Bad Science Awards for Equine Supplements!
Dr David Marlin
How to save yourself money, avoid supplements that will have no effect and that could also potentially be harmful to your horse!
Given the array of equine supplements with long lists of sometime unpronounceable ingredients, not to mention the amazing marketing and unbelievable claims for what they will do, unless you have a degree in nutrition or a PhD in biochemistry, how are horse owners supposed to be able to work out what to use? Without specialist training and knowledge or unless you know where to look and what sources of information are reliable it can be very hard to know whether an ingredient is likely to be effective and or safe. Here are five ingredients which you should stay away from either because they do not work, are expensive and there are much cheaper equivalents or that they may be potentially harmful to your horse.
All cells, and of course muscle cells, can only use ATP for energy. All the food we eat has energy stored in it which must be converted to ATP for cells to be able to use it. The idea of feeding ATP is that you can “cut out the middle man” and provide direct energy for cells which somehow will improve performance.
The level of ATP within cells is carefully regulated by enzymes. When there is not much activity it fluctuates around 6-7 mmol/kg of muscle. When exercise starts the ATP drops but is quickly replenished from energy stored in phosphocreatine and then from glycolysis (breakdown of glycogen) and aerobic metabolism of carbohydrates and fats. There are two problems with the concept of feeding ATP. Firstly, ATP is not absorbed from the gastro-intestinal tract as ATP and when its metabolites are absorbed they can be detected as its breakdown product uric acid in the urine. Secondly, if the ATP did get into the bloodstream, as there are injectable ATPproducts, it would not cross the cell membrane. That’s the explanation as to why the ATP level in cells is several hundred times higher than in the blood! Finally, if it did actually by some miracle get into a cell, guess what, the enzymes that regulate ATP levels would metabolise it. So you would be surprised if there were any supplements with ATP in?
ATP Horse Supplement
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Arts IC, Coolen EJ, Bours MJ, Huyghebaert N, Stuart MA, Bast A, Dagnelie PC. Adenosine 5′-triphosphate (ATP) supplements are not orally bioavailable: a randomized, placebo-controlled cross-over trial in healthy humans. J Int Soc Sports Nutr. 2012 Apr 17;9(1):16.
During intense exercise, surges in usage of ATP with muscular contractions are buffered by a compound called phosphocreatine. Phosphocreatine can rapidly transfer phosphate energy to ADP to regenerate it to ATP so that muscular contractions can continue. This leaves creatine which must have phosphate energy transferred back to it. One of the things that influences how much phosphocreatine is in a cell is the balance between phosphocreatine and creatine. If the creatine is increased then so will the amount of phosphocreatine. So the theory is that feeding creatine to increase the amount of phosphocreatine will increase the capacity for intense short duration exercise.
Creatine supplementation, initially in human athletes, showed significant improvements in muscle power output, muscle strength, muscle mass and as a consequence, performance. There are hundreds of published studies documenting the improvements seen with oral creatine supplementation. Creatine is found in high concentrations in meat and when it came to studies in horses, the horse being a vegetarian, it was found that the horse had not evolved to absorb something that never occurred in its diet. Not surprisingly, other studies where creatine was fed to horses also failed to show any increase in muscle creatine concentration after period of creatine feeding. So presumably, as this information is widely available in the scientific literature, there wont be any creatine supplements for horses?
Creatine Horse Supplement
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D’Angelis FH, Ferraz GC, Boleli IC, Lacerda-Neto JC, Queiroz-Neto A. Aerobic training, but not creatine supplementation, alters the gluteus medius muscle. J Anim Sci. 2005 Mar;83(3):579-85.
Schuback K, Essén-Gustavsson B, Persson SG. Effect of creatine supplementation on muscle metabolic response to a maximal treadmill exercise test in Standardbred horses. Equine Vet J. 2000 Nov;32(6):533-40.
Sewell DA and Harris RC. Effects of creatine supplementation in the Thoroughbred horse. Equine Veterinary Journal. 27(S18), 239–242.
Poortmans JR, Rawson ES, Burke LM, Stear SJ, Castell LM. A-Z of nutritional supplements: dietary supplements, sports nutrition foods and ergogenic aids for health and performance Part 11. Br J Sports Med. 2010 Aug;44(10):765-6.
Spirulina (blue-green algae)
Muscle is made of protein. Proteins are made from amino acids. Feeding high amounts of protein stimulates muscle growth and repair. Spirulina is a type of blue-green algae which is around 50-60% protein. Feeding Spirulina will increase muscle mass and help muscle repair.
The high protein diet approach to muscle building is very outdated. More recent research has indicated that the muscle repair/growth is stimulated by the branched chain amino acids (BCAA) leucine, isoleucine and valine. Other scientific studies have suggested that the majority of the effect is due to leucine and that it is the amount of leucine fed which produces the muscle repair and growth effects rather than the amount of protein, which will contain a range of proteins. Is there anything special about Spirulina? No, it’s just a source of protein and the amino acids are the same as those in oats or forage. In fact the proportions of the different amino acids is very similar to that of forages or cereals such as oats and the US National Library of Medicine also makes the following comment: “You may have been told that blue-green algae are an excellent source of protein. But, in reality, blue-green algae is no better than meat or milk as a protein source and costs about 30 times as much per gram”.
Spirulina Muscle Horse
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US National Library of Medicine Medline Plus
Pasiakos SM, McLellan TM, Lieberman HR. The effects of protein supplements on muscle mass, strength, and aerobic and anaerobic power in healthy adults: a systematic review. Sports Med. 2015 Jan;45(1):111-31.
Poortmans JR, Carpentier A, Pereira-Lancha LO, Lancha Jr A. Protein turnover, amino acid requirements and recommendations for athletes and active populations. Braz J Med Biol Res. 2012 Oct;45(10):875-90.
Campbell B, Kreider RB, Ziegenfuss T, La Bounty P, Roberts M, Burke D, Landis J, Lopez H, Antonio J. International Society of Sports Nutrition position stand: protein and exercise. J Int Soc Sports Nutr. 2007 Sep 26;4:8.
L-Ascorbic acid (Vitamin C)
Vitamin C (L-ascorbic acid) is one of the major antioxidant vitamins and is involved in a range of different functions including protecting the airways, the immune system, wound healing, clotting function, joint function and cartilage formation to name a few. Supplementation with Vitamin C increases plasma, airway and tissue concentrations of Vitamin C leading to greater antioxidant function and associated benefits.
There is good evidence to show that Vitamin C supplementation to horses has beneficial effects, for example, in helping to resolve airway inflammation. However, the main issue with supplements and feed containing Vitamin C concerns the form used. Whilst we have to obtain Vitamin C from our diet, primarily in fruits and vegetables, including carrots and apples, but also to a lesser extent in some animal tissues (liver, some shellfish, some fish) horses, like most mammals, are able to make their own Vitamin C from glucose in the liver. As a result horses do not absorb Vitamin C very well in its natural form as it exists in fruits and vegetables. So it may come as a surprise that the ~10mg of Vitamin C that is in a large apple or the ~4mg of Vitamin C that is in a large carrot are not particularly beneficial. In any case, when we supplement with Vitamin C we tend to be talking grams (g) rather than 1/1000th of grams (i.e. mg). A further issue with the use of L-ascorbic acid as a source of Vitamin C is that it is that it is highly unstable and whilst the levels at the time of manufacture may meet the label claims, after several months the levels are likely to be considerably lower. So any supplement that contains Vitamin C should not list in the ingredients L-ascorbic acid as this is the natural form that is known to be both unstable and poorly absorbed by horses. Instead the form of Vitamin C should be listed as ascorbyl palmitate, ascorbyl sulphate or ascorbyl monophosphate as these are forms of Vitamin C that horses can absorb readily. What if the supplement label lists Vitamin C from herbs, grains, fruits, vegetable ingredients? If you eat the supplement then yes, you will get the Vitamin C but it’s much less effective to feed this to your horse! As this information is widely known by nutritionists, you would imagine that you would not find any supplement manufacturers using ordinary L-ascorbic acid due to its poor stability and low bioavailability?
Vitamin C Supplement Horse
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Snow DH, Frigg M. Bioavailability of ascorbic acid in horses. J Vet Pharmacol Ther. 1990 Dec;13(4):393-403.
Deaton CM, Marlin DJ, Smith NC, Roberts CA, Harris PA, Kelly FJ, Schroter RC. Pulmonary bioavailability of ascorbic acid in an ascorbate-synthesising species, the horse. Free Radic Res. 2003 Apr;37(4):461-7.
Deaton CM, Marlin DJ, Smith NC, Harris PA, Schroter RC, Kelly FJ. Antioxidant supplementation in horses affected by recurrent airway obstruction. J Nutr. 2004 Aug;134(8 Suppl):2065S-2067S.
Tryptophan is one of the nine essential amino acids that the horse cannot make and must get from its diet. Tryptophan is generally present in low amounts in most equine feedstuffs. Increases in the brain neurotransmitter serotonin are associated with reduction in aggression, fear and mild sedation. Tryptophan is required for the formation of serotonin. Thus, the theory is that feeding tryptophan will increase serotonin and induce a calming effect.
There are a number of studies which have given adult horses from around 50mg to over 150g of tryptophan. Low doses appear to cause excitement as opposed to calming. Conversely, high doses of tryptophan lead to respiratory distress and haemolysis (breaking of red blood cells). Commercial calming supplements based on tryptophan typically contain 5-6g of tryptophan and have been shown to result in an elevation in plasma (blood) tryptophan levels but no changes in behaviour or heart rate. Thus, there is absolutely no evidence to support the use of oral tryptophan as a calming agent for horses. So you will hopefully by now thinking that it would be almost impossible to find any tryptophan based calmers on sale right? If only!
Calmer Horse Tryptophan
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Noble GK, Brockwell YM, Munn KJ, Harris PA, Davidson HP, Li X, Zhang D, Sillence MN. Effects of a commercial dose of L-tryptophan on plasma tryptophan concentrations and behaviour in horses. Equine Vet J. 2008 Jan;40(1):51-6.
Grimmett A, Sillence MN. Calmatives for the excitable horse: a review of L-tryptophan. Vet J. 2005 Jul;170(1):24-32.
Paradis MR, Breeze RG, Bayly WM, Counts DF, Laegreid WW. Acute hemolytic anemia after oral administration of L-tryptophan in ponies. Am J Vet Res. 1991 May;52(5):742-7.