HoldsUp

John Gilday

Mara Labs

John Gilday is associated with Mara Labs and has a research background in organic chemistry. His peer-reviewed publications focus on synthetic organic chemistry, including asymmetric synthesis, organolithium-mediated reactions, and the chemical synthesis of nitrogen-containing heterocycles such as aziridines, piperidines, and sparteine derivatives.

26 claims checked on air: 1 context 4 contradicted 6 overstated 11 supported 4 unverified

What they said on air

0:03:36supportedmoderateStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

The estrogen metabolite 4-hydroxyestrone can form DNA adducts and is genotoxic.

"one of those pathways, 4-hydroxyestrone, can be a DNA adduct. So it's it's genotoxic." (said at 0:03:36)

4-Hydroxyestrone is a catechol estrogen metabolite that undergoes metabolic oxidation to reactive catechol estrogen-3,4-quinones. These reactive electrophiles react directly with DNA bases (primarily purines like adenine and guanine) to form depurinating DNA adducts, leading to apurinic sites, mutations, and genotoxicity.

0:04:15overstatedmoderateStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

Up to menopause women are protected against cardiometabolic conditions and fatty liver, but after menopause disease rates accelerate and catch up to men around age 60.

"as um up to menopause a woman is protected against all kinds of disease states, you know, including all cardiometabolic states, fatty liver, just the list goes on and on. And then as you go through menopause, a woman actually catches back up to a man, and so the rate actually accelerates faster than a man as as you lose estrogen and catches back up, you know, close to around 60." (said at 0:04:15)

The speaker accurately describes the sex-specific trajectory of cardiometabolic risk and nonalcoholic fatty liver disease (NAFLD): premenopausal women exhibit relative protection compared to men due to estrogen-mediated effects on fat partitioning and vascular health, followed by accelerated accumulation of visceral adiposity and metabolic risk post-menopause that narrows the gap with men around age 60. However, claiming that premenopausal women are protected against 'all kinds of disease states' and 'all cardiometabolic states' overstates the level of protection, as premenopausal women can and do develop cardiometabolic disorders and liver disease.

0:05:00supportedvery lowStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

Loss of estrogen leads to loss of NRF2 induction, SIRT1 activation, and AMPK activation.

"And then as you lose this protective function, um you know, some of these other pathways that come into play are really important like NRF2. You lose NRF2 induction, um you lose SIRT1 activation, um uh AMPK as well." (said at 0:05:00)

Preclinical models of estrogen deficiency (such as ovariectomy) and translational human tissue studies demonstrate that the loss of estrogen signaling impairs the activation and downstream pathways of NRF2, SIRT1, and AMPK. Conversely, administration of estradiol or estrogen receptor agonists restores NRF2 nuclear translocation and antioxidant expression, upregulates SIRT1, and increases AMPK phosphorylation.

0:07:11supportedvery lowStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

SIRT1 is a histone deacetylase that functions in genome gatekeeping and participates in repairing double-stranded DNA breaks.

"SIRT1 is is a genome gatekeeper. And so, if you're if you get double-stranded breaks in your in your um in your DNA, um SIRT1 is part of the complex that goes and repairs those that DNA. ... It's a histone deacetylase." (said at 0:07:11)

SIRT1 is well established as an NAD(+)-dependent class III histone deacetylase that plays a crucial role in maintaining genomic stability and facilitating the repair of DNA double-strand breaks (DSBs). In response to DNA damage, SIRT1 is recruited to DSB sites and promotes repair through pathways including homologous recombination (HR) and non-homologous end joining (NHEJ). Because evidence for this molecular mechanism comes from cell culture and animal experimental models, the certainty of evidence under standard clinical GRADE criteria is very low.

0:07:50supportedhighStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

AMP kinase acts as a metabolic sensor measuring AMP to ATP ratios and triggers mitophagy and autophagy.

"And then AMP kinase is a metabolic sensor. So it it measures the amount of AMP to ATP. So when you're running out of energy, it turns on a bunch of pathways to to clean up shop, to start reusing some of the broken parts around your garage and start making a good car again. So that's this meta- mitophagy, autophagy." (said at 0:07:50)

The speaker's statement is supported. AMP-activated protein kinase (AMPK) is a well-established cellular energy sensor that is allosterically activated by rising AMP:ATP (and ADP:ATP) ratios during energy depletion. Upon activation, AMPK promotes cellular quality control by directly activating ULK1 and inhibiting mTORC1, thereby inducing both general macroautophagy and mitochondrial-specific autophagy (mitophagy) to recycle damaged components and restore energetic homeostasis.

0:24:44supportedvery lowStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

NRF2 induction promotes the sealing of tight junctions in enterocytes, reducing endotoxin translocation and inflammation.

"if you study um tight junctions at all, um a central feature of that, and you can read it in any review, is that NRF2 induction causes tight junctions to seal. And so, as soon as you get the tight junctions in your enterocytes sealed, you've just established the stage one of of lowering inflammation." (said at 0:24:44)

Preclinical in vitro and animal models support the claim that Nrf2 activation promotes intestinal tight junction integrity (upregulating tight junction proteins such as ZO-1, occludin, and claudins) and attenuates mucosal inflammation and barrier permeability. Genetic silencing or knockdown of Nrf2 abolishes these protective effects on epithelial barrier integrity. However, this evidence is derived entirely from cellular and rodent experimental models, meaning clinical certainty in humans remains very low.

0:32:27contradictedmoderateStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

In young people, exercise increases NRF2 expression, whereas in people over 60, over-exercising causes NRF2 levels to decline.

"Young people, you exercise, your NRF2 goes up like crazy. Um past 60 or so, NRF2 goes down if you over-exercise." (said at 0:32:27)

The speaker bundles two claims: that exercise robustly increases Nrf2 in young individuals, and that in adults over 60, over-exercising causes Nrf2 levels to decline. While acute exercise stimulates Nrf2 pathway activation and downstream antioxidant gene expression in young adults, evidence does not show that exercise causes Nrf2 levels to decline in older adults. Instead, randomized trials comparing adults aged 18–28 to adults aged 60 and older show that acute exercise still activates Nrf2 signaling in older adults, although the acute response is blunted or attenuated compared to younger individuals. Furthermore, sedentary older adults exhibit higher basal Nrf2 levels (reflecting baseline oxidative stress), and aerobic exercise training actually lowers basal Nrf2 while partially restoring its dynamic activation during exercise.

0:37:20overstatedmoderateStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

Direct antioxidants like vitamin A, vitamin C, and vitamin E have been shown to block the exercise stimulus that leads to strength gains.

"So, all the all the ones that have been shown to block exercise um uh were that you know, the stimulus that makes you get stronger are like vitamin E, vitamin A, vitamin C, you know, the direct antioxidants." (said at 0:37:20)

While high-dose antioxidant supplementation (particularly vitamins C and E) has been shown in some studies to dampen acute redox-sensitive intracellular signaling pathways and selectively attenuate certain muscular hypertrophy metrics, meta-analyses and randomized controlled trials show that they do not consistently block or attenuate gains in muscle strength. A 2020 systematic review and meta-analysis of randomized controlled trials (PMID 31851538) found no significant negative effect of vitamin C and/or E supplementation on muscle strength or lean mass gains following resistance training. In individual trials, such as Bjørnsen et al. (PMID 26129928), maximal strength (1RM) improved significantly and similarly in both antioxidant and placebo groups despite minor differences in lean mass gains. Furthermore, evidence specifically demonstrating that vitamin A blocks strength adaptations is lacking.

0:45:00supportedvery lowStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

Pure sulforaphane induces cell death and apoptosis in cell cultures at concentrations of approximately 10 micromolar.

"there's some papers out there showing sulforaphane has some um apoptosis induction, you know, at like 10 micromol, you know... if you order sulforaphane from Sigma where it's 100% sulforaphane, it does start showing cell death at 10 micromol." (said at 0:45:00)

In vitro studies evaluating sulforaphane in cell cultures demonstrate that concentrations around 10 to 30 μM induce cell cycle arrest, inhibition of cell proliferation, reactive oxygen species generation, and apoptotic cell death across various cell lines. Because this evidence is derived exclusively from in vitro cell culture models, certainty for broader biological/in vivo implications is rated very low.

0:47:48overstatedlowStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

Sulforaphane exerts protective antimicrobial effects against Helicobacter pylori and small intestinal bacterial overgrowth (SIBO).

"it's actually protective for bacteria in your stomach like H H. pylori. It's protective of SIBO. Um if you get high doses released right into your um small intestines, it would be protective." (said at 0:47:48)

The speaker overstates the evidence by asserting that sulforaphane is protective against small intestinal bacterial overgrowth (SIBO) and that high doses released into the small intestine are protective, while claiming antimicrobial protection against Helicobacter pylori. For Helicobacter pylori, in vitro and preclinical studies show direct antibacterial activity, and clinical trials demonstrate that sulforaphane-rich broccoli sprout consumption reduces H. pylori colonization markers and attenuates gastric inflammation (PMID 19349290, PMID 39741515). However, human clinical trials show that sulforaphane does not reliably eradicate H. pylori when given alone (PMID 25287166) or improve eradication rates when added to standard clarithromycin-based triple therapy (PMID 31830776). For SIBO, there is no published clinical or preclinical evidence evaluating sulforaphane as a treatment or protective agent against SIBO. A systematic review of sulforaphane's antibacterial effects notes protection against aspirin-induced small intestinal damage in preclinical models, but does not identify evidence for SIBO (PMID 40553560). No published record matching sulforaphane for SIBO was located.

0:47:48overstatedmoderateStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

The majority of the conversion of glucoraphanin to sulforaphane is performed by gut bacteria in the colon.

"the precursor, majority of the conversion happens by bacteria in your colon" (said at 0:47:48)

The claim that the majority of glucoraphanin conversion to sulforaphane occurs via gut bacteria in the colon is overstated. In fresh cruciferous vegetables, the plant enzyme myrosinase rapidly converts glucoraphanin to sulforaphane upon chewing and upper gastrointestinal digestion, providing approximately 3- to 10-fold higher bioavailability than microbial conversion. Mammalian host cells lack myrosinase-like activity, so when plant myrosinase is inactivated by cooking, blanching, or in isolated glucoraphanin supplements, conversion does rely on colonic microbiota; however, microbial conversion is relatively inefficient (bioavailability typically around 10–20%), meaning most ingested glucoraphanin remains unconverted or is metabolized into other compounds.

0:48:20contradictedlowStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

Sulforaphane stimulates bile salt biosynthesis.

"And it also induces um bile salts. That's the master control over bile salt biosynthesis, which is uh another way you protect against SIBO is uh bile salt production." (said at 0:48:20)

Preclinical studies show that sulforaphane and Nrf2 activation suppress rather than stimulate bile acid biosynthesis. In rodent models, pharmacological and genetic activation of Nrf2 downregulates CYP7A1 (cholesterol 7alpha-hydroxylase, the rate-limiting enzyme in bile acid synthesis) and reduces hepatic and serum bile acid concentrations. Furthermore, the master transcriptional regulator of bile acid synthesis and homeostasis is the farnesoid X receptor (FXR), not sulforaphane or Nrf2.

0:54:41unverifiedvery lowStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

Sulforaphane activates NRF2 and inhibits NF-κB via covalent modification of reactive cysteine residues.

"the way it affects NF-κB is the same way it activates um NRF2. It's through a reactive cysteine modification, the covalent change that happens." (said at 0:54:41)

No published record matching the claim that sulforaphane activates NRF2 and inhibits NF-κB through covalent modification of reactive cysteine residues was located; this does not prove the claim false.

0:56:25overstatedvery lowStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

Sulforaphane directly conjugates and inhibits STAT3 dimerization.

"I was going to start talking about STAT3. That's a new thing that that I found out it directly conjugates and and inhibits STAT3, which is in the center of inflammation in in tons of ways. And I was looking for, you know, a supplement to try and um work on, you know, the dimerization of STAT3. And it turns out sulforaphane is the best at that." (said at 0:56:25)

Preclinical cell culture studies show that sulforaphane can suppress STAT3 activation and phosphorylation (typically secondary to upstream kinases such as JAK2/Src, ROS modulation, or interactions with regulatory partners like PKM2). However, published literature does not demonstrate that sulforaphane directly conjugates to STAT3 to block its dimerization, nor is there comparative clinical evidence establishing sulforaphane as the 'best' supplement for targeting STAT3 dimerization. All existing evidence for sulforaphane's effects on STAT3 signaling is limited to preliminary in vitro and animal models.

1:07:40supportedvery lowStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

Sulforaphane activates the lysosomal receptor mucolipin 1 (TRPML1) through a redox-sensitive cysteine, releasing calcium and triggering lysosomal exocytosis via a synaptotagmin complex and LAMP-2.

"it's through a receptor called mucolipin 1. And so it has a redox sensitive cysteine that's just the same as what I was talking about earlier about on Keap1 and on IKKβ for NF-κB pathway. So this is in actually in the lysosome membrane and when you activate that you release calcium from the uh lysosome and it initiates a signaling cascade where um the same the same pathway where you get um neurotransmitters dumped in into uh the synaptic cleft in your brain. Um it's for neurotransmission. It's a synaptotagmin complex and LAMP-2. It fuses with the cell surface and actually um releases the lysosome right into the extracellular space." (said at 1:07:40)

Preclinical in vitro research demonstrates that sulforaphane (SFN) acts on the lysosomal cation channel mucolipin 1 (MCOLN1/TRPML1) through redox-sensitive mechanisms, promoting lysosomal calcium (Ca2+) release. This calcium signaling engages the machinery involved in lysosomal exocytosis and trafficking (including synaptotagmin complexes and lysosomal-associated membrane proteins) and triggers downstream pathways such as TFEB activation. Because this mechanism has only been demonstrated in cell culture and animal models, certainty is graded as very low.

1:09:30supportedhighStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

TFEB is the master transcription factor that regulates lysosome biogenesis.

"there's a master transcription factor that regulates lysosome production. It's called TFEB" (said at 1:09:30)

Published cell biology research establishes transcription factor EB (TFEB) as the master transcription factor coordinating lysosomal biogenesis and autophagy. TFEB binds Coordinated Lysosomal Expression and Regulation (CLEAR) motifs in promoters across the lysosomal gene network, driving lysosomal biogenesis, acidification, and cellular clearance pathways.

1:09:40supportedvery lowStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

Resveratrol induces genes regulated by TFEB to enhance lysosomal system capacity.

"resveratrol is very good at inducing this whole set of genes that are are made to make your lysosomal system a better conveyor belt." (said at 1:09:40)

Preclinical in vitro and animal studies support that resveratrol promotes the activation and nuclear translocation of transcription factor EB (TFEB)—a master transcriptional regulator of the autophagy-lysosome pathway (the CLEAR gene network)—thereby upregulating genes involved in lysosomal biogenesis, autophagosome formation, and lysosomal degradation capacity. However, evidence is currently limited to cellular and animal models, and clinical evidence in humans remains unestablished.

1:14:05needs contextlowStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

Glucuronidated curcumin is completely biologically inactive.

"everybody's competing for the amount of um glucuronidated curcumin because it's completely inactive." (said at 1:14:05)

In direct cellular and molecular assays, glucuronidated curcumin is widely documented to lack the primary antiproliferative, anti-inflammatory, and signaling-inhibition activities seen with free (aglycone) curcumin. However, stating that it is 'completely inactive' requires context: while intrinsically inactive or markedly attenuated at target cellular receptors, curcumin glucuronide serves in vivo as a transport form or prodrug that can undergo deglucuronidation by tissue beta-glucuronidases (e.g., in bone marrow, inflamed sites, or tumor microenvironments) to regenerate active free curcumin.

1:15:35contradictedmoderateStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

Black pepper used in curcumin formulations enhances bioavailability by aggravating and disrupting enterocytes, thereby increasing inflammation.

"HOST: They use black pepper and other things that just and they say, "Oh, we put black pepper in it so it'll absorb." That's just causing leaky gut. The black pepper is just aggravating the enterocytes, like you said. GUEST2: Yeah, and instead of decreasing your inflammation, it's increasing your inflammation." (said at 1:15:35)

The claim that black pepper (piperine) enhances curcumin bioavailability by aggravating or damaging enterocytes (causing 'leaky gut') and thereby increasing inflammation is contradicted by both pharmacokinetic and clinical trial evidence. Pharmacokinetic studies demonstrate that piperine enhances curcumin bioavailability primarily through the reversible inhibition of hepatic and intestinal glucuronidation and modulation of drug efflux transporters, without causing gut barrier disruption. Furthermore, a systematic review of randomized controlled trials examining curcumin combined with piperine found significant reductions in systemic inflammatory markers (such as CRP, hs-CRP, and IL-6) and oxidative stress across diverse clinical populations, rather than an increase in inflammation.

1:16:12unverifiedvery lowStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

Certain highly bioavailable commercial curcumin supplement formulations are composed of approximately 97% detergent (polysorbate 80) and only 3% curcumin.

"Yeah, and the one a lot of doctors say is the most bioavailable actually is 97% um detergent and 3% curcumin." (said at 1:16:12)

No published record matching the claim that certain highly bioavailable commercial curcumin supplement formulations contain approximately 97% polysorbate 80 detergent and 3% curcumin was located; this does not prove the claim false.

1:17:20unverifiedvery lowStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

Polysorbate 80 strips lipopolysaccharide (LPS) off the outer membrane of gram-negative bacteria such as Salmonella.

"if you take um uh one like salmonella and you want to get a really potent um immune reaction, you mix that with polysorbate 80 and it strips the strips the LPS off the surface and then you can use that as a stimulant" (said at 1:17:20)

No published record matching the claim that mixing Salmonella with polysorbate 80 strips lipopolysaccharide (LPS) from the bacterial surface to create a potent immune stimulant was located; this does not prove the claim false. While detergents and surfactants can interact with bacterial outer membranes, standard biochemical extraction of LPS typically uses methods such as hot phenol-water extraction or specific organic solvent protocols rather than simple mixing with polysorbate 80.

1:17:48supportedvery lowStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

EGCG (epigallocatechin gallate) is an effective inhibitor of LPS-induced inflammatory stimulation.

"if people are interested in in blocking some of that is uh EGCG is one of the best inhibitors of that" (said at 1:17:48)

Published in vitro and animal studies consistently demonstrate that epigallocatechin-3-gallate (EGCG) suppresses lipopolysaccharide (LPS)-induced inflammatory activation. In cell culture (such as macrophages and dendritic cells) and rodent endotoxemia models, EGCG inhibits Toll-like receptor 4 (TLR4) signaling, attenuates NF-κB and MAPK pathway activation, and substantially reduces LPS-stimulated production of inflammatory mediators including TNF-α, IL-1β, IL-6, and inducible nitric oxide synthase. Because the available evidence relies primarily on preclinical mechanistic models, the certainty of evidence for clinical translation is very low.

1:19:35unverifiedvery lowStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

Clinical studies show black cohosh acts on serotonin and dopamine pathways in the hypothalamus to aid in temperature regulation and mood.

"the black cohosh is uh clinical studies showing that it it um works on serotonin, dopamine in the hypothalamus. And so, those are sort of the the uh temperature regulation and mood um centers. So, it helps helps with that." (said at 1:19:35)

No published record matching the claim that clinical studies show black cohosh acts on serotonin and dopamine pathways in the hypothalamus to aid in temperature regulation and mood was located; this does not prove the claim false.

1:19:50supportedvery lowStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

Carnosic acid functions as a mild Nrf2 inducer, mild NF-κB inhibitor, and mild AMPK activator.

"carnosic acid is one of these molecules that I've been looking at for a long time because it can work synergistically with a lot of the ones that we already have now. So, it has very broad activity. It's a uh a mild NRF2 inducer, mild NF-κB inhibitor, and and mild AMPK kinase activator." (said at 1:19:50)

Preclinical studies (in vitro and animal models) support the characterization of carnosic acid—a major phenolic diterpene found in rosemary—as an agent that activates the Nrf2 antioxidant response pathway, inhibits NF-κB inflammatory signaling, and activates AMP-activated protein kinase (AMPK). Because available evidence is limited to cell culture and animal studies, overall certainty is very low.

1:20:23contradictedmoderateStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

Resveratrol acts as a selective agonist for estrogen receptor beta (ERβ).

"resveratrol is an estrogen receptor beta uh agonist uh selective agonist so that you know for the people that are worried about the alpha ER alpha issue, um a large number of the side effects from menopause are are because of the loss of estrogen receptor beta activation." (said at 1:20:23)

Pharmacological studies demonstrate that resveratrol is not a selective estrogen receptor beta (ERβ) agonist. In vitro receptor binding assays show that resveratrol binds both estrogen receptor alpha (ERα) and ERβ with comparable affinity (approximately 7,000-fold lower affinity than 17β-estradiol), unlike certain other phytoestrogens (such as genistein or S-equol) that exhibit preferential selectivity for ERβ. Resveratrol functions as a selective estrogen receptor modulator (SERM) with mixed agonist and antagonist properties across both ERα and ERβ depending on cell type, tissue context, and response elements, rather than acting as a subtype-selective ERβ agonist.

1:20:23overstatedlowStop the "Toxic" Estrogen Loop: The Secret to Safer HRT

A large number of the side effects and symptoms of menopause are caused by the loss of estrogen receptor beta (ERβ) activation.

"a large number of the side effects from menopause are are because of the loss of estrogen receptor beta activation." (said at 1:20:23)

While estrogen receptor beta (ERβ) is actively researched as a target for selective therapies to alleviate menopausal symptoms (such as hot flashes and memory dysfunction) without the cancer risks driven by estrogen receptor alpha (ERα) activation, claiming that a "large number of the side effects from menopause are because of the loss of estrogen receptor beta activation" overstates the evidence. Both ERα and ERβ mediate estrogenic signaling, and animal models indicate that activation of either receptor (or predominantly ERα in classical pathways) can regulate thermoregulation and other physiological symptoms. Selective ERβ agonists (e.g., MF101/Menerba, EGX358) are being developed for therapeutic symptom relief, but menopausal symptoms stem broadly from systemic loss of circulating 17β-estradiol acting across both ERα and ERβ, as well as non-genomic estrogen pathways.

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