By Martin Luck
A recent edition of BBC Radio 4’s On Your Farm programme spoke to a dairy farmer who supplies colostrum to athletes as a food supplement.
Colostrum is the first milk secreted by a mother. Cow colostrum is quite different from normal cow’s milk: it has about four times as much protein, twice as much fat, and half as much lactose (sugar). It is especially rich in the mother’s antibodies (IgG and IgM), providing the newborn calf with passive immunity before its own immune system gets going.
People who take colostrum believe it has health and performance benefits. It’s said to reduce muscle recovery time after intense training, maintain gut integrity against the heat stress of exercise, and assist recovery from illness and surgery. The radio programme spoke to cyclists, rugby players, footballers, runners, and others convinced of its value and who are prepared to pay the significant premium which colostrum commands over ordinary milk.
Unfortunately, the scientific evidence for these effects is rather poor, especially on the health side. Nutritional and clinical scientists who have reviewed the research literature report a lack of well-designed and reliable trials. There is some evidence for enhanced speed and endurance and for increased strength in older people undertaking resistance training, but many studies show equivocal or unconvincing results. So for the moment, it’s probably safest to describe the benefits of colostrum consumption as anecdotal.
Colostrum undoubtedly contains some hormones and growth factors in higher amounts than in normal milk. Levels of insulin and IGF-1 can be eight times higher in colostrum, especially during the first few hours after calving. Growth hormone is also present at this time, and disappears later. Other hormones, including prolactin, cortisol, vitamin D and a range of growth factors (hormones controlling cell division and maturation), also occur at relatively high amounts in colostrum.
These hormones all have well known biological effects in the body, but finding them in colostrum doesn’t necessarily mean that they will be active when it is consumed in the diet. There are two main reasons for this. Firstly, protein hormones like insulin and IGF-1 get broken down in the gut and are unlikely to be absorbed in an active state. (If the reverse were true, diabetics could take insulin in pill form rather than injections.) Secondly, naturally-secreted hormones generally work in concentration-related ways, appearing in the blood as repeated pulses with which their receptors become coordinated. This pattern is unlikely to be replicated by pouring colostrum over the breakfast cornflakes.
Nevertheless, the possibility that colostrum is a source of potentially performance enhancing bioactive materials has been considered by the World Anti-Doping Agency. Many hormones and growth factors including insulin, IGF-1, cortisol and Growth Hormone, appear in their list of prohibited substances. So could colostrum make athletes fall foul of the regulations? The WADA website advises that although colostrum is not banned, its growth factor content “could influence the outcome of anti-doping tests” and its consumption is not recommended.
Aside from efficacy, colostrum poses a wider, ethical question: when does a natural food product become an artificial supplement? At one extreme, it might be feasible to extract the active ingredients and take them as a training aid or performance enhancer. At the other, perhaps as recognised by WADA, one might happen to consume colostrum as a food without intending to benefit unduly from it. Somewhere in between would be the deliberate consumption of colostrum knowing that it contains potentially beneficial components.
But then why is that different from, say, increasing ones intake of protein or energy to support a higher level of athletic performance? Neither whey protein nor glucose, nor for that matter caffeine or bananas, appear in WADA’s prohibited list, yet they all have their place in the training and performance regimes of many athletes and sports men and women.
Identifying hormones as discrete, potentially bioactive chemical components of food seems to encourage the drawing of a false line along this continuum. No one condones cheating or the gaining of unfair advantage, but it is not clear why one food product should be restricted when another is not, especially when it is available to all and has no identified side effects.
But this brings us back to the question of efficacy? Does colostrum really work? If it could be shown that it does and if it were made widely available as a food item, there is no doubt that all athletes would use it. This might make the doping authorities review their position, although it could mean, of course, that no one is really advantaged (just as being tall brings no gain when playing basketball against others selected for their height).
To find out if colostrum really does work, many more well-designed, high quality, double blind placebo-controlled trials would be necessary. Such investigations are expensive and difficult and few organisations will have the expertise or resources to devote to something which, as a completely natural product, is unlikely to bring commercial gain. But this is the problem with many food supplements and so-called superfoods (and partly explains why health food shops abound in the high street).
In the end, people use food supplements because they believe them to work, not because there is much reliable evidence that they do. And perhaps this, in turn, means that there is no legitimate reason for banning their use.
Based at the University of Nottingham as a Professor of Physiological Education, Martin Luck is the author of Hormones: A Very Short Introduction. He was awarded a National Teaching Fellowship by the Higher Education Academy in 2011.
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Image credit: Colostrum cakes, by Surya Prakash.S.A., CC-BY-SA-3.0 via Wikimedia Commons