Vitamin C 101

Vitamin C or ascorbic acid is a water-soluble vitamin. It is important in forming collagen. Collagen is an essential component of connective tissue, which plays a vital role in wound healing and gives structure to bones, cartilage, muscle, and blood vessels. It also helps maintain capillaries, bones, and teeth, and aids in the absorption of iron. Vitamin C is also an important physiological antioxidant and has been shown to regenerate other antioxidants within the body, including vitamin E. Ongoing research is examining whether vitamin C, by limiting the damaging effects of free radicals through its antioxidant activity, might help prevent or delay the development of certain cancers, cardiovascular disease, and other diseases in which oxidative stress plays a causal role. In addition to its biosynthetic and antioxidant functions, vitamin C plays an important role in immune function and improves the absorption of nonheme iron, the form of iron present in plant-based foods. Insufficient vitamin C intake causes scurvy, which is characterized by fatigue, widespread connective tissue weakness, and capillary fragility.

Vitamin C can be found ubiquitously in fresh fruits and leafy vegetables such as guava, mango, papaya, cabbage, mustard leaves, and spinach. Animal sources of vitamin C includes meat, fish, poultry, eggs, and dairy products. Based on Malaysia Dietary Food Guideline, it is advisable to consume 5 servings of fruits and vegetables per day, if this recommendation is followed, daily intake of ascorbic acid will be around 210mg to 280mg, depending types of food consumed. However, due to its instability, vitamin C is always fortified in other types of foods and drinks, this is due to its easily destroyed during food process. Hence, best consumed fresh from fruits and vegetables.

Apart from this, there are several things that affect how our bodies absorb vitamin C, like our gender and how different nutrients interact. Even though the absorption of vitamin C decreases when we take a lot of it at once (more than 1g), our bodies still absorb a good amount—around 70-90% of the typical daily intake (30-180 mg/day). Researchers studied how much vitamin C body can absorb and found out that a 200 mg dose of vitamin C our bodies can be completely absorbed at once, and they found that none of it was peed out by most people until the dose reached 100 mg. However, when people took a single dose of 500 mg or more, the amount absorbed decreased, and the excess vitamin C was excreted.


In general, based on Malaysia Recommended Nutrient Intake 2005, vitamin C should be around

RNI for children

1 – 3 years 30 mg/day

4 – 6 years 30 mg/day

 7 – 9 years 35 mg/day

RNI for adolescents

Boys 10 - 18 years 65 mg/day

Girls 10 - 18 years 65 mg/day

RNI for adults

Men 19 – 65 years 70 mg/day

Women 19 – 65 years 70 mg/day

RNI for elderly

Men > 65 years 70 mg/day

Women > 65 years 70 mg/day

RNI for

Pregnancy 80 mg/day

Lactation 95 mg/day


Common side effects of consuming more than upper tolerable intake level of vitamin C include,

  • Heartburn
  • Upset stomach
  • Nausea
  • Diarrhea

To sum it up, it's generally best to get your vitamin C from fresh fruits and vegetables. If you can't get enough through your diet, you can consider taking supplements. Taking up to 1000mg of vitamin C per day is usually safe, but it's important not to overdo it as excessive amounts could be harmful. Aim for an optimal intake of about 100mg to 200mg of vitamin C each day.



  1. Harvard T.H Chan. Nutrition Source.

  2. National Institute of Health (NIH). Vitamin C.

  3. National Health Service (NHS) U.K.

  4. Ministry of Health Malaysia (MOH). Nutrition Department. Recommended Nutrient Intake (RNI).