Perimenopause/Menopause and the Microbiome
What is the microbiome?
The microbiome consists of the trillions of microorganisms that inhabit various parts of the body. While they predominantly reside in the gut, they can be found on the skin, in the oral cavity, as well as the vaginal tract. The microbiome not only consists of bacteria, but also includes other microorganisms such as yeast and viruses. The microbes that make up the microbiome have a symbiotic relationship with us as their human hosts and provide a multitude of beneficial functions.
While none of these are inherently bad, we tend to refer as certain microbes as commensal if they confer some health benefit, while we refer to others as pathogenic given their link to problematic conditions. Those that tend to be problematic might better be described as opportunistic. When commensal microbes become outnumbered by these opportunists, we refer to this as dysbiosis. While there are certain characteristics of the human microbiome that we all share, each microbiome is as unique as a fingerprint.
The microbiome is inherited at birth. Research indicates a difference among microbial profiles of babies born via C-section versus those that pass through the vaginal canal. The microbiome is also inherited during breastfeeding and microbial profiles also look different among breast-fed babies versus formula-fed babies. Other influencing factors include antibiotic exposure, stress, exposure to pets, and of course diet. Here we will focus on diet since this is one of the most modifiable factors.
The role of the microbiome
The microbiome is involved in numerous physiological processes. It helps to support the production of various metabolites such as short chain fatty acids; it's involved in the synthesis of certain vitamins such as the B vitamins and vitamin K; it plays a role in energy metabolism impacting how we assimilate fats and carbohydrates; it regulates pH (how acidic vs alkaline a particular area of the body is); it plays an important role in immune health, communicating with certain immune cells and regulating what is granted access to systemic circulation. Although the mechanisms behind these actions are not fully understood, there is an abundance of research support these roles. Highlighted below are a few key conditions that are closely linked to changes in the microbiome, particularly as they relate to the decline of estrogen during this stage in women’s development.
Insulin Resistance
Insulin resistance is a condition characterized by impaired sensitivity of various cells in the body to insulin, a hormone critical to the regulation of blood glucose levels. The body breaks down the carbohydrates that we eat into glucose, a sugar that is our body's preferred source of energy. This glucose enters our bloodstream and then signals insulin to be released by the pancreas to help deliver it to ourselves for immediate use or storage for later use. Insulin resistance develops when our cells stop responding appropriately to insulin. Estrogen plays an important role in sensitizing our cells to insulin.
The microbiome also influences the production of certain gut hormones such as Glucagon-like peptide-1 (GLP-1) and peptide YY. Both of these play a role in the regulation of insulin secretion. A 2019 study found that certain gut bacteria are linked with improved insulin sensitivity and lower blood sugar levels. Other studies identify a difference in microbial composition between individuals with type 2 diabetes compared with healthy subjects.
Cardiovascular Disease
Cardiovascular disease is a leading cause of mortality worldwide. For women, the loss of ovarian hormones during perimenopause and menopause contributes to a sharp increase in CVD risk and incident, and adverse changes in lipid profiles. In particular, an increase in low density lipoprotein (LDL), referred to as our "bad” cholesterol, and a decrease in high density lipoprotein (HDL), typically referred to as our “good” cholesterol, has been observed. In addition, elevated triglycerides are also common. These are key factors in the development of CVD.
Short chain fatty acids by gut bacteria also play a significant role in cardiovascular disease. These metabolites produced by gut bacteria are anti-inflammatory, thereby contributing to a decrease in inflammation- a critical factor in CVD development. Another important compound produced by gut bacteria from dietary choline and carnitine is called trimethylamine N-oxide (TMAO). This metabolite has a positive association with atherosclerosis. While reducing dietary choline is not recommended since this is a critical nutrient, TMAO may partially explain the red meat/CVD link by way of carnitine. More research is needed to understand the implications of TMAO (1, 2).
Bile acids provide yet another link between the microbiome and CVD. Essential for the absorption of dietary fats and fat soluble vitamins, bile acids also have a cholesterol-lowering effect. Certain gut microbiome profiles have the ability to modulate bile acid production, potentially leading to reduced levels of these essential compounds. This reduction can result in increased circulating LDL cholesterol, ultimately contributing to the progression of CVD.
“The Framingham Heart Study researchers reported a 2.6-fold higher incidence of cardiovascular events in postmenopausal women than in their premenopausal counterparts of the same age. What is more, women develop CVD on average 7–10 years later than men.” (3) In addition to this, early or premature menopause greatly increases CVD risk.
Estrogen Dominance
Although estrogen and progesterone are generally on the decline during perimenopause, estrogen dominance is a condition characterized by an imbalance of estrogen levels in the body relative to other hormones, particularly progesterone. This condition is often linked to obesity, exposure to xenoestrogens (estrogen-like compounds from outside sources such as personal care products, plastics, etc.) chronic stress, and impaired liver function.
Estrogen is metabolized in the liver and eliminated through the feces via a process known as glucuronidation. During this process estrogen molecules are conjugated with glucuronic acid making them more water soluble for excretion in the feces and urine. Certain bacteria produce an enzyme called beta glucuronidase, which has the ability to deconjugate estrogen metabolites. This enzymatic action can reactivate the estrogen molecules, allowing them to be reabsorbed rather than eliminated contributing to increased estrogen levels. Symptoms associated with estrogen dominance include hot flashes, brain fog, and weight gain.
Vaginal Changes
The vaginal canal during perimenopause and menopause also undergoes various changes influenced by the microbiome and fluctuating hormone levels. Normally the vaginal canal maintains a slightly acidic pH ranging from 3.5 to 4.5, creating an environment inhospitable to pathogens like bacteria and yeast. In fact, this environment is also typically inhospitable to sperm. It is during ovulation that the cervical mucous protects the sperm and facilitates its mobility and function.
The dominant species present in a healthy vaginal canal is Lactobacillus and estrogen plays a key role in promoting the growth of this species (4). Estrogen stimulates the production of glycogen in the vaginal tissue, which serves as a food source for Lactobacillus. The metabolism of this glycogen by the Lactobacillus results in the production of lactic acid responsible for the maintenance of an acidic state. A drop in estrogen however, leads to a less acidic environment of the vaginal wall, potentiating various vaginal symptoms including reduced vaginal fluids, dryness and irritation, and sexual discomfort. Moreover, the decrease in estrogen levels can render the individual more susceptible to infections like bacterial vaginosis and yeast infections. Low estrogen levels can also affect the urinary tract, manifesting as increased urgency, incontinence, and risk of urinary tract infections.
Symptoms of Dysbiosis/Microbial Imbalance
It's important to understand that the below list of symptoms can apply to anyone experiencing microbial imbalance, not just individuals experiencing perimenopause and menopause. These symptoms also often overlap with symptoms of other conditions and do not comprise an exhaustive list of potential symptoms.
Digestive issues-excessive gas, bloating, constipation, diarrhea, or alternation of these, indigestion
Fatigue, low energy
Brain fog, cognitive decline (impaired memory/concentration)
Mood disturbances-anxiety/depression
Skin issues
Unexplained weight gain
Inflammation
Vaginal changes mentioned above
Optimizing the Microbiome
Focus on the right kind of carbohydrates-mainly vegetables, fruit, nuts, seeds and whole grains-these provide both soluble and insoluble fiber, which slow down the absorption of glucose, lower cholesterol, and provides prebiotic fuel for the proliferation of commensal microbes
Include fermented foods-kefir, yogurt, sauerkraut, kimchi-probiotic rich foods directly provide beneficial microbes to produce metabolites listed above such as short chain fatty acids-although kombucha is also rich in probiotics, it's also higher in refined sugar so consider implementing in moderation
Probiotic supplements-probiotic supplements can be a great alternative to fermented foods if these are not tolerated or enjoyed-seek support from your nutrition professional in selecting the right probiotic
Mediterranean/Paleo-this approach to eating rich in healthy fats such as monounsaturated fats and omega-rich fats from fish, nuts/seeds, and avocado; it prioritizes whole-food plant carbohydrate sources over refined carbs; it is well documented to provide cardiovascular benefits and reduce inflammation
Antioxidants and polyphenols-these compounds are generally derived from the same whole food fiber-rich plants mentioned above-seek vitamin A, C, and E-rich foods such as carrots, tomato, sweet potato, bell peppers, citrus fruit, nuts and seeds
Liver support-Cruciferous vegetables such as broccoli, kale, bok choy, and Brussel sprouts,, leafy greens high in the B vitamins, and garlic and onions rich in sulfur all support liver detoxification pathways
Stay hydrated-this will help prevent constipation which can play a role in estrogen reabsorption and subsequent estrogen dominance
Manage stress-chronic stress impacts the gut-brain axis and composition of the microbiome
Avoid
High fat/sugar diets associated with dysbiosis-a standard American diet high in refined sugars and fat is associated with dysbiosis- many opportunistic species proliferate from this diet
Avoid unnecessary antibiotic exposure-antibiotics are life-saving and necessary at times so use discretion and seek guidance from your healthcare professional before and after antibiotic use to support your microbiome
Alcohol-reduces microbial diversity
Excessive caffeine
While certain things are best eliminated altogether or limited, the focus should be on what to include that will be supportive; adopting a sustainable approach to fueling ourselves that prioritizes eating habits that support overall-wellbeing and long-term health not limiting or fad “diets”
By incorporating a variety of whole foods rich in fiber, vitamins, and minerals, we can promote a diverse and thriving microbial community. Supporting the microbiome in this way, especially as estrogen declines, will lead to improved digestion, hormone balance and metabolism, and long-term health outcomes. Let's embrace a holistic and optimistic approach to nourishing our bodies and supporting the health of our microbiome for a vibrant and thriving perimenopause-post-menopause.
To learn more about how you can explore the health of your microbiome, check out the Rebel Roots Nutrition functional testing page for information about the GI Map.
References:
https://pubmed.ncbi.nlm.nih.gov/31469291/
https://pubmed.ncbi.nlm.nih.gov/28360349/
https://www.mdpi.com/2077-0383/12/22/7058#B4-jcm-12-07058
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9769055/