supplements including fish oils, evening primrose oil, etc.
• Consumers of high doses of antioxidant vitamins (A, C, E, beta-carotene).
• Red rice yeast (Monascus purpureus) supplement usage.
• High consumers of oily fish (> 2 serving of oily fish per week of herring, mackerel, kippers, pilchards, sardines, salmon, trout, tuna (fresh), crabmeat or marlin). One portion is defined as a small herring or mackerel, one can of salmon or sardines or one salmon or tuna steak. Tinned tuna is permitted as it contains only minor amounts of long chain n-3 PUFAs.
• Highly trained or endurance athletes or those who participate in more than 3 periods of intense exercise per week.
• Volunteers planning to start a special diet or loose weight (e.g. the Slimfast Plan, Atkins Diet etc).
• Weight change equal or >3kg within the last 3 months.
• Alcohol or drug abuse (based on clinical judgement).
• Pregnant / lactating females / women planning a pregnancy in the next 12 months. Women who become pregnant during the dietary intervention period should be removed from the study.