Pure City Research Key takeaways The strongest independent human evidence for collagen peptides is not skin — it is tendon collagen synthesis, where a publicly funded University of California, Davis trial found gelatin plus vitamin C timed before exercise raised collagen-synthesis markers (Shaw et al. 2016). Skin hydration, elasticity, and wrinkle claims are the most heavily marketed use, … Read more
Key takeaways Strongest evidence: berberine 0.9–1.5 g/day lowers fasting glucose, post-meal glucose, and LDL/triglycerides in people with type 2 diabetes or metabolic syndrome, with effect sizes comparable to low-dose oral diabetes drugs in short trials (Wang et al. 2024 meta-analysis, Liu et al. 2025 meta-analysis). “Nature’s Ozempic” is not supported by the data — GLP-1 … Read more
Key takeaways Strongest evidence: 300–600 mg/day of standardized root extract for 8 weeks lowers perceived stress and cortisol in adults with self-reported stress, based on a 2025 meta-analysis of 15 randomized trials in 873 people (Bachour et al. 2025, BJPsych Open). Cortisol reduction is more consistently replicated than “less stress” — a separate 2025 review … Read more
Key takeaways Strongest evidence: creatine monohydrate at 3-5 g/day increases upper-body strength by roughly 4.4 kg and lower-body strength by roughly 11.4 kg beyond resistance training alone in adults under 50, and produces similar gains in older adults doing resistance training (Burke et al. 2024, Sharifian et al. 2025). Cognitive benefits are real but narrow … Read more
Key takeaways St John’s wort has the strongest single-supplement evidence for mild-to-moderate depression — a Cochrane review of 29 trials (5,489 patients) found it superior to placebo and comparable to standard antidepressants — but it carries the highest interaction risk of any supplement covered, including serotonin syndrome risk with antidepressants. L-theanine (200–400 mg/day) and saffron … Read more
Key takeaways A 2024 BMJ network meta-analysis of 218 studies (14,170 participants) found exercise produced moderate reductions in depression symptoms — walking/jogging, yoga, strength training, and tai chi/qigong all showed benefit. CBT is the strongest professional-level intervention: APA describes it as effective for depression, anxiety disorders, and severe mental illness, with evidence it matches or … Read more
Key takeaways Psyllium (soluble fiber) has the strongest guideline-backed evidence among gut supplements — ACG recommends it specifically over insoluble fiber for IBS symptoms. Probiotics only work when strain-matched to a specific outcome: Bifidobacterium infantis 35624 and B. bifidum MIMBb75 show benefit in specific IBS trials, but “more strains is better” claims are not supported … Read more
Key takeaways ACG’s clinical guideline recommends soluble fiber (psyllium) — not insoluble bran — as the best-supported nonprescription first step for IBS symptoms. A structured, time-limited low-FODMAP diet trial improves global IBS symptoms per a 2022 network meta-analysis of RCTs, but it’s meant to be short-term with dietitian-guided reintroduction, not permanent restriction. Enteric-coated peppermint oil … Read more
Key takeaways Potassium has the strongest BP-lowering evidence of any supplement — a WHO-supported meta-analysis found SBP −3.49 mmHg and DBP −1.96 mmHg in adults — but it’s also the riskiest, since ACE inhibitors, ARBs, potassium-sparing diuretics, and kidney disease can turn it into dangerous hyperkalemia. Hibiscus showed the largest effect size among botanicals in … Read more
Key takeaways WHO reports 1.4 billion adults aged 30–79 had hypertension in 2024, 44% were unaware, and only 23% had it controlled — most cases are symptomless and require actual measurement, not guessing (WHO hypertension fact sheet). Combining a DASH-style diet with sodium reduction is the single most powerful non-drug lever: the DASH-Sodium trial found … Read more
