Of course we know intuitively that some foods are bad for us, and some are good for us; no one would argue that choosing a fast food burger is better for us then a serving of vegetables. But what about when it comes to more complicated nutritional matters and eating foods for specific health benefits, can we influence our bodies to be more fertile?

The short answer is yes. In fact studies have shown that both men and women have the power to take in, or NOT take in, specific foods/products to help (or not hinder) their fertility.


The first step to putting your body in the best state for conception and for carrying a baby is to develop a healthy lifestyle which includes appropriate exercise and healthy eating patterns. In fact, obesity in women is associated with lower rates of fertilization, poor quality embryos and higher miscarriage rates[1]. Weight has a profound impact on the reproductive health of those who are getting fertility treatments as well as those working to conceive naturally as overweight and obese women also have poorer outcomes following fertility treatments. It is important to note however that a crash diet is not the answer. Appropriate weight loss will regularize menstrual cycles which incites spontaneous egg release, aiding healthy ovulation, where a crash diet is detrimental as it can wreak havoc with your hormones causing a less regular ovulation cycle.

As with most things to do with conception it is not only the woman who needs to get healthy. "Men who are looking to have a baby also have a responsibility to maintain a healthy body weight and consume a balanced diet, because male obesity may affect fertility by altering testosterone and other hormone levels," says Brooke Schantz, a Loyola University dietician[2].


Caffeine has long been discussed (and researched) as having possible effects on fertility. A number of early studies showed no ill effects to fertility such as the research by P. Thayer and C. Kensler in 1972, following four generations of mice which had doses of caffeine added to their drinking water with no statistically significant ill effects shown. But, as time went on more studies emerged with different results.

In 1981 a study done on cocks (male poultry) found that there was a significant effect to the sperm from caffeine, reporting that the proportion of chicks sired by cocks fed caffeine decreased during treatment (a fourteen day period of being fed caffeine) and remained that way until seventeen days after treatment[3]. Another study on chickens found that young hens which were fed a high level of caffeine caused the production of soft shelled eggs and a cessation of egg production within three days[4]. This research is in keeping with a huge European study of 3,187 women aged 25-44 years tracking their speed of conception and caffeine intake. This study found that women who had the highest levels of caffeine consumption also had an increase in the time leading to their first pregnancy of 11%[5].

Although there may be questions as to the degree of the repercussions, there is no question that caffeine has been shown to have an effect not only on the speed of conception for women, but also on the health and production ability of sperm for men. This means that if you are working on conceiving it is definitely best practice for men and women to lower their caffeine intake to less then 250mg daily. Better safe than sorry.


The jury is still out on this one, with further study needed before hard conclusions can be drawn. There are holistic groups who will very adamantly tell you that soy is bad for fertility (and possibly just that it’s bad overall), but the researchers are still trying to figure it out for sure. Soy has been shown to have beneficial attributes, such as decreasing menopausal symptoms, lowering the risk of osteoporosis, decreasing cholesterol as well as being a healthy meat-free source of protein. Soy, as well as legumes and chick peas, contain isoflavones (a type of plant driven estrogen) which can have one of two effects within the human body; some act as mild estrogens while others act as antiestrogens which reduce the activity of estrogoen (thus aiding menopausal women).

A study done in 1994, found in the American Journal of Clinical Nutrition,  reported that high levels of soy could increase the length of the menstrual cycle by an average of two and a half days; but this was at very high intake levels, the equivalent of drinking three big glasses of soy milk every day for a month[6]. Another study done by King’s College London, reported in 2005, looked at the effects of isoflavone called genistein on mouse and human sperm. It was found in this study that after exposure to the isoflavone the caps covering the head of the sperm, called acrosomes, which enable to them to penetrate the egg, were three times as likely to come off after exposure than before.

But to balance those few studies which show negative effects from soy, there are the statistics from Asian countries where there are high levels of soy taken in normally and there are no trends of infertility issues rampant. Also there are studies which have shown no significant effect on fertility from soy. A study done at Wake Forest University Baptist Medical Center and Emory University of Medicine (reported at the 2004 meeting of the American Society for Reproductive Medicine) gave a group of monkeys a soy supplement which contained twice the levels of plant estrogen taken in by Asian women, and they found no ill effects on ovarian function or characteristics of the menstrual cycle.

What this means is that there are no hard conclusions to be drawn, more research needs to be done before anyone can definitively say that soy is “bad” for fertility. This is another situation where it may be that for those who show more sensitivities to hormone imbalance, or who have particular risk factors for infertility (such as PCOS or endometriosis) it is best to cover all their bases and simply try and limit the amount of soy they are taking in while in the conception phase.


This one is a clear cut case for both men and women, alcohol is not a good choice for those couples who are working on conceiving. Numerous studies have shown that for women even drinking lightly can affect the rates of conception. A Danish study done in 2009 concluded that drinking between one and five drinks a week could reduce a woman’s chance of conceiving, and ten drinks or more would decrease the likelihood of conception even further[7].  

The effects of alcohol for men are also well researched. A recent Danish study showed that men who take in more than five drinks a week have detrimental effects on their sperm quantity and quality. The effects were the most significant with those men who drank 40 units per week and had 51% less normal looking sperm as compared to normal, as well as sperm counts that were up to 33% lower than normal[8].


This is a very simple one, that really probably all of us know by now. Smoking is bad for us, plain and simple. Smokers take longer to conceive and have higher levels of infertility. Smoking also increases your chances of miscarriage. Having a spouse who smokes is also detrimental, with rates of conception decreasing for those couples where the husband smokes. Also, second hand smoke can still affect your fertility and further has been shown to increase the chances of SIDS[9].

(1) “The Impact of female obesity on the outcome of fertility Treatement” S. Pandey, A. Mahaeshwari and S. Bhattacharya, Journal of Human Reproductive Sciences. 201 MAy-Aug; 3(2): 62-67

(2) http://www.nydailynews.com/life-style/health/6-ways-boost-fertility-nutrition-article-1.1491700

(3) “Detection of the effects of ingested caffeinve on fertility of cocks by homospermic and heterospermic insemination” D. Hagen and P. Dziuk, Journal of Society for Reproduction and Fertility. 1981, 63:11-15

(4) “Effects of Dietary Caffeine on FEritlity and Embryonic Loss in Chickens” Poultry Science (1974); 53 (1); 428-429

(5) “Caffeine Intake and Delayed Coception: A European Multicenter Study on Infertility and Subfecundity” American Jouranl of Epidemilogy. (1997) 145 (4): 324-334

(6) “Biological effects of a diet soy protein rich in isoflavones on the menstural cycle of premenopausal women” A. Cassidy, S. Bingham and KD. Setchell, American Journal of Clinical Nutritution. 1994 Sep;60(3):333-40
(7) T Koldjensen, NHI Hjollund, TB Henriksen, T Scheike, H Kolstad, A Giwercman, E Ernst, JP Bonde, NE Skakkebaek & J Olsen, “Does moderate alcohol consumption affect fertility? Follow up study among couples planning first pregnancy”, BMJ 1998; 317:505-510.
(8) Habitual alcohol consumption associated with reduced semen quality and changes in reproductive hormones; a cross-sectional study among 1221 young Danish men, Tina Kold Jensen, et al., BMJ Open, http://dx.doi.org/10.1136/bmjopen-2014-005462, published 2 October 2014
(9) “The effects of smoking on ovarian function and fertility during assisted reporduction cycles.” http://www.ncbi.nlm.nih.gov/pubmed/8885914

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