Health Tips

Many of us take vitamin C supplement during this COVID-19 pandemic, as it helps boosting our immune system, reducing the risk of getting COVID-19 infection.

But, is vitamin C the more the merrier?

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While vitamin C is an important nutrient for all of us, taking it excessively (the upper limit is 2000 mg) might cause undesirable side effects. 

Most common side effects of vitamin C

1. Digestive distress

Symptoms such as diarrhea and nausea may occur, if more than 2000 mg vitamin C is consumed. However it depends on individual, some may experience diarrhea at 1000 mg.

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2. Kidney stones

First of all, excess vitamin C is excreted in the form of oxalate, a bodily waste product. Oxalate exists naturally in many foods, fruits and vegetables. It exits the body via urine. However, it is likely to bind with minerals like calcium, therefore forming kidney stones, when oxalate levels are high.

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3. Iron overload a.k.a. Hemochromatosis

Consequences of iron overload include serious damages to the pancreas, liver, heart, thyroid and central nervous system. These damages are due to the overproduction of reactive oxygen species (ROS) in the presence of excess iron. Vitamin C is known to enhance iron absorption, therefore increases the risk of iron overload, especially when you are consuming iron supplement or have conditions that increase risk of iron accumulation in the body.

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How much is enough?

Generally in a day, the recommended amount for adult men is 90 mg, whereas for adult women, it is 75 mg. You may want to read more here.

But the normal amount of vitamin C supplement is 500 mg, where did the excess ‘mg’ go?

As mentioned, excess vitamin C will be excreted via urine. Vitamin C is a water soluble vitamin, that means it dissolves in water. It does not get absorbed into the body, instead, it is transported to the tissues through body fluids. (And yea, any extra gets excreted in urine)

Take only sufficient amount of vitamin C, as the more is not always the merrier!

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References:

1. Healthline: Does Too Much Vitamin C Cause Side Effects?

2. WebMD: Foods High in Oxalates

3. PubMed: Body Iron Metabolism and Pathophysiology of Iron Overload

Written by

Ms. Elaine Fung