HoldsUp

Pierre Capel

Utrecht University

Pierre Capel is a professor emeritus of experimental immunology at Utrecht University in the Netherlands. His academic research has covered topics ranging from genetic modification to cancer immunotherapy. Additionally, he has collaborated with Wim Hof to study the scientific mechanisms behind extreme cold exposure and physical feats.

21 claims checked on air: 2 context 3 contradicted 3 overstated 11 supported 2 unverified 6 flagged

What they said on air

0:05:00supportedlowDr. Pierre Capel on the Power of the Mind & the Science of W

Meditating 20 minutes a day alters the expression of hundreds of genes in the body.

"if you meditate 20 minutes a day, you will change the use of hundreds of genes in your body." (said at 0:05:00)

Published genomic studies investigating daily mind-body practices and meditation (such as the 20-minute daily relaxation response protocol) show significant changes in the expression of hundreds to thousands of genes. In clinical trials evaluating 8-week training protocols in healthy novices as well as long-term practitioners, whole-blood transcriptome profiling identified between 400 and over 1,500 differentially expressed genes. These changes were characterized primarily by the downregulation of pro-inflammatory pathways (such as NF-κB) and the upregulation of pathways involved in mitochondrial energy metabolism, oxidative phosphorylation, and telomere maintenance. However, the overall certainty is low due to small sample sizes in the genomic trials and reliance on peripheral blood cells.

0:07:06contradictedmoderateDr. Pierre Capel on the Power of the Mind & the Science of W

Complete lack of sleep causes death within seven days.

"Without sleep, seven days you die." (said at 0:07:06)

There is no evidence that complete lack of sleep causes death within seven days in humans. In experimental animal models of total sleep deprivation (such as Rechtschaffen's disc-over-water studies in rats), fatal outcomes or states requiring imminent sacrifice occurred after 11 to 32 days of continuous deprivation, not within seven days. Furthermore, documented human case observations of extended voluntary wakefulness (up to 11 days or 264 hours) have produced severe cognitive impairment, perceptual disturbances, and metabolic strain, but not death.

0:08:30needs contextlowDr. Pierre Capel on the Power of the Mind & the Science of W

During meditation, brain electrical activity starts altering within 30 seconds and cerebral blood flow changes within 5 to 10 minutes.

"if these people start to meditate, electrical activity and especially in this part of the brain changes within 30 seconds, starts to change. Blood flow is changing within 5 to 10 minutes." (said at 0:08:30)

The speaker's statement reflects standard neurophysiological principles of meditation research: electroencephalographic (EEG) activity responds rapidly (within seconds of task engagement or eyes closure) with shifts in alpha and theta rhythms, whereas regional cerebral blood flow (rCBF) and hemodynamic changes develop and stabilize over multi-minute epochs (typically measured across 5–20 minutes of sustained practice). Comprehensive reviews and neuroimaging studies confirm that meditation induces rapid EEG alterations followed by regional perfusion changes (particularly in prefrontal and anterior cingulate networks), though exact latencies vary considerably depending on the meditation style, practitioner expertise, and measurement modality.

0:11:40overstatedvery lowDr. Pierre Capel on the Power of the Mind & the Science of W

A gene expression study on white blood cells found that subjective loneliness altered at least 209 elementary biological functions across the immune system, metabolism, and hormones.

"In the case that somebody is lonely, uh in that article was at least 209 elementary functions in life were changed inside the immune system, inside metabolism, hormone levels, and whatever." (said at 0:11:40)

The landmark 2007 leukocyte gene expression study on subjective loneliness by Cole et al. identified 209 differentially expressed genes (transcripts) in circulating white blood cells between individuals experiencing high versus low chronic loneliness, rather than 209 distinct elementary biological functions. The altered gene profiles were primarily related to immune activation, pro-inflammatory signaling (NF-κB), transcription control, and suppression of type I interferon responses and mature B lymphocyte function. In addition, the original microarray study was a small cross-sectional investigation in 14 participants, representing preliminary correlational data rather than established causal effects across broad physiological functions.

0:12:45supportedvery lowDr. Pierre Capel on the Power of the Mind & the Science of W

In a breast cancer-susceptible rat strain, social isolation increased tumor incidence from 20% to 80%, enlarged tumor size by 84-fold, and caused metastasis.

"What you see is that the tumor incidence, which at a certain time is 20% in the population, goes to 80. The tumor size is 84 times bigger, and it starts to spread out in the body, metastasize." (said at 0:12:45)

The speaker accurately describes the findings of a preclinical lifespan study in tumor-prone Sprague-Dawley rats (Hermes et al., 2009). The researchers found that female rats subjected to chronic social isolation developed a mammary tumor burden (size/mass) up to 84 times greater than age-matched group-housed controls, alongside significantly higher rates of malignancy and invasive ductal carcinoma. Because these findings are derived from an animal model, the certainty of evidence for direct application to humans is very low.

0:15:05supportedhighDr. Pierre Capel on the Power of the Mind & the Science of W

The transcription factor NF-κB regulates about 200 genes involved in immune response and regulates vascular endothelial growth factor (VEGF).

"a very important protein in DNA regulation is called NF-κB, which is a factor which switches on and off about 200 genes very strongly involved in the immune response, but also responsible for this vascular growth factor." (said at 0:15:05)

Nuclear factor kappa B (NF-κB) is a well-characterized family of inducible transcription factors that regulates the expression of hundreds of target genes central to innate and adaptive immune responses, inflammation, and cell survival. Among its regulated targets is vascular endothelial growth factor (VEGF), an essential promoter of angiogenesis.

0:16:20unverifiedvery lowDr. Pierre Capel on the Power of the Mind & the Science of W

In animal experiments with standardized incisions, providing extra nesting material and comfort accelerated wound healing.

"And they did experiments with standardized incision which had to heal in animals. And depending if they give extra nest material and extra comfort by which he was feeling better, the wound healing is feeling more safe. The wound healing increased incredibly, was much faster." (said at 0:16:20)

No published record matching the claim that providing extra nesting material or comfort accelerated wound healing in animal experiments with standardized incisions was located; this does not prove the claim false.

0:18:06supportedlowDr. Pierre Capel on the Power of the Mind & the Science of W

A 12-year retrospective study of surgical ward patients found that patients with a window view of trees required less pain medication and had shorter hospital stays than those facing a brick/concrete wall.

"So then he started to analyze for 12 years all the documentation on surgery, the outcome of it, how long and how well did the patient perform. Guess what? The guys who were laying in the room looking at the tree have less pain medication, shorter hospitalization days, were doing better and whatever." (said at 0:18:06)

The speaker accurately describes the findings of Roger Ulrich's landmark 1984 study published in Science. Examining retrospective medical records of cholecystectomy patients from 1972 to 1981 (a 9-year span), the study compared 23 patients assigned to surgical recovery rooms with a window view of trees against 23 matched patients whose windows faced a brick wall. Patients with the natural view had significantly shorter postoperative hospital stays (8.70 days vs. 9.60 days), took fewer potent analgesic pain medications, and had fewer negative evaluative comments in their nursing notes. Because this evidence comes from a single retrospective matched cohort with a small sample size (n = 46 total patients), the overall certainty of evidence is low.

0:20:30supportedmoderateDr. Pierre Capel on the Power of the Mind & the Science of W

The cortisol receptor complex acts as a transcription factor regulating approximately 20% of the human genome.

"and the complex of cortisol and receptor goes into the nucleus and is called a transcription factor and regulates 20% of our genome. So one in five genes is under control of cortisol." (said at 0:20:30)

Cortisol (the primary endogenous glucocorticoid) binds to the intracellular glucocorticoid receptor (GR). Upon ligand binding, the glucocorticoid-receptor complex translocates into the nucleus where it functions as a ligand-activated transcription factor. Published reviews in human and mammalian endocrinology establish that the glucocorticoid receptor directly or indirectly influences the transcriptional rate of up to approximately 10% to 20% of expressed genes in the genome depending on tissue type and cellular context.

0:22:05overstatedmoderateDr. Pierre Capel on the Power of the Mind & the Science of W

In the early 1970s, using gamma interferon as a cancer therapy caused treated patients to develop psychosis.

"A very strong but sad example is that in the early '70s when gamma interferon was used as therapeutic agent for certain type of cancer, the only effect was that all these people who were treated ended up psychotic in the psychiatry ward because gamma interferon influences the immune system, but also influences the central nervous system." (said at 0:22:05)

While interferon therapies are well-documented to cross into or influence the central nervous system and cause neuropsychiatric adverse effects—such as depression (affecting approximately 20–50% of patients), anxiety, confusional states, and, in rarer instances, manic or psychotic symptoms—the claim that trials caused 'all' treated patients to become psychotic and end up in psychiatric wards is a substantial overstatement. Furthermore, psychiatric complications occur across interferon formulations (primarily interferon-alpha) rather than being the universal or sole outcome of early gamma interferon administration.

0:26:54supportedmoderateDr. Pierre Capel on the Power of the Mind & the Science of W

Meditation directly lowers circulating levels of the pro-inflammatory cytokine IL-6.

"you can measure this pro-inflammatory cytokines, IL-6 and whatever, and you directly influence IL-6 by meditation. It goes down." (said at 0:26:54)

Multiple meta-analyses of randomized controlled trials (RCTs) confirm that mindfulness-based interventions and meditation practices lead to statistically significant reductions in circulating levels of the pro-inflammatory cytokine interleukin-6 (IL-6), alongside other inflammatory markers such as C-reactive protein (CRP) and TNF-alpha.

0:30:20overstatedlowDr. Pierre Capel on the Power of the Mind & the Science of W

After 7 weeks of regular meditation, brain activity shifts from a balanced 50/50 state toward greater left prefrontal cortex activity.

"Normally it's a 50/50 activity left-right, but with meditation it shifts a little bit to the left, and the left part is more the harmonious, well-being, feeling okay instead of the troublesome on the right. And this shift, and you make new neuronal, neuronal connections, new nerve cells are being made, gives you a really constant feeling of emotional stability. And you can measure the number of brain activities at different levels after 7 weeks of meditation, and you see a fantastic change to the positive." (said at 0:30:20)

The claim refers to seminal research on mindfulness-based stress reduction (notably Davidson et al., 2003), which evaluated an 8-week (rather than 7-week) meditation training program in 25 healthy employees compared to 16 wait-list controls. That randomized trial found a statistically significant shift toward greater left-sided anterior activation on electroencephalography (EEG), a pattern linked to positive affect and approach-oriented emotion regulation. However, framing baseline brain activity as a literal '50/50' split is a physiological oversimplification, as baseline frontal asymmetry varies widely across individuals as a trait marker. Furthermore, asserting that this practice generates 'new nerve cells' (adult neurogenesis) in the prefrontal cortex is not supported by human neuroimaging or cellular evidence, which primarily demonstrates functional changes and structural plastic alterations rather than cortical neurogenesis.

0:43:00supportedhighDr. Pierre Capel on the Power of the Mind & the Science of W

Normal physiological baseline human blood pH is approximately 7.4.

"In the normal situation, the acid-alkaline balance, which is called pH, the strict balance is pH 7, and our body is 7.4. That is our regular situation." (said at 0:43:00)

Normal baseline arterial blood pH in humans is tightly maintained around 7.40 (typically within a physiological reference range of 7.35 to 7.45).

0:43:38supportedmoderateDr. Pierre Capel on the Power of the Mind & the Science of W

Wim Hof's specialized breathing technique expels carbon dioxide and elevates blood pH up to 7.7 or 7.8.

"By this breathing technique and pumping out a lot of carbon dioxide and having periods in not breathing, heavy breathing, and well, he can tell people how to do, you change your pH. And now comes a little trick that in his training, that type of breathing raises the pH sometimes to 7.7, 7.8, and for biology that is a lot." (said at 0:43:38)

Controlled experimental research evaluating the Wim Hof method (which combines cyclic hyperventilation with breath retention) demonstrates that the breathing technique causes marked hypocapnia (elimination of carbon dioxide) resulting in acute respiratory alkalosis and profound temporary elevations in blood pH, reaching levels around 7.7. In randomized testing by Kox and colleagues, this intermittent respiratory alkalosis and hypoxia voluntarily triggered a major sympathetic surge, characterized by significant epinephrine release and modulation of innate immune responses.

0:48:28contradictedhighDr. Pierre Capel on the Power of the Mind & the Science of W

At a blood pH of 7.7, pain receptors dissociate into monomeric forms, preventing the trimerized active signaling state and eliminating pain and anxiety signaling in the spinal cord and amygdala.

"And at pH 7.7 the pain receptor is a monomer, so it's out, so no pain. But the same receptor is also in the amygdala giving fear and pain, but also in the spinal cord and all over your body. So all of the sudden you don't feel pain, don't feel anxiety" (said at 0:48:28)

The claim that pain receptors dissociate into inactive monomers at an alkaline blood pH of 7.7 to eliminate pain and anxiety contradicts structural and biophysical evidence on proton-sensitive receptors. Acid-sensing ion channels (ASICs), which mediate proton-activated signaling in nociceptive pathways and fear/anxiety circuits in the amygdala, assemble as stable, chalice-shaped trimers embedded in the membrane. Gating is mediated by proton binding to acidic residues and carboxyl-carboxylate pairs that drive conformational changes within the intact trimeric complex to open or close the pore, not by dissociation into monomers. Furthermore, severe systemic alkalosis (pH 7.7) is a life-threatening medical emergency and does not eliminate pain or anxiety signaling through receptor monomerization.

0:49:15unverifiedvery lowDr. Pierre Capel on the Power of the Mind & the Science of W

Wim Hof is able to sit in ice-cold water for roughly 1 hour and 58 minutes without a significant drop in core body temperature by activating brown fat thermogenesis.

"And Wim Hof is able to sit for 2 hours, or 1 hour and 58 minutes or something like that to be precise, in ice-cold water without a a significant change in body temperature. Why? Because this thermosensor is heating up and burning the brown fat." (said at 0:49:15)

No published record matching the claim that Wim Hof maintained his core body temperature during nearly two hours of ice-water immersion specifically through brown fat thermogenesis was located; this does not prove the claim false.

0:57:30supportedmoderateDr. Pierre Capel on the Power of the Mind & the Science of W

Capsaicin from red peppers binds to thermal receptors sensitive to temperatures around 40°C, triggering physiological mechanisms that reduce core body temperature.

"a compound with a beautiful name in uh the red pepper is binding to one of these family members which senses heat. Not the extreme heat, not 50, but so around 40° C or so around 100 Fahrenheit. What it's doing that the pepper stimulates this receptor. So the receptor thinks you are too hot... Capsaicin is that... specifically that is the the name. But uh the receptor senses, hey, it's hot. And is reducing your body temperature to neutralize the effect of the outside temperature. So you lower your body temperature by spicy food." (said at 0:57:30)

Capsaicin from chili peppers is a well-established agonist of the transient receptor potential vanilloid 1 (TRPV1) channel, a thermal receptor activated by warm to noxious temperatures (~42–43°C). Binding of capsaicin to TRPV1 activates sensory afferents that project to central thermoregulatory circuits, mimicking heat exposure and triggering physiological heat-loss responses (such as cutaneous vasodilation and sweating), which acutely reduces core body temperature.

0:58:50supportedhighDr. Pierre Capel on the Power of the Mind & the Science of W

Menthol and eucalyptus compounds bind to cold-sensing TRP receptors on the skin, causing local vasodilation and increased blood flow to generate heat after an initial cold sensation.

"The point is that compounds from these plants bind to the cold receptor. So as soon as you rub in your chest it feels cold because you sense cold like the pepper you feel hot but um that temperature receptor is not only making more energy and whatever but changing the blood flow. So the blood flow increases in this area where you put menthol or eucalyptus and you generate heat." (said at 0:58:50)

Menthol and related plant-derived compounds (such as eucalyptol) activate transient receptor potential melastatin 8 (TRPM8) cold receptors on sensory neurons and vascular tissue. In randomized human crossover studies, topical application induces a sensory cooling effect alongside localized cutaneous vasodilation and significantly increased skin blood flow mediated by sensory nerve activation, nitric oxide, and endothelium-derived hyperpolarizing factors.

1:03:30supportedmoderateDr. Pierre Capel on the Power of the Mind & the Science of W

Studies demonstrate that an optimistic versus pessimistic psychological attitude statistically correlates with differences in disease recovery, life expectancy, and disease-free days.

"And there are a lot of studies of people who are optimistic or pessimistic and that really makes a difference statistically in how they cope with diseases, life expectance, the number of days without disease. That is directly related to a positive or negative uh attitude to life." (said at 1:03:30)

Multiple systematic reviews and meta-analyses of prospective observational cohort studies support the claim that dispositional optimism and positive psychological attitudes statistically correlate with lower all-cause mortality, improved survival, and better disease outcomes. A 2019 meta-analysis of 15 cohort studies involving 229,391 participants found that high optimism was significantly associated with a lower risk of all-cause mortality (RR 0.86) and cardiovascular events (RR 0.65). Similarly, a 2023 meta-analysis in cancer patients demonstrated that positive psychological factors, including optimism, were associated with longer survival and lower overall mortality. In patients with established cardiovascular disease, positive psychological constructs have also been systematically linked to reduced rates of rehospitalization and mortality.

1:05:07needs contextvery lowDr. Pierre Capel on the Power of the Mind & the Science of W

Pubic and body hair in sexually mature humans evolved primarily to increase surface area for the dissemination of volatile scent molecules and secreted peptide signals for mate selection.

"So as soon as you become sexually active, you have to distribute your smell uh your little molecules as much as possible. So you need a big surface. So therefore in the areas where a lot of in these molecules are secreted uh you got a lot of hair to increase the surface" (said at 1:05:07)

The idea that pubic and axillary hair evolved to increase surface area for the dispersion of olfactory or pheromonal secretions (the 'scent organ' hypothesis) is a longstanding hypothesis in evolutionary biology and human anatomy. Apocrine glands are concentrated in these regions and become active during puberty alongside terminal hair growth. However, this remains an unproven evolutionary hypothesis among several competing, non-mutually exclusive theories—such as reduction of friction during bipedal locomotion or intercourse, visual signaling of sexual maturity, and thermal/mechanical protection. Furthermore, the role and existence of true human pheromones in mate selection remain contested.

1:06:15contradictedmoderateDr. Pierre Capel on the Power of the Mind & the Science of W

Human mate selection and attraction are influenced by olfactory perception of highly polymorphic Major Histocompatibility Complex (MHC/HLA) peptide fragments secreted in body fluids and sweat.

"these vital molecules which are different in each individual are being chopped up in little peptides and secreted by all type of body fluids which uh are in the armpits and between the legs and in all the sexual organs and sweat. There they are secreted. uh and as soon as you smell them you know how the immune system of the other person is and so therefore you come into the area that smell is an important thing for a genetic selection with whom you have to mate" (said at 1:06:15)

While early small studies such as Wedekind et al. (1995) suggested that humans prefer the scent of MHC-dissimilar individuals, subsequent research and comprehensive meta-analyses contradict the claim that MHC peptide olfaction reliably drives human mate selection. A 2020 meta-analysis synthesizing genomic mate selection, relationship satisfaction, and body odour preference studies found no statistically significant association between MHC dissimilarity and body odour preferences, nor any overall significant effect on actual human mate choice.

Fact-checked episodes

Publications

No PubMed publication profile has been built for this speaker yet.