Velvet antler (VA) is a dietary supplement made from the antlers of deer or elk that have been surgically removed from a live animal under anaesthetic. It is valued for its medicinal purposes for a wide range of health-based and performance issues.
For example, it is claimed that (www.deervelvet.org)1 deer velvet antler:
- Improves immune system functioning;
- Improves athletic performance and strength;
- Improves muscle recovery after exercise;
- Reduces negative effects of stress;
- Enhances sexual functioning for both men and women;
- Promotes rapid recovery from illness;
- Has anti-cancer and anti-inflammatory properties.
VA is typically available powdered and capsulated, or as an extract in liquid form, and it is marketed as a food supplement, although it is described as an important part of Traditional Chinese Medicine.2 Deer velvet antler (DVA) is chemically synonymous to elk velvet antler (EVA) and is utilised commercially for identical purposes.3
Like many supplements based upon Traditional Chinese Medicine, the scientific rationale for why benefits of velvet antler (VA) might accrue is somewhat unclear, at least when interpreted from a western perspective. However, the rationale is quite likely related to the belief that the properties inherent in a substance (e.g., VA is the only mammalian organ with the ability to regenerate itself) will, if ingested, confer similar benefits on its user. This argument is known as the principle of correspondence.4
It is currently estimated that New Zealand will produce 430 tonnes of DVA,5 aroundone-third of the global production. At a price of between $86–106/kg, this would equate to a value between $36.98m–$45.58m,6 although the price of DVA is somewhat volatile (e.g., in NZ the value of the raw product fell from $250 per kilogram to $45 in 2004–5 and rebounded to $160 in 2006–7).
In 2011, New Zealand’s exports were predominantly to China (~$14m) and Korea (~$12m). An indication of the value added price of the final product can be found by examining websites selling VA products. One such example, 100 × 250mg capsules for NZ$52,7 would equate to ~$2000 per kilogram of raw VA. No data appears to be available for the number of users in New Zealand or, indeed, elsewhere in the world.
The aim of this systematic review was to critically evaluate randomised controlled studies (RCTs) for the effectiveness of VA supplements for any condition, using the QOURAM statement as a guiding framework.8
A computerised literature search conducted in July 2011 returned 483 articles. Two reviews of velvet antler research returned a further 241 articles.2,3 Of the 724 articles potentially of interest, 246 duplicates were excluded. The remaining articles (478) were read first on the basis of the title and abstract. Of these, 7 articles were found to meet all inclusion criteria and were reviewed in full by both authors. A flowchart of study selection may be inspected in Figure 1.
The included RCTs scored between 3 and 5 points on the Jadad scale and investigated the effectiveness of velvet antler supplements for: rheumatoid arthritis (2), osteoarthritis (1), sexual function (1), and sport performance enhancement (3). Key characteristics of the included RCTs are presented in Table 1.
Two studies by Allen et al (2002; 2008)10,11 investigated the effect of EVA on rheumatoid arthritis (RA) and both concluded that there was no effect (although the earlier study was underpowered). Allen et al. (2008) noted that non-significant improvements tended to be in the experimental group and also that none of the participants who indicated that they felt ‘markedly better’ were in the placebo group.
Although there were a lack of significant findings, Allen et al (2008) concluded that, on the basis of promising animal research, further human research is warranted. Although claims about the effect of velvet antler supplements on rheumatic conditions are not supported by evidence from RCTs, it may hold some promise.
Three RCTS explored the effect of velvet antler on sport performance.12,15,16 Broeder et al (2004)12tested the effect of DVA on body composition, strength and maximal aerobic and anaerobic performance. It was concluded that DVA may be effective on the basis that some within-subject tests for DVA were significant, while similar within-subject tests for the placebo were not. However, to test this comparison one must actually examine the interaction term for a factorial test of both within- and between-subject factors to determine whether there is a statistically significant difference between the two arms of the trial.
No a priori power analysis was conducted and the study was certainly underpowered on completion, by which time 44% of participants had dropped-out. Due to flaws in this study, it fails to provide convincing support for the use of velvet antler supplements to enhance sport performance.
Sleivert et al (2003)15 reported that there was an increase in isokinetic strength and muscular endurance in the DVA powder group compared to the placebo. However, a similar effect was not observed in the DVA extract group, which might reasonably have been expected, and there were also no concomitant changes in the hormonal mechanisms hypothesised to underlie such changes.
On the balance of evidence, in particular the lack of convergent validity, the authors concluded that the findings were most likely explained by type I error.
Syrotuik et al (2005)16 found no effect on either strength or hormonal changes after 10 weeks of EVA supplements on the performance of rowers when compared to placebo, although low experimental power may conceivably have caused type II errors. It is also possible that benefits do accrue, but not within the first 10 weeks of supplementation (e.g., one RCT15 suggested that there may be an effect of DVA supplements on osteoarthritis after 3 and 6 months, but not after 1 month).
The first and only study to have investigated the effect of velvet antler supplements on sexual functioning, Conaglen et al (2003),13 found no effects on the sexual functioning of either 32 male participants or their partners. However, this study was again somewhat underpowered and therefore, like six of the seven reviewed RCTs, may have been prey to type II error. Although underpowered, this study was judged to be of high methodological quality. The authors concluded that there was “no advantage in taking deer velvet to enhance sexual function”.
Finally, Edelman et al (2000)14 reported that participants with osteoarthritis treated with DVA showed improvement over baseline, relative to those treated with placebo. While the results are promising, it is important to note that there was a significant difference in duration of symptoms at baseline, with the placebo group having experienced symptoms for more than 50% longer duration. Furthermore, the lack of details of blinding and randomisation precludes any firm conclusions from being drawn. The findings therefore appear to offer some promise, but unless replicated are somewhat unconvincing.
Overall, seven RCTs were found to fulfil the inclusion criteria for this systematic review. Five were of moderate methodological quality and two of high quality. In contrast to the numerous claims that there are benefits of velvet antler supplements, this systematic review of RCTs of velvet antler supplements found no convincing evidence of effectiveness when compared to placebo. However, it is possible that the lack of significant findings may be false negatives due to low experimental power, although the one trial with adequate power reported no effect of EVA on RA.11 There were some potentially promising findings for treating osteoarthritis,14 but these would require replication.
Given the size of the velvet antler industry(e.g.,6) and the plethora of claims made, the velvet antler industry could fund trials to test the claims being made. A further source of funding may also be available from the National Center for Complementary and Alternative Medicine (NCCAM). There are at least two university based departments with interests in deer velvet (AgResearch, Invermay, NZ, and the University of Alberta, Edmonton), who may also be able to trial velvet antler supplements as part of their own research program.
Future trials should ensure that there is sufficient experimental power to have a reasonable chance of detecting meaningful effects. Blinding and randomisation techniques should also be fully reported so that readers can draw informed opinions as to the validity of the trial.
This systematic review is not without limitations. The quality of the studies varied, although none were deemed to be of low quality. All except one of the included RCTs were underpowered and therefore the possibility of type II error cannot be ruled out. It is possible that trials with positive findings have not been published, although we are not aware that publication bias has ever discriminated on the basis of positive trials.
Despite a dearth of good quality positive human trials on the effectiveness of velvet antler supplements, numerous suppliers of velvet antler products make or imply claims about its use for a number of conditions.
Claims that velvet antler supplements have beneficial effects for any human condition are not currently supported by sound clinical data from human trials.