Nature's Plus Mega B-150 Sustained Release - 90 Tablets Nature's Plus is pleased to offer the highest potency B-Complex available in an all-natural rice bran base. Mega B-150 contains no yeast and is easily digested and absorbed. Each tablet is in a special base which provides for the gradual release of ingredients over a prolonged period of time. Free of artificial colors and preservatives Free of yeast, wheat, corn, soy, and milk B-ComplexThe vitamin B-complex refers to all of the known essential water-soluble vitamins except for vitamin C. These include thiamine (vitamin B1), riboflavin (vitamin B2), niacin (vitamin B3), pantothenic acid (vitamin B5), pyridoxine (vitamin B6), biotin, folic acid and the cobalamins (vitamin B12). "Vitamin B" was once thought to be a single nutrient that existed in extracts of rice, liver, or yeast. Researchers later discovered these extracts contained several vitamins, which were given distinguishing numbers. Unfortunately, this has led to an erroneous belief among non-scientists that these vitamins have a special relationship to each other. Further adding to confusion has been the "unofficial" designation of other substances as members of the B-complex, such as choline, inositol, and para-aminobenzoic acid (Paba), even though they are not essential vitamins. Each member of the B-complex has a unique structure and performs unique functions in the human body. Vitamins B1, B2, B3, and biotin participate in different aspects of energy production, vitamin B6 is essential for amino acid metabolism, and vitamin B12 and folic acid facilitate steps required for cell division. Each of these vitamins has many additional functions. However, contrary to popular belief, no functions require all B-complex vitamins simultaneously. Human requirements for members of the B-complex vary considerablyfrom 3 mcg per day for vitamin B12 to 18 mg per day for vitamin B3 in adult males, for example.