It has been reported that male fertility is declining across the world, with male factor infertility accounting for 40–50% of all infertility cases, making it important that men are provided with adequate lifestyle and nutrition guidance.
A recent review, published in the journal 'Dietetics' reveals the psychosocial impacts of infertility in males whilst assessing nutritional and lifestyle interventions that can be used in personalised nutrition care.
It states that reviewed data indicates dietary modification or supplementation with antioxidants such as vitamin C, vitamin E, coenzyme Q10, selenium, carnitine and zinc can improve markers of male fertility and reduce markers of seminal oxidative damage.
From the collected findings, the review provides preconceptual guidelines for men based upon a Mediterranean diet high in omega 3 fatty acids, antioxidants, vitamins and minimally processed foods and minimising exposure to environmental pollutants and radiation.
"Infertility is emotionally challenging for men and nutrition, and personalised nutrition and lifestyle therapies have potential to support men trying to conceive," it states, "pre-conceptual nutrition and lifestyle guidelines for men have been developed from this review and the use should be considered as the basis for more tailored nutrition care in practice."
The big taboo
"Despite the increasing trend in male factor infertility, it still remains largely taboo and the male experience of infertility is a poorly researched area hence improved understanding should help improve care of these individuals," the report states.
Concerningly, Rossi et al. found that the majority of men undergoing fertility treatment did not believe diet, caffeine, artificial sweeteners, or over-the-counter medicines affected fertility.
"This is also potentially important in terms of the health of offspring as the quality of sperm is related to both fetal outcomes and also significant in terms of health outcomes of offspring in later life. This theory is known as the Developmental Origins of Health and Disease and it highlights how later outcomes of health and disease (particularly regarding future metabolic health) occurs via the control of gene expression through mechanisms such as external environmental factors, including maternal or paternal diet."
A systematic approach was used with three electronic databases (CINAHL, Medline and Academic Search Complete) searched and 125 papers found for review, with additional hand searches to ensure recent evidence was included.
The databases were searched on four broad topics; psychosocial impact of male infertility, diet and lifestyle factors affecting sperm parameters, environmental factors affecting sperm health and the effect of supplementation on sperm health.
This was followed by an empirical study investigating the lived experience of men with infertility, also exploring their views on lifestyle and nutritional interventions that can support fertility.
The review concludes that there is a general lack of interventional studies investigating the impact of poor dietary patterns on semen parameters, presumably because it is not ethically justifiable to cause harm to participants through adherence to an unhealthy diet. Therefore, much of the data is observational.
Nevertheless, it notes a number of studies which have shown how intake of specific micronutrients can impact male fertility.
Polyunsaturated fatty acids
Increasing PUFA intake is a common intervention for improving markers of male fertility. Unfortunately, strong evidence is lacking, in the most part due to the nature of dietary analysis using food frequency questionnaires (FFQ), meaning that any relationship outlined cannot prove causation.
However, supplementation with eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA) omega 3 fatty acids have been studied in controlled trails (RCTs). Three RCT’s and one Meta-analysis were found in the current review which all showed beneficial effect of omega 3 supplementation on semen parameters at dosages ranging from 500 mg to 2000 mg/day.
Co Q10 or ubiquinol, is a naturally occurring antioxidant, found in meat, fish and nuts that plays an important role in cellular metabolism and energy production. Co Q10 is found in high concentrations in seminal fluid, neutralizing reactive oxygen species that may damage the structure or function of the sperm cell.
Co Q10 is also found in the mitochondria of the spermatozoa where it facilitates energy production in the sperm to assist motility.
Supplementation with Co Q10 was shown in an RCT of sixty infertile men to significantly improve sperm motility at 200 mg/day.
The greatest improvements in semen parameters and DNA fragmentation through Co Q10 supplementation appear to be in studies that are at least 6 months in duration and have a supplementation level of between 200–400 mg Co Q10/day. Studies that were 3 months in duration also show a benefit to morphology but no significant effects on motility or sperm count.
Folic acid (FA), aka vitamin B9, naturally occurs as folate while FA is the synthetic form which is used in supplements and fortified foods.It has been established for some time that maternal deficiency of FA is linked to spina bifida in the offspring and supplementation in the first trimester of pregnancy is recommended in many countries.
In terms of sperm parameters FA is also known to have antioxidant properties. Three papers examining FA in male fertility (often in connection with the mineral zinc) were identified through the searches in the review, all studies used a 5 mg a day dose of FA though intervention timescale varied.
Supplement therapy in varicocelectomized subjects was investigated in one study using a six-month intervention including FA 5 mg and a combination of FA 5 mg and zinc sulphate 66 mg and zinc sulfate 66 mg alone versus placebo.
Semen samples were taken before surgery, 3 months and 6 months post-surgery and analysed in terms of number of sperm, morphology, motility, progressive motility and in addition the researchers assessed acrosome integrity and protamine content.
The authors concluded mild improvements in most sperm parameters in the placebo group post-surgery and that most sperm parameters improved significantly with a combination of zinc and folic acid, with improved sperm numbers being reported in the group that received folic acid alone.
Zinc is essential in the formation of spermatozoa, and present in high concentrations in seminal fluid. Two RCT’s by the same author investigating (Zn) on semen parameters were found which showed a significant increase in sperm count, motility and antioxidant potential. The same author also found that Zn supplementation significantly reduced DNA fragmentation and markers of oxidative stress.
Wong et al. found a significant increase in sperm count of 74% when supplementing with 5 mg/day FA and 66 mg Zn/day for 26 weeks.Dosing of Zn was significantly higher in the previously mentioned studies by Omu et al. at 500 mg per day compared to the studies of Zn combined with folic acid supplementation. Such a high dosage of 500 mg/day is classed as toxic and may lead to acute Zinc toxicity and poisoning.
Vitamin E is known to inhibit lipid peroxidation and reactive oxygen species formation and has been shown in RCT’s to significantly reduce oxidative damage to the lipid cellular membrane of the sperm cells and subsequently increase sperm motility in sub-fertile men.In addition to this, vitamin E has also been shown to significantly improve DNA fragmentation, reduce reactive oxygen species (ROS) in seminal fluid and improve semen parameters.
Carnitine is an amino acid and is found to be in high concentrations throughout the structure of the testes and the epididymis and the spermatozoa. Carnitine is involved in a wide range of physiological processes, thought to play many important functions in semen cells including maturation of the sperm, initiation of motility and protecting sperm chromatin from oxidative damage.
Carnitine has been studied extensively for the impact on semen and fertility parameters, predominantly in those diagnosed with idiopathic oligoasthenozoospermia.
L-Carnitine has been shown in double-blind, placebo controlled RCT to significantly improve semen parameters including DNA fragmentation, motility and sperm concentration.
"Pre-Conceptual Guidelines for Men: A Review of Male Infertility Experience, including Nutrition and Lifestyle Factors"
Authors: Bold, J., and Swinburne, D.