All sources, graded

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

Transparent rubric — every item shows its grade and computed weight. RCT > cohort > case > preclinical > opinion; predatory sources are knocked down 90%.

Weight = grade weight × log₁₀(sample size + 10). So a stronger study grade dominates, a bigger trial counts for a bit more, and predatory sources are cut to 10%. It is the exact number the score is built from — nothing hidden.

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Showing 3 of 3 sources.

rct · n=25,000Randomized trial

Large randomized trial found no reduction in respiratory infections overall.

Source: VITAL-type trial

contradicts · weight 17.59 · Randomized trial

rct · n=5,000Randomized trial

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

Source: Deficiency-subgroup RCT

contradicts · weight 14.80 · Randomized trial

cohort · n=11,000Cohort study

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

Source: Observational cohort

supports · weight 12.13 · Cohort study