The highest return-on-investment interventions for under $100/month — every item RCT-backed.
Once lifestyle foundations are in place, a small number of generic, evidence-backed supplements produce outsized returns. Vitamin D (VITAL trial, n≈25,000), omega-3 EPA+DHA (REDUCE-IT, ASCEND), magnesium (multiple meta-analyses on BP/sleep/insulin sensitivity), and creatine (300+ RCTs over 30+ years) are available inexpensively in generic form, all have large randomized human evidence, and collect