What Is The Black Layer On Your Onions? Know If It Is Safe To Consume

Onions are often praised as a superfood that supports liver health due to their rich antioxidants and sulfur compounds. But that dark black streak or layer you sometimes spot inside an onion is a warning sign, not a harmless blemish. It may indicate fungal contamination that could harm your liver if consumed repeatedly.

Why onions turn black

The appearance of black or dark patches inside an onion usually signals a fungal infection, most commonly caused by Aspergillus niger. This fungus thrives in warm, humid environments and can invade onions during cultivation, transportation, or storage. Over time, the fungus produces mycotoxins, toxic compounds known to damage liver cells and impair detoxification processes in the body.

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Liver risks from contaminated onions

According to health experts, ingesting mycotoxin-contaminated foods may lead to liver stress, inflammation, and even chronic conditions like fatty liver disease if exposure continues over time. A report in the Journal of Diabetes and Metabolic Disorders highlights that while clean onions can support liver health, contaminated ones may have the opposite effect. Even though a single exposure might not be dangerous, repeated consumption could increase long-term health risks.

How to spot unsafe onions

Before cooking, always check for these warning signs:

-Black streaks or specks between layers

-Soft, wet, or mushy bulbs

-A sour or musty odor

-Unusual discoloration of the flesh

If you notice any of these, it’s best to discard the onion completely.

Safe onion habits for a healthy Liver

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Store onions in a cool, dry, and ventilated area, away from moisture. Remove any mildly affected outer layers only if the contamination hasn’t spread inside. To keep your liver protected, avoid using onions with any sign of mold or dark discoloration, it’s better to waste one onion than risk your health.