Background. Randomized controlled trials (RCTs) remain the reference standard for establishing clinical efficacy for candidate drugs, but their restrictive eligibility criteria limit generalizability, and for dietary supplements the body of well-powered RCTs is small relative to the number of proposed health claims. Self-reported real-world data (RWD) by patients in social media are increasingly recognized as a complementary evidence source, yet their value in the nutraceutical domain is largely uncharacterized. Objective. To test whether benefits that users positively report for natural ingredients on Reddit are statistically associated with benefits demonstrated for those ingredients in the clinical-trial literature, and to characterize what a community corpus can reveal about application areas and side effects. Methods. We assembled a cross-sectional corpus of 216,350 distinct comments from 86 supplement-related subreddits (January 2022 - April 2026), covering 329 canonical ingredients and a shared, MeSH/MedDRA-aligned vocabulary of 581 benefit terms. Comment-level directionality (benefit/no-effect/irrelevant) was assigned by a natural-language-inference model. The independence of clinical efficacy and Reddit endorsement was tested with 2x2 chi-squared and Fisher exact tests across a sweep of endorsement thresholds, plus per-ingredient tests with Bonferroni correction. Results. Of 31,359 unique (ingredient, benefit) pairs, 2,508 were efficacy-demonstrated under the primary definition. The two signals were statistically associated. The association strengthened monotonically with endorsement volume, reaching OR 3.06 at [≥]20 comments and 7.14 at [≥]100. Among heavily-endorsed benefits ([≥]100 comments) 38% were RCT-demonstrated, versus ~9% overall. Community attention concentrated on sleep, skin and anxiety, whereas the trial literature concentrated on cardiovascular, pain, metabolic and mood indications. The most discussed and clinically validated nutraceutical-health claim pairs include melatonin-sleep cycle and quality, ginger with gastrointestinal relief and zinc with skin conditions. The concordance analysis revealed that 81% (573/711) of clinically proved nutraceutical-health claim pairs were in agreement with the reported experience of the Reddit community. Conclusions. Community endorsement and clinical efficacy are independent at the single-comment noise floor but positively concordant once a benefit is endorsed by multiple users, with concordance rising with consensus. Reddit-derived RWD is a useful hypothesis-generating prior for nutraceutical efficacy and a complementary, though not confirmatory, signal for prioritizing ingredients and indications for formal clinical study taking into consideration personalized characteristics.