Eating Fried Food at Night Hurts Your Kidneys

The body’s internal clock can change how we react to food. A new study shows that eating fried oil at the wrong time of day can damage kidneys. Mice that ate oxidised frying oil whenever they wanted had trouble turning certain harmful molecules, called epoxides, into safer ones, called diols. This switch is normally controlled by kidney enzymes that follow a daily rhythm. When the mice ate fried oil during their normal active period (the “day” for them), kidney damage was mild. But eating the same oil during their rest period (the “night”) caused serious kidney injury.

The culprit was a specific epoxide called epoxy stearic acid (EpSA). Consuming EpSA at night disrupted the daily pattern of the enzymes that normally break it down. As a result, markers of kidney inflammation and scarring—SMA and E‑cadherin—rose sharply. If the mice lacked the genes that make those enzymes (Ephx1 or Ephx2), the harmful effects of EpSA disappeared. This shows that the enzymes are key to protecting kidneys from late‑night fried food. Adding linoleic acid, a fatty acid that blocks the enzymes, helped mice survive late‑night fried oil without kidney damage. These findings suggest that eating fried foods at the wrong part of your day can push your kidneys toward disease, especially if you’re exposed to oxidised oil. Timing your meals and choosing healthier fats may keep your kidneys safe.

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