An 8-Week Triple-Blind, Randomized, Placebo-Controlled Trial Evaluating High-Dose Vitamin D3 and Flaxseed Oil for...

This study aimed to evaluate the effects of cosupplementation with high-dose vitamin D3 and flaxseed oil on inflammatory markers, oxidative stress, and metabolic health in elderly patients with T2DM.

We conducted an 8-week, triple-blind, randomized, placebo-controlled clinical trial in Iran, enrolling 104 elderly patients with T2DM, of whom 102 completed the study. The intervention group received 500 mg of flaxseed oil three times daily and 50,000 IU of vitamin D3 orally every two weeks, while the control group received matching placebos.

The primary outcome, serum hs-CRP, was significantly reduced in the intervention group compared to controls (MD: -0.98 μg/mL, p = 0.034). Exploratory analyses of secondary outcomes suggested additional potential benefits: total antioxidant capacity improved (MD: +0.60 mmol/L, p < 0.05), and reductions were observed in weight (MD: -1.73 kg, p < 0.001), BMI (MD: -0.67 kg/m², p < 0.001), fasting blood glucose (MD: -22.83 mg/dL, p = 0.015), fasting insulin (MD: -0.94 μIU/mL, p = 0.008), homeostatic model assessment of insulin resistance (MD: -1.31, p = 0.001), triglycerides (MD: -15.00 mg/dL, p = 0.020), and total cholesterol (MD: -2.52 mg/dL, p = 0.028). Physical health-related quality of life, including pain scores and physical functioning, also improved significantly (p < 0.05). The intervention was well tolerated with minimal adverse events.

Cosupplementation with flaxseed oil and high-dose vitamin D₃ significantly reduced systemic inflammation in elderly patients with T2DM. Exploratory findings further suggest potential benefits for oxidative stress, glycemic control, lipid profile, and physical quality of life, warranting confirmation in future trials. Trial Registration: Iranian Clinical Trials Register: IRCT20161022030424N8.