The L and D Conference for amino acid configuration refers not into the optical activity from the amino acid alone but relatively to your optical action on the isomer of glyceraldehyde from which that amino acid can, in theory, be synthesized (D-glyceraldehyde is dextrorotatory; L-glyceraldehyde is levorotatory). To counter this, https://www.supplementsbymail.com/product-category/amino-acids/