nutrient status and Fertility Antioxidant Status and Fertility • Free radicals can damage lipids, cell membranes, DNA, and tissues by altering their chemical structure and functions. • Over time oxidative stress causes damage to lipids, cell membranes, DNA, cells, and tissues. • In men ,Reactive oxygen molecules attack polyunsaturated fatty acids in sperm membranes, and that decreases sperm motility and reduces the ability of sperm to fuse with an egg. • Once the membrane surrounding sperm is damaged, reactive oxygen molecules can enter the sperm cell and damage DNA • Oxidative stress is observed in approximately half of all infertile men. • In women, oxidative stress can harm egg and follicular development and can interfere with corpus luteum function and implantation of the egg in the uterine wall. • Antioxidant nutrients are needed to protect cells of the reproductive system, including eggs and sperm, from damage due to oxidative stress • antioxidants such as vitamin E, vitamin C, beta-carotene, selenium, and antioxidant-rich pigments in vegetables and fruits play important roles in fertility in women and men studies • A number of studies have shown lower intakes of antioxidant nutrients in infertile than fertile women and men. • higher average intakes of antioxidants are associated with improvements in levels of oxidative stress in infertile women and improved sperm maturation, motility, concentration, and reduced DNA and chromosome damage in men • But a number of studies addressing the effects of antioxidant supplements on fertility have been undertaken but due to weaknesses in study designs no reliable conclusions about the effects can be stated. • dietary sources of antioxidants and correction of specific deficiencies with nutrient supplements may be beneficial. Zinc Status and Fertility • in Men Zinc plays important roles in the reduction of oxidative stress, sperm maturation, and testosterone synthesis. • Zinc deficiency in men has been found to be related to poorer sperm quality and sperm concentrations, and to abnormal sperm shapes. • Although it is clear that zinc deficiency can impair normal reproductive functions, it is not clear that supplemental zinc improves fertility in the absence of zinc deficiency Soy Isoflavones and Fertility • Soy isoflavones are chemically similar to estrogen. • In humans, regular intake of soy foods such as tofu, soymilk, tempeh, and textured soy protein is related to reduced sperm count in men and decreased fertility in women. • Effects of high soy-food diets on fertility may be related to the influence of isoflavones on levels or the activity of estradiol, or possibly on other hormones such as progesterone and luteinizing hormone Iron status and fertility • Poor iron status is common problem in women of childbearing age and is related to reduced fertility. • In this study, women who regularly used iron supplements and consumed plant sources of iron were 60 percent less likely to develop ovulatory infertility than women who did not. • 18mg\day Caffeine and Fertility • researchers found that the chance of conception was half as likely among women who consumed over 4 cups of coffee per day (500 mg caffeine) versus the conception rate of women who consumed a cup of coffee or less • . Another study reported that intake of over 300 mg of caffeine daily from coffee, sodas, and tea decreased the chance of conceiving by 27 percent per cycle compared to negligible caffeine intake • Results of research on the effects of caffeine or coffee intake on fertility in women are conflicting Alcohol and Fertility • Alcohol intake has been found to affect fertility in men and women. • In men, intakes of 5–25 drinks per week appear to increase testosterone levels and reduce sperm concentration, total sperm count, and the percent of sperm with normal shape. • consumption of from 1 to 5 alcohol-containing drinks per week by women was related to a 39 percent lower chance of conception. • Consumption of over 10 alcoholic beverages per week was related to a 66 percent reduction in the probability of conception • Consumption of 7 or more drinks a week has been associated with a doubling of risk for infertility in women over the age of 30 only. • Individual genetic characteristics may be involved in the relationship between alcohol intake and fertility. Alcohol intake has been found to reduce fertility only in women with a specific gene variant that reduces the rate of alcohol breakdown in the body Heavy-Metal Exposure and Fertility • Exposure to excess levels of cadmium, molybdenum, manganese, boron, cobalt, copper, nickel, silver, or tin may also affect male fertility. • Exposure to high levels of lead is related to decreased sperm production and abnormal sperm motility and shape. • Inhaled or ingested lead is transported to the pituitary gland, where it appears to disrupt hormonal communications with the testes. • The result is lowered testosterone levels and decreased sperm production and motility. • The men most likely to be exposed to excess lead tend to be workers in smelting and battery factories. • These metals may build up in male reproductive systems through the inhalation of fumes or dust Physical Activity and Fertility • a number of studies have shown that young female athletes may experience delayed age of puberty and lack menstrual cycles. • Average age of menarche is often delayed by 2 to 4 years . • The presence of abnormal cycles reportedly ranges from about 23 percent in joggers to 86 percent in female bodybuilders. • Reduced levels of estrogen that accompany low levels of body fat and amenorrhea, for example, may decrease bone density and increase the risk of bone fractures, and osteoporosis. • Metabolic and hormonal status generally reverts to normal after high levels of training and caloric deficits end.
