Assessment of oxidative stress and muscle damage in exercising horses in response to level and form of vitamin E

Vitamin E is an essential antioxidant noted for reducing oxidative stress. The goal was to determine (1) if supplemental vitamin E is beneficial to exercising horses and (2) if there is a benefit of natural vs synthetic supplements. After a 2wk washout 18 horses were divided into groups and fed a control diet plus: (1) 1000 IU synthetic -tocopherol (SYN-L), or (2) 4000 IU/d synthetic -tocopherol (SYN-H), or (3) 4000 IU/d RRR--tocopherol (NAT). Horses began a 6wk exercise protocol, with standard exercise tests (SET) performed pre and post the protocol. Venous blood samples were collected. NAT horses had higher -tocopherol (P<0.05). Plasma MDA levels were lower in NAT vs SYN-L horses post SET2 (P=0.02). Serum AST was significantly lower post SET2 in NAT horses vs SYN-L or SYN-H (P<0.05). In conclusion, feeding higher levels of the more bioavailable natural vitamin E source had a beneficial effect of reducing oxidative stress.