As β-hydroxy-β-methyl-butyrate is a precursor to the amino acid leucine, the effects of which have just been discussed, some researchers have suggested that HMB may have a better effect than leucine itself, but although some (Koevering, 1994; Smith, 2004) report positive results in animal tests, especially in combination with ω-3, many others do not support this theory (Nissen, 1996; Slater, 2001; Ransone, 2003; Hoffman, 2004). HMB, it should be noted, has no adverse effects. With regard to form and dosage, please refer to the section on products with a direct influence on performance devoted to this supplement.