Effects of chia seed (Salvia hispanica L.) supplementation on cardiometabolic health in overweight subjects: a systematic review and meta-analysis of RCTs

Background Obesity is a significant public health issue associated with various chronic diseases. Research has indicated that chia seeds have the potential to improve cardiometabolic health. However, due to the diversity of research and inconsistencies in study design, further investigation is needed to fully understand their clinical effects on overweight individuals. This review aims to comprehensively analyze the available evidence on the effects of chia seeds on cardiometabolic indices in overweight populations through a meta-analysis. Methods A comprehensive literature search was performed across PubMed, Web of Science, Scopus, and Embase databases from their inception until 01-03-2024 to identify randomized controlled trials (RCTs) evaluating the effect of chia on cardiometabolic indices in overweight subjects. The search strategy incorporated both Medical Subject Headings (MeSH). Following the screening, ten RCTs were finally included. The data, including subject characteristics, study design, and changes in serum biomarkers, were extracted and analyzed using Stata software version 18. Results The meta-analysis results reveal that chia supplementation no significant changes in lipid profile, including triglycerides (TG) (MD: - 5.80 mg/dL, p = 0.47), total cholesterol (TC) (MD: - 0.29 mg/dL, p = 0.95), high-density lipoprotein (HDL) (MD: 1.53 mg/dL, p = 0.33), and low-density lipoprotein (LDL) (MD: 0.63 mg/dL, p = 0.88). Similarity fasting blood glucose (FBG) (MD: - 0.03 mg/dL, p = 0.98), hemoglobin A1c (HbA1c) (MD: - 0.13%, p = 0.13), and insulin levels (MD: 0.45 mu IU/mL, p = 0.78). However, chia seed supplementation was associated with a significant reduction in C-reactive protein (CRP) (MD: - 1.18 mg/L, p < 0.0001), but no significant changes were observed in interleukin-6 (IL-6) (MD: - 0.15, p = 0.70) or tumor necrosis factor-alpha (TNF-alpha) (MD: 0.03, p = 0.91). There was no significant effect on body mass index (BMI) (MD: 0.1 kg/m(2), p = 0.91), but a significant reduction in waist circumference (WC) (MD: - 2.82 cm, p < 0.001) was noted. Additionally, chia seed supplementation resulted in a significant reduction in systolic blood pressure (BP) (MD: - 3.27 mmHg, p = 0.03), though diastolic BP changes were non-significant (MD: - 2.69 mmHg, p = 0.09). The studies showed low to moderate heterogeneity in outcome measures, with I-2 < 50%. Conclusion Chia seed supplementation does not significantly impact most lipid profile parameters and glycemic markers. However, it shows potential benefits in reducing WC, BP, and CRP. While chia seeds can be a valuable addition to cardiometabolic health management, they should be part of a broader health strategy that includes a balanced diet, exercise, and lifestyle modifications for optimal results.