vitamin B complexn. A group of water-soluble vitamins, including thiamine, riboflavin, niacin, pantothenic acid, biotin, folate, vitamin B6, and vitamin B12, that are found in a variety of foods, especially yeast, liver, eggs, cereal grains, legumes, and some vegetables. Also called B complex.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.vitamin B complex n (Biochemistry) a large group of water-soluble vitamins occurring esp in liver and yeast: includes thiamine, riboflavin, nicotinic acid, pyridoxine, pantothenic acid, biotin, choline, folic acid, and cyanocobalamin. Sometimes shortened to: B complex Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014vitamin B complex n. an important group of water-soluble vitamins containing vitamin B1, vitamin B2, etc. [1925?30] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.vitamin B complex Any of a group of related vitamins important for normal cell growth and metabolism. The vitamins of the vitamin B complex include thiamine (vitamin B1), riboflavin (vitamin B2), pantothenic acid, niacin, biotin, and folic acid. ? The complex also includes vitamin B6 (also called pyridoxine), which is important in protein and fat metabolism and in healthy nerve function. It is found in liver, whole-grain foods, fish, yeast, and many vegetables. ? Another vitamin in this complex, vitamin B12 (also called cobalamin), is important in maintaining the health of blood and nerves. It is found in meat, eggs, milk, and milk products.The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.