Previously I discussed how the Paleo Diet could be beneficial for couples with infertility problems. Let’s not forget infertility is a two sided coin involving health issues which may affect sexual activity and reproduction in both males and females. In this blog I will focus upon a number of recent scientific studies which confirm that male reproductive health (including sperm quality, quantity and erectile function) are closely associated with diet and overall health.
Infertility affects 10-15% of reproductive aged couples in the U.S.1, 2 as well as 60-80 million couples worldwide.3 The male contribution to this problem has been identified to be as high as 58%.4 Erectile dysfunction (ED) is estimated to affect over 100 million men internationally.5 ED is defined as the inability of a male to attain and maintain a sufficient erection for satisfactory sexual intercourse. A review of the current literature supports the notion that the typical western, junk food diet is a major contributory factor to male infertility and ED.6-8 Further, as I will shortly demonstrate, adoption of a contemporary Paleo Diet may reduce male infertility and improve ED.
Semen/Sperm Quantity and Quality
A number of large population studies,9-12 including a review of more than 100 scientific papers dating back to 1934,13 show that male semen/sperm quantity and function (motility) per ejaculation has severely declined over the past 80 years. If we go backwards in time to the 1920s or 1930s, the decline in semen quantity and quality occurred shortly after the widespread introduction of processed foods.14 Are these two facts serendipitous or are they causally related? Let’s examine the data.
We are what we eat, and it should not be surprising to know that food has the capacity to positively or adversely affect all tissues of the body14-16 including the penis, the prostate gland, the testicles, semen and male hormones (androgens) – all of which regulate normal reproductive function in males. Accordingly, changes in the western diet that have occurred since the industrial revolution and earlier14 have now been implicated in male reproductive dysfunction.
Refined sugars comprise 15-18 % of the calories in the typical U.S. diet, whereas 200 years ago, except for honey these foods were rarely or never consumed by the average citizen.14 A recent study has shown that consumption of sugar laden soft drinks impairs sperm mobility in healthy young men.17 Consequently, soft drinks or more accurately, “liquid candy” consumed on a regular basis may adversely affect your sperm’s ability to fertilize your partners egg, thereby reducing you and your partner’s chances for a successful conception. If this data doesn’t get your attention, then maybe the following information will.
Regular ingestion of soda pop and sugary soft drinks is intimately involved in ED.18 If you have bought into the Viagra commercials and wasted your monies on this pharmaceutical, there is an alternative and healthier solution – stop drinking sugar laden soft drinks and stop eating processed foods loaded with refined sugars. A good starting point would be for you to adopt the Paleo Diet which is almost totally devoid of refined sugars and processed foods.
It has long been known that ED and poor semen quality are associated with overweight and obesity, insulin resistance, cardiovascular disease, type 2 diabetes, high blood pressure19-22 and lack of exercise.23 These health issues get progressively worse as you age, as does ED.24 A good strategy to counteract obesity, insulin resistance, cardiovascular disease, type 2 diabetes and high blood pressure is the Paleo Diet.14-16, 25 You may just find that your ED and Viagra will become things of the past.
Over the years since Paleo has increasingly come into the public eye, more and more versions of Paleo Diets have been put forth by people from all walks of life. One issue is dairy – should you or should you not include milk, yogurt, cheese and other dairy products in your modern day Paleo Diet? If we look at the anthropological and evolutionary data, the answer is a resounding no!26 Ancestral hunter gatherers could have never included dairy products in their daily menus because it is nearly impossible to approach large, wild mammals – much less milk them.
Dairy products comprise about 12% of the average daily caloric intake in the U.S. diet,14 yet these foods may have a number of nutritional factors which adversely impact human health14-16, 27-30 including male reproductive function. The data speaks for itself.
A recent epidemiological study31 in healthy, physically active young men showed that increased total dairy intake was related to impaired sperm morphology, particularly for full fat dairy products. A similar study in men attending a fertility clinic demonstrated that increased cheese intake was related to lower sperm concentrations.32
At first, most people wouldn’t have a clue why milk and dairy consumption should have anything to do with male reproductive health. But, a deeper dig into PubMed reveals that cow milk ingestion by humans has long been associated with male reproductive disorders.33, 34 One of the suspected mechanisms is that cow’s milk represents a major route of human exposure to exogenous estrogens,35, 36 a likely factor in male infertility and ED.37, 38 Further, as our research group has pointed out, milk and yogurt yield low glycemic loads, but paradoxically increase blood insulin concentrations39 and produce insulin resistance in young boys.40 Accordingly consumption of milk and dairy products, have the potential to adversely affect male reproductive function by increasing circulating blood concentrations of female hormones while simultaneously altering insulin metabolism in a fashion similar to chronic diseases of insulin resistance known to present concurrently with ED and poor semen quality.19-22
We’re not done with milk, dairy and male reproductive health just yet. Milk and dairy products are concentrated sources of calcium which impair absorption of zinc and iron.40, 41 So if you decide to put a slice of cheese on your grilled burger, you unknowingly will severely reduce absorption of the zinc and iron normally present in ground beef. The number one nutrient most lacking in the U.S. diet is zinc, and 73% of all U.S. citizens do not meet the DRI (dietary reference intakes) recommended for zinc.14 It turns out that zinc is an absolutely essential dietary element required for normal sperm development and function.42 Low blood concentrations of zinc in males are associated with poor sperm quality and increase the risk for infertility.43, 44 Plant foods (such as whole grains and legumes) are poor sources of zinc because this mineral is bound to a compound called phytate which reduces its absorption by as much as 75% in the intestine.45, 46 Further, the type of zinc found in animal foods is highly absorbable. Beef is a great dietary source of zinc – eat it regularly (particularly the grass produced variety) and your blood concentrations of zinc will rise. One of the richest sources of zinc is found in oysters, a food which historically has been associated with increased male libido and fertility.
Salt, Nitric Oxide and Erectile Dysfunction
In the “Paleo-sphere” there seems to be widespread approval of sea salt as an acceptable ingredient in Paleo recipes and menus. As I have laboriously pointed out, nothing could be further from the truth – our Stone Age ancestors rarely or never added salt to their foods.47 Sea salt maintains the same adverse health effects as does commercially manufactured salt. Both should be avoided in contemporary Paleo Diets for a wide variety of health reasons including erectile dysfunction.
A increasing body of scientific research demonstrates that high salt diets impair a normal erection. Most men eating an average American diet are completely unaware that they are consuming a high salt diet. We have shown that the typical western diet contains 10 grams of salt per day, whereas our hunter gatherer ancestors ate a tenth of this amount.14 The majority of our present day salt intake comes from processed foods, particularly breads and cereals.14
Comprehensive experimental studies in both humans and animals demonstrate that salt ingestion causes a profound reduction in nitric oxide (NO) in vascular (blood vessels) tissues throughout the body, including the penis.47 Normal levels of NO in the penis bloodstream are required to sustain a sufficient erection for intercourse, without which ED may occur.48-50
OK – let’s review. Salt which we get mainly from processed foods and cereals severely reduces NO in blood vessels, including the penis. An erection required for intercourse cannot occur without normal blood concentrations of NO. So any nutritional factor, such as salt, which reduces synthesis and production of NO should be avoided, if your goal is to maintain a fully erect penis during intercourse. Virtually all contemporary processed foods have high salt contents14– another good reason to adopt The Paleo Diet.
Therapeutic Foods for Erectile Dysfunction
A caveat to this concept are foods which increase NO production and promote normal erectile function. These are the foods which you should focus upon. You don’t have to look far to discover these healthful NO eliciting foods, as they are nothing less than the quintessence of The Paleo Diet.
Omega 3 fatty acids stimulate NO release.51 The Paleo Diet is rich in long chain omega 3 fatty acids because it encourages regular consumption of fatty fish (salmon, mackerel, herring, and other seafood), free ranging meats, poultry and eggs. Additionally antioxidants such as zinc in the form of glutathione boost NO production while preventing its breakdown.51 Contemporary Paleo diets are both high in omega 3 fatty acids and zinc, much more so than the USDA recommended Food Pyramid/My Plate.52 Foods high in antioxidant vitamins and minerals (particularly zinc and selenium) and folic acid support the release of NO and may prevent degradation in sperm quality.43, 44, 51, 53-58 The Paleo Diet is rich in fresh fruits and veggies making up approximately 30-45% of calories52 and inherently is high in antioxidant vitamins, minerals and phytochemicals, whereas the typical U.S. diet contain less than 10 % of its daily calories as fruits and vegetables.14
A Few Final Thoughts and Recommendations
As I have indicated time and again, The Paleo Diet is not a diet at all, but rather a lifelong program to maximize health and well being by consuming, natural living foods and avoiding processed foods. All body tissues (be they male or female), including our reproductive organs respond positively when they are provided an environment and milieu consistent with that which shaped our species over millions of years of evolutionary wisdom. Male reproductive function including ED can improve by eliminating the ubiquitous processed foods in the standard American Diet. You can go a long way in improving your erection and sperm quantity and quality by eliminating refined sugars, high glycemic load carbohydrates, dairy products and salted foods. Here are a few additional scientific tidbits of advice which add credence to The Paleo Diet and men’s reproductive health.
With contemporary Paleo Diets, I advise you to avoid processed meats like bacon, sausages, bologna, salami, prosciutto, liverwurst, hot dogs, ham, and the like. All of these meats are incredibly high in salt and typically maintain a fatty acid profile that looks nothing like fresh, unadulterated wild or grass produced meats59, 60 – to say nothing of the preservatives and additives which are part of these meats.
A recent study indicates consumption of processed meats in healthy young men is associated with a lower sperm count.61
Trans Fatty Acids
I’m sure that I’m not going to get much disagreement in the Paleo community when I say that we should avoid trans fatty acids produced via the hydrogenation process used to manufacture margarines, shortenings and the vegetable fats found in many processed foods. These fats may increase shelf life of processed foods, yet have been known for more than two decades to have adverse effects upon human health.14 If you regularly eat a doughnut, bagel or pancake at breakfast or a sandwich at lunch you will most likely be consuming a trans fatty acid (trans elaidic acid) which has been shown to be related to a reduced sperm count in healthy men.62
If you voluntarily decide to eliminate or reduce animal foods from your diet via vegetarian or vegan protocols, you will almost certainly become deficient in vitamin B12. As I have previously pointed out, B12 deficiencies universally result in elevated homocysteine concentrations throughout the body, including the testicles and ovaries which impair fertility for both men and women.
A recent study evaluating vitamin B12 concentrations in infertile couples had this to say, “Thirty nine percent of all men with an abnormal semen analysis had cobalamin (vitamin B12) deficiency.”
Infertility and ED are diseases which have increasingly been associated with the same dietary and environmental factors that elicit the chronic diseases of civilization (obesity, overweight, cardiovascular disease, type 2 diabetes, hypertension, acne, gout and a number of cancers). The same protective dietary measures (The Paleo Diet) that reduce or eliminate symptoms of the diseases of civilization almost certainly will promote positive reproductive function in men of all ages.
Loren Cordain, Ph.D., Professor Emeritus
1. Louis JF, Thoma ME, Sørensen DN, McLain AC, King RB, Sundaram R, Keiding N, Buck Louis GM. The prevalence of couple infertility in the United States from a male perspective: evidence from a nationally representative sample. Andrology. 2013 Sep;1(5):741-8.
2. Thoma ME, McLain AC, Louis JF, King RB, Trumble AC, Sundaram R, Buck Louis GM. Prevalence of infertility in the United States as estimated by the current duration approach and a traditional constructed approach. Fertil Steril. 2013 Apr;99(5):1324-1331.
3. Rutstein SO et al. MEASURE DHS+ (Programme) and World Health Organization. Infecundity, Infertility, and Childlessness in Developing Countries. Calverton, MD, Geneva, Switzerland: ORC Macro World Health Organization, 2004.
4. Thonneau P, Marchand S, Tallec A, Ferial ML, Ducot B, Lansac J, Lopes P, Tabaste JM, Spira A. Incidence and main causes of infertility in a resident population (1,850,000) of three French regions (1988-1989). Hum Reprod. 1991 Jul;6(6):811-6.
5. Braun M1, Wassmer G, Klotz T, Reifenrath B, Mathers M, Engelmann U. Epidemiology of erectile dysfunction: results of the ‘Cologne Male Survey’. Int J Impot Res. 2000 Dec;12(6):305-11.
6. Hannan JL, Maio MT, Komolova M, Adams MA. Beneficial impact of exercise and obesity interventions on erectile function and its risk factors. J Sex Med. 2009 Mar;6 Suppl 3:254-61.
7. Gaskins AJ, Colaci DS, Mendiola J, Swan SH, Chavarro JE. Dietary patterns and semen quality in young men. Hum Reprod. 2012 Oct;27(10):2899-907.
8. Eslamian G, Amirjannati N, Rashidkhani B, Sadeghi MR, Hekmatdoost A. Intake of food groups and idiopathic asthenozoospermia: a case-control study. Hum Reprod. 2012 Nov;27(11):3328-36.
9. Auger J, Kunstmann JM, Czyglik F, Jouannet P. Decline in semen quality among fertile men in Paris during the past 20 years. N Engl J Med. 1995 Feb 2;332(5):281-5.
10. Carlsen E, Giwercman A, Keiding N, Skakkebaek NE. Evidence for decreasing quality of semen during past 50 years. BMJ. 1992 Sep 12;305(6854):609-13.
11. Irvine S, Cawood E, Richardson D, MacDonald E, Aitken J. Evidence of deteriorating semen quality in the United Kingdom: birth cohort study in 577 men in Scotland over 11 years. BMJ. 1996 Feb 24;312(7029):467-71.
12. Zou Z, Hu H, Song M, Shen Y, Guo X, McElreavey K, Bittles AH, Wang W. Semen quality analysis of military personnel from six geographical areas of the People’s Republic of China. Fertil Steril. 2011 May;95(6):2018-23.
13. Swan SH, Elkin EP, Fenster L. The question of declining sperm density revisited: an analysis of 101 studies published 1934-1996. Environ Health Perspect. 2000 Oct;108(10):961-6.
14. Cordain L, Eaton SB, Sebastian A, Mann N, Lindeberg S, Watkins BA, O’Keefe JH, Brand-Miller J. Origins and evolution of the Western diet: health implications for the 21st century. Am J Clin Nutr. 2005 Feb;81(2):341-54.
15. Cordain L, Eades MR, Eades MD. Hyperinsulinemic diseases of civilization: more than just Syndrome X. Comp Biochem Physiol A Mol Integr Physiol. 2003 Sep;136(1):95-112
16. Carrera-Bastos P, Fontes-Villalba M, O’Keefe JH, Lindeberg S, Cordain L. The western diet and lifestyle and diseases of civilization. Res Reports Clinl Cardiol 2011:2 15–35
17. Chiu YH, Afeiche MC, Gaskins AJ, Williams PL, Mendiola J, Jørgensen N, Swan SH, Chavarro JE. Sugar-sweetened beverage intake in relation to semen quality and reproductive hormone levels in young men. Hum Reprod. 2014 May 8. [Epub ahead of print]
18. Adamowicz J, Drewa T. Is there a link between soft drinks and erectile dysfunction? Cent European J Urol. 2011;64(3):140-143. Epub 2011 Sep 6
19. Araña Rosaínz Mde J1, Ojeda MO, Acosta JR, Elías-Calles LC, González NO, Herrera OT, García Álvarez CT, Rodríguez EM, Báez ME, Seijas EÁ, Valdés RF. Imbalanced low-grade inflammation and endothelial activation in patients with type 2 diabetes mellitus and erectile dysfunction. J Sex Med. 2011 Jul;8(7):2017-30
20. Eisenberg ML, Kim S, Chen Z, Sundaram R, Schisterman EF, Buck Louis GM. The relationship between male BMI and waist circumference on semen quality: data from the LIFE study. Hum Reprod. 2014 Feb;29(2):193-200
21. Sermondade N, Faure C, Fezeu L, et al. BMI in relation to sperm count: an updated systematic review and collaborative meta-analysis. Hum Reprod Update. 2013 May-Jun;19(3):221-31
22. Bosman E, Esterhuizen AD, Rodrigues FA, Becker P, Hoffmann WA. Influence of male hyperinsulinaemia on IVF outcome. Andrologia. 2014 Jan 23. doi: 10.1111/and.12227. [Epub ahead of print]
23. Rosen RC, Wing RR, Schneider S, Wadden TA, Foster GD, West DS, Kitabchi AE, Brancati FL, Maschak-Carey BJ, Bahnson JL, Lewis CE, Gendrano. Erectile dysfunction in type 2 diabetic men: relationship to exercise fitness and cardiovascular risk factors in the Look AHEAD trial. J Sex Med. 2009 May;6(5):1414-22
24. Gareri P, Castagna A, Francomano D, Cerminara G, De Fazio P. Erectile Dysfunction in the Elderly: An Old Widespread Issue with Novel Treatment Perspectives. Int J Endocrinol. 2014;2014:878670. Epub 2014 Mar 17
25. Cordain L. The nutritional characteristics of a contemporary diet based upon Paleolithic food groups. J Am Neutraceut Assoc 2002; 5:15-24.
26. Cordain, L., Hickey, M. , Kim K. Malaria and rickets represent selective forces for the convergent evolution of adult lactase persistence. In: Biodiversity in Agriculture: Domestication, Evolution and Sustainability, Gepts P, Famula T, Bettinger R et al. (Eds.), Cambridge University Press, Cambridge, UK, 2011, pp 299-308.
27. Melnik BC, Schmitz G, John S, Carrera-Bastos P, Lindeberg S, Cordain L. Metabolic effects of milk protein intake strongly depend on pre-existing metabolic and exercise status. Nutr Metab (Lond). 2013 Oct 2;10(1):60. doi: 10.1186/1743-7075-10-60.
28. Melnik BC, John SM, Carrera-Bastos P, Cordain L. The impact of cow’s milk-mediated mTORC1-signaling in the initiation and progression of prostate cancer. Nutr Metab (Lond). 2012 Aug 14;9(1):74. doi: 10.1186/1743-7075-9-74.
29. Melnik BC. Permanent impairment of insulin resistance from pregnancy to adulthood: the primary basic risk factor of chronic Western diseases. Med Hypotheses. 2009 Nov;73(5):670-81
30. Cordain L. Dietary implications for the development of acne: a shifting paradigm. In: U.S. Dermatology Review II 2006, (Ed.,Bedlow, J). Touch Briefings Publications, London, 2006.
31. Afeiche M, Williams PL, Mendiola J, Gaskins AJ, Jørgensen N, Swan SH, Chavarro JE. Dairy food intake in relation to semen quality and reproductive hormone levels among physically active young men. Hum Reprod. 2013 Aug;28(8):2265-75
32. Afeiche MC, Bridges ND, Williams PL, Gaskins AJ, Tanrikut C, Petrozza JC, Hauser R, Chavarro JE. Dairy intake and semen quality among men attending a fertility clinic. Fertil Steril. 2014 May;101(5):1280-1287
33. Ganmaa D, Wang PY, Qin LQ, Hoshi K, Sato A. Is milk responsible for male reproductive disorders? Med Hypotheses. 2001 Oct;57(4):510-4
34. Ma YX, Ebine N, Aoki K, Kusunoki M, Misumi J. Effects of cow’s milk on reproduction in ICR male mice. Biomed Environ Sci. 2009 Apr;22(2):161-3
35. Ganmaa D, Sato A. The possible role of female sex hormones in milk from pregnant cows in the development of breast, ovarian and corpus uteri cancers. Med Hypotheses. 2005;65(6):1028-37
36. Farlow DW, Xu X, Veenstra TD. Quantitative measurement of endogenous estrogen metabolites, risk-factors for development of breast cancer, in commercial milk products by LC-MS/MS. J Chromatogr B Analyt Technol Biomed Life Sci. 2009;877(13):1327-34.
37. Srilatha B, Adaikan PG. Oestrogen-androgen crosstalk in the pathophysiology of erectile dysfunction. Asian J Androl. 2003 Dec;5(4):307-13.
38. Adaikan PG, Srilatha B. Oestrogen-mediated hormonal imbalance precipitates erectile dysfunction. Int J Impot Res. 2003 Feb;15(1):38-43.
39. Hoyt G, Hickey MS, Cordain L. Dissociation of the glycaemic and insulinaemic responses to whole and skimmed milk. Br J Nutr 2005;93:175-177.
40. Hoppe C, Mølgaard C, Vaag A, Barkholt V, Michaelsen KF. High intakes of milk, but not meat, increase s-insulin and insulin resistance in 8-year-old boys. Eur J Clin Nutr. 2005 Mar;59(3):393-8.
41. Castillo-Duran C, Solomons NW. Studies on the bioavailability of zinc in humans. IX. Interaction of beef-zinc with iron, calcium and lactose. Nutr Res 1991;11:429-38.
42. Hallberg L, Rossander-Hulten L, Brune M, Gleerup A. Calcium and iron absorption: mechanism of action and nutritional importance. Eur J Clin Nutr. 1992 May;46(5):317-27.
43. Foresta C, Garolla A, Cosci I, Menegazzo M, Ferigo M, Gandin V, De Toni L. Role of zinc trafficking in male fertility: from germ to sperm. Hum Reprod. 2014 Jun;29(6):1134-45
44. Colagar AH1, Marzony ET, Chaichi MJ. Zinc levels in seminal plasma are associated with sperm quality in fertile and infertile men. Nutr Res. 2009 Feb;29(2):82-8.
45. Atig F, Raffa M, Habib BA, Kerkeni A, Saad A, Ajina M. Impact of seminal trace element and glutathione levels on semen quality of Tunisian infertile men. BMC Urol. 2012 Mar 19;12:6. doi: 10.1186/1471-2490-12-6.
46. Cordain L. (1999). Cereal grains: humanity’s double edged sword. World Review of Nutrition and Dietetics, 84: 19-73.
47. Cordain L. The trouble with beans. In: The Paleo Answer, John Wiley & Sons, New York, NY, 2012, pp 130-147.
48. Denton D. Hominoid evolution and the influences on sodium homeostasis. In: The Hunger for Salt. Springer-Verlag, New York, 1984, pp. 53-75.
49. Boegehold MA. The effect of high salt intake on endothelial function: reduced vascular nitric oxide in the absence of hypertension. J Vasc Res. 2013;50(6):458-67
50. Fraga-Silva RA, Montecucco F, Mach F, Santos RA, Stergiopulos N. Pathophysiological role of the renin-angiotensin system on erectile dysfunction. Eur J Clin Invest. 2013 Sep;43(9):978-85
51. da Costa Gonçalves AC, Leite R, Fraga-Silva RA, Pinheiro SV, Reis AB, Reis FM, Touyz RM, Webb RC, Alenina N, Bader M, Santos RA. Evidence that the vasodilator angiotensin-(1-7)-Mas axis plays an important role in erectile function. Am J Physiol Heart Circ Physiol. 2007 Oct;293(4):H2588-96
52. Fraga-Silva RA, Costa-Fraga FP, Savergnini SQ, De Sousa FB, Montecucco F, da Silva D, Sinisterra RD, Mach F, Stergiopulos N, da Silva RF, Santos RA. An oral formulation of angiotensin-(1-7) reverses corpus cavernosum damages induced by hypercholesterolemia. J Sex Med. 2013 Oct;10(10):2430-42.
53. Meldrum DR, Gambone JC, Morris MA, Ignarro LJ. A multifaceted approach to maximize erectile function and vascular health. Fertil Steril. 2010 Dec;94(7):2514-20.
54. Cordain L. The nutritional characteristics of a contemporary diet based upon Paleolithic food groups. J Am Neutraceut Assoc 2002; 5:15-24.
55. Mínguez-Alarcón L, Mendiola J, López-Espín JJ, Sarabia-Cos L, Vivero-Salmerón G, Vioque J, Navarrete-Muñoz EM, Torres-Cantero AM. Dietary intake of antioxidant nutrients is associated with semen quality in young university students. Hum Reprod. 2012 Sep;27(9):2807-14.
56. Benedetti S, Tagliamonte MC, Catalani S, Primiterra M, Canestrari F, De Stefani S, Palini S, Bulletti C. Differences in blood and semen oxidative status in fertile and infertile men, and their relationship with sperm quality. Reprod Biomed Online. 2012 Sep;25(3):300-6
57. Kroeger N, Belldegrun AS, Pantuck AJ. Pomegranate Extracts in the Management of Men’s Urologic Health: Scientific Rationale and Preclinical and Clinical Data. Evid Based Complement Alternat Med. 2013;2013:701434. doi: 10.1155/2013/701434. Epub 2013 Mar 26.
58. Flohé L. Selenium in mammalian spermiogenesis. Biol Chem. 2007 Oct;388(10):987-95
59. Michaelis M, Gralla O, Behrends T, Scharpf M, Endermann T, Rijntjes E, Pietschmann N, Hollenbach B, Schomburg L. Selenoprotein P in seminal fluid is a novel biomarker of sperm quality. Biochem Biophys Res Commun. 2014 Jan 17;443(3):905-10
60. Schmid TE, Eskenazi B, Marchetti F, Young S, Weldon RH, Baumgartner A, Anderson D, Wyrobek AJ. Micronutrients intake is associated with improved sperm DNA quality in older men. Fertil Steril. 2012 Nov;98(5):1130-7
61. Cordain L, Watkins BA, Florant GL, Kehler M, Rogers L, Li Y. Fatty acid analysis of wild ruminant tissues: Evolutionary implications for reducing diet-related chronic disease. Eur J Clin Nutr, 2002;56:181-191.
62. Cordain L, Eaton SB, Brand Miller J, Mann N, Hill K. The paradoxical nature of hunter-gatherer diets: Meat based, yet non-atherogenic. Eur J Clin Nutr 2002;56 (suppl 1):S42-S52.
63. Afeiche MC, Williams PL, Gaskins AJ, Mendiola J, Jørgensen N, Swan SH, Chavarro JE. Meat intake and reproductive parameters among young men. Epidemiology. 2014 May;25(3):323-30
64. Chavarro JE, Mínguez-Alarcón L, Mendiola J, Cutillas-Tolín A, López-Espín JJ, Torres-Cantero AM. Trans fatty acid intake is inversely related to total sperm count in young healthy men. Hum Reprod. 2014 Mar;29(3):429-40
65. Pront R, Margalioth EJ, Green R, Eldar-Geva T, Maimoni Z, Zimran A, Elstein D. Prevalence of low serum cobalamin in infertile couples. Andrologia. 2009 Feb;41(1):46-50.