Why Microbes, Weight & Nutrition Matter


Available on Amazon Kindle and in Paperback

Whether you are just starting on the quest to parenthood or have been trying for a long time, prepare like a life depends on it. It does. Microbes. Weight. Nutrition. They all matter profoundly in fertility and reproductive health.

Other publications on fertility may address some of these topics but often only as they relate to women. But men are absolutely a significant part of the formula. The magic happens with a brilliant choreography of reproductive systems.

More people need help with fertility these days. One data set from the Centers for Disease Control and Prevention (CDC) suggests that more than 10% of American women seek fertility treatment over their lifetimes.

Countless things can derail this dance of a lifetime. Infections, obesity, and poor diet are just a few. Fortunately, my investigation—many hundreds of studies from peer-reviewed journals and other respected sources were scoured—led to optimism that fertility can be improved. Probiotics, simple diet changes, and/or a daily nutritional supplement are among the evidence-based suggestions that may enhance natural or assisted fertility.

Both women AND men should read this book to improve fertility

This book stands out because it strives to provide a comprehensive record of the available research on how microbes, weight, and nutrition impact fertility in both women and men. It leans heavily on evidence-based research.

Valuable resource for healthcare practitioners

The format makes it an easy and reliable resource for healthcare practitioners who work in obstetrics and gynecology as well as in fertility clinics. Doctors, nurses, and dietitians who work in these areas will find the compiled information invaluable in their practices, with the assurance that it is based only on trustworthy sources.

Valuable information for ALL women and men

Yet every man and woman on this journey can also benefit from this book. No one needs a Ph.D. in microbiology to understand the content. When possible, simpler language is used rather than the dense semantics of academia. In addition, a helpful glossary explains the various vocabulary involved in reproduction as well as terms not used in daily conversation.

An action plan to enhance fertility

As a complete work, the information and extensive data can lead to an action plan for enhancing fertility and reproductive health.

A few of the many striking findings from my research:

  • The vaginal microbiota of women with a history of recurrent miscarriage or infertility differs from that of healthy fertile women.
  • The microbiome may prove to be a worthy target to improve IVF outcomes.
  • Evidence indicates that semen quality and quantity may suffer in obese men.
  • Dietary changes improved fertility in both men and women.
  • Vitamin, mineral, and other micronutrient status will affect fertility and reproduction processes all the way to a healthy birth and beyond.

You will learn practical ways to address these issues and more in order to improve your fertility. Basic lifestyle choices must be examined. This is true whether you and your partner are trying to conceive for the first time or are seeking professional help after a year of attempts. Avoiding alcohol, tobacco, drugs, stress and environmental toxins is mandatory. Exercise moderately. Optimize your microbiota. Aim for a healthy weight. Consume nutrient-dense foods. Supplement when necessary.

Believe in the science and you will be richly rewarded. In the case of fertility, the remarkable research gathered in this book on microbes, weight, and nutrition may lead to your cherished goal: a baby.

Start now. A life depends on you.



Available on Amazon Kindle and in Paperback

Product details

  • ASIN ‏ : ‎ B0B6Q528Z7
  • Publisher ‏ : ‎ Origin Story Press (July 16, 2022)
  • Language ‏ : ‎ English
  • Paperback ‏ : ‎ 338 pages
  • ISBN-13 ‏ : ‎ 979-8218024024
  • Item Weight ‏ : ‎ 1.12 pounds
  • Dimensions ‏ : ‎ 5.5 x 0.77 x 8.5 inches

Check out this Amazon review!

5.0 out of 5 stars
“well written and impeccably researched”
Reviewed in the United States on September 29, 2022

“Clare Fleishman has written an excellent handbook for couples seeking to understand and optimize their efforts to conceive, in a time when environmental factors and other conditions affect our lives at a very basic level. It’s easy to read and implement the suggestions, yet has a depth of knowledge and detail. The glossary is so helpful! It is all pretty sensible, “A healthy diet can make men and women more fertile,” although this is not the whole story. Cautions against relying too heavily on supplements, and including recommendations for food-based nutrients and vitamins are specific, and the negative role of stress is explored. The author, an expert in probiotic regimes, delves into this area.
It takes two–Fleishman gives equal time to issues with male fertility, a welcome development from the way things used to be.
Couples should think ahead, you cannot just start applying these principles at the last minute and expect to get good results, although the human body contains many mysteries we do not yet understand completely, and the best we can do is adopt healthy habits. I am giving this book to my engaged daughter, and I know she will welcome this very practical advice.”

Take a look at this sample section:

The Role of Semen Microbiome on Reproduction

In the past, bacteria in semen were thought to be a sign of infection. Today, new technology has identified these organisms as an essential part of the environment. Far from being interlopers, these microbes are in the right place. But their origins are not always clear. Scientists think they migrate from the urethra, gut, mouth, blood and a partner’s vagina.

Taken together as a group, the set of organisms is called the microbiome. And it can be very different from one man to the next.

Published in 2020, Microbiota and Human Reproduction: The Case of Male Infertility delves into how the semen microbiota impacts a man’s health. Significantly, evidence suggests a link between semen microbiome dysbiosis and infertility.

First, take a look at the many ways that microorganisms can impair spermatozoa functions:

  • Agglutination (clumping) of motile sperm
  • Induction of apoptosis (programmed cell death)
  • Production of immobilization factors
  • Impairment of the acrosome reaction, a required step before the sperm fertilizes the egg

When organisms cause disease or illness to the host, they are considered pathogenic. Pathogens can cause inflammation (they are not the only cause) in the male genital tract. This inflammation is linked to poor semen quality, partially correlated with an increase in pathogens and a reduction in Lactobacillus strains.

These disease mongers drive inflammation through a cascade of cytokines (signaling proteins of the immune system) or by enhanced production of reactive oxygen species (capable of causing damage to biomolecules). Oxidative stress ensues.

Oxidative stress: An imbalance between the systemic manifestation of reactive oxygen species and a biological system’s ability to readily detoxify the reactive intermediates or to repair the resulting damage.

Current evidence links oxidative stress to male infertility, reduced sperm motility, sperm DNA damage and increased risk of recurrent abortions and genetic diseases. Sperm cells may be overwhelmed by these natural byproducts of oxygen during metabolism. Though numerous antioxidants are present in semen, including Vitamins A, E, C, and B complex, GSH, coenzyme Q10, carnitine, and minerals such as zinc, copper, selenium, and chromium, there may not be enough to avoid oxidative stress in some males. More discussion of antioxidants appears in the supplement section of this book.

Oxidative stress can cause big problems. Some 30% to 80% of male sub-fertility may be associated with oxidative stress that damages spermatozoa. It can also reduce the success of in vitro fertilization (IVF) techniques.

Escherichia coli (E. coli) are among the dominant bacteria isolated from the semen samples of males with infertility. E.coli inhibits spermatozoa motility in vitro and readily adheres to and agglutinates sperm. In one study, a single incubation with E. coli, Enterococcus fecalis, and Staphylococcus aureus induced apoptosis (cell death) in human sperm.

The most commonly detected sexually transmitted pathogen worldwide is Chlamydia trachomatis. The pathogen is linked with infertility. Moreover, microbiota dysbiosis may increase the risk of Chlamydia infections. Women with bacterial vaginosis have a reduced presence of Lactobacillus spp.; after exposure to a male partner with chlamydial urethritis, a study observed a higher risk of Chlamydia infection. Fortunately, the acidic (pH-lowering) impact of lactobacilli inactivates Chlamydia.

A 2020 analysis was done of 55 observational studies with 51,299 subjects (collected between 1992 and 2019) to identify bacteria in the semen of infertile and fertile men:

Major findings:

The semen microbiome was rich and diverse in both fertile and infertile men. But the predominant bacteria were different. Ureaplasma urealyticum, Enterococcus faecalis, Mycoplasma hominis and Prevotella negatively impact semen parameters whereas Lactobacillus appears to protect sperm quality.

Though antibiotics have traditionally treated these pathogens, increasing antibiotic drug resistance calls for alternate therapies. Correcting dysbiosis of the microbiota is a solution with potential for infertility.

Positive Effects of Lactobacilli

Lactobacilli appear to protect sperm quality. Not all strains though.

Certain strains of lactobacilli may have a protective role in the male genital tract, similar to what is seen in females. The transfer of microorganisms to the partner and offspring indicates that the seminal microbiome is important for the reproductive health of men, the health of the couple and the health of offspring as well.

In one study, Lactobacillus fermentum L23 produced both preventative and curative effects on E. coli growth in a mouse model of vaginal tract infection.

In another trial with mice, Lactobacillus plantarum 2621 overcame vaginal colonization and infertility induced by sperm-agglutinating E. coli. This particular strain of Lactobacillus was able to interrupt the dysbiotic impact of pathogens on fertility.

Importantly, not all species act the same at all times. One such report suggested that Lactobacillus iners could either be health‐promoting or implicated in dysbiosis and disease. The mutable nature of some of these organisms makes forming recommendations more complicated.

Semen Microbes: Healthy or Not

Beyond looking at toxic microbes in infertility, scientists like to compare healthy semen donor samples alongside those with characteristics of infertility. Think of it as shooting for optimal conditions as opposed to merely avoiding disease or dysfunction.

For example, in one study which compared the semen microbiome of patients with prostatitis (inflammation of the prostate gland) versus healthy controls, a higher amount of lactobacilli, and in particular L. iners, was seen in the healthy subjects group.

In the review Microbiota and Human Reproduction: The Case of Male Infertility, the authors assembled a concise list of microbial features in semen samples. They stressed that these are correlations only and not conclusive or predictive of infertility:

  • Good-quality semen: Lactobacillus
  • Low-quality semen: Anaeroccus, Bacteroides ureolyticus, Proteobacteria, Prevotella-predominant
  • Azoospermic semen (no sperm in a man’s ejaculate): Bacteroidetes and Firmicutes

The semen microbiome appears to be vital to sperm quality. But the effects may be even more far-reaching. See, partners share microbes during sexual intercourse. Many of the bacterial taxa identified in semen also occur in the vaginal communities of some women, especially those with bacterial vaginosis, which suggests heterosexual sex partners may share bacteria. Each partner can influence the microbiome composition of the other partner. How much influence varies with a host of factors: frequent sexual intercourse, multiple sexual partners, and uncircumcised male partners can alter vaginal microbiota and are linked to bacterial vaginosis.

So we see that male and female microbiomes can engage. For example, microbiomes of semen and vaginal fluid (before and after intercourse) of 23 couples were profiled in a 2015 study. Gardnerella vaginalis in female partners was related to significant inflammation in male genital tracts. Also, the relative abundance of Lactobacillus crispatus decreased after intercourse, with a high consistency between semen and vaginal samples.

In addition to influencing the vaginal microbiome, the semen microbiome may be able to overcome the cervical barrier and colonize the uterus. Microbes entering the uterus can cause infections and inflammation, which are linked to preterm birth, chronic lung disease and cerebral palsy. A dysbiotic male microbiome is no small matter. The future health of children can be impacted.

Targeting the Seminal Microbiome


Probiotics are thought to enhance male fertility by improving sperm characteristics and testosterone levels.

Probiotics: Live microorganisms that, when administered in adequate amounts, confer a health benefit on the host.

The following trials in animals and humans illustrate probiotic effects:

A strain of Lactobacillus rhamnosus PB01 (DSM 14870) improved sperm quality parameters in obese mouse models.

And a study with rats indicated that dietary probiotics had antioxidant activity and a protective effect against sperm damage induced by a high-fat diet.

In a study in humans, Lactobacillus rhamnosus CECT8361 and Bifidobacterium longum CECT7347 improved sperm motility and reduced the percentage of sperm DNA fragmentation in asthenozoospermic (reduced sperm motility) males.

In another study, a combination of three selected strains of lactobacilli (Lactobacillus brevis CD2, L. salivarius FV2, and L. plantarum FV9) used as vaginal tablets to treat bacterial vaginosis prevented sperm lipid peroxidation (oxidative deterioration) and preserved sperm motility and viability. Vaginal probiotic lactobacilli protected sperm from radical oxygen species in the presence of vaginal disorders. Simply put, the sperm had a better shot at fertilizing an egg.

Because older men have falloffs in blood testosterone, some opt for supplemental hormones. But probiotics may be able to offset some of that decline. In one study with mice, Lactobacillus reuteri was able to sustain youthful levels as well as testicular size.

Numerous fermented foods may contain probiotics but few are described adequately to be consistently reliable. For that reason, a probiotic supplement is often recommended.


Prebiotic: A substrate that is selectively utilized by host microorganisms conferring a health benefit.

Once again, many fermentable carbohydrates can be prebiotic, as long as they are selectively used by the host microbiota and promote health.

Prebiotics were able to ameliorate some semen parameters in both animal models and humans.

Many foods and supplements provide much-needed prebiotics. Plants that are rich in prebiotics include onions, garlic, bananas, chicory root, and Jerusalem artichokes. Prebiotics added to foods or supplements include galacto- oligosaccharides (GOS), fructo-oligosaccharides (FOS), oligofructose (OF), chicory fiber, and inulin.


Synbiotic: A mixture comprising live microorganisms and substrate(s) selectively utilized by host microorganisms that confer a health benefit on the host.

A synbiotic of Lactobacillus paracasei B21060 with added prebiotics and additional ingredients over a period of 6 months improved sperm count and motility, and reduced the rate of atypical forms, in comparison to the control group. Testosterone levels were also improved.

Supplement formulations often contain both probiotics and prebiotics. Read your labels.

This may be good news for infertility issues. These initial studies reveal that alterations to the male microbiota may enhance fertility.

Restoring male fertility with probiotics may be enabled by:

  • Reversing the impact of oxidative stress induced by a high-fat diet or old age
  • Improving testosterone levels
  • Improving sperm quality

New research suggests that ensuring a healthy seminal microbiome is an important step in health measures before trying to conceive. And know that making sure your microbiota is in good shape is recommended for all men—not just the infertile—who wish to optimize the health of their future child.