Mark Hyman, MD · 2026-04-29 · Mark Hyman (host), William Li

Your Diet Is Secretly Destroying Your Mental Health (Science Explained)

32 research-tied claims examined: 7 overstated 2 context 18 supported 5 unverified

Needs context

Studies at the University of Massachusetts showed that pesticides sprayed on apples penetrate 20% deep into the skin of the apple.

"So again, it turns out studies at UMass, University of Massachusetts, have studied if you take regular pesticides, spray them on an apple like in a conventional farm, basically the pesticides will penetrate 20% deep into the skin of the apple." (said at 0:20:11)

A 2017 study conducted at the University of Massachusetts Amherst (Yang et al.) evaluated the penetration of pesticides into apples and the efficacy of various washing agents. The researchers found that after 24 hours of exposure, 20% of the applied amount of the systemic fungicide thiabendazole (and 4.4% of the non-systemic insecticide phosmet) had penetrated into the apples. The speaker slightly mischaracterizes the metric by describing the 20% figure as a depth percentage ('penetrate 20% deep into the skin') rather than the fraction of applied pesticide quantity that entered the fruit tissue.

context: Effectiveness of Commercial and Homemade Washing Agents in Removing Pesticide Residues on … (Journal of agricultural and food chemistry 2017) · cited 130x in the literature
"LC-MS/MS results showed, however, that 20% of applied thiabendazole and 4.4% of applied phosmet had penetrated into the apples following the 24 h exposure. Thiabendazole, a systemic pesticide, penetrated 4-fold deeper into the apple peel than did phosmet, a non-systemic pesticide, which led to more thiabendazole residues inside the apples, which could not be washed away using the NaHCO 3 washing solution." (abstract, results, passage verified)
pubmed full study (doi)

0:23:26 William Lineeds contextvery low

Feeding Lactobacillus reuteri as a probiotic doubled the rate of wound healing in a study by prompting VEGF gene expression and blood vessel growth.

"So we actually did a research study where we were actually looking at whether or not feeding Lactobacillus reuteri as a probiotic would speed up wound healing. And indeed it doubled the rate of wound healing, and it did it from the gut by increasing the gene expression, turning on the genetic machinery for a protein called vascular endothelial growth factor, VEGF, just to prompt new blood vessels to grow just to be able to heal the wound." (said at 0:23:26)

In a controlled animal study in mice (PMID 24205344), oral administration of Lactobacillus reuteri in drinking water accelerated skin wound closure to occur in half the time of control animals (effectively doubling the rate of wound healing). The mechanism was shown to involve vagus nerve signaling, neuropeptide oxytocin up-regulation, and enhanced immune regulatory T-cell responses. Evidence is currently limited to preclinical rodent models, meaning translation to clinical wound healing rates in humans remains unestablished.

supports: Microbial symbionts accelerate wound healing via the neuropeptide hormone oxytocin. (PloS one 2013) · cited 310x in the literature
"We discover that supplementing the gut microbiome with lactic acid microbes in drinking water accelerates the wound-healing process to occur in half the time required for matched control animals. Further, we find that Lactobacillus reuteri enhances wound-healing properties through up-regulation of the neuropeptide hormone oxytocin, a factor integral in social bonding and reproduction, by a vagus nerve-mediated pathway." (abstract, results, passage verified)
pubmed full study (doi)

Unverified means no publication matching the claim was located; it does not prove the claim false. Spotted an error? See the corrections policy - disputes from the people quoted are prioritized.