Vitamin C is a water-soluble vitamin your body needs every day to make collagen, protect cells, heal wounds and absorb iron. Malaysian adults need 70 mg a day, according to the Ministry of Health's Recommended Nutrient Intakes (RNI 2017), an amount most people can get from fruit and vegetables: 100 g of guava, papaya or kai-lan covers it. Many supplements contain 500 mg or 1000 mg, far more than this. Research shows the body absorbs vitamin C less efficiently above about 500 mg at a time, and that more than 1,000 mg a day can cause stomach upset and may raise the risk of kidney stones. This guide explains the proven benefits, how much you really need, whether 1000 mg is too much, and how to choose a supplement if you need one.
What does vitamin C do?
Vitamin C (ascorbic acid) has several important jobs in the body. According to the NHS and Malaysia's RNI, it:
- helps protect cells and keep them healthy, acting as an antioxidant;
- is needed to make collagen, the protein that gives structure to skin, blood vessels, bones, cartilage and muscle;
- helps with wound healing;
- helps the body absorb iron from plant foods (non-haem iron). Malaysia's RNI describes vitamin C as the most potent enhancer of non-haem iron absorption.
The body cannot make or store large amounts of vitamin C, so you need some every day. A severe lack causes scurvy, with symptoms such as swollen, inflamed gums, loose teeth, dry itchy skin and hair loss. Scurvy is rare in Malaysia, and the RNI notes that average adult intake in the 2014 Malaysian Adults Nutrition Survey was about 75 mg a day, just above the recommended level. Some groups, however, eat little fruit and vegetables and fall short.
How much vitamin C do you need?
The upper limits in the RNI are taken from the US Institute of Medicine. Malaysia's 70 mg includes an extra 25 mg on top of the WHO/FAO figure, to help iron absorption in a region where anaemia is still common. Smokers lose more vitamin C than non-smokers, and the RNI notes that heavy smokers need more.
For comparison, the UK NHS recommends 40 mg a day for adults. Research from the US National Institutes of Health found that blood levels rise steeply between 30 and 100 mg a day and are close to their plateau at about 200 mg a day, which is still easy to reach with a diet rich in fruit and vegetables.
Best Malaysian food sources
These local fruits and vegetables are listed in Malaysia's RNI 2017 as good sources of vitamin C:
A few tips to get the most from food:
- Eat some fruit raw. The RNI notes that prolonged heating, oxygen and light destroy vitamin C, so vegetables lose some of it when cooked for a long time.
- Pair it with iron-rich meals. Having guava, papaya or a squeeze of lime with dhal, tempeh, kangkung or other plant foods helps you absorb their iron. If you have low iron, see our guide to kurang darah (anaemia).
- Do not rely on orange-flavoured drinks. Fresh fruit also gives you fibre and other nutrients without added sugar.
Is 1000 mg of vitamin C too much?
Vitamin C 1000 mg tablets are popular, but more is not always better:
- Absorption drops at high doses. Malaysia's RNI states that 70 to 90% of vitamin C is absorbed at moderate intakes of 30 to 180 mg a day, but absorption falls below 50% above 1000 mg a day. In the NIH study, absorption was complete for a single 200 mg dose but declined at single doses of 500 mg and higher, and the extra was passed out in urine.
- Stomach side effects. The NHS says that more than 1,000 mg a day can cause stomach pain, diarrhoea and wind, and that less than 1,000 mg a day from supplements is unlikely to cause harm.
- Kidney stones. High intakes raise oxalate in the urine. In a study of more than 23,000 Swedish men followed for 11 years, those who took vitamin C supplements (typically 1000 mg tablets) had about twice the risk of kidney stones compared with non-users, and the risk rose with how often they took them. The findings may not apply to women or to vitamin C from food.
Bottom line: 1000 mg a day is below the 2,000 mg upper limit for healthy adults, but for most people it offers little extra over 500 mg or less. If you choose a supplement, a moderate dose taken consistently makes more sense than a very high one.
Does vitamin C prevent colds?
This is the most common reason people buy vitamin C, and the evidence is mixed. A Cochrane review of placebo-controlled trials (at least 200 mg a day) found that:
- taking vitamin C regularly did not reduce how often people in the general population caught colds;
- it shortened colds by about 8% in adults and 14% in children, and made them slightly less severe;
- it halved the risk of colds in people under heavy physical stress, such as marathon runners, skiers and soldiers in subarctic conditions;
- taking vitamin C only after a cold started showed no consistent benefit.
In short, vitamin C helps maintain normal immune function as part of a healthy diet, but it is not a cure for colds or flu.
Vitamin C for skin and collagen
Because vitamin C is needed to make collagen, getting enough supports healthy skin. Dry, itchy skin is one of the signs of a severe lack of vitamin C. Vitamin C is also an antioxidant, which is why it is often paired with glutathione in brightening routines; our guide to stacking glutathione with vitamin C explains what the research shows, and our collagen food guide covers the other nutrients your skin needs.
Keep expectations realistic: vitamin C supplements support normal skin health, but they are not a treatment for pigmentation, acne or skin disease. Sun protection remains the most important step for even skin tone.
How to choose a vitamin C supplement
You may benefit from a supplement if you rarely eat fruit and vegetables, smoke, or have been advised to improve your iron absorption. When choosing one:
- Check the dose. A product providing 500 mg or less a day is enough for most people; very high doses add cost and stomach side effects.
- Check the form. Common forms include plain ascorbic acid, buffered forms such as calcium ascorbate, and newer forms such as PureWay-C (vitamin C combined with lipid metabolites) and liposomal vitamin C. A small study in healthy volunteers found that a single 1000 mg dose of PureWay-C produced higher blood vitamin C levels than ascorbic acid, calcium ascorbate or Ester-C. In another small study, 4 g of liposomal vitamin C produced higher blood levels than ordinary oral vitamin C but lower levels than an intravenous drip. These studies were small, so the practical difference for everyday health is not yet clear.
- Check registration. Look for a product registered with Malaysia's National Pharmaceutical Regulatory Agency (NPRA); our guide to checking KKM registration and halal status shows how.
- Take it with food if plain ascorbic acid upsets your stomach.
Drann's Vitamin C 500 mg uses PureWay-C, with one capsule a day providing 500 mg of vitamin C to support collagen formation, normal immune function and antioxidant protection as part of a balanced diet.
Who should be careful?
Vitamin C from food is safe for almost everyone. Speak to a doctor or pharmacist before taking high-dose supplements if you:
- have had kidney stones or have kidney disease, because high intakes raise oxalate in the urine;
- have a condition that causes iron overload, such as haemochromatosis, because vitamin C increases iron absorption;
- are pregnant or breastfeeding and considering doses well above the RNI.
Malaysia's RNI lists other possible effects of very high intakes, including stomach upset, increased uric acid excretion and erosion of tooth enamel.
Frequently asked questions (FAQ)
How much vitamin C do I need a day?
Malaysia's Recommended Nutrient Intakes (RNI 2017) set 70 mg a day for adults aged 19 and over, 80 mg during pregnancy and 95 mg while breastfeeding. Most people can get this from food: 100 g of guava provides about 152 mg.
Is 1000 mg of vitamin C too much?
For most healthy adults, 1000 mg a day is below the 2,000 mg upper limit listed in Malaysia's RNI, but it is more than the body can use. Absorption falls below 50% at intakes above 1000 mg a day, and the NHS notes that more than 1,000 mg a day can cause stomach pain, diarrhoea and wind. In a Swedish study, men who took vitamin C supplements had about twice the risk of kidney stones.
Is 500 mg or 1000 mg of vitamin C better?
For most people, 500 mg is enough. A US National Institutes of Health study found that blood levels are close to their plateau at about 200 mg a day, and that absorption declines at single doses of 500 mg and above, with the extra excreted in urine. Higher doses mainly add cost and the risk of stomach upset.
Does vitamin C prevent colds?
Not for most people. A Cochrane review found that taking vitamin C regularly did not reduce the number of colds in the general population, but it shortened colds by about 8% in adults. Taking it only after a cold starts showed no consistent benefit.
What are the benefits of vitamin C (kebaikan vitamin C)?
Vitamin C helps protect cells, is needed to make collagen for healthy skin, blood vessels, bones and cartilage, supports wound healing, and helps the body absorb iron from plant foods. A lack of vitamin C causes scurvy.
When is the best time to take vitamin C?
There is no single best time. Taking it with a meal can be gentler on the stomach, and taking it with an iron-rich meal or iron tablet can help iron absorption. Splitting larger amounts is unnecessary for most people, because 500 mg or less a day is enough.
Who should be careful with vitamin C supplements?
Speak to a doctor before taking high-dose vitamin C if you have had kidney stones, have kidney disease, or have a condition that causes iron overload, such as haemochromatosis. Vitamin C increases iron absorption and very high intakes raise oxalate in the urine.
Disclaimer
This article is for general information only and is not a substitute for advice, diagnosis or treatment from a doctor or pharmacist. Health supplements are not intended to diagnose, treat, cure or prevent any disease.
References
- Recommended Nutrient Intakes for Malaysia (RNI 2017), Chapter 12: Ascorbic Acid (Vitamin C) — National Coordinating Committee on Food and Nutrition, Ministry of Health Malaysia
- Vitamin C — NHS
- Levine M, et al. Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance. Proc Natl Acad Sci U S A. 1996;93(8):3704-3709.
- Hemilä H, Chalker E. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev. 2013;(1):CD000980.
- Thomas LDK, et al. Ascorbic acid supplements and kidney stone incidence among men: a prospective study. JAMA Intern Med. 2013;173(5):386-388.
- Pancorbo D, et al. Vitamin C-lipid metabolites: uptake and retention and effect on plasma C-reactive protein and oxidized LDL levels in healthy volunteers. Med Sci Monit. 2008;14(11):CR547-551.
- Davis JL, et al. Liposomal-encapsulated ascorbic acid: influence on vitamin C bioavailability and capacity to protect against ischemia-reperfusion injury. Nutr Metab Insights. 2016;9:25-30.
