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expert reaction to study looking at a compound found in tomatoes and sperm quality

A study, published in the European Journal of Nutrition, reports that sperm quality can be improved by a compound found in cooked tomatoes. 

 

Prof Richard Sharpe, Honorary Professor, MRC Centre for Reproductive Health, University of Edinburgh, said:

“Our understanding of the causes of poor semen quality (and consequent poor fertility) in men is lamentably bad, although in recent years evidence has begun to emerge to suggest that dietary factors might be important in this regard.  However, our longstanding ignorance about causes also explains why there are few if any treatments to offer affected men.

“Although many claims have been made that various factors have beneficial effects, this has mainly derived from small studies that were not randomised or placebo-controlled (which offers the only definitive proof of efficacy).  The present study thus constitutes a methodical small ray of sunshine, as it involves optimal design (randomized, double-blind placebo-controlled) and a reasonable, if still small, number of subjects.

“The results obtained offer some encouragement that an extract from tomatoes (already established as having other health-beneficial properties) is able to improve the number of fast-swimming sperm and sperm with good morphology in those men who took it for 12 weeks.  As both of these parameters are associated with chances of pregnancy, the finding could mean that consumption of this tomato extract compound might have a beneficial effect in men with infertility because of poor sperm motility and/or morphology.  However, as the authors point out, this may be an overly optimistic interpretation, given the relatively modest positive changes in the treatment group and the fact that the men recruited were not selected because of any diagnosis of infertility.

“Nevertheless, the study adds to the growing evidence that diet might be an important factor in male fertility and that eating a healthy balanced diet containing plenty of fresh fruit and vegetables is a sensible thing for men to adopt as it can only have beneficial effects on their overall health and may improve their sperm quality.  Conversely, eating a modern Western diet is likely to be detrimental, perhaps more because of what it lacks than what it contains too much of.”

 

Dr Rod Mitchell, Research Group Leader, MRC Centre for Reproductive Health, University of Edinburgh, said:

“Current options to improve sperm quality in men with fertility problems are limited, primarily involving lifestyle modification.  This study in healthy men investigated the effect of short-term supplementation with lactolycopene (an antioxidant that occurs naturally in tomatoes) on sperm quality.

“The effect of this antioxidant on sperm quality has been investigated previously and results suggest that lycopene may improve sperm quality.  However, these previous studies had limitations, such as lack of randomization, which the present study aims to address.

“This carefully conducted study randomly allocated men to either receive the supplement or a ‘dummy pill’ for 3 months and performed sperm counts at the end of the trial.  Importantly, neither the study participants, nor the researchers, knew which treatment had been allocated.

“There was no difference in the concentration of motile (moving) sperm, the primary outcome of the study.  However, there was a significant increase in the proportion of sperm that had a ‘normal appearance’ and that were ‘fast swimmers’, although the impact this has on fertility cannot be concluded from this study.

“The results of this study warrant further investigation in order to determine whether lycopene supplementation could have clinical benefit for patients with regard to fertility.  Importantly, this would include testing it in men with known fertility problems and determining whether it improves the chance of achieving a pregnancy and having a live birth.

“Overall, the study supports the concept that dietary factors may have positive effects for sperm quality in males.  In addition, it is well recognized that modification of other lifestyle factors such as reducing smoking and achieving a healthy weight are associated with improvements in sperm quality.  Therefore, maintaining a healthy lifestyle can be an important contributor to fertility potential in males.”

 

Dr Graham Wheeler, Senior Statistician, UCL, said:

“There was weak evidence to suggest that the primary outcome of this study, motile sperm concentration level, had improved after 12 weeks in participants receiving LactoLycopene.  Therefore, the authors claim LactoLycopene improves sperm quality based on other measurements in this study instead, which is slightly misleading.

“This study looked at the changes in key measurements of sperm quality for each group separately.  Alarmingly, the authors did not directly analyse whether the changes in the LactoLycopene group were better than the changes observed in the placebo group, which is the whole point of running a randomised controlled trial.  So we can’t say whether the impact of LactoLycopene is genuinely better than placebo.

“Only 56 men were analysed in this study, and this number of participants was not statistically justified.  This study may be too small to conclusively say whether the observed results are genuine effects, or simply due to chance.

“All participants were healthy volunteers.  Given that we do not know how LactoLycopene may influence sperm quality, it is unclear whether such a supplement would benefit men with fertility issues.”

 

Prof Ying Cheong, Professor of Reproductive Medicine, University of Southampton, said:

“This randomised controlled trial, part funded by the supplement manufacturer Cambridge Nutraceuticals Ltd, investigated the effect of taking 12 weeks of lactolycopene supplement on semen parameters, namely concentration, motility morphology and DNA fragmentation.

“They found no significant difference in the primary outcome, which was the overall motile sperm concentration or DNA fragmentation between the two groups; but they observed in their sub-analysis, more fast progressive sperm and normal looking sperm in the lactolycopene arm, and a decrease in non progressive sperm in the placebo arm.

“This study, undoubtedly, will add to our current knowledge of yet another anti-oxidant type supplement on sperm parameters, but what the study fails to tell us is if taking lactolycopene supplements improves fertility, that is the chance of actually having a successful pregnancy.  It would be more impactful if the authors could use live birth as the end point.

“Hence, the tomato’s culinary history remains firmly in gastronomy rather than fertility.”

 

Prof Simon Fishel, Founder and President, CARE Fertility, said:

“We know compromises in sperm quality – morphology and motility – can affect fertility.  This is an intriguing study, from a highly respected scientific group, showing improvements in the parameter of ‘fast moving sperm’ and in their shape (morphology) by the use of lactolycopene; but in healthy volunteers.  The issues for placing any potential value on this for fertility purposes are:

“a) This was undertaken on healthy men and needs to be repeated on men who actually have issues with poor motility or low percentage of normally-shaped sperm.

“b) The fact that men with good quality sperm may not fertilise an egg, and men with poor quality sperm can be natural fathers, demonstrates there is more to a man’s fertility that just the movement and numbers of normally-formed sperm.

“c) It was a very small study.

“So, as the authors agree, the outcome of this study does not have any bearing on fertility issues that relate to compromised sperm, and especially no bearing on whether it may be beneficial for sub-fertile males.  But it does make this lab-based study worthy of larger, more clinically relevant trials.

Does the press release accurately reflect the science?

“Yes.

Is this good quality research?  Are the conclusions backed up by solid data?

“Yes – in their limited capacity.

How does this work fit with the existing evidence?

“It is supportive of other anti-oxidant studies and other potential benefits of lactolycopene.

Have the authors accounted for confounders?

“Not clinically relevant here, but some, such as BMI, are included.

Are there important limitations to be aware of?

“As mentioned above – particularly that it is not yet clinically relevant.

What are the implications in the real world?  Is there any overspeculation?

“No relevance yet to the potential benefits in subfertile men – the relevant studies need to be done.”

 

Prof Sheena Lewis, Emeritus Professor of Reproductive Medicine, Queen’s University Belfast, and Chair of the British Andrology Society, said:

“This is a small study where the volunteers were healthy, not infertile; with sperm parameters close to normal.  Hence it is difficult to extrapolate any lycopene benefits to infertile men with poor semen quality.  There are no clinical outcomes to the study.”

 

‘A randomized placebocontrolled trial to investigate the effect of lactolycopene on semen quality in healthy males’ by Elizabeth A. Williams et al. was published in the European Journal of Nutrition at 22:00 UK time on Tuesday 8 October 2019.

 

Declared interests

Prof Richard Sharpe: “No conflicts to declare.”

Dr Rod Mitchell: “None.”

Dr Graham Wheeler: “I am an employed by UCL, am a Fellow, Chartered Statistician and Statistical Ambassador of the Royal Statistical Society, and a voluntary research committee member for Chiltern Music Therapy, a not-for-profit organisation providing music therapy services.  I have previously received honoraria from Novametrics Consulting Ltd.”

Prof Ying Cheong: “No conflict of interest.”

Prof Simon Fishel: “I am a minor shareholder in CARE Fertility and CEO, Co-Founder and shareholder in ProFaM.”

Prof Sheena Lewis: “Sheena is CEO of SpermComet Ltd, a university spin-out company marketing a test for male infertility.”

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