FEMALE FERTILITY DUE TO OVULATION DISORDERS
There is increasing evidence on the effectiveness of dietary and lifestyle interventions in relation to fertility and healthy pregnancy (1, ambulance 2). According to Chavarro et al (3,4), ovulation disorders, leading to infertility in many cases, can be prevented through modification of diet and lifestyle. Dietary changes include avoiding trans fats and use more of unsaturated vegetable oils e.g. olive oil, eat vegetable protein like nuts and beans and less of animal protein. Choose good sources of carbohydrates like whole grains that have low glycemic index which have slow effect on blood sugar and insulin production. Use full-fat dairy products like whole milk and less of low-fat dairy products. Iron intake should rather come from vegetable sources like vegetables, beans, fruits and supplements, instead of read meat.
Insulin sensitivity seems to be an important determinant of ovulatory function and infertility (5,6). Insulin sensitivity is affected by diet (7) and the protein source, and the amount can influence insulin sensitivity(8,9).
Chavarro et al (10) evaluated, in a cohort of healthy women, if ovulatory infertility were related to protein intake from animal and vegetable sources as well as specific protein-rich foods. After adjusting for age and energy, total protein intake (animal and vegetable) were not related to ovulatory infertility, but after adjusting for potential cofounders (BMI, parity, specific fatty acids), women in the lowest quintile of intake had 41% less risk of ovulatory infertility than women in the highest quintile.
Inverse association was seen between vegetable protein intake and ovulatory infertility. Meat intake was positively associated with ovulatory infertility and 32% greater risk was seen with one added serving of meat per day, whilst modest decrease was seen with consumption of vegetable protein. In the same study, 43% lower risk of ovulatory infertility was seen when 5% of total energy intake was replaced by vegetable protein instead of carbohydrate whilst replaced with animal protein increased the risk of 19% and exchanging animal protein for vegetable protein (5% of total energy intake) was associated with more than 50% lower risk of ovulatory infertility. This association was seen more among women over 32 years but no clear explanation was found.
In an animal study on pigs, increased ovulation rates were associated with increased vegetable protein intake from soy (11).
In two small, randomized trials, no effects of protein content (15% of energy vs. 30% of energy) in the diet were found on the reproductive function in overweight PCOS women, but without specifying the food source used for increasing the protein (12,13)
Modifiable lifestyle practices like the role of diet is largely unexplored. However, some evidence revealing association between dietary factors affecting insulin sensitivity, which might play a part in the etiology in some cases of infertility.
Hyperglycemia has been associated with decreased fertility (5). The risk of developing type 2 diabetes (T2DM) decreases with higher intake of cis unsaturated fatty acids, lower concentration of inflammatory markers (14,15), is known and endocrine and metabolic characteristics in PCOS women have been improved (16).
According to Chavarro et al (20) ovulatory infertility might be increased with consumption of trans-unsaturated fatty acids (TFAs), when replaced for carbohydrates or the unsaturated fats, and consumption of polyunsaturated fats (PUFAs) might reduce the risk. Consuming non-hydrogenated vegetable oils instead of trans-fats is likely to decrease the risk of T2DM (17) and coronary heart disease (CHD) (21), a good strategy for women planning to become pregnant.
Estimating the effect of the isocaloric substitution of fat for the average macronutrient mixture in the study population by analyzing each of the types of fats separately, total fat intake and intakes of MUFAs and saturated fats were inversely related to the risk of infertility (adjusted for energy and age) but in multivariate-adjusted models, it was unrelated to infertility, according to Chavarro et al (20). Estimating the effect of the isocaloric substitution of fat for carbohydrate the intakes of all major types of fat as well as protein were simultaneously included. The risk of ovulatory infertility was associated with intake of TFA and 94% greater risk of ovulatory infertility was seen by 2% increase in energy intake from TFAs in age- and energy- adjusted analyses (20).
Evidence point to some relationship between iron status and reproductive function in women. A higher pregnancy rate was documented in the treatment group receiving iron-containing supplements in a small, clinical trial (22). Iron deficiency is know in coeliac disease and these women often have altered reproductive function including infertility of unknown cause (23,24).
Chavarro et al (25) evaluated the association between total iron intake, iron supplement use and the incidence of ovulatory infertility. There was a difference between heme iron intake and non-heme iron intake and occurrence of ovulatory infertility. Increased risk of ovulatory infertility was seen with heme iron intake whilst total and non-heme iron intakes were inversely associated with ovulatory infertility, after adjusting for age and energy. Comparing women from the highest quintile of heme iron intake, to the lowest quintile, 31%-increased risk of ovulatory infertility was seen with the highest quintile. Compared to the lowest quintile, women in the highest quintile had 40% lower risk of ovulatory infertility, after adjusting for potential confounders. A statistically significant linear trend towards decreasing risk with increasing consumption was seen. There was similar result seen for total iron intake as with non-heme iron intake. Association of non-heme iron with the risk of ovulatory infertility was attenuated by inclusion of multivitamin and iron supplements.
Limitations of the study from Chavarro et al (25) include that is was not a cohort of women planning to become pregnant but only married women were included and they are more likely to be intentional (26).
It is important to consider diet and lifestyle when planning for pregnancy. Nutrients like protein, lipids and iron have all been associated with fertility in women. These nutrients affect the body in multiple ways, which can either increase fertility or even lessen it to a degree.
1 Allaire AD, Cefalo RC. Preconceptional health care model. Eur J Obstet Gynecol Repr Biol 1998;78:163-168.
2 Cetin I, Berti C, Calabrese S. Role of micronutrients in the periconceptional periond. Hum Reprod Update 2010;16(1):80-95. Available from: doi: 10.1093/humupd/dmp025
3 Chavarro JE, Willett WC. Fertility diet. United States of America: President and Fellow of Harvard College;2008.
4 Chavarro JE, Rich-Edwards JW, Rosner BA, Willett WC. Diet and lifestyle in the prevention of ovulatory disorder infertility. Obstet Gynecol 2007;110(5):1050-8.
5 Hjollund NHI, Nensen TK, Bonde JPE, Henridsen NE, Andersson AM, Skakkebaek NE. Is glycosylated haemoglobin a marker of fertility? A follow-up study of first-pregnancy planners. Hum Reprod 1999;14:1478-1482. Available from: http://humrep.oxfordjournals.org/content/14/6/1478.long
6 Azziz R, Ehrmann D, Legro RS, Whitcomb RW, Hanley R, Fereshetian AG, et al. Troglitazone improves ovulation and hirsutism in the polycystic ovary syndrome: a multicenter, double blind, placebo-contolled trial. J Clin Endocrinol Metab 2001;86(4):1626-32. Available from: http://jcem.endojournals.org/content/86/4/1626.long
7 The Duabetes Prevention Program Research Group. Role of insulin secretion and sensitivity in the evolution of type 2 diabetes in the Diabetes Prevention Program: effects of lifestyle intervention and Metrormin. Diabetes 2005;54:2404-2414. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1360738/?report=reader
8 Gannon MC, Nuttall FQ, Saeed A, Jordan K, Hoover H. An increase in dietary protein improves the blood glucose response in persons with type 2 diabetes. Am M Clin Nutr 2003,78(4):734-41. Available from: http://ajcn.nutrition.org/content/78/4/734.long
9 Gannon MC, Nuttall FQ, Neil BJ, Westphal SA. The insulin and glucose responses to meals of glucose plus various proteins in type II diabetic subjects. Metabolism 1988,37(11):1081-1088. Available from: http://www.sciencedirect.com/science/article/pii/0026049588900728
10 Chavarro JE, Rich-Edwards JW, Willett WC. Protein intake and ovulatory infertility. Am J Obstet Gynecol 2008;198(2):201.e1-201.e7. Available from:http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3066040/#!po=86.3636
11 Mejia-Guadarrama CA, Pasquier A, Dourmad JY, Prunier A, Quesnel H. Protein (lysine) restriction in primiparous lactating sows: effects on metabolic state, somatotropic axis, and reproductive performance after weaning. J Anim Sci 2002;80:3286-3300. Available from: http://www.journalofanimalscience.org/content/80/12/3286.long
12 Stamets K, Taylor DS, Kunselman A, Demers LM, Plkamn CL, Legro RS. A randomized tial of the effects of two types of short-term hypocaloric diet on weight loss in women with polycystic ovary syndrome. Fertil Steril 2004;81:630-637. Available from: http://www.sciencedirect.com/science/article/pii/S0015028203030231
13 Moran LJ, Noakes M, Clifton PM, Tomlinson L, Norman RJ. Dietary composition in restoring reproductive and metabolic physiology in overweight women with polycystic ovary syndrome. J Clin Endocrinol Metab 2003;88:812-819. Available from: http://jcem.endojournals.org/content/88/2/812.long
14 Pischon T, Hankinson SE, Hotamisligil GS, Rifani N, Willett WC, Rimm EB. Habitual dietary intake of n-3 and n-6 fatty acids in relation to inflammatory markers among US men and women. Circulation 2003;108:155-60. Available from: http://circ.ahajournals.org/content/108/2/155.full
15 Baer DJ, Judd JT, Clevidence BA, Tracy RP. Dietary fatty acids affect plasma markers of inflammation in healthy men fed controlled diets: a randomized crossover study. Am J Clin Nutr 2004;79:969-73. Available from: http://ajcn.nutrition.org/content/79/6/969.full
16 Kasim-Karakas SE, Almario RU, Gregory L, Wong R, Todd H, Lasley BL. Metabolic and endocrine effects of a polyunsaturated fatty acid-rich diet in polycystic ovary syndrome. J Clin Endocrinol Metab 2004;89:615-20. Available from: http://jcem.endojournals.org/content/89/2/615.full
17 Salmeron J, Hu FB, Manson JE, Stampfer MJ, Coditz GA, Rimm EB, et al. Dietary fat intake and risk of type 2 diabetes in women. Am J Clin Nutr 2001;73(6):1019-1026. Available from: http://ajcn.nutrition.org/content/73/6/1019.full
18 Lefevre M, Lovejoy JC, Smith RS, Delany JP, Champagne C, Most MM, et al. Comparison of the acute response to meals enriched with cis- or trans-fatty acids on glucose and lipids in overweight individuals with differing FABP2 genotypes. Metabolism 2005;54(12):1652-8. Available from: http://www.sciencedirect.com/science/article/pii/S0026049505002659
19 Mozaffarian D, Pischon T, Hankinson SE, Rifai N, Joshipura K, Willett WC, et al. Dietary intake of trans fatty acids and systemic inflammation in women. Am J Clin Nutr 2004;79(4):606-612. Available from: http://ajcn.nutrition.org/content/79/4/606.full
20 Chavarro JE, Rich-Edwards, Rosner BA, Willett WC. Dietary fatty acid intakes and the risk of ovulatory infertility. Am J Clin Nutr 2007;85(1):231-237. Available from: http://ajcn.nutrition.org/content/85/1/231.full
21 Hu F, Stampfer MJ, Manson JE, Rimm E, Colditz GA, Rosner BA, et al. Dietary fat intake and the risk of coronary heart disease in women. N Engl J Med 1997;337(21):1491-9. Available from: doi: 10.1056/NEJM199711203372102
22 Westphanl LM, Polan ML, Trant AS, Mooney SB. A nutritonal supplement for improving fertility in women: a pilot study. J Reprod Med 2004;49:289-93. [Abstract]. Available from: http://www.ncbi.nlm.nih.gov/pubmed/15134155
23 Collin P, Kaukinen K, Valimaki M, Slimi J. Endocrinological disorders and celiac disease. Endocr Rev 2002;23:464-83.
24 Freeman HJ. Reproductive changes assocated with celiac disease. World J Gastroenterol 2010;14
25 Chavarro JE, Rich-Edwards JW, Rosner BA, Willett WC. Iron intake and risk of ovulatory infertility. Obstet Gynecol 2006,108(5):1145-1152. Available from: doi: 10.1097/01.AOG.0000238333.37423.ab
26 Chandra A, Martinez GM, Mosher WD, Abma JC, Jones J. Fertility, family planning, and reproductive helath of U.S. women: data from the 2002 National Sruvey of Famliy Growth. Vital Helath Stat 2005;25:1-160.