Expert ReviewDiet and fertility: a review
Section snippets
Antioxidants
A 2013 Cochrane review of randomized controlled trials (RCTs) of antioxidant supplementation during the course of infertility treatment concluded that the current evidence does not show benefits of female antioxidant supplementation for increasing pregnancy or live birth rates.10 The authors pointed out many deficiencies of the available evidence including a high risk of bias, incomplete reporting, and high variability of the interventions tested in the trials.10 For example, the trials
Fatty acids
In vitro studies have shown that fatty acids are important substrates in early reproductive events including oocyte maturation71 and embryo implantation.72 Moreover, animal and human studies suggest that polyunsaturated fatty acids (PUFAs) may have a specific impact on fertility, through effects on oocyte quality and embryo implantation73, 74 while trans fatty acids may promote greater insulin resistance,75 which could adversely affect ovulatory function.76
Results from the NHS-II cohort
Dairy
Dairy foods have been suggested as potential reproductive toxicants because of their high content of galactose, which in mice was shown to decrease ovulation and lead to premature ovarian failure,83, 84 and their potential to contain high amounts of environmental estrogens.85 In 1994 an ecological study among 31 countries was published showing that the decline in fertility with age is steeper among populations with higher per-capita milk consumption.86 However, a subsequent case-control study
Meats, fish, and soy
Intake of protein sources has received attention in the context of fertility, mostly because of their potential to contain high levels of environmental contaminants, which could adversely affect reproductive health. While red meats can be good sources of protein and other essential nutrients, they also contain high levels of saturated fat and can serve as a vehicles for exposure to hormonal residues, antibiotics, and polybrominated diphenyl ethers.91, 92
Similarly, while seafood is a recognized
Dietary patterns
To date, 2 studies have examined the relationship between preconception dietary patterns and risk of infertility.111, 112 In the NHS-II, women in the highest quintile of an investigator-generated fertility diet score, which prioritizes higher intakes of protein from vegetable sources, full-fat dairy foods, iron, the ratio of monounsaturated fatty acids to trans fats, and more frequent use of multivitamins and lower intakes of protein from animal sources, dietary glycemic load, and low-fat dairy
Alcohol and caffeine
Intakes of caffeine and alcohol are, unquestionably, the most studied dietary factors as potential disruptors of fertility, with more than 30 studies on this topic to date. Results, however, are inconsistent, with multiple studies showing deleterious effects of caffeine116, 117, 118, 119, 120, 121, 122, 123, 124, 125 and alcohol,126, 127, 128, 129, 130, 131 but just as many studies showing no association125, 126, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144 or even improved
Paternal diet
The role of paternal diet on semen quality and couple fertility has been recently examined and summarized in several systematic reviews.153, 154, 155, 156 Some general trends are worth brief mention. First, a Cochrane review of randomized trials of antioxidant supplementation for men in couples undergoing infertility treatment found evidence of benefit for antioxidant supplements in improving semen quality and clinical pregnancy rates.153 Despite the evidence for benefit, the large
Conclusion
The literature on the relationship between diet and human fertility has greatly expanded over the last decade and led to the emergence of some clear patterns. Intake of supplemental folic acid has been consistently related to numerous markers of female fertility, from lower frequency of anovulation to higher reproductive success in the setting of ART, suggesting that the reproductive benefits of folate extend beyond the prevention of NTDs.
On the other hand, despite promising evidence from
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Cited by (0)
This study was supported by grant K99ES026648 from the National Institutes of Health, grant R01ES009718 from the National Institute of Environmental Health Sciences, grant L50-HD085359 from the Eunice Kennedy Shriver National Institute of Child Health and Human Development, and grant P30DK46200 from the National Institute of Diabetes and Digestive and Kidney Diseases.
The authors report no conflicts of interest.