Research Summaries
Plain-language summaries of the most important clinical research on dietary supplements. Each summary includes key findings, study quality assessment, and practical takeaways.
Magnesium and Sleep: 2023 Meta-Analysis of 8 RCTs
A 2023 meta-analysis of 8 RCTs (n=2,132) found that magnesium supplementation significantly reduced sleep onset latency by an average of 17 minutes and improved subjective sleep quality scores. Effects were strongest with magnesium glycinate at doses of 200-400mg.
Ashwagandha and Cortisol Reduction: 2022 Meta-Analysis of 12 RCTs
A 2022 meta-analysis of 12 RCTs (n=1,002) found that ashwagandha supplementation significantly reduced serum cortisol levels by a weighted mean of 11.3% compared to placebo (p < 0.001). Effects were strongest with KSM-66 extract at 600mg/day for 8+ weeks.
Vitamin D and Immune Function: 2024 Systematic Review
A 2024 systematic review of 25 trials found that vitamin D supplementation (1,000-4,000 IU/day) reduced the risk of acute respiratory infections by 12% overall, with a 42% reduction in participants who were vitamin D deficient at baseline (serum 25(OH)D < 25 nmol/L).
Creatine and Cognitive Performance: 2023 RCT in Healthy Adults
A 2023 RCT (n=281) found that 5g/day of creatine monohydrate for 6 weeks significantly improved working memory scores by 8.5% and reduced cognitive fatigue under sleep deprivation conditions. Effects were most pronounced in vegetarians and during mentally demanding tasks.
Lion's Mane and Nerve Growth Factor: 2023 Systematic Review
A systematic review of clinical trials (n=897) found that lion's mane supplementation significantly improved cognitive function in adults with mild cognitive impairment, stimulated NGF synthesis via hericenones and erinacines, and demonstrated a favorable safety profile. Effects required 8-16 weeks of daily supplementation to manifest.
Beetroot Supplementation and Blood Pressure: 2023 Meta-Analysis of 22 RCTs
A meta-analysis of 22 RCTs (n=1,551) found that beetroot supplementation significantly reduced systolic blood pressure by 3.55 mmHg and diastolic blood pressure by 1.32 mmHg. Effects were mediated through dietary nitrate conversion to nitric oxide, which promotes vasodilation. Benefits were dose-dependent and more pronounced with supplementation lasting 2+ weeks.
Berberine and Blood Sugar Control: 2019 Meta-Analysis
A 2019 meta-analysis (n=2,569) found that berberine significantly reduced fasting blood glucose by 0.87 mmol/L, HbA1c by 0.72%, and improved insulin sensitivity. These effects were comparable to metformin in head-to-head trials. Berberine also provided additional lipid-lowering benefits not seen with metformin alone. Note: These findings do not justify replacing prescribed diabetes medication without medical supervision.