Nurturing a diverse gut microbiome [Part 2 of the 21-day challenge]
Add in fabulous fermented foods
I’ll never forget the day I saw blood in my stool. I was 11 weeks pregnant and freaked out. After seeing it repeatedly and visiting dr. google, I was terrified of the big C.
For the first time in my life, I was actually hoping for a hemorrhoid.
Yet after a sigmoidoscopy, the doctor's diagnosis of ulcerative colitis surprised me. Say what? It was mild, and I got put on medicine that goes directly to the source, if you know what I mean.
After I had my son, I breastfed, so I didn't have a period for months. Even though I stopped the medicine, my symptoms were gone. But as soon as my periods started back up, they came back.
I thought my hormones must be playing some kind of role in changing the microbiome in my gut in a way that increased inflammation in my colon. Lucky for me, a probiotic helped put me in remission and I’m happy to say over 10 years later after two colonoscopies, it has not returned.
Not everyone is so lucky, but it illustrates the point that hormones impact the gut, something that researchers are only beginning to explore.
Midlife is a time women become vulnerable to gut changes (yet again) because of Aging Pause.
Last week in part 1 of the gut health challenge, we touched on the oral-intestinal connection. This week, we’re going straight to the gut!
Gut health 101
The human microbiome is the largest organ in the body, with the gut containing 90%, comprising over 500 different bacteria.
Over 90% of the phyla (divisions of bacteria) in the gut are Firmicutes and Bacteroidetes, and a consistent ratio of the two helps maintain gut health. With aging pause, this ratio increases and the diversity of the gut decreases.
A highly diverse gut microbiome contributes to good health, while a reduction in diversity is associated with dysbiosis, the imbalance of bad to good bacteria.
In adulthood, microbiome diversity increases until around 40 and decreases from that point on. By the time someone is 60 the microbiome is noticeably different. (Peter)
Dysbiosis impacts not only nutrient absorption but also the gut's defense against toxins, since 80% of the immune system is governed by the gut. This is because the layer of protective mucus and tight junctions create a barrier that can become compromised.
It’s not just aging alone but the increased use of over-the-counter medications like pain killers, certain drugs (e.g., antibiotics) and a change to diet and physical activity.
When gut dysbiosis ensues, it becomes a source of inflammation, increasing the risk of chronic disease. But then chronic disease and disruption of the One Health Principle also negatively affects the gut.
“While it can be hard to know whether an unbalanced microbiome is the cause or consequence of an illness, negative alterations in the gut microbiome have been linked to age-related diseases.” - Peters et al, Int J Womens Health. 2022
Sex hormones and the gut
Like everything in the body, changes in sex hormones impact gut health. In fact, there is a bidirectional relationship between sex hormones and the gut microbiome.
In premenopausal women, estrogen and progesterone play protective roles by increasing microbiome diversity and inhibiting the buildup of harmful bacteria.
The gut can also modulate estrogen levels. These bacterial genes capable of breaking down (de-conjugating) estrogen are called the estrobolome. These bacteria deconjugate estrogens, releasing them back into circulation.
During the menopause transition bacteria in the gut shifts, reducing beneficial bacteria such as Lactobacillus and Bifidobacteria and short chain fatty acid (SCFA) producing bacteria. SCFA-producing bacteria have anti-inflammatory effects by regulating T cells.
Researchers have linked changes in the gut microbiome to the development of breast cancer. When the gut is less diverse, women have a lower estrogen metabolite to parent estrogen ratio, which has been shown to increase breast cancer risk in postmenopausal women.
The microbiome has also been implicated in bone-related diseases like osteoporosis. In intervention studies, adding probiotic rich yogurt helps increase calcium absorption and improve bone density. And when researchers analyze the fecal contents of women with and without osteoporosis, they observe distinct differences in their gut microbiota.
It’s important to note that not all women experience changes to their microbiome during the menopause transition, and this research is in the very early stages.
In short, midlife is a vulnerable time for gut health where, once again, sex hormones do some heavy lifting. So, we need to pay more attention. This is where diet comes in.
Diet and the gut microbiome
The American Society for Nutrition has established “Nutritional Microbiology” as an active area of research aimed at investigating the relationship between compounds in the diet and the gut microbiota.
Components in the diet act as prebiotics, fuel for the gut microbiota, probiotics, the bacteria itself and symbiotics, which are a mix of both.
As far as fuel for the gut, plant foods are stars in this area, as stated in this 2022 review:
Whole-plant foods provide phytochemicals and dietary fibers that, via their biotransformation by gut microbiota, are health-promoting through numerous mechanisms.
But today I’m focusing on fermented foods with live and active cultures, leaving plant foods for the last challenge post next week. I am no including probiotic supplements, centering on diet (gotta keep in simple)
Fermented foods have been around for centuries to preserve food and increase shelf life. They undergo microbial growth because of the fermentation process, which breaks down sugars into gases, acids or alcohol. This is why they have that tangy taste.
According to the International Scientific Association for Probiotics and Prebiotics, fermented foods are “food made through desired microbial growth and enzymatic conversions of food components.” These include fermented dairy foods like yogurt, kefir and cheese, fermented vegetables, vegetable brine drinks and kombucha.
A systematic review of both intervention and observation studies with fermented foods like yogurt and kefir, show favorable gut-health outcomes, decreasing the risk of various conditions.
There are hardly any studies on midlife women. One intervention study provided postmenopausal women with daily yogurt but showed no change in the microbiome.
A 17-week randomized, prospective study small study looking at high fiber and fermented food and the effects on the microbiome and immune system. The group of adults who ate the fermented food increased from .4 at baseline to an average of 6 servings by the end of the study.
The fermented group not only saw increases in microbiota diversity, but they also saw a reduction in inflammatory markers. The researchers conclude:
Fermented foods may be valuable in countering the decreased microbiome diversity and increased inflammation pervasive in industrialized society.
Now on to the challenge!