HoldsUp

Mark Hyman, MD · 2025-06-04 · Mark Hyman (host), Jeff Bland

Eat This to Regulate Your Immune System and Fight Inflammation

45 research-tied claims examined: 9 contradicted 4 overstated 4 context 20 supported 8 unverified

4

Overstated

0:01:55Jeff Blandoverstatedlow

There are approximately 30,000 edible food species, yet humans derive 90% of their caloric intake from fewer than eight foods.

"there are 30,000 edible foods of which we constitute 90% of our calories from less than eight foods." (said at 0:01:55)

The figure of approximately 30,000 edible plant species worldwide is well-supported in agro-biodiversity literature. However, stating that 90% of global caloric intake comes from fewer than eight foods overstates the concentration of the human diet. Published literature indicates that while three major staple crops (rice, wheat, and maize) provide about 60% of plant-derived calories, approximately 30 plant species comprise the vast majority of human diets, with about 150 species cultivated for food.

0:38:41Jeff Blandoverstatedmoderate

A Nature Medicine study of Tanzanians showed that individuals eating a traditional African diet had lower inflammatory potential and lower gene activation in their immune cells compared to those consuming a Westernized diet.

"Just this week, as we're having this conversation, in a very well-respected journal, Nature Medicine, is published this incredible study from Tanzania. Several thousand Tanzanians were divided into two groups. One group were individuals that were eating the traditional African diet. The other group were people that had become westernized, eating the westernized diet." (said at 0:38:41)

A 2025 randomized controlled trial published in Nature Medicine investigated the immune and metabolic consequences of transitioning between traditional African heritage diets and Western-style diets in Northern Tanzania. The study found that switching from a heritage-style diet to a Western-style diet promoted a pro-inflammatory state, whereas switching to a heritage-style diet or consuming a traditional fermented beverage had largely anti-inflammatory effects. However, the study evaluated 77 healthy young men in a short-term dietary crossover trial, not a cohort of 'several thousand Tanzanians'.

  • supports: Immune and metabolic effects of African heritage diets versus Western diets in men: a rand… (Nature medicine 2025) · cited 53x in the literature
    "We conducted a randomized controlled trial in the Kilimanjaro region in Northern Tanzania to investigate the immune and metabolic effects of switching between Kilimanjaro heritage-style and Western-style diets for 2 weeks and consuming a traditional fermented banana beverage ('Mbege') for 1 week. Seventy-seven young and healthy volunteers assigned male at birth, some living in urban areas and some living in rural areas, were recruited in the trial... The switch from heritage-style to Western-style diet affected different metabolic pathways associated with noncommunicable diseases and promoted a pro-inflammatory state with impaired whole-blood cytokine responses to microbial stimulation. In contrast, the switch from Western-style to heritage-style diet or consuming the fermented beverage had a largely anti-inflammatory effect." (abstract, results, passage verified)
    pubmedfull study (doi)
0:41:42Jeff Blandoverstatedmoderate

The biological age of a person's immune system is the single best predictor of longevity and year of death.

"In fact, what has been found—this is the last 10 years—is if you were to only measure one thing that would determine the year of your death, it'd be the age of your immune system. That's the best data we have today to predict your longevity, is the age of your immune system." (said at 0:41:42)

While longitudinal research shows that metrics of immune system aging (such as the IMM-AGE score) predict all-cause mortality independently of chronological age and traditional risk factors, claiming it is the single best predictor or can determine the exact year of death is an overstatement. No biological marker or aging clock can pinpoint an individual's specific year of death, nor has immune age been established as definitively superior to all other clinical or biological predictors of longevity.

1:02:35Jeff Blandoverstatedlow

Clinical trials demonstrate that the anthocyanin delphinidin improves cognitive function and blood sugar levels.

"And there are clinical trials on delphinidin as a cognitive improver, as a substance that improves blood sugar." (said at 1:02:35)

The claim overstates the clinical evidence. While small clinical trials and acute crossover studies using delphinidin-rich maqui berry extract (such as Delphinol) have shown modest reductions in postprandial glucose and improvements in glycemic parameters in humans with prediabetes or impaired glucose tolerance, evidence for delphinidin improving cognitive function is limited to preclinical animal models (such as Alzheimer's and high-fat diet rodent models) and surrogate biomarkers (such as transient increases in circulating BDNF). There are no established human clinical trials demonstrating that delphinidin acts as a cognitive enhancer.

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.