In fact, "drinking lemon water will turn black" is mainly because lemons contain photosensitive substances such as furanocoumarin, psoralen, and limonene. People with special constitutions ingest these photosensitizing substances, and after sufficient ultraviolet radiation, they will have photosensitivity reactions, which will indeed cause skin allergies, inflammation, pigmentation, and other problems.
Three necessary conditions for a photosensitivity reaction to occur:
1. Physical specificity;
2. Sufficient dose of sunlight;
3. Sufficient dose of photosensitizing substances.
If these conditions are not met, the photosensitivity reaction will not occur.
Half a lemon a day, the intake of coumarin is only 28.25μg, which is 0.02825mg. To achieve photosensitivity, you need to eat at least 353 lemons.
Therefore, drinking lemon water often can also whiten and nourish the skin, inhibit melanin deposition, and promote body metabolism.