Adaptive and innate immunity

Two 2021 reviews presented aspects of human immune systems:

“The adaptive immune system’s challenge is to protect the host through generation and differentiation of pathogen‐specific short‐lived effector T cells, while in parallel developing long‐lived memory cells to control future encounters with the same pathogen.

The system highly relies on self‐renewal of naïve and memory T cells, which is robust, but eventually fails. Genetic and epigenetic modifications contribute to functional differences in responsiveness and differentiation potential.

Less than 20% of nascent T cells are produced from the thymus in young adults, which dwindles to less than 1% after the age of 50 years. Even in young adults, the majority of T cells are produced in the periphery. A pickup in proliferation has been described in late life, possibly as a consequence of increased cell death and evolving lymphopenia.

One challenge of the aging process is to replenish cells while keeping integrity of the organ. The dynamic lymphoid system employs a vast number of T cells (>1011) and maintains a balance between cell production, death, and differentiation.

Enormous TCR ( T cell receptor) diversity is required to be able to respond to the universe of possible peptides (>209). Only T cell generation in the thymus can add new TCR specificities. Homoeostatic proliferation at best maintains diversity, >108 unique TCRs in a given adult.

Antigen-specific memory T cells adopt several fates with age:

  • Decrease in stem-like memory T cells;
  • Increase in NK (natural killer) cell-like TEMRA (terminally differentiated effector T cells);
  • Increase in exhausted T cells;
  • Increase in short-lived effector memory T cells; and
  • Decrease in tissue-residing T memory cells.

Virtual memory T cells without prior experience of antigen encounter also increase with age.”

https://febs.onlinelibrary.wiley.com/doi/epdf/10.1111/febs.15770 “Hallmarks of the aging T cell system”


“Trained immunity is characterized by long‐term functional reprogramming of innate immune cells following challenge with pathogens or microbial ligands during infection or vaccination. This cellular reprogramming leads to increased responsiveness upon re‐stimulation, and is mediated through epigenetic and metabolic modifications.

Trained immunity has been shown to last for at least 3 months and up to 1 year, while heterologous protection against infections can last for at least 5 years. These long-term effects are mediated through reprogramming of myeloid progenitor cells in bone marrow, which in turn generate myeloid cells with a trained immunity phenotype.

Molecular mechanisms underlying trained immunity, for example induced by β‐glucan or Bacille Calmette‐Guérin (BCG) vaccination, can be investigated by using and integrating different layers of information, including genome, epigenome, transcriptome, proteome, metabolome, microbiome, immune cell phenotyping and function. Interplay between epigenetic and metabolic reprogramming is necessary for induction of trained immunity, as certain metabolites have a direct effect on enzymes involved in epigenetic remodeling.

High-throughput methods allow researchers to use an unbiased approach examining many potential genes or markers in relation to health and disease, rather than examining a limited number of candidate genes or markers.

One strength of integrating multiple levels of data is an increased power to identify key regulatory molecular networks driving trained immunity. For example, results obtained from one level (i.e. genes) can be used to reduce the number of traits to test in a second level (i.e. proteins), thereby increasing power.

One important pitfall when it comes to designing effective omics studies, is sample size. With a large number of markers measured, and the relatively small contributing effect size of individual analytes, the risks of both type 1 and 2 errors are high without sufficient sample sizes for both discovery and validation cohorts.”

https://onlinelibrary.wiley.com/doi/pdf/10.1002/eji.202048882 “Resolving trained immunity with systems biology”

Go with the Alzheimer’s Disease evidence

This 2021 study investigated gut microbiota differences between 100 AD patients and 71 age- and gender-matched controls:

“Structural changes in fecal microbiota were evident in Chinese AD patients, with decreased alpha-diversity indices and altered beta-diversity ones, evidence of structurally dysbiotic AD microbiota.

Interestingly, traditionally beneficial bacteria, such as Bifidobacterium and Akkermansia, increase in these AD patients while Faecalibacterium and Roseburia decrease significantly. Different species of Bifidobacterium may have different effects that can explain why Bifidobacterium spp. are commonly associated with healthy and diverse microbiota but sometimes also isolated in other conditions. We needed to re-examine the therapeutic potential of Bifidobacterium in terms of maintaining cognitive function and treating dementia.

Surprisingly, our data indicate that Akkermansia was among the most abundant genera in AD-associated fecal microbiota. Similar to Bifidobacterium, Akkermansia was negatively correlated with clinical indicators of AD, such as MMSE, WAIS, and Barthel, and anti-inflammatory cytokines such as IFN-γ.

Based on our present observations, Akkermansia cannot always be considered a potentially beneficial bacterium. It might be harmful for the gut–brain axis in the context of AD development in the elderly.

Aging is associated with an over-stimulation of both innate and adaptive immune systems, resulting in a low-grade, chronic state of inflammation defined as inflammaging. This can increase gut permeability and bacterial translocation.

Characteristics of AD microbial profiles changed from butyrate producers, such as Faecalibacterium, into lactate producers, such as Bifidobacterium. These alterations contributed to shifts in metabolic pathways from butyrate to lactate, which might have participated in pathogenesis of AD. Specific roles of AD-associated signatures and their functions should be explored in further studies.”

https://www.frontiersin.org/articles/10.3389/fcell.2020.634069/full “Structural and Functional Dysbiosis of Fecal Microbiota in Chinese Patients With Alzheimer’s Disease”


The control group’s 73-year-olds were better off than AD patients. How were they compared with their previous life stages?

Since we’re all aging, how do we each prepare ourselves? I’ll return to evidence including 2020 A rejuvenation therapy and sulforaphane, recently amplified in Part 2 of Switch on your Nrf2 signaling pathway:

“A link between inflammation and aging is the finding that inflammatory and stress responses activate NF-κB in the hypothalamus and induce a signaling pathway that reduces production of gonadotropin-releasing hormone (GnRH) by neurons.

The case is particularly interesting when we realize that the aging phenotype can only be maintained by continuous activation of NF-κB. So here we have a multi-level interaction:

  1. Activation of NF-κB leads to
  2. Cellular aging, leading to
  3. Diminished production of GnRH, which then
  4. Acts (through cells with a receptor for it, or indirectly as a result of changes to GnRH-receptor-possessing cells) to decrease lifespan.

Cell energetics is not the solution, and will never lead to a solution because it makes the assumption that cells age. Cells take on the age-phenotype the body gives them.

Aging is not a defect – it’s a programmed progressive process, a continuation of development with the body doing more to kill itself with advancing years. Progressive life-states where each succeeding life-stage has a higher mortality (there are rare exceptions).

Cellular aging is externally controlled (cell non-autonomous). None of those remedies that slow ‘cell aging’ (basically all anti-aging medicines) can significantly extend anything but old age.

For change at the epigenomic/cellular level to travel up the biological hierarchy from cells to organ systems seems to take time. But the process can be repeated indefinitely (so far as we know).”

We may express concern about others. But each of us should also take responsibility for our own one precious life.

Treat your gut microbiota as one of your organs

Two 2021 reviews covered gut microbiota. The first was gut microbial origins of metabolites produced from our diets, and mutual effects:

“Gut microbiota has emerged as a virtual endocrine organ, producing multiple compounds that maintain homeostasis and influence function of the human body. Host diets regulate composition of gut microbiota and microbiota-derived metabolites, which causes a crosstalk between host and microbiome.

There are bacteria with different functions in the intestinal tract, and they perform their own duties. Some of them provide specialized support for other functional bacteria or intestinal cells.

Short-chain fatty acids (SCFAs) are metabolites of dietary fibers metabolized by intestinal microorganisms. Acetate, propionate, and butyrate are the most abundant (≥95%) SCFAs. They are present in an approximate molar ratio of 3 : 1 : 1 in the colon.

95% of produced SCFAs are rapidly absorbed by colonocytes. SCFAs are not distributed evenly; they are decreased from proximal to distal colon.

Changing the distribution of intestinal flora and thus distribution of metabolites may have a great effect in treatment of diseases because there is a concentration threshold for acetate’s different impacts on the host. Butyrate has a particularly important role as the preferred energy source for the colonic epithelium, and a proposed role in providing protection against colon cancer and colitis.

There is a connection between acetate and butyrate distinctly, which suggests significance of this metabolite transformation for microbiota survival. The significance may even play an important role in disease development.

  • SCFAs can modulate progression of inflammatory diseases by inhibiting HDAC activity.
  • They decrease cytokines such as IL-6 and TNF-α.
  • Their inhibition of HDAC may work through modulating NF-κB activity via controlling DNA transcription.”

https://www.hindawi.com/journals/cjidmm/2021/6658674/ “Gut Microbiota-Derived Metabolites in the Development of Diseases”


A second paper provided more details about SCFAs:

“SCFAs not only have an essential role in intestinal health, but also enter systemic circulation as signaling molecules affecting host metabolism. We summarize effects of SCFAs on glucose and energy homeostasis, and mechanisms through which SCFAs regulate function of metabolically active organs.

Butyrate is the primary energy source for colonocytes, and propionate is a gluconeogenic substrate. After being absorbed by colonocytes, SCFAs are used as substrates in mitochondrial β-oxidation and the citric acid cycle to generate energy. SCFAs that are not metabolized in colonocytes are transported to the liver.

  • Uptake of propionate and butyrate in the liver is significant, whereas acetate uptake in the liver is negligible.
  • Only 40%, 10%, and 5% of microbial acetate, propionate, and butyrate, respectively, reach systemic circulation.
  • In the brain, acetate is used as an important energy source for astrocytes.

Butyrate-mediated inhibition of HDAC increases Nrf2 expression, which has been shown to lead to an increase of its downstream targets to protect against oxidative stress and inflammation. Deacetylase inhibition induced by butyrate also enhances mitochondrial activity.

SCFAs affect the gut-brain axis by regulating secretion of metabolic hormones, induction of intestinal gluconeogenesis (IGN), stimulation of vagal afferent neurons, and regulation of the central nervous system. The hunger-curbing effect of the portal glucose signal induced by IGN involves activation of afferents from the spinal cord and specific neurons in the parabrachial nucleus, rather than afferents from vagal nerves.

Clinical studies have indicated a causal role for SCFAs in metabolic health. A novel targeting method for colonic delivery of SCFAs should be developed to achieve more consistent and reliable dosing.

The gut-host signal axis may be more resistant to such intervention by microbial SCFAs, so this method should be tested for ≥3 months. In addition, due to inter-individual variability in microbiota and metabolism, factors that may directly affect host substrate and energy metabolism, such as diet and physical activity, should be standardized or at least assessed.”

https://www.hindawi.com/journals/cjidmm/2021/6632266/ “Modulation of Short-Chain Fatty Acids as Potential Therapy Method for Type 2 Diabetes Mellitus”


Increasing soluble fiber intake with inulin

From a 2015 USDA technical report:

“Inulin is a naturally-occurring carbohydrate found in roots of chicory and many other food plants. Oligofructose is derived from inulin.

Inulin is a polymer chain of multiple fructose molecules with a glucose molecule at one end. Length of the fructose chain of inulin can range from 2–60 fructose molecules.

Inulin is mostly indigestible by human enzymes due to its shape, but is digestible by microbes in the large intestine. It can serve as a prebiotic, a nutrient source for microflora in the human digestive system.”


From a 2021 review Friend or foe? The roles of inulin-type fructans (not freely available):

“Inulin-type fructans are a mixture of inulin, oligofructose and fructooligosaccharide (FOS). They aren’t absorbed in the stomach and small intestine. They can be completely fermented by bacteria in the large intestine.

They treat digestive diseases, metabolic syndrome, immune system and inflammatory diseases, endothelial dysfunction, and prevent infection and cancer.

A 2010 gastrointestinal tolerance of chicory inulin products study indicated that 10 g/day of native inulin or 5 g/day of oligofructose were well-tolerated in healthy, young adults. Over this dose would induce mild gastrointestinal symptoms.”


I bought this last month:

From the manufacturer:

“A powdered food ingredient based on chicory inulin with a high level of oligofructose 1 (DP2-DP10). This product is characterized by a high solubility.

Inulin from chicory is a polydisperse mixture of linear fructose polymers with mostly a terminal glucose unit, coupled by means of beta (2-1) bonds. The number of units (degree of polymerization) can vary between 2 and 60.

It is a fine, white powder with 30% the sweetness of sucrose. It has >=85% inulin/oligofructose and <15% fructose, glucose, sucrose. It has 2.2 kcal/gram and a glycemic response of 20.”

From the vendor:

“You pay for the product… not the product packaging! Each teaspoon (tsp) delivers 2g fiber.

Inulin is hygroscopic so will take on moisture, especially in humid environments. Store in a dry place and remove as much air from the pouch as able before resealing after each use. Alternately, you could store in several smaller air-tight containers. This will limit exposure to possible humidity. Room temperature or cooler is ideal.”


It tastes like cotton candy. 🙂 Its first use was to replace 2 grams of soluble fiber I got from eating 56 grams of noodles:

Probably won’t reorder FOS when I run out. I’ve taken 1.5 grams FOS every day for 16 years.

Eat broccoli sprouts for your kidneys

Starting Year 7 of curating research with a 2021 review of kidney disease and sulforaphane:

“Many chronic kidney disease (CKD) patients progress to end-stage kidney disease – the ultimate in failed prevention. While increased oxidative stress is a major molecular underpinning of CKD progression, no treatment modality specifically targeting oxidative stress has been established clinically.

Pathophysiologic effects occur when there is an imbalance between oxidation and reduction – an altered redox state in which excess free radicals react with other molecules, including lipids, proteins, and nuclear DNA. Mitochondrial DNA is also susceptible to oxidative damage.

All mechanisms discussed above have been shown to be present in CKD. When levels of antioxidant agents such as SOD, CAT, GPx/glutathione, and NRF2 are reduced, harmful effects of oxidation and generation of ROS cannot be appropriately mitigated.

Data suggest continued SFN [sulforaphane] administration is needed to maintain activation of the NRF2 pathway to confer protection against oxidative damage of diabetes. Renal protective effect of SFN has been demonstrated in many other models of kidney injury.

SFN may have therapeutic potential in kidney disease by stimulating the NRF2 pathway.”

https://www.mdpi.com/2072-6643/13/1/266/htm “Eat Your Broccoli: Oxidative Stress, NRF2, and Sulforaphane in Chronic Kidney Disease”


Didn’t see where these researchers intended to perform a suggested “clinical study to assess the effect of SFN in CKD.” Keep reading before experimentally treating patients, please. Targets they missed included:

  • Parameters of myrosinase hydrolizing glucoraphanin;
  • “Consumption of broccoli strains with more glucoraphanin leads to higher plasma levels of SFN” and
  • “It follows that SFN could also pose similar adverse effects, particularly if taken in an isolated preparation.”

Also missing from this kidney review were connections to broccoli sprouts’ effectiveness in preventing bladder disease. Not coincidentally, isothiocyanate metabolites accumulate in the bladder.

I came across this paper from it citing Sulforaphane: Its “Coming of Age” as a Clinically Relevant Nutraceutical in the Prevention and Treatment of Chronic Disease. I curated it due to informatively citing Microwave broccoli to increase sulforaphane levels.

Harnessing endogenous defenses with broccoli sprouts

This 2019 article was by the author of Sulforaphane: Its “Coming of Age” as a Clinically Relevant Nutraceutical in the Prevention and Treatment of Chronic Disease. It isn’t widely available, so I’ll quote liberally:

“Demand for solutions to digestive health issues is accelerating, especially since both scientific literature and popular press dedicate significant resources to promoting awareness of what has come to be known as ‘gut health’. In considering available therapies and the possibility that a somewhat different approach may more comprehensively optimise function of the gut ecosystem, a number of questions which do not yet have satisfactory answers are ponderable dilemmas:

  1. If diet alone can dramatically shift composition of the microbiome within 24 hours, what do we expect of a probiotic supplement?
  2. Even though probiotics as food or supplements demonstrate favourable clinical outcomes, they typically don’t colonise the gut. How do we expect them to restore diversity and lost species to the gut microbiome after antibiotics? If no trace of an administered probiotic organism can be found a few weeks later, is there any sustained benefit?
  3. Presence of obesity and other diseases is indirectly proportional to diversity of microbial organisms inhabiting the human gut. What can we expect of a few selected probiotic strains in helping to solve this problem?
  4. No antimicrobial approach selectively destroys a pathogen without impacting commensals to some degree. If we select a tool to eradicate gut pathogens, pathobionts or rogue commensals, how do we avoid damaging protective commensals with which we live symbiotically?
  5. The value of using a probiotic supplement after antibiotic therapy to recolonise the gut is uncertain. A 2018 multi-centre study showed that probiotic supplementation after antibiotics delayed gut microbiome reconstitution by around five months.
  6. If the gut can harbour around 1,000 different species, why do we expect a probiotic supplement harbouring just a few species to favourably modify a human microbiome?
  7. If Lactobacilli make up <0.1% of total microbes, why do we so readily choose them as probiotic supplements?
  8. If L-glutamine is a preferred energy source for the small intestine and not the colon, why is it used almost universally in gut repair programmes regardless of the affected region?

Removal of gluten and administration of probiotics have lesser impact than endogenous factors like elevated HbA1c:

Shift emphasis closer to optimising colonocyte metabolism as the primary driver of dysbiosis in the colon. Since these mechanisms within the human gut ecosystem already exist, intervene at this level, as distinct from using antimicrobials and exogenous probiotic strains to influence host cell function.

Phytonutrients that potently activate these core processes have been identified and are sufficiently bioavailable to achieve this end. Restoring homeostasis to the intestinal epithelial cells can be readily justified as a key initial step.

Sulforaphane is a potent inducer of hundreds of genes associated with cellular defences mechanisms. In this context, these genes include those that code for antioxidant and phase II detoxification enzymes, glutathione and metallothionein.

Sulforaphane exhibits other more specific gut and immune-related effects. As the most potent single food-derived activator of Nrf2, sulforaphane is capable of upregulating protective genes in colonocytes and other cells.

A growing body of work has identified the colonocyte as the driver of dysbiosis. Targeting colonocyte function provides an alternative to targeting microbes for remediation of dysbiosis.”

https://www.researchgate.net/publication/336578800_Restoring_Gut_Ecology_Harnessing_the_Inbuilt_Defence_Mechanisms_of_the_Gut_Epithelium “Restoring Gut Ecology: Harnessing the Inbuilt Defence Mechanisms of the Gut Epithelium” (registration required)


If you can’t access this paper, read The future of your brain is in your gut right now. If you can’t access that paper, listen to Switch on your Nrf2 signaling pathway.

Mid-life gut microbiota crisis

This 2019 rodent study investigated diet, stress, and behavioral relationships:

“Gut microbiome has emerged as being essential for brain health in ageing. We show that prebiotic supplementation with FOS-Inulin [a complex short- and long-chain prebiotic, oligofructose-enriched inulin] is capable of:

  • Dampening age-associated systemic inflammation; and
  • A profound yet differential alteration of gut microbiota composition in both young adult and middle-aged mice.

Middle-aged mice exhibited an increased influx of inflammatory monocytes into the brain. However, neuroinflammation at this stage was not significant enough to manifest in major cognitive impairments.

A much longer exposure to prebiotics might be needed to achieve significant effects, suggesting that supplementation may have to start earlier to be effectively preventative before alterations in the brain occur. This is particularly evident for behaviour.

Targeting gut microbiota, as we have done with a prebiotic, can affect the brain and subsequent behaviour through a variety of potential pathways including SCFAs [short-chain fatty acids], amino acids and immune pathways. All of these are interconnected. Future studies are needed to better deconvolve [figure out] such pathways in eliciting beneficial effects of inulin.

Modulatory effects of prebiotic supplementation on monocyte infiltration into the brain and accompanied regulation of age-related microglia activation highlight a potential pathway by which prebiotics can modulate peripheral immune response and alter neuroinflammation in ageing. Our data suggest a novel strategy for the amelioration of age-related neuroinflammatory pathologies and brain function.”

https://www.nature.com/articles/s41380-019-0425-1 “Mid-life microbiota crises: middle age is associated with pervasive neuroimmune alterations that are reversed by targeting the gut microbiome” (not freely available)


This study’s experiments subjected young and middle-aged mice to eight stress tests. I appreciated efforts to trace causes to behavioral effects, since behavior provided stronger evidence.

I’m in neither life stage investigated by this study. Still, per Reducing insoluble fiber, I’ll start taking inulin next week. See Increasing soluble fiber intake with inulin.

I came across this study through its citation in How will you feel?

Inauguration day

Don’t take Beano if you’re stressed

This 2021 rodent study investigated diet and stress relationships:

“We show that dietary raffinose metabolism to fructose couples stress-induced gut microbial remodeling to intestinal stem cells (ISC) renewal and epithelial homeostasis. Chow diet (CD) and purified diet (PD) confer distinct vulnerability to gut epithelial injury, microbial alternation and ISC dysfunction in chronically restrained mice.

raffinose

  • We hypothesized that CD components might provide a favorable condition to sustain the expansion of Lactobacillus spp. during stress. We performed a thorough chemical analysis of the diets with special attention to oligosaccharide and polyphenol compounds.
  • To understand whether raffinose could underlie diet-shaped epithelial response to stress, we fed mice with raffinose-supplemented PD (RD) and examined effects of chronic restraint stress (RS) on gut epithelial integrity. Mice receiving RD had noticeably increased density of stem cells in the intestine and colon after stress.
  • We next investigated whether dietary supplementation with raffinose could recapitulate the effect of CD to increase resilience to epithelial injury. Dietary raffinose abundance appears to be the major factor driving gut microbial and epithelial response to stress.
  • A striking change in fructo-oligosaccharide (FOS) and raffinose utilization was intensified after stress. Given the specific increase of fructose after raffinose supplementation to mice, we further explored effects of fructose on intestinal epithelial renewal in stressed mice.

Dietary components and chronic stress interactively modulate gut microbial metabolism and its crosstalk with ISCs. In particular, we identify that dietary raffinose and L. reuteri constitute a metabolic feedforward circuit promoting ISC proliferation via fructose-augmented and engaged glycolysis.

Our data shed light on the dynamic nature of psychological stress-gut microbe crosstalk in adaption to host diets, which highlights diet-microbe interplay in dictating gut response to psychological stress.”

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7801547/ “A diet-microbial metabolism feedforward loop modulates intestinal stem cell renewal in the stressed gut”


These researchers conducted more than a dozen-and-a-half experiments, with each successively investigating previous ones’ outcomes. One that caught my interest identified raffinose as a major difference between chow and purified diets, which was further investigated.

Our gut microbiota will handle raffinose better than us eating Beano to make raffinose immediately digestible. Lookup raffinose, and you’ll see many more articles condemning it for social purposes than praising it for health purposes.

Experiments weren’t done with soluble fiber as It’s the fiber, not the fat did. There may have been unstudied effects of soluble fiber:

  • The two studies’ chow diets were similar; and
  • Soluble fiber contents of both purified diet and refined diets were zero, as they contained only insoluble cellulose.

I came across this study by it citing 2018’s Colonocyte metabolism shapes the gut microbiota, which was a notable citation in The future of your brain is in your gut right now.

And 2021 will look like..?

Gut microbiota and aging

This 2020 review explored the title subject:

“The human body contains 1013 human cells and 1014 commensal microbiota. Gut microbiota play vital roles in human development, physiology, immunity, and nutrition.

Human lifespan was thought to be determined by the combined influence of genetic, epigenetic, and environmental factors including lifestyle-associated factors such as exercise or diet. The role of symbiotic microorganisms has been ignored.

Age-associated alterations in composition, diversity, and functional features of gut microbiota are closely correlated with an age-related decline in immune system functioning (immunosenescence) and low-grade chronic inflammation (inflammaging). Immunosenescence and inflammaging do not have a unidirectional relationship. They exist in a mutually maintained state where immunosenescence is induced by inflammaging and vice versa.

Immunosenescence changes result in both quantitative and qualitative modifications of specific cellular subpopulations such as T cells, macrophages and natural killer cells as opposed to a global deterioration of the immune system. Neutrophils and macrophages from aged hosts are less active with diminished phagocytosing capability.

Gut microbiota transform environmental signals and dietary molecules into signaling metabolites to communicate with different organs and tissues in the host, mediating inflammation. Gut microbiota modulations via dietary or probiotics are useful anti-inflammaging and immunosenescence interventions.

The presence of microbiomic clocks in the human body makes noninvasive, accurate lifespan prediction possible. Prior to occurrence of aging-related diseases [shown above], bidirectional interactions between the gut and extraenteric tissue will change.

Correction of accelerated aging-associated gut dysbiosis is beneficial, suggesting a link between aging and gut microbiota that provides a rationale for microbiota-targeted interventions against age-related diseases. However, it is still unclear whether gut microbiota alterations are the cause or consequence of aging, and when and how to modulate gut microbiota to have anti-aging effects remain to be determined.”

https://www.tandfonline.com/doi/abs/10.1080/10408398.2020.1867054 “Gut microbiota and aging” (not freely available; thanks to Dr. Zongxin Ling for providing a copy)


1. The “Stable phase” predecessor to this review’s subject deserved its own paper:

“After initial exposure and critical transitional windows within 3 years after birth, it is generally agreed that human gut microbiota develops into the typical adult structure and composition that is relatively stable in adults.

gut microbiota by age phenotype

However, the Human Microbiome Project revealed that various factors such as food modernization, vaccines, antibiotics, and taking extreme hygiene measures will reduce human exposure to microbial symbionts and led to shrinkage of the core microbiome, while the reduction in microbiome biodiversity can compromise the human immune system and predispose individuals to several modern diseases.”

2. I looked for the ten germ-free references in the “How germ-free animals help elucidate the mechanisms” section of The gut microbiome: its role in brain health in this review, but didn’t find them cited. Likewise, the five germ-free references in this review weren’t cited in that paper. Good to see a variety of relevant research.

There were a few overlapping research groups with this review’s “Gut-brain axis aging” section, although it covered only AD and PD research.

3. Inflammaging is well-documented, but is chronic inflammation a condition of chronological age?

A twenty-something today who ate highly-processed food all their life could have gut microbiota roughly equivalent to their great-great grandparents’ at advanced ages. Except their ancestors’ conditions may have been byproducts of “an unintended consequence of both developmental programmes and maintenance programmes.

Would gut microbiota be a measure of such a twenty-something’s biological age? Do we wait until they’re 60, and explain their conditions by demographics? What could they do to reset themself back to a chronological-age-appropriate phenotype?


The future of your brain is in your gut right now

A 2020 paper by the author of Sulforaphane: Its “Coming of Age” as a Clinically Relevant Nutraceutical in the Prevention and Treatment of Chronic Disease:

“The gut and brain communicate bidirectionally via several pathways which include:

  1. Neural via the vagus nerve;
  2. Endocrine via the HPA axis;
  3. Neurotransmitters, some of which are synthesized by microbes;
  4. Immune via cytokines; and
  5. Metabolic via microbially generated short-chain fatty acids.

How does nature maintain the gut-microbiome-brain axis? Mechanisms to maintain homeostasis of intestinal epithelial cells and their underlying cells are a key consideration.

The symbiotic relationship that exists between microbiota and the human host is evident when considering nutrient requirements of each. The host provides food for microbes, which consume that food to produce metabolites necessary for health of the host.

Consider function of the human nervous system, not in isolation but in integration with the gastrointestinal ecosystem of the host, in expectation of a favorable impact on human health and behavior.”

https://www.sciencedirect.com/science/article/pii/B9780128205938000148 “Chapter 14 – The gut microbiome: its role in brain health” (not freely available)


Always more questions:

  • What did you put into your gut today?
  • What type of internal environment did it support?
  • What “favorable impact on human health and behavior” do you expect from today’s intake?
  • How will you feel?
  • Will you let evidence guide feeding your gut environment?

See Switch on your Nrf2 signaling pathway for an interview with the author.

How will you feel?

Consider this a partial repost of Moral Fiber:

“We are all self-reproducing bioreactors. We provide an environment for trillions of microbes, most of which cannot survive for long without the food, shelter and a place to breed that we provide.

They inhabit us so thoroughly that not a single tissue in our body is sterile. Our microbiome affects our development, character, mood and health, and we affect it via our diet, medications and mood states.

The microbiome:

  • Affects our thinking and our mood;
  • Influences how we develop;
  • Molds our personalities;
  • Our sociability;
  • Our responses to fear and pain;
  • Our proneness to brain disease; and
  • May be as or more important in these respects than our genetic makeup.

Dysbiosis has become prevalent due to removal of prebiotic fibers from today’s ultra-processed foods. I believe that dietary shift has created a generation of humans less able to sustain or receive love.

They suffer from reduced motivation and lower impulse control. They are more anxious, more depressed, more selfish, more polarized, and therefore more susceptible to the corrosive politics of identity.


Other recent blog posts by Dr. Paul Clayton and team include Skin in The Game and Kenosha Kids.

Image from Thomas Cole : The Consummation, The Course of the Empire (1836) Canvas Gallery Wrapped Giclee Wall Art Print (D4060)

Part 2 of Switch on your Nrf2 signaling pathway

To follow up topics of Part 1‘s interview:

1. “We each have a unique microbial signature in the gut. Metabolites that you produce might not be the same ones that I produce. This makes clinical studies very difficult because you don’t have a level playing field.”

This description of inter-individual variability could inform researchers’ investigations prior to receiving experimental results such as:

Post-experimental analysis with statistical packages of these types of results is apparently required. But it doesn’t produce meaningful explanations for such individual effects.

Analysis of individual differences in metabolism can better inform explanations, because it would investigate causes for widely-variable effects. Better predictive hypotheses could be a result.

2. Today I’m starting my 40th week of eating a clinically-relevant amount of microwaved 3-day-old broccoli sprouts every day. To encourage sulforaphane’s main effect of Nrf2 signaling pathway activation, I won’t combine broccoli sprouts with anything else either during or an hour before or after.

I had been taking supplements at the same time. This interview got me thinking about the 616,645 possible combinations of my 19 supplements and broccoli sprouts.

That’s way too many to be adequately investigated by humans. Especially because contexts for each combination’s synergistic, antagonistic, or additive activities may be influenced by other combinations’ results.

I’ll just eat food and take supplements outside of this sulforaphane window.

I’ve taken 750 mg fructo-oligosaccharides (FOS) twice a day for sixteen years. I’ve considered it as my only prebiotic. Hadn’t thought of either of these points:

  • “Polyphenols are now considered to be a prebiotic food for microflora in the gut. They tend to focus on producing additional amounts of lesser known species like Akkermansia muciniphila, and have a direct prebiotic effect. Microbiota break these big, bulky molecules down into smaller metabolites, which clearly are absorbed. Some beneficial effects that come from polyphenols are not from the original molecule itself, but from a variety of metabolites produced in the gut.
  • We use a prebiotic, actually called an immunobiotic, which is a dead lactobacillus plantarum cell optimised for its cell wall content of lipoteichoic acid. Lipoteichoic acid attaches to toll-like receptor 2, and that sets off a whole host of immune-modulating processes, which tend to enhance infection control and downregulate inflammation and downregulate allergenicity.”

3. “Quinone reductase is critical because it is the final enzyme in the phase two detox pathway that stops DNA being mutated or prevents deformation of DNA adducts which are mutagenic. I want to look at genes that govern redox balance, inflammation, detoxification processes, cellular energetics, and methylation.”

Gene functional group classifications are apparently required in studies, to accompany meaningless statistics. When I’ve read papers attaching significance to gene functional groups, it often seemed like hypothesis-seeking efforts to overcome limited findings.

I’ll start looking closer when study findings include Nrf2 signaling pathway targets quinone reductase, DNA damage marker 8-hydroxydeoxyguanosine, and enzymes glutathione peroxidase and glutathione S-transferase.

4. I bolded “unregulated inflammation” in Part 1 because it’s a phrase I’d ask to be defined if that site enabled comments. Thinking on inflammation seems to come from:

“We focus on the intestinal epithelial cell as a key player because if you enhance function of that cell, and Nrf2 is part of that story, once you get those cells working as they should, they are modulating this whole underlying immune network.”

An environmental signaling paradigm of aging and Reevaluate findings in another paradigm have a different focus. That paradigm looks at inflammation in the context of aging:

“A link between inflammation and aging is the finding that inflammatory and stress responses activate NF-κB in the hypothalamus and induce a signaling pathway that reduces production of gonadotropin-releasing hormone (GnRH) by neurons.

The case is particularly interesting when we realize that the aging phenotype can only be maintained by continuous activation of NF-κB. So here we have a multi-level interaction:

  1. Activation of NF-κB leads to
  2. Cellular aging, leading to
  3. Diminished production of GnRH, which then
  4. Acts (through the cells with a receptor for it, or indirectly as a result of changes to GnRH-receptor-possessing cells) to decrease lifespan.

Cell energetics is not the solution, and will never lead to a solution because it makes the assumption that cells age. Cells take on the age-phenotype the body gives them.

Aging is not a defect – it’s a programmed progressive process, a continuation of development with the body doing more to kill itself with advancing years. Progressive life-states where each succeeding life-stage has a higher mortality (there are rare exceptions).

Cellular aging is externally controlled (cell non-autonomous). None of those remedies that slow ‘cell aging’ (basically all anti-aging medicines) can significantly extend anything but old age.

For change at the epigenomic/cellular level to travel up the biological hierarchy from cells to organ systems seems to take time. But the process can be repeated indefinitely (so far as we know).”


Switch on your Nrf2 signaling pathway

An informative interview to start this year with the author of Sulforaphane: Its “Coming of Age” as a Clinically Relevant Nutraceutical in the Prevention and Treatment of Chronic Disease:

The Antioxidant Dilemma with Dr. Christine Houghton

“The thing about science is, the more you know, the more you realise you don’t know. And I have this enormous respect now for signalling processes that are going on within the cell, and not just signalling. The way mother nature switches on, switches off, foot on brake, foot on accelerator, continuously all of the time.

Things have changed in understanding the function of Nrf2 for a start, in controlling in many ways those cellular defences. We could then switch on Nrf2. You switch on a whole host of protective molecules all at the same time.

We use NAC [N-acetyl-cysteine] in the lab all the time because it stops an Nrf2 activation. So, that weak pro-oxidant signal that you use to activate Nrf2, you switch it off by giving a dose of NAC. It’s a potent antioxidant in that right, but it’s blocking signalling. And that’s what I don’t like about its broad use.

The real advantage of sulforaphane is not only is it the most potent inducer of Nrf2, or activator, but it’s also highly bioavailable. It’s a very tiny, low-molecular weight, lipophilic molecule that just glides straight in through cell membranes. It’s about 80% bioavailable. Whereas big, bulky polyphenols are about 1% bioavailable just simply because of their chemical structure.

We focus on the intestinal epithelial cell as a key player because if you enhance function of that cell, and Nrf2 is part of that story, once you get those cells working as they should, they are modulating this whole underlying immune network.

I’m particularly interested in looking at core upstream factors that govern cellular defences. So, I want to look at genes that govern redox balance, inflammation, detoxification processes, cellular energetics, and methylation.

Intestinal epithelial, just like any other cell in the body, will respond to Nrf2 activation. It will respond to NF-κB downregulation. That’s going to enhance redox control. It’s going to reduce unregulated inflammation. It’s going to enhance detoxification processes. It’ll increase glutathione synthesis.

All of those core factors that any cell needs to work normally will be enhanced by activating Nrf2. And I use a high-yielding sulforaphane supplement of about 20 milligrams a day to do that. So, that’s the beginning.

Probiotics don’t typically colonise in an adult. That’s where we come back to this idea of restoring the gut ecosystem and using prebiotic foods.

In an ideal world, we’d be looking at 600 to 800 grams of non-starchy plant foods a day. In a real world, that isn’t always going to happen.

I never use the term leaky gut because it isn’t that. It’s a dynamic structure that becomes unresponsive.”


Hadn’t thought about weighing my daily AGE-less Chicken Vegetable Soup dinner (half) then tomorrow for lunch. Its total weight tonight was 2,575.5 grams.

  • Subtract 207.2 g wine, 985.6 g chicken broth, and 64.2 g noodles;
  • Add 131 g 3-day-old broccoli sprouts microwaved to ≤ 60°C (140°F) eaten earlier;
  • Subtract an estimated 170 g (6 oz.) chicken, didn’t measure juice squeezed from one lemon, didn’t estimate evaporation from 20 minutes cooking; and
  • Didn’t include either 81 g dry weight steel-cut oats which becomes 308 g for breakfast, or 103.8 g 3-day-old hulled oat sprouts.
  • Net 1,279.5 grams non-starchy plant foods

I’m doing alright by the “600 to 800 grams of non-starchy plant foods a day” guideline. Should exercise more, though, because I eat a lot.

Topics continued in Part 2.

Part 2 of Eat broccoli sprouts for DIM

Continuing Part 1 with three DIM studies, the first of which was a 2020 chemical analysis investigating:

“Anti-estrogenic, anti-androgenic, and aryl hydrocarbon receptor (AhR) agonistic activities of indole-3-carbinol (I3C) acid condensation products.

I3C is a breakdown product [isothiocyanate] of glucobrassicin. Most biological activities attributed to I3C are believed to result from its acid condensation products, as it is expected that after ingestion of cruciferous vegetables, I3C is completely converted in the stomach before it reaches the intestine.

The reaction mixture was prepared from I3C under acidic conditions. Based on the various HPLC peaks, 9 fractions were collected and tested.

DIM (3,3-diindolylmethane) displayed clear estrogenic activity, showing an additive effect when co-exposed with low concentrations of E2 [estradiol] (below EC50) [effective concentration that gives half-maximal-response of a biological pathway]. However, an anti-estrogenic activity was observed when DIM was co-exposed with higher concentrations of E2, i.e. above EC50. None of the nine fractions was able to inhibit response of E2.

I3C and DIM showed clear anti-androgenic activities when co-exposed with concentrations of T [testosterone] at EC50 or ECmax. DIM showed a relatively strong antagonistic activity, and was able to completely inhibit response of T.

All fractions displayed an AhR agonist activity. Poor activity of fraction 3 seems surprising, as it contains ICZ, which was shown to be a strong AhR agonist. This is a strong indication that ICZ is only present at a very low concentration.

Observed estrogenic and anti-androgenic effects of the reaction mixture are most likely due to DIM.

The present study is the first that demonstrates that DIM also possesses anti-estrogenic properties when co-administered with E2 concentrations above EC50. Rather than ICZ, LTr1 and several other compounds present in fractions 1 and 4 (CTr), and larger molecules present in fractions 7, 8 (LTe1) and 9 seem responsible for observed AhR activity of the reaction mixture.”

https://www.sciencedirect.com/science/article/pii/S1878535220302811 “Acid condensation products of indole-3-carbinol and their in-vitro (anti)estrogenic, (anti)androgenic and aryl hydrocarbon receptor activities”

I came across this study as a result of its citation in Brassica Bioactives Could Ameliorate the Chronic Inflammatory Condition of Endometriosis.


A second 2016 study was with humans:

“Forty-five subjects consumed vegetables, a mixture of brussels sprouts and/or cabbage, at one of seven discrete dose levels of glucobrassicin ranging from 25 to 500 μmol, once daily for 2 consecutive days.

‘Blue Dynasty’ cabbage contained 33.5 ± 4.0 μmol glucobrassicin per 100 grams food weight. ‘Jade Cross’ brussels sprouts contained 206.0 ± 12.9 μmol per 100 grams.

At 50 μmol, variability in 24-hour urinary DIM levels appears to stem from both within an individual and between individuals. At 200 and 500 μmol dose levels, most variability is coming from between individuals rather than within an individual.

Inter-individual DIM variability may reflect the relative benefit an individual derives from consuming glucobrassicin from vegetables, responsive not only to how much glucobrassicin was consumed but also to variations in I3C uptake and DIM metabolism, many of which are not characterized.

Dose curve between glucobrassicin dose (25–500 μmol) [25, 50, 100, 200, 300, 400, 500] and urinary DIM. Bars represent SD. Estimated parameters in the original scale (95% CI): Maximum DIM 421.5 pmol/mL (154.7–1,148.4), minimum DIM 5.4 pmol/mL (0.7–44.3), EC50 90.2 μmol (29.1–151.3).

We conclude that urinary DIM is a reliable biomarker of glucobrassicin exposure and I3C uptake and that feeding glucobrassicin beyond 200 μmol did not consistently lead to more urinary DIM. Our data support the notion that cancer-preventive properties that might be derived from cruciferous vegetable consumption may require neither a large quantity of vegetables nor high-dose supplements.”

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5220883/ “Harnessing the Power of Cruciferous Vegetables: Developing a Biomarker for Brassica Vegetable Consumption Using Urinary 3,3′-Diindolylmethane”


1. Most subjects had trouble eating 500 μmol / 242.72 grams of Jade Cross brussels sprouts:

“At the 500 μmol dose level, two subjects could not finish due to the taste of the raw Brussels sprouts and were reassigned to 50 μmol dose level.

Two of the remaining five subjects at the 500 μmol dose level “Did not eat all of the assigned vegetables.” 🙂 That amount of brussels sprouts may have made two more sick because one “Missed one void during 2–6 hour collection period” and another “Missed 2 voids during the 6–12 hour collection period.”

2. From its supplementary material, there were ten subjects who ate a 200 μmol glucobrassicin dose. That’s a lot of raw cabbage (179.10 g) and brussels sprouts (67.96 g).

  • On Day 1 at the 2-6 hour point, Subject 27’s urinary DIM measured 10.21 pmol/mL and Subject 20’s measured 991.88, > 9700% higher.
  • At that 2-6 hour point on Day 2, the same subjects measured 16.15 and 687.44 pmol/mL, > 4200% higher.
  • From Table 1, their respective Mean 24-h DIM ± SE, pmol/mL measurements were 20.7 ± 4.0 and 1105 ± 45, > 5300% higher.

The 100 μmol glucobrassicin dose was 149.25 g Blue Dynasty cabbage and 24.27 g Jade Cross brussels sprouts. Could you eat that every day?

3. There’s sufficient data to make individual DIM bioavailability calculations. Don’t know why this study didn’t do that, nor did any of its 18 citing papers.

One study came close for broccoli and radish sprouts, 2017’s Bioavailability and new biomarkers of cruciferous sprouts consumption (not freely available) by researchers in the same group as Our model clinical trial for Changing to a youthful phenotype with broccoli sprouts. They didn’t disclose and analyze individual DIM bioavailability evidence, though:

“Broccoli and radish sprouts content in GB [glucobrassicin] were ~11.4 and ~7.7 μmol/20 g F.W, respectively. After ingestion of broccoli sprouts, 49% of GB was suitably metabolised and excreted as hydrolysis metabolites, calculated as the sum of I3C and DIM (~5.57 μmol /24 h). Following radish ingestion, the percentage of GB hydrolysed and absorbed was 38% (~2.92 μmol /24 h).

These results of bioavailability contrast with the extremely low percentage (< 1%) of GB excreted as DIM after consumption of Brussels sprouts and cabbage in a previous study (Fujioka, et al., 2014). Further studies about conversion of other indole GLS [glucosinolates] to I3C and DIM are needed to know more about bioavailability of these compounds, as there is no information in literature.”


A ten-subject study in Microwave broccoli seeds to create sulforaphane found inter-individual variability of sulforaphane and its metabolites in blood plasma for the highest and lowest individuals was > 500% (2.032 / 0.359 μmol). The urinary % of dose excreted by the same subjects was > 400% higher (86.9% and 19.5%, respectively.)

These studies present an opportunity for further discovery:

  1. Which researchers will try to understand causal experiences in people’s lives that produced such effects?
  2. Which researchers will produce evidence for factors that make people responsively either alive or dead to external influences on their internal environment?
  3. Where are studies that show when an individual needs to change their responses – their phenotype – they can successfully do so?

Herding, the story of 2020

A case for carnitine supplementation

This 2020 review subject was carnitine, acetyl-L-carnitine, and its other molecular forms:

“Carnitine is necessary to deliver long-chain fatty acids from cytosol into mitochondria. Carnitine homeostasis is maintained by diet and renal absorption, as only a small amount (about 25%) is obtained by endogenous biosynthesis.

Defective fatty acid oxidation occurs with reduced intracellular levels of carnitine, leading to glucose consumption instead of lipid consumption, resulting in hypoglycemia. Non-metabolized lipids accumulate in tissues such as heart, skeletal muscle, and liver, resulting in myopathy and hepatic steatosis.

2000 mg/day is unlikely to provoke unwanted side effects and is safe for humans. In-depth studies are needed to identify a unique method of analysis which can guarantee efficient monitoring of supplement active component amounts.”

https://www.mdpi.com/1420-3049/25/9/2127/htm “The Nutraceutical Value of Carnitine and Its Use in Dietary Supplements”


The review listed animal studies of L-carnitine alone and in combination with:

  • Vitamin D3;
  • Coenzyme Q10;
  • Nicotinamide riboside;
  • Selenium;
  • L-arginine;
  • Anti-histamine drugs cetirizine hydrochloride and chlorpheniramine maleate; and
  • Hypertension drug olmesartan.

Human studies of its effects included:

  • Muscle soreness, damage biomarkers, and cramps;
  • Osteoarthritis knee pain and inflammation markers;
  • Ischemic cerebrovascular injury;
  • Peripheral neuropathy;
  • Nonalcoholic fatty liver disease;
  • Insulin resistance and Type 2 diabetes;
  • Kidney diseases;
  • Inherited diseases phenylketonuria and maple syrup urine;
  • Stress, depression, and anxiety;
  • Male infertility; and
  • Hepatitis C.