Soft Drinks Affect Sperm Count and More

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Soft Drinks Affect Sperm Count and More

SUMMARY: DO SOFT DRINKS REDUCE SPERM COUNT

In this study, males who consumed a median of 220ml per day of fizzy / soft drinks had decreased sperm count (-28 million) and sperm concentration (-13 million/ml) due to a reduction in spermatogenesis (inhibin-B/FSH hormone ratio).

doi.org/10.1093/humrep/deab179

Background

Male partners are now widely accepted as potential contributors to subfertility in couples seeking infertility treatment. While the exact causes of male infertility are still being researched, it is believed that environmental exposures, such as air pollution, chemicals and diet, play a bigger role than genetics.  

In recent times, the world has seen an increase in sugar-sweetened beverages (SSB) intake such as fizzy or soft drinks. Several studies have already established a link between SSB and various health issues like obesity and heart disorders. However, there is a lack of evidence supporting any correlation between SSB and reproductive function in men.   

While SSB continue to receive bad press, the impact of the other types of beverages, artificially sweetened beverages (ASB), fruit juices and energy drinks, on human health is even less studied. Some of these beverages have sugar content as high as SSB and are not necessarily a healthier alternative.

It is therefore important to thoroughly examine the affects, of different types of beverages, on the reproductive health of males. 

Aim

To examine the association of intakes of SSB, ASB, energy-drinks, and fruit juices among young Danish men with markers of testicular function including semen quality, testicular volume, and serum reproductive hormones.

Methodology

In this cross-sectional study carried out between 2008 and 2017, healthy men (median age: 19 years) completed questionnaires covering demographics, medical history, lifestyle and food intake. They then underwent a physical examination and provided a semen and blood sample.

The previously validated food frequency questionnaire (FFQ) was used to assess the intake of SSBs, ASBs, fruit juices, and energy-drinks, with non-consumers of these 4 beverage groups used as a control group.

All semen samples were collected, after at least 48 hours of abstinence, and analysed for semen volume, sperm concentration, sperm motility and sperm morphology according to World Health Organization (WHO) guidelines. Testicular volumes was measured during the physical examination by ultrasonography and an average volume was calculated.

In total, 2935 men who answered the FFQ and provided a non-azoospermic semen sample, were enrolled in the study.

The blood sample from each participant was used then to measure serum reproductive hormone concentrations.

Total testosterone (TT) was initially measured using time-resolved fluoroimmunoassay up to 2013, and then via enzyme-linked immunosorbent assay (ELISA). Free-testosterone (cFT) was calculated from TT concentration and sex hormone-binding globulin (SHBG) while assuming a fixed albumin concentration.

Inhibin-B concentrations were measured using a specific two-sided enzyme-immunometric assay while other hormones such as FSH, LH and SHB were measured using time-resolved immunofluorometric assays. Estradiol (E2) was also initially measured by the same method but switched to radioimmunoassay (RIA) in 2014 onwards.

Results

Initial analysis of participant demographics showed that the median age and BMI of the participants was 19 years and 22 kg/m2 respectively.

The authors noticed that men who consumed more SSB and energy drinks were also more likely to smoke, use marijuana or other drugs.

Unadjusted analysis of semen and reproductive hormone results showed that the consumption of SSBs was inversely related to (i.e. reduced):

  • Sperm concentration
  • Total sperm count
  • Serum inhibin-B
  • Inhibin/FSH ratio

 Similarly ASB consumption was associated with lower:

  • Total sperm motility
  • Progressive sperm motility
  • Serum SHBG

While the intake of energy drinks was positively related to (i.e. increased) normal sperm morphology, serum E2 and serum LH.

After statistical adjustment for potential confounders, the same associations remained evident with only the magnitude of the association changing for some parameters.

Multivariable adjusted analyses was then carried out to quantify the effects.

In the biggest consumers of SSB (median intake 220, range 140 to 1720ml/day) compared to non-consumers:

  • Median sperm concentration was 13.0 million/ml lower
  • Total sperm count was 28 million lower
  • Serum inhibin-B was 12 pg/ml lower
  • Inhibin-B/FSH ratio was 9 lower

In the biggest consumers of ASBs (median intake 180, range 100-1520 ml/day) compared to non-consumers:

  • Total sperm motility was 3.6% lower
  • Progressive motility was 3.5% lower
  • Serum SHBG was 2.2 nmol/L lower

In the biggest consumers of energy drinks (median intake: 80, range: 60-1420 ml/day) compared to non-consumers:

  • Morphologically normal sperm was 1.5% higher
  • E2 was 4 pg/ml higher
  • LH was 0.4 IU/l higher

On the other hand, consumption of fruit juices and water was not found to be related to any of the outcomes analysed.

Finally, statistical modelling tests evaluating the effect of consuming SSB or ASB instead of water estimated that:

  1. Increasing SSB by one serving (200ml) per day correlated with lower sperm concentration (-3.4 million sperm/ml) and lower serum concentration of inhibin-B (–7 pg/ml).
  2. Increasing ASBs by one serving (200ml) per day correlated with lower total motility (–1.8%), increased E2 (+6 pmol/l) concentrations and higher LH (+0.4 IU/l).

The authors stressed however that the lower semen quality observed in this study does not translate necessarily into decreased fertility given the ability of standard semen analysis to predict pregnancy is limited.

Limitations

  1. Inability to assess causality due to cross-sectional study design.
  2. Potential unadjusted confounders.

Funding

This study was supported by the Danish Council for Strategic Research, Independent Research Fund Denmark, European Union, DEER, the Danish Ministry of Health, the Danish Environmental Protection Agency, Kirsten and Freddy Johansen’s Foundation, the Research Fund of the Capital Region of Denmark and NIH.

Glossary

Assay
A laboratory test.

Azoospermia
A complete absence of sperm in ejaculated semen.

Confounders
A distortion that modifies the estimated measure of an association.

Median
The middle number of a sorted data set.

Subfertility
Reduced fertility with prolonged time of unwanted non-conception.

Similar studies

Hatch E E, et al. (2018). Intake of Sugar-sweetened Beverages and Fecundability in a North American Preconception Cohort. https://doi.org/10.1097/EDE.0000000000000812

Yang H, et al. (2015). Lifestyles Associated With Human Semen Quality: Results From MARHCS Cohort Study in Chongqing, China. https://doi.org/10.1097/MD.0000000000001166

Chiu Y H, et al. (2014). Sugar-sweetened beverage intake in relation to semen quality and reproductive hormone levels in young men. https://doi.org/10.1093/humrep/deu102

Jensen T K, et al. (2010). Caffeine intake and semen quality in a population of 2,554 young Danish men. https://doi.org/10.1093/aje/kwq007


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