What are the harms of taking vitamin C before bedtime at night?

VC usually refers to vitamin C. Taking vitamin C before bedtime may lead to various adverse effects such as gastrointestinal discomfort, reduced sleep quality, increased kidney burden, dental problems, and interference with nutrient absorption—especially when taken in excess. If persistent stomach pain, worsened insomnia, or other discomfort occurs after taking it, prompt medical attention is advised.

1. Gastrointestinal discomfort: Vitamin C is acidic. Since the stomach contains less food before bedtime, the acidic substance can easily irritate the gastric mucosa, causing symptoms such as stomach pain, acid reflux, and nausea. Individuals with pre-existing conditions like gastritis or gastric ulcers may experience more pronounced symptoms.

2. Impaired sleep quality: Some people may feel slightly stimulated or excited after taking vitamin C. Combined with frequent nighttime urination, this can disrupt the sleep cycle, leading to difficulty falling asleep, lighter sleep, or increased dreaming.

3. Increased kidney burden: Vitamin C is metabolized and excreted through the kidneys. When taken before bedtime, the body's metabolic rate slows down, which may delay excretion and cause vitamin C to accumulate in the kidneys. Over time, this increases the metabolic strain on the kidneys.

4. Dental problems: If effervescent or chewable vitamin C tablets are taken before bed without subsequent rinsing or tooth brushing, the residual acidic components can erode tooth enamel. Long-term exposure may lead to tooth sensitivity or cavities.

5. Interference with nutrient absorption: Taking vitamin C before bedtime may cause it to bind with minerals such as calcium and iron consumed at the same time, forming compounds that are difficult to absorb. This reduces the effectiveness of nutrient uptake and overall nutritional benefits.

It is recommended to take vitamin C after breakfast or lunch. Taking it with meals helps reduce gastrointestinal irritation. Avoid taking it within 1–2 hours before bedtime, and keep the daily dosage within the recommended range. Rinse your mouth promptly after taking vitamin C to maintain oral hygiene and protect dental health.