NOW Foods Vitamin D-3 400 IU provides a gentle, entry-level dose of cholecalciferol — the bioidentical form of vitamin D — suitable for children, infants (with appropriate dosing guidance), or adults with minimal deficiency who simply want to supplement their dietary intake. At 400 IU this matches the traditional RDA for vitamin D established before modern research revealed the prevalence of deficiency and the need for higher doses in most populations. It remains an appropriate maintenance dose for those who receive regular sun exposure or whose 25(OH)D blood levels are already within optimal range. NOW Foods delivers D-3 in an oil-based softgel for maximum fat-soluble vitamin absorption, manufactured in their GMP-certified facility. A gentle, affordable daily vitamin D option.