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By Stephanie Cold
Infertility – the inability to conceive a child after at least 12 months of frequent, unprotected sex – is a source of great concern for would-be parents worldwide. It has been estimated to affect up to 15 percent of couples in the United States, with male infertility playing a role in over one-third of cases. Twelve percent of women of child-bearing age are afflicted with impaired fecundity, which includes both difficulty getting pregnant and problems with carrying a baby to term.
Some fertility factors are quite obvious – stress, age, genetics, and overall health, to name a few. Common causes of male infertility include low sperm count, poor sperm motility, semen abnormalities, erectile or ejaculate dysfunction, low testosterone levels, and other hormonal imbalances. For women, causes of infertility include ovulation problems, hormonal disorders such as polycystic ovary syndrome (PCOS), endometriosis, blocked fallopian tubes, and anatomical abnormalities of the cervix. However, some couples have difficulty getting pregnant even though no direct cause can be detected through standard medical assessments. In fact, 15 to 30 percent of infertile couples who seek treatment are diagnosed with unexplained, or idiopathic, infertility.
In the case of unexplained infertility, dietary and environmental toxins may be less obvious causes or contributing factors. Other aspects of diet and lifestyle may also impact fertility. This article will shed light on some of these overlooked influences, and, in doing so, potentially help couples dealing with infertility to overcome some hurdles on their way to a healthy pregnancy.
Toxic chemicals may be lurking in our water, food, air, soil, and household products – basic things we come in contact with on a daily basis. Many of these chemicals affect fertility through their actions as endocrine disruptors, which interfere with the proper functioning of hormones responsible for the reproductive and developmental processes. Endocrine disruptors can imitate naturally occurring hormones, such as estrogens and androgens, potentially overstimulating hormonal pathways. Conversely, they can act as antagonists and bind to the hormone receptors within the cells, blocking the endogenous hormone and preventing the normal signal from occurring. Many common endocrine disruptors affect hormonal regulation, fertility, successful pregnancy, and overall reproductive health.
Pesticides and herbicides
Pesticide residue on conventionally grown crops is a primary concern. Nearly 70 percent of the produce on the market in the United States is contaminated with pesticide residues. In fact, USDA testing has detected over 200 pesticides and pesticide breakdown products on popular fruits and vegetables.
Ingesting pesticide residue may result in oxidative stress, disrupt hormonal activity, and contribute to both male and female infertility. A recent study from Harvard T.H. Chan School of Public Health found that eating produce that has high amounts of pesticide residue – such as conventionally farmed strawberries, spinach, and grapes – may reduce women’s chances of conceiving and bearing children.
Glyphosate-based herbicides, such as Roundup, have raised particular concern. Studies connect these herbicides to reproductive problems in animals, including impaired reproductive development in offspring. Moreover, a recent epidemiological study of the population of a typical Argentine agricultural town showed an association between high environmental exposure to glyphosate and increased rates of reproductive disorders (spontaneous abortion and congenital abnormalities). With genetically modified crops and glyphosate-based herbicides becoming increasingly prevalent in our food system, it is obvious that further research is needed to confirm the risks they pose to human reproduction, as well as general health.
Actions to Take: Avoid conventionally grown produce and grains, and choose organic whenever possible. Keep in mind that certified organic farms are allowed to use certain approved pesticides, so thoroughly wash all fruits and vegetables before eating, even if they’re organic. If you buy from local farmers markets, you can ask the farmers about their growing practices and pesticide use. The Environmental Working Group (www.ewg.org) has helpful resources, including their Dirty Dozen, a list of foods with the highest concentration of pesticides; and the Clean Fifteen, which lists foods with the least pesticide residue.
Exposure to heavy metals in food or drinking water can also disrupt fertility. Lead and cadmium, in particular, have been recorded as causing damage to male and female reproductive systems. In one small study, cadmium was detected in 91 percent of women with unexplained infertility, compared with 34 percent of fertile women. New research from Carnegie Mellon University has found that lead exposure from air and topsoil impacts the fertility of both men and women.
Elemental mercury and its man-made relative, methylmercury, are largely accepted as neurotoxins that interfere with proper brain development. Mercury also plays a role in infertility. Fossil fuel emissions and dental amalgams are common sources of elemental mercury exposure, while seafood is the primary source of methylmercury exposure. A study out of Hong Kong found that infertile subjects – both males and females – had abnormally high blood mercury readings, compared to fertile subjects. Mercury toxicity is suspected to affect fertility by disrupting hormones, such as estrogen and progesterone, and has been linked to negative fertility outcomes in both men and women, including erectile dysfunction and menstrual disorders, respectively.
Actions to Take: Avoid high-mercury fish. Since mercury has been found to bioaccumulate in seafood, cut your consumption of large, predatory fish noted for high mercury content, such as swordfish, shark, and king mackerel. Doctors commonly recommend that pregnant women avoid seafood with high levels of mercury, and the same should go for those trying to get pregnant. Use the Natural Resource Defense Council’s Smart Seafood Buying Guide (www.nrdc.org/stories/smart-seafood-buying-guide) to find out which types of seafood are low in mercury.
Filter your drinking water. If possible, install a household water purification system or a shower filter. In addition to heavy metals and pesticide run-off, tap water may contain many chemicals that impact health and fertility. Men exposed to high amounts of chlorine through drinking, bathing, showering, and swimming were found to have reduced sperm motility and lower sperm count. Animal studies have found that fluoride can adversely affect the male reproductive system. Note that activated carbon filters are not very effective at removing fluoride or heavy metals from water. If these are considerations, another method – such as a bone char filter, reverse osmosis, or an ion exchange system – may be a better choice. If your water comes from a private well, test it for heavy metals or contaminants specific to your area.
Personal care products
Personal care products – from shampoo, conditioner, shaving gel, and perfume to deodorant, cosmetics, sunscreen, and diaper cream – are a significant source of chemical exposure. One study by the Environmental Working Group found that, on average, women use 12 personal care products per day and are exposed to 168 chemicals from daily use of cosmetics and other personal care items. Men tend to use fewer personal care products but are still exposed to 85 such chemicals per day.
While many of us would assume these products to be safe, the reality is that the US Food and Drug Administration (FDA) does no systematic reviews of their safety, and the cosmetic industry is largely self-regulated. The Environmental Working Group found that, in 30 years, the industry’s self-policing safety panel reviewed the safety of only 11 percent of the 10,500 ingredients used in personal care products.
Many personal care products are laden with parabens, phthalates, synthetic fragrances, and other chemicals. In fact, such products are our primary source of paraben exposure. Parabens, which are used as preservatives, can be found under multiple names in personal care and household products. The most common are methylparaben and propylparaben. Associated with infertility in multiple animal studies, parabens seem to have an estrogenic effect that disrupts hormonal activity and inhibits mitochondrial function.
Many personal care products also contain phthalates, whose regular use has been associated with a number of serious health problems, including infertility. Exposure to phthalates in utero may lead to anatomical changes in male children that can impact their later fertility. In adult males, exposure has been linked to decreased fertility, lower testosterone levels, and alterations in sperm. Several studies suggest that phthalates can affect female fertility as well.
Actions to Take: Throw out all personal care products and cosmetics that contain parabens, phthalates, and unfamiliar chemicals. Replace them with products that have natural ingredients or make your own products at home. You can find a multitude of do-it-yourself skin and hair care recipes online. If you aren’t a DIY enthusiast, you can use the Environmental Working Group’s Skin Deep Cosmetics Database (www.ewg.org/skindeep) to investigate the toxicity of individual products and ingredients and to find safer alternatives.
Note that many household cleaners also contain parabens, phthalates, and other potentially harmful chemicals. Shop carefully to avoid these, or make homemade cleaning products with safer ingredients, such as vinegar, baking soda, and lemon juice.
Food packaging, baby bottles, children’s toys, grocery bags, and any number of other products may be made from plastics that contain endocrine disruptors such as phthalates, bisphenol-A (BPA), bisphenol-S (BPS), and bisphenol-F (BPF). These chemicals are found in various food contact products, including the inside coating of beverage and food cans. Plastics used in the packaging, heating, and storage of food are especially problematic, since those chemicals can easily leach into our food and beverages through heating, repeated use, or contact with acidic or alkaline substances.
BPA is also found in a wide variety of paper products, including thermal receipt paper, food wrappers, tickets, and recycled paper towels and toilet paper. This is a problem because BPA is dermally absorbed through contact.
Animal studies indicate that exposure to BPA can cause early puberty, increased mammary development, prolonged estrous cycles, chromosomal abnormalities in eggs, and other fertility problems in females. In males, decreased testosterone levels, reduction in sperm motility and quantity, and an increase in abnormal sperm can result. A review of BPA conducted by the National Toxicology Program (NTP) Center for the Evaluation of Risks to Human Reproduction expressed concern regarding the effects of the chemical on the brain, behavior, and prostate glands of fetuses and children from current rates of human exposure.
Actions to Take: Reduce the amount of plastic in your home. When possible, choose jars, glass bottles (especially baby bottles), and glass or stainless steel containers to store and heat food and water. Decline store receipts, bring reusable cloth bags to carry your groceries, try cloth towels and dish cloths instead of paper towels, use wooden cutting boards instead of plastic ones, and buy fresh foods or foods packed in glass jars instead of packaged and canned foods.
Brominated flame retardants (BFRs) are common in furniture, mattresses, car seats, and various children’s products, as well as computers, electronics, and electrical equipment. These chemicals are gradually released into household environments, and can be inhaled, accidentally ingested, or dermally absorbed via house dust. BFRs are endocrine disruptors that have the potential to affect both male and female reproductive development and may pose a threat to fertility by interfering with normal hormone function.
Actions to Take: Choose furniture and mattresses without brominated flame-retardant chemicals. Select products that state “flame retardant-free” or are made from relatively inflammable materials, such as wool and leather.
Foods and fertility
The wide variety of food choices available in modern society have the potential to either boost or reduce our fertility. In general, a nutrient-dense, whole foods diet is best to enhance reproductive health. However, there are some categories of foods that should be considered individually.
Many plant-based foods contain phytoestrogens, naturally occurring compounds that are structurally and/or functionally similar to the estrogen found in the human body. Soybeans, however, are particularly high in phytoestrogens known as soy isoflavones, which include genistein and daidzein. Soy isoflavones can bind to the body’s estrogen receptors and exert estrogenic or anti-estrogenic activity.
While eating small amounts of soy may cause little harm, consuming soy products in large amounts – as in many vegetarian diets and soy-based baby formulas – is cause for concern. Notably, infants are often given soy-based formulas during the first year of life, a period of development when they are particularly sensitive to dietary and environmental compounds.
Because of this, concerns have arisen about soy’s possible adverse effects on brain and reproductive organ development and, ultimately, on fertility.
A few studies have pinpointed other food groups that may be detrimental to fertility. One of these is reduced-fat dairy products. Researchers found an association between intake of low-fat dairy foods and increased anovulatory infertility, a condition in which the woman fails to ovulate. Conversely, full-fat dairy products were positively associated with fertility. In fact, the study found that one additional daily serving of whole milk reduced the risk of infertility by more than 50 percent. Full-fat dairy products, particularly those from pastured cows, are full of bioavailable nutrients, including eight vitamins and conjugated linoleic acid (CLA), an essential omega-6 fatty acid.
It should be noted that almost 10 percent of US dairy farmers inject recombinant bovine growth hormone (rBGH), also known as recombinant bovine somatotropin (rBST), into their cows to boost milk production, although this practice is banned in the European Union, Canada, and other countries. Cows treated with this synthetic hormone often develop significant reproductive problems, including infertility, cystic ovaries, fetal loss, and birth defects.
The amount and type of carbohydrates in the diet may also impact fertility. A prospective or longitudinal study found that total carbohydrate intake and dietary glycemic load were both positively related to ovulatory infertility in apparently healthy women. In addition, dietary glycemic index was related to this condition in those members of the group who were nulliparous (in other words, had never given birth). However, the researchers qualified their findings, stating that consumption of high-glycemic carbohydrates may not have been the sole factor at play, as the women with greater carbohydrate intakes consumed lower amounts of natural fats that may beneficially affect fertility.
Nutrients that boost fertility
Vitamin A is necessary for both conception and a healthy pregnancy because it is involved in the manufacture of estrogen and the other pregnancy hormones that guide fetal development. This vitamin gives the undifferentiated fetal stem cells, or germ cells, signals that prompt them to differentiate into the various organs, such as the heart, liver, and lungs. Without sufficient vitamin A, organs may develop abnormally – or not at all.
Preformed vitamin A, also known as retinol, is only found in animal-sourced foods, such as beef liver, oily fish, eggs, and butter. Keep in mind that beta-carotene is not true vitamin A; it is a precursor that must be converted to vitamin A in the body, and many people do not make this conversion efficiently.
Although pregnant women need extra vitamin A for fetal growth and support of their own metabolism, excessive dosages of preformed vitamin A can lead to reproductive toxicity. According to the Office of Dietary Supplements, total intakes of preformed vitamin A that exceed the Food and Nutrition Board’s tolerable upper intake level of 10,000 IU per day (for women age 19 and above) can cause birth defects.
Folate is a member of the B vitamin complex and is also known as vitamin B9. It is an essential nutrient for a healthy pregnancy because it is needed when cells are dividing rapidly – exactly what happens when a fetus is growing. In addition, folate is particularly important for the development of the fetal nervous system and for the synthesis of DNA.
Folate’s ability to reduce the risk of neural tube defects (NTDs) has been widely studied. NTDs are severe congenital abnormalities of the brain or spinal cord. Because these defects occur very early in the pregnancy – sometimes before a woman even knows she is pregnant – folate must be part of any preconception regimen. The negative consequences of folate deficiency are so severe that it is usually necessary to supplement this nutrient, particularly through the first trimester of pregnancy.
Folic acid, a synthetic form of B9, is often added to prenatal vitamins, as well as many cereal grain products. However, the body may not convert folic acid into the active form of the vitamin efficiently, and high levels of unmetabolized B can occur. Thus, it may be advantageous to select a supplement that contains a type of folate called 5-methyltetrahydrofolate (5-MTHF).
Food sources of folate are also important. Dark leafy greens, such as kale, collard greens, arugula, mustard greens, and spinach, are high in folate. Other sources include liver, chickpeas, lentils, cabbage, peas, asparagus, and broccoli.
Vitamin B complex
In addition to folate, the rest of the B-complex vitamins, including B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyroxidine), B7 (biotin), and B12 (cobalamin), all have varying impacts on fertility and preconception health. The B vitamins in general are important for the proper growth and development of the fetus. Thiamine, riboflavin, niacin, B6, and B12 work with folate to decrease the occurrence of NTDs. B6 may be useful in preventing or alleviating nausea during early pregnancy, and B12 is needed for the healthy development of the brain.
Most people can obtain sufficient amounts of the B vitamins with a varied diet of traditional whole foods, containing plenty of vegetables and products from pastured animals. Because B12 can only be obtained from animal products, include liver, red meat, whole milk, and eggs in your diet. Choose pastured and organic products to avoid antibiotics, synthetic hormones, pesticides, herbicides, and genetically modified feeds.
Vitamin C is a powerful antioxidant that helps with the absorption of other vitamins and minerals and is essential during the preconception period. Infertility can often be a result of oxidative stress, and an abundance of antioxidants can help tip the scales in favor of a successful pregnancy. Researchers have found that, in males, a lower intake of some antioxidant nutrients – including vitamins A, C, and E; carnitines; folate; zinc; and selenium – has been associated with infertility. Vitamin C, in particular, protects sperm against oxidative stress and free radical damage, thus improving male fertility.
Vitamin C is found in all fruits and vegetables. Some of the fruits containing the highest amounts are cantaloupe, citrus fruits, kiwi, mango, and papaya. The highest vegetable sources of vitamin C include broccoli, Brussels sprouts, cauliflower, peppers, and leafy greens.
Vitamin D3 improves ovulatory fertility and is essential for a healthy pregnancy. Adequate levels are associated with decreased risk of the following: preterm birth, infections, pre-eclampsia, gestational diabetes, and high blood pressure. Pregnant women are often deficient in vitamin D3; therefore, supplementation is generally recommended from preconception through the entire period of pregnancy and nursing.*
Our bodies naturally produce vitamin D3 when ultraviolet rays from the sun hit our exposed skin. However, the vitamin can also be obtained from foods. Wild salmon and other fatty fish are the best dietary sources of vitamin D, and beef liver, cheese, and egg yolks also provide small amounts.
Vitamin E is especially important in a preconception diet for male fertility. It is a powerful antioxidant that protects sperm from oxidative damage. This vitamin also works together with selenium and glutathione (another antioxidant) to create the enzyme glutathione peroxidase. An abundance of this enzyme may improve sperm motility, while a deficiency can result in abnormal sperm cells.
Food sources of vitamin E include sunflower seeds, almonds, spinach, avocados, trout, shrimp, wheat germ oil, and olive oil.
DHA (docosahexaenoic acid) is an omega-3 fatty acid essential for fetal brain, cognitive, and motor development. Maternal DHA stores must increase prior to conception and be maintained at adequate levels during pregnancy to ensure sufficient placental transfer of DHA to the fetus during the third trimester, when rapid brain growth takes place.
Oily fish, such as anchovies, salmon, herring, and sardines, are good sources of DHA. Choose fish that are low in mercury. Cod liver oil is an excellent supplemental source of this vital omega-3 fatty acid.
Iron plays a role in preparing the uterine lining for pregnancy and is essential in the production of blood. This is significant because blood plasma volume increases by at least 50 percent during pregnancy.
An important component of red blood cells, iron helps to facilitate the transfer of oxygen throughout the body. If there is not enough iron in the mother’s body during pregnancy, the fetus may not get sufficient oxygen. This may limit growth and development, leading to low birth weight and/or a preterm delivery.
Shellfish, liver, and other organ meats are especially high in iron. White beans, lentils, and spinach are among the plant-based foods that contain this mineral.
Selenium and zinc
Both selenium and zinc boost fertility, especially in men, as well as being important for fetal development. Selenium is required for normal testicular development and sperm production, motility, and function. It may also protect against oxidative damage to the sperm DNA.
In cases of infertility due to heavy metal toxicity, selenium can serve as a detoxifying agent. In several animal studies, a selenium supplement was shown to reverse cadmium-induced infertility.
Selenium can be found in meat, mushrooms, and seafood.
Zinc assists in activating antioxidants and is needed for normal sperm count, motility, and health. In females, it is required for successful fertilization of the egg. Researchers have observed that the egg accumulates zinc prior to fertilization, at which time a massive release of zinc appears to set it on the path to cell division.
Oysters contain more zinc per serving than any other food. Other good sources include red meat, poultry, and other shellfish, as well as beans and seeds, particularly pumpkin seeds.
Copper is important for early fetal brain development. However, copper interacts with both zinc and iron, and all of these must remain in balance. High blood copper levels with low zinc may cause negative pregnancy outcomes. Similarly, adequate copper levels with inadequate levels of iron may result in impairment to brain development.
Good sources of copper include liver, oysters, shiitake mushrooms, cashews, and sesame seeds.
Up to 95 percent of pregnant women may have suboptimal intakes of choline. Adequate maternal choline during pregnancy is important for the prevention of NTDs and for optimal fetal brain development.
While a variety of foods contain small amounts of choline, eggs are the most abundant dietary source of this essential nutrient. In fact, eggs provide women with an abundance of vitamins needed during preconception and pregnancy, including vitamins A, D, E, and K2, biotin, and folate. They are also a good source of cholesterol, which is crucial for fertility and fetal development and is required for the production of sex hormones.
Incorporating lacto-fermented foods and beverages – such as sauerkraut, pickles, kefir, kombucha, and kimchi – into the diet is also important for pregnancy preparation. These contain both beneficial enzymes and probiotic bacteria, which help to create a healthful gut environment in the mother. Maintaining an abundance of beneficial gut bacteria helps to prepare her body for the baby’s passage through the birth canal, when bacteria from the mother begin to populate the baby’s skin, mouth, and gut. Taking probiotic supplements during pregnancy may also help set the stage for establishment of a healthy microbiome in the baby.
We can have an enormous impact on our fertility by modifying our diet. During the period of preconception, it is particularly important that both male and female partners commit to improving their diet to optimize fertility and ensure the healthiest offspring possible.
An optimal diet to enhance fertility, for both men and women, should focus on traditional, whole foods – a wide variety of vegetables and fruits, and adequate protein from seafood and pastured meats, particularly organ meats. Healthy fats from both plant and animal sources are necessary to nourish the body and prepare for sustaining new life.
At the same time, preconception planning should include steps that avoid or reduce exposure to toxins. Many of the potential risks to fertility in men and women involve environmental and household contaminants, including chemicals in personal care products. Ridding your home of such risks can be an important step towards resolving difficulties in achieving a healthy pregnancy.
About the Author
Stephanie Cold is the communications specialist for the College of Agriculture, Food and Environmental Sciences at the University of Wisconsin-River Falls. She has previously worked with multiple local food cooperatives in the areas of marketing and communications and has taught community education classes on the topics of fermentation, raw milk, and more.
*For more information on vitamin D and pregnancy, see “Stop Vitamin D Deficiency in Its Tracks,” in the Winter 2017 issue of the Price-Pottenger Journal.
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Published in the Price-Pottenger Journal of Health and Healing
Winter 2018 – 2019 | Volume 42, Number 4
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