Eggplant.

Eggplant flesh carries chlorogenic acid and the peel carries the anthocyanin nasunin. Both bind non-heme iron in the gut lumen and drop its solubility, which lowers the fraction absorbed from a plant-source iron dose eaten in the same meal. The chelation itself is measured in laboratory assays, so read it as mechanistic rather than as a measured drop in iron status. Separating an iron supplement from a large polyphenol-rich vegetable meal by a couple of hours sidesteps the issue.

Ascorbate reduces ferric iron to the ferrous form and holds it in a soluble complex, which competes with the phenolic binding that eggplant and other polyphenol-rich vegetables exert. Adding a vitamin C source to the same meal partly offsets the inhibition. This is meal chemistry, not a claim about anyone's iron numbers.

Eggplant contributes flavonols and hydroxycinnamates to a mixed polyphenol intake, so a quercetin supplement taken alongside it adds to the same pool rather than doing something separate. Antioxidant readouts in test tubes are additive across such mixtures. Nobody has shown that the combination changes an outcome in people, and the amounts from a normal serving are small next to a supplement dose.

Eggplant is mostly water and cell wall material, including pectin and insoluble fibre. Eaten in quantity with a bulking fibre such as psyllium it adds to total stool bulk and to the fluid the gut needs to handle it. People who ramp both up quickly tend to report gas and fullness, so stepping the total up slowly is sensible.

Pectin is one of the main soluble polysaccharides in eggplant cell walls, so supplemental pectin and cooked eggplant feed the same fermentable substrate pool to colonic bacteria. The effect is additive on short-chain fatty acid production in fermentation models. Read that as substrate arithmetic rather than as a demonstrated clinical result.

Eggplant grown on selenium-rich soils takes up selenium and contributes to total dietary intake, which matters when a selenium supplement is stacked on top of an already high-selenium food supply. The survey measured selenium in crops and water, not in the people eating them, so this is exposure accounting rather than an effect. Selenium has a narrow window between adequate and excessive, which is what makes the accounting worth doing.

Glycine betaine applied to harvested eggplant changed the infrared signature of the peel during cold storage, consistent with less cold-induced membrane and cell wall damage. This is produce handling before the fruit reaches a plate, not anything that happens after either substance is swallowed. It is included because it is the only direct eggplant finding in the citable set and it explains why stored fruit quality varies.

Eggplant contains small amounts of the glycoalkaloids solasonine and solamargine, which inhibit acetylcholinesterase and butyrylcholinesterase in enzyme assays. Huperzine A is a deliberate cholinesterase inhibitor, so the theoretical direction of the pairing is additive. Dietary glycoalkaloid amounts from eggplant are low and no interaction has been documented in people, so this is a mechanistic flag and nothing more.