The urgent need to recommend an intake of vitamin D that is effective - Vieth, R; Bischoff-Ferrari, H; Boucher, B J; Dawson-Hughes, B; Garland, C F; Heaney, R P; Holick, M F; Hollis, B W; Lamberg-Allardt, C; McGrath, J J; Norman, A W; Scragg, R; Whiting, S J; Willett, W C; Zittermann, A (Am J Clin Nutr, 2007)