Nrf2 Week #6: Phytochemicals

This 2023 review explored Nrf2 relationships with plant chemicals:

“This review focuses on possible mechanisms of Nrf2 activation by natural phytochemicals in preventing or treating chronic diseases, and regulating oxidative stress. Excess oxidative stress is closely related to many kinds of chronic diseases, such as cardiovascular diseases, cancer, neurodegenerative diseases, diabetes, obesity, and other inflammatory diseases.

Mitochondrial dysfunction and hyperglycemia lead to the massive production of ROS, which triggers molecular damage, inflammation, ferroptosis, insulin resistance, and β-cell dysfunction.

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Crosstalk between Keap1-Nrf2-ARE pathway and other signaling pathways endows it with high complexity and significance in the multi-function of phytochemicals. Limited human data makes an urgent need to open the new field of phytochemical-original supplement application in human chronic disease prevention.”

https://www.mdpi.com/2076-3921/12/2/236 “The Regulatory Effect of Phytochemicals on Chronic Diseases by Targeting Nrf2-ARE Signaling Pathway”


Top ten mentions, not including references:

  • 21 Sulforaphane
  • 16 Broccoli
  • 9 Curcumin
  • 5 Resveratrol
  • 5 Green tea catechins
  • 4 Luteolin
  • 3 Garlic
  • 3 Soy isoflavones
  • 3 Lycopene
  • 3 Quercetin

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Nrf2 Week #4: Aging

Two 2023 reviews of Nrf2 and aging, starting with Nrf2-mitochondria interactions:

“We discuss molecular mechanisms of interactions between Nrf2 and mitochondria that influence the rate of aging and lifespan. Nrf2 activity positively affects both mitochondrial dynamics and mitochondrial quality control.

Nrf2 influences mitochondrial function through regulation of nuclear genome-encoded mitochondrial proteins and changes in the balance of ROS or other metabolites. In turn, multiple regulatory proteins functionally associated with mitochondria affect Nrf2 activity and even form mutual regulatory loops with Nrf2. These loops enable fine-tuning of cellular redox balance and, possibly, of the cellular metabolism as a whole.

mtDNA-encoded signal peptides interact with nuclear regulatory systems, first of all, Nrf2, and are possibly involved in regulation of the aging rate. Interactions between regulatory cascades that link programs ensuring maintenance of cellular homeostasis and cellular responses to oxidative stress are a significant part of both aging and anti-aging programs.

Understanding these interactions will be of great help in searching for molecular targets to counteract aging-associated diseases and aging itself. Future research on Nrf2 signaling and ability of various substances that activate the Nrf2 pathway to prevent age-associated chronic diseases will provide further insight into the role of Nrf2 activation as a possible longevity-promoting intervention.”

https://link.springer.com/article/10.1134/S0006297922120057 “Transcription Factor Nrf2 and Mitochondria – Friends or Foes in the Regulation of Aging Rate” (not freely available) Thanks to Dr. Gregory A. Shilovsky for providing a copy.


The second review evaluated whether Nrf2 is a master regulator of aging:

“This paper briefly presents main mechanisms of mammalian aging and roles of inflammation and oxidative stress in this process. Mechanisms of Nrf2 activity regulation, its involvement in aging and development of the senescence-associated secretory phenotype are also discussed.

The age-related decrease in Nrf2 activity is of universal interspecies character:

  • Rodents with high Nrf2 activity have a longer lifespan than rodents with low activity.
  • Genetic knockout of Nrf2 usually leads to the increased senescent phenotype in a variety of animal organs and tissues, and also reduces lifespan of female mice.
  • There are also opposite examples, where Nrf2 knockout in aging mice reduced iron ions deposition in the brain, lowered the level of oxidative damage in the striatum, and also alleviated age-related motor dysfunction.

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It would be incorrect to consider the effect of Nrf2 transcription factor at the organism level as exclusively antioxidant, anti-inflammatory, and, ultimately, anti-aging. Nrf2 controls many genes, products of which have complex, pleiotropic effects on the body:

  • No experiments that use Nrf2 chemical inducers as anti-aging drugs have been performed so far.
  • Nrf2 is not involved in life extension caused by caloric restriction.
  • Epigenetic clocks do not reveal transcription factors activity of which changes with aging.

Aging is accompanied by changes in gene expression profiles, which are tissue- and species-specific. These changes only to a small extent include genes controlled by Nrf2. At the moment, it cannot be concluded that Nrf2 is the master regulator of the aging process.”

https://link.springer.com/article/10.1134/S0006297922120045 “Does Nrf2 Play a Role of a Master Regulator of Mammalian Aging?”


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Don’t eat yourself into disease, Part 2

This blog’s 1000th curation is a 2023 rodent study associating gut microbiota, behavior, memory, and food reward:

“Energy intake and energy expenditure is regulated by the hypothalamus, and is referred to as homeostatic regulation of food intake. The reward system is the non-homeostatic regulation of food intake – pleasure-related consumption of foods enriched in fat and sugar. The pleasure is encoded by dopamine release from dopaminergic neurons projecting from the ventral tegmental area to the striatum, the nucleus accumbens, and the prefrontal cortex.

Food reward can be divided into three components – liking, wanting, and learning:

  • Liking refers to food hedonic value;
  • Wanting to the motivational process to seek out and consume certain foods; and
  • Learning to reinforcing conditioning behavior associated with food intake stimulus.

We confirmed that obese mice have a dysregulation of the learning and the wanting components of  food reward. Our previous data showed that the liking component was transferable through fecal material transplantation.

We demonstrated that gut microbes play a role in the regulation of food reward, and could be responsible for compulsive behavior and excessive motivation to obtain sucrose pellets. Moreover, obese gut microbes affected dopaminergic and opioid markers involved in reward system.

We identified 33HPP (produced exclusively by gut bacteria) as particularly increased in mice recipients of gut microbes from obese mice. We were able to demonstrate its effects as key mediator of the gut-brain axis controlling the reward response to palatable food.”

https://microbiomejournal.biomedcentral.com/articles/10.1186/s40168-023-01526-w “Obese-associated gut microbes and derived phenolic metabolite as mediators of excessive motivation for food reward”


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No exit

This 2023 rodent study investigated aging processes and gut microbiota in crowded conditions:

“Our study provides clear evidence that high-density crowding accelerates the aging process of Brandt’s voles. We also found that ‘high-density microbiota’ promote the aging-related phenotype in voles.

Because we minimized effects of direct fighting on mortality of voles, observed changes in lifespan in this study should mostly represent the natural aging processes of voles.

high-density survival

High density increased the level of stress hormone corticosterone, which disrupted gut microbiota composition by:

  • Decreasing abundance of anti-aging or anti-inflammatory bacterial species; and
  • Increasing the proportion of pathogenic bacteria.

This caused an increase in DNA oxidation and inflammation through upregulation of NF-kB and COX-2 pathways.

Although high-density relief and butyric acid administration interventions could reverse aging-related processes of adult voles, it remains unclear whether they could reverse the aging process in terms of lifespan.

Our results suggest that gut microbiota play a significant role in mediating aging-related processes of voles under high-density conditions, and can be used as a potential therapeutic target for treating stress-related diseases in humans.”

https://onlinelibrary.wiley.com/doi/10.1002/advs.202205346 “Gut Microbiota is Associated with Aging-Related Processes of a Small Mammal Species under High-Density Crowding Stress”


I came across this study by it citing Reversing hair greying for effects of stress interventions.

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What do we know about human aging from mouse models?

Here is a 2021 rodent study and relevant parts from 3 of its 26 citing papers:

“A long line of evidence has established the laboratory mouse as the prime model of human aging. However, relatively little is known about detailed behavioral and functional changes that occur across their lifespan, and how this maps onto the phenotype of human aging.

To better understand age-related changes across the lifespan, we characterized functional aging in male C57BL/6J mice of five different ages (3, 6, 12, 18, and 22 months of age) using a multi-domain behavioral test battery. Assessment of functional aging in humans and mice: age-related patterns were determined based on representative data (Table 2), and then superimposed onto survival rate. (A) Body weight, (B) locomotor activity, (C) gait velocity, (D) grip strength, (E) trait anxiety, (F) memory requiring low attention level, and (G) memory requiring high attention level.

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These functional alterations across ages are non-linear, and patterns are unique for each behavioral trait. Physical function progressively declines, starting as early as 6 months of age in mice, while cognitive function begins to decline later, with considerable impairment present at 22 months of age.

Functional aging of male C57BL/6J mice starts at younger relative ages compared to when it starts in humans. Our study suggests that human-equivalent ages of mice might be better determined on the basis of its functional capabilities.”

https://www.frontiersin.org/articles/10.3389/fnagi.2021.697621/full “Functional Aging in Male C57BL/6J Mice Across the Life-Span: A Systematic Behavioral Analysis of Motor, Emotional, and Memory Function to Define an Aging Phenotype”


“Studies in mice show that physical function (i.e., locomotor activity, gait velocity, grip strength) begins to deteriorate around post-natal day (PND) 180, but cognitive functions (i.e., memory) do not exhibit impairment until roughly PND 660. Our results should be considered within the context of behavior changing throughout vole adulthood. Caution should be taken to avoid categorizing the oldest age group in our study as ‘elderly’ or ‘geriatric.'”

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0276897 “Behavioral trajectories of aging prairie voles (Microtus ochrogaster): Adapting behavior to social context wanes with advanced age”


“We used adult mice ranging in age from 5-6 months, not enough to modify experimental autoimmune encephalomyelitis progression. Mice are considered adult after 8 weeks; however, rapid growth for most biological processes is observed until 3 months of age, while past 6 months, mice might be affected by senescence.”

https://www.frontiersin.org/articles/10.3389/fimmu.2022.1036680/full “Age related immune modulation of experimental autoimmune encephalomyelitis in PINK1 knockout mice”


“Locomotor activity and gait velocity of 12 months old male C57BL/6 correlates with an elderly human being aged 60 or older, supporting that the ~15 months old mice we used in our study were aged mice at the time of tissue collection.”

https://www.mdpi.com/1422-0067/23/20/12461 “Genomic Basis for Individual Differences in Susceptibility to the Neurotoxic Effects of Diesel Exhaust”


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Do broccoli sprouts treat gout and kidney stones?

This 2022 rodent study investigated glucoraphanin’s effects on reducing uric acid:

“Hyperuricemia is a chronic disease characterized by abnormally elevated serum uric acid levels. Sulforaphane could lower uric acid by decreasing urate synthesis and increasing renal urate excretion in hyperuricemic rats.

A hyperuricemia model was established by administering feedstuffs with 4% potassium oxonate and 20% yeast. Forty male Sprague–Dawley rats were randomly divided into the normal control, hyperuricemia, allopurinol, and sulforaphane groups. Animals were treated by oral gavage for six consecutive weeks, and then phenotypic parameters, metabolomic profiling, and metagenomic sequencing were performed.

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We identified succinic acid and oxoglutaric acid as critical host-gut microbiome co-metabolites. Sulforaphane improved diversity of microbial ecosystems and functions, as well as metabolic control of the kidney. Sulforaphane exerted its renoprotective effect through epigenetic modification of Nrf2 and interaction between gut microbiota and epigenetic modification in hyperuricemic rats.

Limitations of this study include:

  1. We used glucoraphanin bioactivated with myrosinase for our experiments. Future experiments may directly involve sulforaphane.
  2. Bioinformatics analysis resulted in speculations that require further experimental testing.
  3. Further investigation of interactions between microbiota and the host epigenome is still needed.”

https://www.sciencedirect.com/science/article/pii/S209012322200251X “Sulforaphane-driven reprogramming of gut microbiome and metabolome ameliorates the progression of hyperuricemia”


It was a stretch to label treatment subjects as the “sulforaphane group” by claiming “Glucoraphanin (10 mg/kg) was metabolized to SFN by myrosinase as described in previous studies.” Both this and the referenced 2014 study “(RS)-glucoraphanin purified from Tuscan black kale and bioactivated with myrosinase enzyme protects against cerebral ischemia/reperfusion injury in rats” measured glucoraphanin and myrosinase, but not sulforaphane.

A human equivalent to this study’s daily glucoraphanin intake of 10 mg / kg weight would be (.162 x 10 mg) x 70 kg = 113 mg. Whether 10 mg was dry or wet weight wasn’t disclosed.

If 10 mg was wet, 113 mg is a little more than twice our model clinical trial’s average glucoraphanin intake of 51 mg fresh weight from eating 30 grams / day of super sprouts. In April 2020’s Understanding a clinical trial’s broccoli sprout amount, a study coauthor said:

“We considered 30 g and 60 g to be 1/2 and 1 portion per day, respectively, of broccoli sprouts. When we carried out tests with consumers, previous to the bioavailability studies, higher amounts per day were not easy to consume and to get eaten by participants.”

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Broccoli sprouts activate the AMPK pathway, Part 4

Today someone viewed the 2020 Part 3 of Broccoli sprouts activate the AMPK pathway which lacked citations at the time. Checking again, here are three citing 2022 papers, starting with a review:

“Nrf2 is an important transcription factor that regulates expression of a large number of genes in healthy and disease states. Nrf2 regulates expression of several key components of oxidative stress, mitochondrial biogenesis, mitophagy, autophagy, and mitochondrial function in all organs of the human body, and in the peripheral and central nervous systems.

Overall, therapeutic drugs including sulforaphane that target Nrf2 expression and Nrf2/ARE pathway are promising. This article proposes additional research in Nrf2’s role within Parkinson’s disease, Huntington’s disease, and ischemic stroke in preclinical mouse models and humans with age-related neurodegenerative diseases.”

https://www.sciencedirect.com/science/article/pii/S1568163722001982 “Role of Nrf2 in aging, Alzheimer’s and other neurodegenerative diseases” (not freely available) Thanks to Dr. P. Hemachandra Reddy for providing a copy.


One of the Part 3 study’s coauthors contributed to this very detailed review:

“Due to observed overlapping cellular responses upon AMPK or NRF2 activation and common stressors impinging on both AMPK and NRF2 signaling, it is plausible to assume that AMPK and NRF2 signaling may interdepend and cooperate to readjust cellular homeostasis.

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The outcome and underlying signaling events of AMPK-NRF2 crosstalk may diverge between:

  1. in vitro and in vivo studies (one cell type in isolation vs inter-organ crosstalk in living organisms);
  2. Different cell types/organs/organisms of different cultivation conditions, genetic background, age or sex;
  3. Different stress-regimens (chronic vs acute, nature of stress (lipotoxicity, redox stress, xenobiotic, starvation, etc));
  4. Different modes of Nrf2 or AMPK activation and inhibition (genetic vs pharmacological, constitutive vs transient/intermittent, systemic vs organ-specific, electrophilic vs PPI, allosteric vs covalent, or pan vs subtype-specific);
  5. Different target genes with distinct promoter and enhancer structure; or
  6. Different timing of activation.

The latter should deserve increased attention as Nrf2 is one of the most cycling genes under control of the circadian clock. Feeding behavior, metabolism and hence AMPK activity follow and substantiate the biological clock, indicating an entangled circadian regulation of metabolic and redox homeostasis.”

https://www.sciencedirect.com/science/article/pii/S089158492200497X “AMPK and NRF2: Interactive players in the same team for cellular homeostasis?”


A third citing paper was a study of lens cells that provided an example of similar metformin effects noted in Part 2 of Broccoli sprouts activate the AMPK pathway:

“Loss of Nrf2 and Nrf2 antioxidant genes expression and activity in aging cells leads to an array of oxidative-induced deleterious responses, impaired function, and aging pathologies. This deterioration is proposed to be the primary risk factor for age-related diseases such as cataracts.

AMPK regulates energy at physiological levels during metabolic imbalance and stress. AMPK is a redox sensing molecule, and can be activated under cellular accumulation of reactive oxygen species, which are endogenously produced due to loss of antioxidant enzymes.

The therapeutic potential of AMPK activation has context-dependent beneficial effects, from cell survival to cell death. AMPK activation was a requisite for Bmal1/Nrf2-antioxidants-mediated defense, as pharmacologically inactivating AMPK impeded metformin’s effect.

Using lens epithelial cell lines (LECs) of human or mouse aging primary LECs along with lenses as model systems, we demonstrated that metformin could correct deteriorated Bmal1/Nrf2/ARE pathway by reviving AMPK-activation and transcriptional activities of Bmal1/Nrf2, resulting in increased antioxidants enzymatic activity and expression of Phase II enzymes. Results uncovered crosstalk between AMPK and Bmal1/Nrf2/antioxidants mediated by metformin for blunting oxidative/aging-linked pathobiology.”

https://www.mdpi.com/2073-4409/11/19/3021/htm “Obligatory Role of AMPK Activation and Antioxidant Defense Pathway in the Regulatory Effects of Metformin on Cellular Protection and Prevention of Lens Opacity”


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If you were given a lens to see clearly, would you accept it?

Two papers, starting with a 2022 rodent study of maternal behaviors’ effects on offspring physiologies:

Early life adversity (ELA) is a major risk factor for development of pathology. Predictability of parental care may be a distinguishing feature of different forms of ELA.

We tested the hypothesis that changes in maternal behavior in mice would be contingent on the type of ELA experienced, directly comparing predictability of care in the limited bedding and nesting (LBN) and maternal separation (MS) paradigms. We then tested whether predictability of the ELA environment altered expression of corticotropin-releasing hormone (Crh), a sexually-dimorphic neuropeptide that regulates threat-related learning.

MS was associated with increased expression of Crh-related genes in males, but not females. LBN primarily increased expression of these genes in females, but not males.”

https://www.sciencedirect.com/science/article/pii/S2352289522000595 “Resource scarcity but not maternal separation provokes unpredictable maternal care sequences in mice and both upregulate Crh-associated gene expression in the amygdala”


I came across this first study by it citing a republished version of 2005 epigenetic research from McGill University:

“Early experience permanently alters behavior and physiology. A critical question concerns the mechanism of these environmental programming effects.

We propose that epigenomic changes serve as an intermediate process that imprints dynamic environmental experiences on the fixed genome resulting in stable alterations in phenotype. These findings demonstrate that structural modifications of DNA can be established through environmental programming and that, in spite of the inherent stability of this epigenomic marker, it is dynamic and potentially reversible.”

https://www.tandfonline.com/doi/full/10.31887/DCNS.2005.7.2/mmeaney “Environmental programming of stress responses through DNA methylation: life at the interface between a dynamic environment and a fixed genome”


This post commemorates the five-year anniversary of Dr. Arthur Janov’s death. Its title is taken from my reaction to his comment on Beyond Belief: Symptoms of hopelessness. Search his blog for mentions of the second paper’s coauthors, Drs. Meaney and Szyf.

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All about walnuts’ effects

Five 2022 papers focusing on walnuts, starting with a comparison of eight tree nuts:

“The aim of the present study was to examine 8 different popular nuts – pecan, pine, hazelnuts, pistachio, almonds, cashew, walnuts, and macadamia. Total content of phenolic compounds in nuts ranged from 5.9 (pistachio) to 432.9 (walnuts) mg/100 g.

Walnuts had the highest content of polymeric procyanidins, which are of great interest as important compounds in nutrition and biological activity, as they exhibit antioxidant, anti-inflammatory, antimicrobial, cardio- and neuroprotective action. Walnuts are good sources of fatty acids, especially omega-3 and omega-6.”

https://www.sciencedirect.com/science/article/pii/S2590157522002164 “Nuts as functional foods: Variation of nutritional and phytochemical profiles and their in vitro bioactive properties”


A second study compared the same eight tree nuts plus Brazil nuts and peanuts:

“The highest total content of all analyzed flavonoids was determined in walnuts (114.861 µg/g) with epicatechin the most abundant, while the lowest was in almonds (1.717 µg/g). Epicatechin has antioxidant, anti-inflammatory, antitumor, and anti-diabetic properties. Epicatechin has beneficial effects on the nervous system, enhances muscle performance, and improves cardiac function.”

https://www.mdpi.com/1420-3049/27/14/4326/htm “The Content of Phenolic Compounds and Mineral Elements in Edible Nuts”


Next, two systematic reviews and meta-analyses of human studies:

“We carried out a systematic review of cohort studies and randomized controlled trials (RCTs) investigating walnut consumption, compared with no or lower walnut consumption, including those with subjects from within the general population and those with existing health conditions, published from 2017 to 5 May 2021.

  • Evidence published since 2017 is consistent with previous research suggesting that walnut consumption improves lipid profiles and is associated with reduced CVD risk.
  • Evidence pointing to effects on blood pressure, inflammation, hemostatic markers, and glucose metabolism remains conflicting.
  • Evidence from human studies showing that walnut consumption may benefit cognitive health, which is needed to corroborate findings from animal studies, is now beginning to accumulate.”

https://academic.oup.com/nutritionreviews/advance-article/doi/10.1093/nutrit/nuac040/6651942 “Walnut consumption and health outcomes with public health relevance – a systematic review of cohort studies and randomized controlled trials published from 2017 to present”


“We aimed to perform a systematic review and meta-analysis of RCTs to thoroughly assess data concerning effects of walnut intake on selected markers of inflammation and metabolic syndrome in mature adults. Our findings showed that:

  • Walnut-enriched diets significantly decreased TG, TC, and LDL-C concentrations, while HDL-C levels were not significantly affected.
  • No significant changes were noticed on anthropometric, cardiometabolic, and glycemic indices after higher walnut consumption.
  • Inflammatory biomarkers did not record statistically significant results.”

https://www.mdpi.com/2076-3921/11/7/1412/htm “Walnut Intake Interventions Targeting Biomarkers of Metabolic Syndrome and Inflammation in Middle-Aged and Older Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials”


Finishing with a rodent study that gave subjects diabetes with a high-fat diet, then mixed two concentrations of walnut extract in with the treatment groups’ chow:

“This study was conducted to evaluate the protective effect of Gimcheon 1ho cultivar walnut (GC) on cerebral disorder by insulin resistance, oxidative stress, and inflammation in HFD-induced diabetic disorder mice. After HFD feed was supplied for 12 weeks, samples were orally ingested for 4 weeks to GC20 and GC50 groups (20 and 50 mg/kg of body weight, respectively).

  • Administration of GC improved mitochondrial membrane potential function, and suppressed oxidative stress in the brain.
  • GC inhibited hepatic and cerebral lipid peroxidation and the formation of serum AGEs, and increased serum antioxidant activity to improve HFD-induced oxidative stress.
  • The HFD group showed significant memory impairment in behavioral tests. On the other hand, administration of GC showed improvement in spatial learning and memory function.

walnut brain effects

Based on these physiological activities, GC showed protective effects against HFD-induced diabetic dysfunctions through complex and diverse pathways.”

https://www.mdpi.com/1420-3049/27/16/5316/htm “Walnut Prevents Cognitive Impairment by Regulating the Synaptic and Mitochondrial Dysfunction via JNK Signaling and Apoptosis Pathway in High-Fat Diet-Induced C57BL/6 Mice”


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Minds of their own

It’s the weekend, so it’s time for: Running errands? Watching sports? Other conditioned behavior?

Or maybe broadening our cognitive ability with Dr. Michael Levin’s follow-ups to his 2021 Basal cognition paper and 2020 Electroceuticals presentation with a 2022 paper and presentation starting around the 13:30 mark:

Michael Levin - Cell Intelligence in Physiological and Morphological Spaces

“A homeostatic feedback is usually thought of as a single variable such as temperature or pH. The set point has been found to be a large-scale geometry, a descriptor of a complex data structure.”


His 2022 paper Technological Approach to Mind Everywhere: An Experimentally-Grounded Framework for Understanding Diverse Bodies and Minds:

“It is proposed that the traditional problem-solving behavior we see in standard animals in 3D space is just a variant of evolutionarily more ancient capacity to solve problems in metabolic, physiological, transcriptional, and morphogenetic spaces (as one possible sequential timeline along which evolution pivoted some of the same strategies to solve problems in new spaces).

Developmental bioelectricity works alongside other modalities such as gene-regulatory networks, biomechanics, and biochemical systems. Developmental bioelectricity provides a bridge between the early problem-solving of body anatomy and the more recent complexity of behavioral sophistication via brains.

This unification of two disciplines suggests a number of hypotheses about the evolutionary path that pivoted morphogenetic control mechanisms into cognitive capacities of behavior, and sheds light on how Selves arise and expand.

While being very careful with powerful advances, it must also be kept in mind that existing balance was not achieved by optimizing happiness or any other quality commensurate with modern values. It is the result of dynamical systems properties shaped by meanderings of the evolutionary process and the harsh process of selection for survival capacity.”


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Gut microbiota, SCFAs, and hypertension

Two 2022 rodent studies from the same research group on short-chain fatty acid effects, beginning with butyrate:

“Maternal nutrition, gut microbiome composition, and metabolites derived from gut microbiota are closely related to development of hypertension in offspring. A plethora of metabolites generated from diverse tryptophan metabolic pathways show both beneficial and harmful effects.

Butyrate, one of the short-chain fatty acids (SCFAs), has shown vasodilation effects. We examined whether sodium butyrate administration in pregnancy and lactation can prevent hypertension induced by a maternal tryptophan-free diet in adult progeny, and explored protective mechanisms.

Decreased tryptophan metabolites indole-3-acetamide and indoleacetic acid observed in offspring born to dams that received the trytophan-free (TF) diet coincided with hypertension. This suggested that gut microbiota-derived tryptophan metabolites might be an offsetting mechanism, but not a cause of TF-induced hypertension. Considering that TF intervention reduced abundance of Romboutsia and Akkermansia, and many species are able to metabolize tryptophan, further studies linking abundance of bacterial species and concentrations of tryptophan metabolites are still required to identify main tryptophan metabolite producers.

Sodium butyrate treatment during pregnancy and lactation offset effects of maternal tryptophan-deficiency-induced offspring hypertension, mainly related to shaping gut microbiome, mediating SCFA receptor GPR41 and GPE109A, and restoring the renin–angiotensin system. A better understanding of mechanisms behind tryptophan metabolism implicated in programming of hypertension is critical for developing gut microbiota-targeted therapies to halt hypertension.”

https://www.sciencedirect.com/science/article/abs/pii/S0955286322001619 “Sodium butyrate modulates blood pressure and gut microbiota in maternal tryptophan-free diet-induced hypertension rat offspring” (not freely available) Thanks to Dr. You-Lin Tain for providing a copy.


A second study was on propionate effects:

“Early-life disturbance of gut microbiota has an impact on adult disease in later life. Propionate, one of predominant SCFAs, has been shown to have antihypertensive property.

We examined whether perinatal propionate supplementation can prevent offspring hypertension induced by maternal chronic kidney disease (CKD). CKD is closely linked to adverse maternal and fetal outcomes, and is reported to affect at least 3%-4% women of childbearing age.

Male offspring were divided into four groups: control, CKD, control+propionate (CP), and CKD+propionate (CKDP).

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Perinatal propionate supplementation:

  • Prevented offspring hypertension;
  • Shaped gut microbiota with increases in species richness and evenness;
  • Increased plasma propionate level; and
  • Upregulated renal GPR41 expression.

Results reveal the feasibility of manipulating gut microbiota by altering their metabolites with early-life use of propionate to prevent offspring hypertension in later life.”

https://www.mdpi.com/2072-6643/14/16/3435/htm “Perinatal Propionate Supplementation Protects Adult Male Offspring from Maternal Chronic Kidney Disease-Induced Hypertension”


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Glucoraphanin is not sulforaphane

A poorly-conceived and intentionally-misrepresented human 2022 broccoli product study:

“We investigated whether a sulforaphane (SFN) [actually, sulforaphane precursor glucoraphanin] intake intervention improved cognitive performance and mood states in healthy older adults in a 12-week, double-blinded, randomized controlled trial.

The SFN group showed improvement in processing speed and a decrease in negative mood compared to the placebo group. However, there were no significant results in other biomarkers of oxidant stress, inflammation, or neural plasticity.

These results indicate that nutrition interventions using SFN can have positive effects on cognitive functioning and mood in healthy older adults.”

https://www.frontiersin.org/articles/10.3389/fnagi.2022.929628/full “Effects of sulforaphane intake on processing speed and negative moods in healthy older adults: Evidence from a randomized controlled trial”


Contrary to this study’s title, actual sulforaphane intake was not measured. The glucoraphanin product used in this study was the same item and daily dose as Eat broccoli sprouts for your workouts, which investigated effects with 19-to-23-year-old men. The treatment was taken all at once at an unspecified time of day rather than three times a day with young subjects.

These researchers knew from the 2012 study cited for dose that:

“Individual conversions of glucosinolates [like glucoraphanin] to isothiocyanates [like sulforaphane] varied enormously, from about 1% to more than 40% of dose. In contrast, administration of isothiocyanates (largely sulforaphane)-containing broccoli sprout extracts, resulted in uniformly high (70-90%) conversions to urinary dithiocarbamates.”

Young or old, a daily 30 mg glucoraphanin intake isn’t sufficient to fully activate human Nrf2 signaling pathways. A daily 17 mg sulforaphane intake could accomplish that.


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Don’t bother eating broccoli sprouts if you’re old?

I try to not curate research that wastes resources. Couldn’t help but present this 2022 rodent study:

“We aimed to evaluate if sulforaphane (SFN) long-term treatment was able to prevent age-associated cognitive decline in adult (15-month-old) and old (21-month-old) female and male rats.

Our results showed that SFN restored redox homeostasis in brain cortex and hippocampus of adult rats, preventing cognitive decline in both sexes. However, redox responses were not the same in males and females.

Old rats were not able to recover their redox state as adults did, but they had a mild improvement. These results suggest that SFN mainly prevents rather than reverts neural damage; though, there might also be a range of opportunities to use hormetins like SFN, to improve redox modulation in old animals.”

https://link.springer.com/article/10.1007/s10522-022-09984-9 “Long-term sulforaphane-treatment restores redox homeostasis and prevents cognitive decline in middleaged female and male rats, but cannot revert previous damage in old animals” (not freely available)


These researchers cited Sulforaphane in the Goldilocks zone for hormetic effects of sulforaphane, so I asked:

“Did you develop any preliminary dose/response data for stating ‘there might also be a range of opportunities to use hormetins like SFN to improve redox modulation in old animals’?”

They cited Broccoli sprouts activate the AMPK pathway for long-term effects of a small sulforaphane dose, so I asked:

“Also, the three studies cited for ‘0.5 mg/Kg, i.e. 2.82 μmol/Kg BW for 3 months’ were all mouse studies. Since this was a rat study, wouldn’t there be increased dose and duration equivalencies?”

I’ll update this blog post in the event either of my questions to these researchers are answered.

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Sulforaphane nose drops

This 2022 rodent study compared capabilities of intranasal nanoparticle sulforaphane and free sulforaphane to mitigate brain damage caused by a common cancer treatment:

“Non-invasive intranasal (IN) trafficking of therapeutic agents with nanocarriers can enhance efficacy of drug delivery, biodistribution, bioavailability, and absorption against enzymatic degradation and extracellular transportation. Direct IN trafficking of nanocarriers is expected to reduce drug wastage, administration frequency, and undesirable adverse effects.

The nasal route for brain-targeted delivery of sulforaphane (SF) loaded within iron oxide nanoparticles (Fe3O4-NPs) was based on improving physicochemical stability of SF, and to enhance its bioavailability by avoiding oral route drawbacks like extensive first-pass metabolism and intestinal drug degradation.

Cisplatin (CIS) significantly induced a significant increase in acetylcholinesterase activities and lipid peroxides, and a significant decrement in glutathione and nitric oxide contents. We aimed to explore the nanotherapeutic potential of intranasally delivered SF loaded within Fe3O4-NPs (N.SF) against CIS-induced neurotoxicity through different biochemical, behavioral, and histological investigations.

hippocampus damage

Treatment with N.SF was more capable of mitigating both CIS-induced striatal and cortical injuries. IN treatment with either SF or N.SF showed equal alleviative potential regarding CIS-induced hippocampal or cerebellar injury.

These encouraging results demonstrated the potential use of iron-oxide NPs as neurotherapeutic agents, and confirmed the possibility of developing a novel promising and non-invasive intranasal delivery system for treatment of CIS-induced neurotoxicity.”

https://link.springer.com/article/10.1007/s12640-022-00555-x “Neuroprotective Potential of Intranasally Delivered Sulforaphane-Loaded Iron Oxide Nanoparticles Against Cisplatin-Induced Neurotoxicity”


I found this study from it citing a paper in Do broccoli sprouts treat migraines?

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Non-patentable boron benefits

To follow up Is boron important to health? I’ll highlight a 2022 review of boron intake:

“Boron is essential for activity of several metabolic enzymes, hormones, and micronutrients. It is important for growth and maintenance of bone, reduction in inflammatory biomarkers, and increasing levels of antioxidant enzymes.

The average person’s daily diet contains 1.5 to 3 milligrams of boron. Boron intakes of 1–3 mg/day have been shown to improve bone and brain health in adults when compared to intakes of 0.25–0.50 mg/day.

One week of 10 mg/d boron supplementation resulted in a 20% reduction in inflammatory biomarkers TNF-α, as well as significant reductions (nearly 50%) in plasma concentrations of hs-CRP and IL-6. Calcium fructoborate, a naturally occurring, plant-based boron-carbohydrate complex, had beneficial effects on osteoarthritis (OA) symptoms. A double-blind study in middle-aged patients with primary OA found that all groups except the placebo group saw a reduction in inflammatory biomarkers after 15 days of food supplementation with calcium fructoborate.

Dietary boron intake significantly improves brain function and cognitive functioning in humans. Electroencephalograms showed that boron pharmacological intervention after boron deficiency improved functioning in older men and women, such as less drowsiness and mental alertness, better psychomotor skills (for example, motor speed and dexterity), and better cognitive processing (e.g., attention and short-term memory). Boron compounds can help with both impaired recognition and spatial memory problems.

We discussed the role of boron-based diet in memory, boron and microbiome relation, boron as anti-inflammatory agents, and boron in neurodegenerative diseases. Boron reagents will play a significant role to improve dysbiosis.”

https://www.mdpi.com/1420-3049/27/11/3402/htm “The Role of Microbiome in Brain Development and Neurodegenerative Diseases”


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