Evidence for Decreasing Quality of Semen During Past 50 Years

Carlsen, Elisabeth; Giwercman, Aleksander; Keiding, Niels; Skakkebæk, Niels E.

doi:10.1097/00006254-199303000-00023

Cited by 625 publications

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“…1 Sperm density had fallen by 40% over the past 50 years. 2 One of the reasons for the impaired semen parameters over the years is dietary factors. 3,4 The significant effects of dietary fatty acids (FAs) on male fertility have been well documented both in animal and human studies.…”

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confidence: 99%

The roles of omega-3 and omega-6 fatty acids in idiopathic male infertility

Safarinejad¹,

Safarinejad²

2012

Asian J Androl

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mega-3 fatty acids found in some foods have a wide-range of health benefits. The omega-3 supplementation results in higher antioxidant activity in human seminal fluid and enhanced sperm count, sperm motility, and sperm morphology. Considerable number of infertile men with idiopathic oligoasthenoteratozoospermia might be benefit from omega-3 fatty acids administration.Infertility caused by idiopathic oligoasthenoteratozoospermia(OAT) syndrome without any female factor represents one of the biggest patients group in the daily practice of urologists. Despite great advances in the field of infertility, still many cases of male infertility are diagnosed as idiopathic and remained untreated. In low-income communities where health service resources are restricted and basic health needs are unmet, health resources are not used to provide expensive technologies for the treatment of infertility. Social and family consequences of infertility, especially in developing and under developed communities are devastating. A decrease in male fertility has been occurred over the years. 1 Sperm density had fallen by 40% over the past 50 years. 2 One of the reasons for the impaired semen parameters over the years is dietary factors. 3,4 The significant effects of dietary fatty acids (FAs) on male fertility have been well documented both in animal and human studies. 5,6 There are three types of natural FAs: saturated, monounsaturated and polyunsaturated. Polyunsaturated fatty acids (PUFAs) are essential FAs, because they cannot be synthesized by the human body. Docosahexanoic acid (DHA), eicosapentanoic acid (EPA) and alinolenic acid are the main omega-3 PUFAs.Linoleic acid, c-linolenic acid and arachidonic acid (AA) are the main omega-6 PUFAs. The first mechanism by which omega-3 and omega-6 PUFAs affect spermatogenesis, is by the incorporation into spermatozoa cell membrane. Omega-3 and omega-6 PUFAs are structural components of cell membranes. 7 The lipid bilayer of cellular membranes is maintained by the presence of these PUFAs. 8 The successful fertilization of spermatozoa depends on the lipids of the spermatozoa membrane. 9 Deleterious health effects of increased dietary omega-6/omega-3 ratios have been documented in many studies. 10 The ideal ratio is 1:1. During the past 100 years, omega-6 PUFAs of Western diets have increased dramatically. This has resulted in an omega-6/omega-3 ratio of 25:1 to 40:1. 11 Increased omega-6/omega-3 ratio in spermatozoa has also been implicated in impaired semen quality in oligozoospermic and/or asthenozoospermic men. 12 Spermatozoa from asthenozoospermic and oligozoospermic men exhibit decreased concentrations of DHA compared with those from normozoospermic men. Conquer et al. 13 demonstrated that, compared with normozoospermic men, spermatozoa from asthenozoospermic men have diminished concentrations of DHA and higher concentrations of oleic acid. Safarinejad et al., 14 investigated PUFA composition of the blood plasma and spermatozoa in men with idiopathic OAT. They found that, fertile men h...

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confidence: 99%

The roles of omega-3 and omega-6 fatty acids in idiopathic male infertility

Safarinejad¹,

Safarinejad²

2012

Asian J Androl

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“…This challenges the assertions of previously published reports indicating a decline in sperm counts over a similar period of time. [1][2][3][4][5] …”

Section: Discussionmentioning

confidence: 99%

“…[1][2][3][4][5] We have recently published data showing no decline in sperm counts in men who banked sperm prior to vasectomy from 1970 to 1994 from three United States sperm banks at different geographic locations. 6 Since MacLeod and Gold 7 is still cited most prominently in defining a ''normal'' sperm count, we compared our sperm count data from 374 men with proven fertility who banked sperm prior to vasectomy in Minnesota from 1971 to 1994 to MacLeod and Gold's data from 1951 to look at whether sperm count distributions have changed over the last 40 years.…”

Section: Commentmentioning

confidence: 99%

“…[1][2][3][4][5] In 1992 Carlsen et al 1 in a meta-analysis of 61 studies published from 1938 to 1991 suggested a worldwide decline in semen quality over the last 50 years. Auger et al 3 in 1995 reported a 30% decrease in sperm concentration over a 20-year period among fertile sperm donors from a single sperm bank in Paris, France.…”

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confidence: 99%

“…In the meta-analysis by Carlsen et al, 1 criticism has focused on differing protocols for semen analysis in the 61 included studies, variations in inclusion criteria, methodologic inconsistencies, patient selection bias, and geographic bias. When the data from the metaanalysis were reanalyzed by Olsen et al, 5 an increase in sperm counts was noted from 1970 to 1990.…”

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confidence: 99%

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Macleod Revisited: Sperm Count Distributions in 374 Fertile Men From 1971 to 1994

Emanuel

Goluboff

Fisch

1998

Urology

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Incidence of testicular germ-cell malignancies in England and Wales: Trends in children compared with adults

et al. 1999

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The incidence of testicular cancer has been increasing markedly in most industrialised countries. This rise is known to have affected young adults, but it is less clear whether it has affected other age groups, particularly children. We used data from the National Cancer Registry file at the Office of National Statistics (ONS) and the National Registry of Childhood Tumours to examine trends in testicular germ-cell malignancies overall in England and Wales from 1962 to 1990 and in children from 1962 to 1995. The incidence of testicular cancer at all ages rose by 3.4% (95% CI 3.3-3.6%) per annum from 1962 to 1990. A similar rise in the incidence of germ-cell malignancies occurred during the years for which histological information was available in the ONS files, 1971-1989 (3.4%; 3.1-3.6%), to which both seminomas and non-seminomas contributed equally. The incidence of non-seminomas in adults rose in men under age 55 years and declined in older men, whereas there were increases in the incidence of seminomas in both young and older men. Cohort analysis at young ages showed a marked rise in the risk of germ-cell malignancies up to the cohort born in 1955-1959 but no further rise for those born subsequently. The rise in the incidence of these tumours in young adults was paralleled by a similar trend, although less marked, in children aged under 15 years (1.3% per annum; 0.2-2.5%). The increase in risk for children in this very large data set alongside the rise in young adults is compatible with the hypothesis that childhood and adult testicular germ-cell malignancies may have some common risk factors, presumably pre-natal.

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Evidence for Decreasing Quality of Semen During Past 50 Years

Cited by 625 publications

References 0 publications

The roles of omega-3 and omega-6 fatty acids in idiopathic male infertility

The roles of omega-3 and omega-6 fatty acids in idiopathic male infertility

Macleod Revisited: Sperm Count Distributions in 374 Fertile Men From 1971 to 1994

Incidence of testicular germ-cell malignancies in England and Wales: Trends in children compared with adults

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