Friday, January 1, 2016

Environmental Factors and Sperm Quality Indicators

Approximately half of the couples who seek treatment for infertility exhibit semen abnormalities in the male partner. While body weight and smoking are known behavioral risk factors, additional research is needed to examine the impact of dietary exposures and elucidate the relationship between exercise, diet, spermatogenesis and male fertility.

A trio of studies published in 2014 and 2015, co-authored by Cigdem Tanrikut, MD, director of male reproductive medicine and urologist at the Massachusetts General Hospital Department of Urology, shows the impacts of diet and modes of exercise on sperm quality indicators and reproductive ability.

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Correlating Dietary Patterns With Sperm Count
Relative difference in total normal count in 155 men (338 semen samples) associated with consuming two servings of fish per week instead of other meats. Data points and bars represent means and 95% confidence intervals. Keeping total meat intake constant, but switching out processed meats for fish, was associated with significantly higher total normal count.

Intake of Processed Meat and Pesticides

The first of the three studies, published in the Journal of Nutrition in May 2014(1), suggests that consuming fish instead of other meats correlates positively to semen quality indicators. Linear mixed regression models showed that processed meat intake among 155 subjects was highly associated with abnormal sperm counts. Men in the highest quartile of processed meat intake had, on average, 1.7% fewer morphologically normal sperm than did men in the lowest quartile of intake. Fish intake was related to higher sperm count and percentage of morphologically normal sperm.

Researchers anticipated that saturated fat would account for the relationship between processed meat and total sperm count, given previous findings, but this was not borne out. They hypothesize that this relationship may be associated with preservative agents or hormonal residues in processed meat.

chart reviewing sperm quality and pesticide intake

Sperm Quality and Pesticide Intake
Adjusted prevalence of excellent sperm quality (95% CI) according to quartile intake of high or low-to-moderate pesticide residue fruits and vegetables (n=155 men, 338 semen samples). Excellent sperm quality is defined as semen sample that met the following criteria: total sperm count ≥39 million, sperm concentration ≥15 million/ml, total motility ≥40%, normal morphology ≥4% and ejaculate volume ≥1.5 ml. The prevalence of excellent sperm quality decreased with increasing intake of high pesticide residue fruits and vegetables (P=0.05), while low-to-moderate pesticide residue fruits and vegetables had no significant deleterious effects (P=0.79).

Another study, published in Human Reproduction in March 2015(2) examined whether consumption of fruits and vegetables with high levels of pesticide residues was associated with lower sperm quality. Occupational and environmental exposure to pesticides has already been shown to be associated with lower semen quality, but the influence of dietary intake of pesticides on semen health had not.

Researchers found that total fruit and vegetable intake was not associated with semen quality, but there was an inverse relationship between intake of fruits and vegetables with high pesticide residue and semen quality. On average, men in the highest quartile of such intake had 49% lower total sperm count, 32% fewer morphologically normal sperm and 29% lower ejaculate volume than did men in the lowest quartile of intake.

These findings are consistent with previous research that found consumption of organic diets to be associated with higher sperm quality. But further confirmation is needed, the researchers said, given that measurements of exposure to pesticides were based on surveillance data rather than individual-level pesticide exposures.

Exercise and Male Fertility

Another study, published in Human Reproduction in July 2014(3), examined time spent in leisure physical and sedentary activities. It found that higher levels of moderate-to-vigorous physical activity were associated with higher sperm concentrations but not with greater reproductive success among couples engaged in fertility treatment.

Specifically, men in the highest category of outdoor activity (≥1.5 hrs/week) and weight lifting (≥2 hrs/week) had 42% and 25% higher sperm concentrations, respectively, than men with 0 hours a week. But men who reported bicycling ≥1.5 hrs/week had 34% lower sperm concentration compared with men who reported no bicycling, a finding consistent with previous research. This may be due to mechanical trauma caused by compression of the scrotum on the bicycle saddle.

Such findings on sperm quality indicators and environmental factors could, according to Dr. Tanrikut, also offer insight into how male fertility at a population level might be used as a marker for male health and public health more broadly.

chart reviewing the affect of weight lifting excercise on sperm count
chart reviewing the affect of biking excercise on sperm count

Sperm Concentration and Exercise
Adjusted mean (95% CI) sperm concentration (million/ml) by type of moderate-to-vigorous physical activity. Greater time spent weightlifting was associated with higher sperm concentration while time spent biking was inversely associated with sperm concentration. All analyses were run using log-transformed concentration and linear mixed models with random intercepts and autoregressive correlation structure. The marginal means are presented adjusted for abstinence time (<48, 48–72, >72 h), age (continuous), smoking status (ever, never), race (white, other), education (less than college, college, graduate) and BMI (continuous).

Source: Gaskins et al., Human Reproduction

References

(1) Afeiche, Myriam C., Audrey J. Gaskins, Paige L. Williams, Thomas L. Toth, Diane L. Wright, Cigdem Tanrikut, Russ Hauser, and Jorge E. Chavarro. “Processed Meat Intake Is Unfavorably and Fish Favorably Associated with Semen Indicators Among Men Attending a Fertility Clinic,” The Journal of Nutrition. 144(7): 1091-8.

(2) Chiu, Yu-Han, Myriam C. Afeiche, Audrey J. Gaskins, Paige L. Williams, John C. Petrozza, Cigdem Tanrikut, Russ Hauser, and Jorge E. Chavarro. “Fruit and Vegetable Intake and Their Pesticide Residues in Relation to Semen Quality Among Men from a Fertility Clinic,” Human Reproduction. 30(6): 1342-51.

(3) Gaskins, Audrey J., Myriam C. Afeiche, Russ Hauser, Paige L. Williams, Matthew W. Gillman, Cigdem Tanrikut, John C. Petrozza, and Jorge E. Chavarro. “Paternal Physical and Sedentary Activities in Relation to Semen Quality and Reproductive Outcomes Among Couples from a Fertility Center,” Human Reproduction. 29(11): 2575-82.

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