The U.S. National Institutes of Health therefore recommends that during the winter in the northern latitudes, people over 50 in particular should increase their intake of vitamin D by eating foods such as fatty fish and taking cod - liver oil or by taking vitamin D supplements, though not to exceed 2,000 international units, 50 micrograms, per day.
Oleh karena itu, Lembaga Kesehatan Nasional AS merekomendasikan agar selama musim dingin di kawasan lintang utara, orang - orang yang berusia di atas 50 tahun khususnya perlu meningkatkan konsumsi vitamin D mereka dengan menyantap makanan seperti ikan yang berlemak dan minum minyak ikan atau memakan suplemen vitamin D, tetapi tidak melebihi 2.000 unit internasional, 50 mikrogram, per hari.