First of all....a little lesson for some background.
It is well established in exercise physiology that an increase in EPO production may result in an increase in the number of red blood cells (RBC) and thus an increase in oxygen transport capacity of the blood and that an increase in oxygen transport capacity may result in an increase in the ability to perform endurance exercise. The whole process relies upon the production of volume of red blood cells.
The total mass of RBCs in the circulatory system is regulated within narrow limits in order to maintain sufficient tissue oxygenation and to prevent deleterious effects of severe hemoconcentration (that is too many RBCs for the blood volume making it like sludge). The principle factor that stimulates RBC production is a circulating hormone named erythropoietin (EPO) that is derived mainly from the kidneys.
Erythrocythemia is the term used to denote the state of having an increase in total red cell mass of the blood. While the thoroughbred dumps up to a third of its total red blood cell content from its spleen (a flight or fit mechanism), manipulating erythrocythemia is still seen to confer an advantage, especially with those horses that have slightly smaller spleens (and thus less total blood cell volume).
Induced erythrocythemia, blood doping, blood boosting are terms used to describe the procedure of increasing RBC's, the consequence of which is an increase in hemogloblin to levels that are above normal in an attempt to improve endurance exercise performance. This state may be achieved through a number of methods that include:
1) the infusion of RBCs from a donor,
2) the removal and subsequent infusion of one's own RBCs, and
3) the use of recombinant erythropoietin (r-EPO).
Obviously all of the above methods are 100% illegal in horse racing. Abuse of synthetic EPO can result in an increase in the viscosity of the blood, and if red blood cells increase beyond a certain point the blood becomes thickened (unless you add an anticolagulant to the mix). This means it won’t ﬂow well through vessels, increasing blood pressure, and could possibly lead to states such as stroke/cardiac arrest.
So are there other options?
In recent months there has been quite a bit of buzz, at least in North American training circles, about the claims made by certain products to boost the number and quality of red blood cells in racehorses. One company linked here readily advertises their product in the Blood Horse and Thoroughbred Daily News.
Most, if not all of the companies claiming to have a "natural EPO" supplement are relying on the naturally occurring plant Echinacea angustifolia as the central element of the supplement. In the late 1800's, Echinacea angustifolia was the most commonly used plant remedy in the United States, however, use began to decline around 1920 due to primarily to the advent of antibiotics. Presently, Echinacea is primarily used as a non-specific immunostimulant and to prevent upper respiratory infections.
So just what is the science behind efficacy of Echinacea angustifolia in altering EPO and red blood cell count in horses?
Most of it hangs on one paper published over a decade ago. Back in 2002, O'Neill et al published a paper on the efficacy of Echinacea in stimulating the immune system of the horse. With the reservation that the study was only completed on 8 horses (although a well constructed randomized and cross-over study), they found that Echinacea effectively acts as a haematinic agent and improves the quality of blood by increasing haemoglobin levels and the number of red blood cells. Thus supplementation of Echinacea would be considered to naturally improve parameters of exercise physiology and performance. That said, the authors did note that the results observed on RBC parameters were unexpected and should be investigated further in order to confirm the effects and to determine if the increase results in measurable differences in equine exercise performance and/or physiology. No such follow up study was completed or published.
That's as far as the peer-reviewed science goes in racehorses. One paper...not much to go off really and it hasn't been followed up with more peer-reviewed research on the subject. In other species however there has been a greater number of studies thankfully. More Recently (2007) Whitehead, et al found that a four week oral supplementation of Echinacea results in significant increases in EPO, VO2max, and running economy in humans. Interestingly however it did not significantly alter RBCs, hemoglobin or hematocrit levels (which is probably what O'Neill,et al were expecting). There is also some scientific evidence in a study on mice to suggest that Echinacea has some anti inflammatory effects.
So where does this leave us?
I would say that the jury is out as to the efficacy of "natural EPO" supplements in racehorses that use Echinacea angustifolia. It's hard to based all science on one study, even if it is peer reviewed, so further studies as suggested by the authors of the only material available would give us a clearer idea if Echinacea angustifolia is a worthwhile supplement or just another waste of time and money in an effort to get an "edge".