Assessment

Daily vitamin D supplementation prevents the common cold in the general population.

Evidence strength (0–100) = the quality-weighted share of evidence that supports the claim, out of all evidence for and against. Each source is weighted by study grade (RCT > cohort > case > preclinical > opinion) and, more gently, by sample size; predatory sources are cut 90%. Bands: ≥66 well supported, 40–65 mixed, <40 not supported. No meaningful evidence → “insufficient”, never a verdict from noise.

Evidence strengthNot supported · 27/100

Conflicting high-grade studies. Strong studies disagree — we show the conflict instead of silently picking a winner.

The strongest supporting evidence is a cohort study (n=11,000). The strongest contradicting evidence is a randomized trial (n=25,000). High-grade studies disagree, so we show the conflict rather than pick a winner. Strength is the quality-weighted balance of supporting vs contradicting evidence; study quality outweighs sample size.

Strongest counter-evidence (always shown)

The honesty rule: we pin the single strongest study that disagrees with the claim — even when the claim is well supported — so the best counter-argument is never hidden from you.

Large randomized trial found no reduction in respiratory infections overall.

Randomized trial · n=25,000

Supporting (1)

cohort · n=11,000Cohort study

Observational link between low vitamin D and more colds in some subgroups.

Source: Observational cohort

Contradicting (2)

rct · n=25,000Randomized trial

Large randomized trial found no reduction in respiratory infections overall.

Source: VITAL-type trial

rct · n=5,000Randomized trial

Benefit seen only in severely deficient participants, not the general population.

Source: Deficiency-subgroup RCT

See all sources, graded Get shareable card →

Compare with another assessed claim

verify.log

$ assess claim cmr1fimma0000atxf89rwbywb
evidence gathered: 3 item(s)
support weight=12.13  contradict weight=32.39
strength = support / (support + contradict) = 27/100
verdict: Not supported  [conflict flagged]
honesty rule: strongest counter shown

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