A number of natural substances have been shown to have an effect on the chemistry of the body to produce an increase in muscle growth, similar to the effect of anabolic steroids.
Some examples are Gamma oryzanol, Chromium and Creatine. These substances are natural chemicals found in feed, and it has been demon-strated that supplementing these chemicals at a higher level can stimulate muscle growth.
Gamma Oryzanol is a rice bran oil derivative with two major active molecules, Sterol and Ferulic acid. Trials in the U.S., Japan and Australia have shown that gamma oryzanol has effects on weight gain and performance comparable to some anabolic steroids. Gamma oryzanol has effects on the body's endocrine system resulting in increased metabolism of fat and increased synthesis of protein.
Human studies with weight lifters and athletes have shown increased muscle mass and definition, reduced fatigue and reduced post-exercise muscle soreness, which contributes to better training sessions. One trial of weight lifters in the U.S. compared a group taking gamma oryzanol with a group taking an anabolic steroid. The gamma oryzanol group showed greater weight gains, with better muscle definition and a leaner appearance. In a trial in Australia of 40 thoroughbred horses in full training a group supplemented daily with gamma oryzanol was compared with a control group. The gamma oryzanol group showed improved muscle to fat ratio, with better muscle definition in the rump, neck and over the withers. The horses supplemented with gamma oryzanol also maintained appetite better than the control group.
In addition, studies have shown that gamma oryzanol is a natural antioxidant and can lower cholesterol levels in the blood. It has been used in humans to lower the risk of heart disease (Scavariello and Arellano, 1998). Gamma oryzanol has also been shown to reduce the risk of gastric ulcers and increased gastrointestinal motility caused by stress (Ichimaru et al, 1984).
- Chromium enhances the activity of insulin, which is vital to many body functions, most importantly in dealing with dietary sugar and in facilitating muscle growth (Colgan, 1993). Chromium is a component of glucose tolerance factor, which potentiates the action of insulin. Insulin has anabolic effect as it promotes glucose uptake by cells, stimulates amino acid synthesis and inhibits tissue lipase. Chromium excretion is greater in athletic animals and the chromium requirement is increased by physical activity. In addition, many diets are deficient in chromium and supplementation is vital for optimal muscular development. Supplementation with chromium has been shown, in scientific trials in both humans and pigs, to increase muscle weight gain and decrease body fat (Press et al, 1990; Page et al, 1991). In feed-lot calves chromium excretion is increased by stress and supplementing with chromium has been shown to stimulate the immune system resulting in decreased incidence of disease (Jackson, 1997). In a trial of performance horses, supplementation with 5mg/day of chromium resulted in an improvement in performance of an exercise stress test (Pagan et al, 1995). Horses receiving chromium showed lower peak lactic acid levels and more efficient utilisation of fat during exercise. Chromium may be beneficial for horses who tie-up due to more efficient utilisation of glucose (Jackson, 1997). Chromium picolinate is a unique form of chromium that is very well absorbed and completely safe.
- Creatine is an amino acid involved in energy supply to muscles. During exercise the initial energy supply to muscles is adenosine tri-phosphate (ATP), which releases energy as it is converted to adenosine di-phosphate (ADP).Creatine, as creatine phosphate, converts ADP back to ATP, so it can be reused. A contributing factor in the development of muscle fatigue is a deficiency of creatine. Supplementing with creatine results in an increase in muscle creatine stores (Greenhaff et al, 1994). This means that more creatine phosphate is available to form ATP. Increased ATP supply prevents the muscle using glycolysis for energy and thus lactic acid production, associated with glycolysis, is reduced and the onset of muscle fatigue is delayed. Delaying the onset of fatigue means that exercise can continue for longer, at a higher level, which results in increased muscle size, strength and power (Sahelian and Tuttle, 1997).
Creatine supplementation also increases muscle size by bloating the muscle cells with creatine rich fluid. This swelling of the muscle cells results in stretching, which stimulates muscle cells to grow. One of the stimulating factors of anabolic steroid use is water retention, which causes muscles to swell and grow. Creatine also promotes greater nitrogen retention and protein synthesis by increasing intracellular water levels. Studies have shown that creatine supplementation increases power output and total work output (Birch et al, 1994), increases sprint performance (Dawson et al, 1995) and increases body mass (Balsom et al, 1993).
Creatine is in high concentrations in meat and vegetarian athletes benefit particularly from creatine supplementation. The cereal and herbage diet of horses is low in creatine and supplementation would similarly benefit equine athletes.
The most effective way to achieve high creatine levels in muscles is by a consistent elevation in the amount of creatine in the blood over a prolonged period (Sahelian and Tuttle 1997). It is best to supplement creatine in the feed so that the insulin response that occurs with feeding facilitates the uptake of creatine into the muscle cells.
The absorption of creatine varies with the type of creatine molecule. Creatine citrate is an innovative molecule where creatine is bonded to citric acid, which is an intermediate in the Krebs cycle. The Krebs cycle, or citric acid cycle is the final common pathway into which the major fuel molecules, carbohydrates, fatty acids and amino acids are broken down to ATP. Increasing cellular concentrations of citric acid potentiates the rate of ATP formation. Creatine citrate has been shown to be absorbed up to five times better than creatine monohydrate.
Balsom, P.D. et al. Creatine supplementation per se does not enhance endurance exercise performance. Acta Physiol Scand 1993;149:521-523. Birch, R. et al. The influence of dietary creatine supplementation on performance during repeated bouts of maximal isokinetic cycling in man. Eur J Appl Physiol Occup Physiol 1994;69:268-270.
Colgan, M. Optimum Sports Nutrition, Advanced Research Press, New York, 1993. Dawson, B. et al. Effects of oral creatine loading on single and repeated maximal short sprints. Aust J Sci Med Sport 1995;27:56-61.
Greenhaff, P.H. et al. The effect of oral creatine supplementation on skeletal muscle phosphocreatine resynthesis. Am. J. Physiol. 1994, 266, E725-E730.
Ichimaru, Y. et al. Effects of gamma-oryzanol on gastric lesions and small intestinal propulsive activity in mice. Nippon Yakurigaku Zasshi 1984;84(6)537-542.
Jackson, S.G. Trace minerals for the performance horse known biochemical roles and estimates of requirements. Aust. Eq. Vet. 1997;16(3),119-126.
Pagan, J.D. et al. The effect of chromium supplementation on the metabolic response to exercise in Thoroughbred horses. Proc. 14th Equine Nutr. and Physiol. Soc. Symp., Ontario, California, 1995.
Page, T.G. et al. Effect of chromium picolinate on growth and carcass characteristics of growing-finishing pigs. J Anim Sci 1991;69:403. Press, R.I. et al. The effect of chromium picolinate on serum cholesterol and apolipoprotein fractions in human subjects. Western J Med 1990;152:41-45.
Sahelian, R. and Tuttle, D. Creatine: Nature's Muscle Builder. Avery Publishing Group, Garden City Park, NY, 1997. Scavariello, E.M. and Arellano, D.B. Gamma-oryzanol: an important component in rice bran oil. Arch. Latinoam Nutr. 1998;48(1):7-12.
Dr. Finola McConaghy, BVSc, DipVetClinStud, PhD
Technical Manager at Nature Vet, P.O. Box 413, Richmond NSW 2753, Australia, telephone: 0245 781 022