The RIO-Study project is a randomized, controlled, double-blind, crossover trial aimed at determining the effectiveness of omega-3 fatty acids at nutritional doses on lipid metabolism and inflammation in overweight and obese individuals with hypertriglyceridemia in Chile.

The study will include 40 participants (each participant will serve as their own control) aged 18-65, with 25-34.9 kg/m2 BMI and fasting triglycerides (TG) of 100-215 mg/dL. The intervention consists of 250 mg EPA from algae oil versus high oleic sunflower oil (HOSO) for 6 weeks each, after a 10-week washout period, the treatments will be switched for another 6 weeks, considering four visits during the whole study. The main outcomes to be evaluated are serum triglyceride levels, expression of target genes in peripheral blood mononuclear cells (PBMCs), low-grade inflammation biomarkers, and very low-density lipoprotein (VLDL) atherogenic properties. The study also analyzes background diet, chrononutrition, and physical activity aspects. Results are expected to provide new insights into the effects of nutritional doses of omega-3 in the Chilean population, particularly on fasting and postprandial triglyceride metabolism and cardiovascular disease risk reduction.

Before and after each intervention period, fasting blood samples will be collected. On each visit day, participants will consume a standardized breakfast (three slices of white bread with butter and jam), and postprandial blood samples will be taken at 0, 2, 4, and 6 hours to measure triglycerides and other lipid parameters.

The study will assess:

1. Serum triglyceride levels in fasting and postprandial states
2. Expression of target genes Peroxisome proliferator-activated receptor alpha (PPARα) and Sterol regulatory element binding protein-1 (SREBP1c) in peripheral blood mononuclear cells (PBMCs) at fasting (0h) and postprandial (4h) states
3. Levels of low-grade inflammation biomarkers Tumor Necrosis Factor-Alpha (TNFα) and Interleukin 6 ( IL-6) at fasting (0h) and postprandial (4h) states
4. Very low-density lipoprotein (VLDL) atherogenic properties in the fasting state Additionally, the investigators will collect data on chrononutrition, physical activity, and energy drink intake to understand their impact on lipid metabolism. Anthropometric measurements and bioimpedance analysis will be performed at each visit.

The study will collaborate with international partners for specialized analyses, including gene expression studies and VLDL atherogenic properties assessment.

This comprehensive approach aims to provide new insights into the effects of nutritional doses of omega-3 fatty acids on lipid metabolism and inflammation in the Chilean population, with a particular focus on postprandial triglyceride metabolism and cardiovascular disease risk reduction.

Inclusion Criteria:

• Adults between 18 and 65 years old, male and female.
• Body mass index (BMI) between 25 - 34,9 kg/m2.
• Fasting triglycerides between 100-215 mg/dL (1.13-2.43 mmol/L).

Exclusion Criteria:

• Unable to give informed consent.
• If you consume Omega-3 (you must stop consumption at least 10 weeks prior).
• Normal or Obesity Nutritional Status. Large weight variation (>10%) in the last 3 months.
• Triglycerides > 215 mg/dL.
• Blood pressure > 140/90 mmHg.
• Uncontrolled metabolic and chronic diseases (reference parameters for the disease in question will be considered).
• Pregnant women or those who are breastfeeding.
• Allergy or intolerance to gluten, milk protein and/or lactose, or any ingredient in the capsules (omega-3, oleic acid oil).
• Use of medications that affect lipid metabolism: Fibrates. (Statins will be allowed only if the treatment has been ongoing for over 3 months).
• Blood donation two months before or during the study period.
• Excessive alcohol consumption (>3 cans of beer per day)
• Taking anticoagulants.

The principal investigator will have exclusive access to the randomization code, which specifies the order of administration (either starting with HOSO or omega-3). This code is generated by an external statistician. The PI will ensure that the identical boxes containing capsules (both HOSO and Omega-3) are marked only with an Identification (ID). The randomization code will remain unknown to the participant, care provider, and outcomes assessor until after the primary outcome data has been analyzed.