Translations:Vitamin/63/en

The missing numbered B vitamins were reclassified or determined not to be vitamins. For example, B₉ is folic acid and five of the folates are in the range B₁₁ through B₁₆. Others, such as PABA (formerly B₁₀), are biologically inactive, toxic, or with unclassifiable effects in humans, or not generally recognised as vitamins by science, such as the highest-numbered, which some naturopath practitioners call B₂₁ and B₂₂. There are also lettered B substances (e.g., B_m) listed at B vitamins that are not recognized as vitamins. There are other "D vitamins" now recognised as other substances, which some sources of the same type number up to D₇. The controversial cancer treatment laetrile was at one point lettered as vitamin B₁₇. There appears to be no consensus on the existence of substances that may have at one time been named as vitamins Q, R, T, V, W, X, Y or Z.