Count: 0 — No recognized vitamins start with the letter L. Health authorities such as the NIH, WHO, and EFSA recognize vitamins A, the B‑complex group (individual B vitamins), C, D (D2/D3), E, and K; none of these official vitamin names begin with L. Interesting detail: early vitamin naming used single letters as compounds were discovered, and gaps or reclassifications (for example vitamins once labeled F or G) left a definitive set that does not include L.

Understand that the absence results from historical naming and biochemical classification, not from a lack of important nutrients that happen to start with L. Name assignments followed discovery order and chemical characterization; letters that were used and later reclassified are removed from the vitamin list, and the letter L is simply unused for any essential vitamin. Remember that the prefix “L‑” in biochemistry usually denotes molecule chirality (L‑amino acids), which is unrelated to vitamin naming.

Consider related compounds that often prompt this search: lutein and lycopene (carotenoids important for eye health), alpha‑lipoic acid (an antioxidant sometimes discussed as “vitamin‑like”), and linoleic acid (an essential fatty acid). Note that these are not classified as vitamins by major public‑health bodies, so consult NIH/EFSA/WHO references for authoritative lists and recommended intakes when you need official vitamin information.