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Vitamin C Benefits: Exploring the Science

Vitamin C is also known as ascorbic acid. It is a water-soluble nutrient with many essential biological functions.

Most animals and plants can synthesize vitamin C. However, humans and other primates lack this ability due to a genetic mutation that occurred millions of years ago. Therefore, we must get it from food. But how much vitamin C do we need, and what happens if we do not get enough?

This article aims to answer these common questions and more. We will also explore the best-known vitamin C benefits and whether it is worth taking a supplement.

The Benefits of Vitamin C

The human body requires vitamin C to carry out many of its vital functions.

It is involved in protein synthesis, including collagen, which keeps our skin, bones, and connective tissues strong.

It is also necessary to produce carnitine, a chemical that helps us generate energy from fats.

The synthesis of certain neurotransmitters, including norepinephrine and serotonin, also requires vitamin C.


Furthermore, the nutrient has antioxidant activity, protecting our cells from damage. It also assists the regeneration of other antioxidant compounds, such as vitamin E.

It plays a role in immunity and iron absorption and acts as a cofactor for numerous enzymes. Therefore, vitamin C is indispensable for many of our biological functions.

Vitamin C deficiency causes a condition called scurvy. It leads to:

  • Fatigue
  • Weak connective tissues
  • Bruising
  • Slow healing
  • Gum inflammation
  • Hair and tooth loss

These symptoms may occur within a month of intakes lower than 10mg daily. Fortunately, scurvy is rare in the United States.

The recommended daily intake is 90mg for adult males and 75mg for adult females. The figure rises to 85 mg daily during pregnancy and 120mg daily during lactation. Smokers also require more vitamin C than non-smokers, an additional 35mg each day.

Most people get enough vitamin C from their diets, and it is present in many different fruits and vegetables. Find out more about the best sources in our related article: Vitamin C Foods: The Best Dietary Sources.

Now, let’s look at what vitamin C is good for and when to consider a supplement. 

May Lower the Risk of a Number of Chronic Diseases

Due to its antioxidant effects, many scientists have proposed a role for vitamin C in disease prevention.

Some have suggested that it could protect against cancer, cardiovascular disease, diabetes, neurodegenerative diseases, and more. However, research on the subject has produced mixed results.

Some observational studies suggest a link between vitamin C status and chronic disease prevalence.

For example, some observational studies suggest a link between vitamin C status and chronic disease prevalence. But clinical trials into whether supplementation can prevent or treat specific conditions have failed to produce consistent results.

It seems likely that eating a diet rich in fruit and vegetables does play a role in disease prevention. However, it is unclear whether this is due to vitamin C or other beneficial plant compounds. Further research is required to determine the specific effects of these nutrients and how they might work together. 

Does It Help Manage High Blood Pressure?

It appears that vitamin C could have beneficial effects on blood pressure.

A 2012 meta-analysis of 29 clinical trials found that the nutrient significantly reduced systolic and diastolic blood pressure. The median dose of vitamin C administered in the trials was 500mg daily.

The paper’s authors stated that vitamin C could alter blood vessel function and increase nitric oxide (NO) activity. NO is a chemical that our bodies produce naturally. It relaxes and widens the blood vessels, thus decreasing blood pressure.

However, despite these promising findings, the researchers concluded that additional long-term trials should take place before vitamin C supplementation can be recommended for hypertension. 

Can It Reduce the Risk of Heart Disease?

In addition to reducing blood pressure, research suggests vitamin C could decrease low-density lipoprotein (LDL) cholesterol oxidation. This process can lead to atherosclerosis, a significant risk factor for heart disease.

Vitamin C also appears to improve endothelial function, meaning it could help the blood vessels relax and contract efficiently.


These findings have led numerous scientists to believe the nutrient could prevent or slow the progression of heart disease. However, while some trials on vitamin C and heart disease have produced positive results, others have demonstrated no benefits.

Overall, it seems to be beneficial to consume more fruit and vegetables rather than vitamin C alone. That said, supplementation could prove helpful for some groups of people, especially those who are vitamin C deficient. 

Vitamin C and Iron Deficiency

There are two types of iron present in food; heme and non-heme iron. Heme iron is found in animal products and is easier for the body to absorb than non-heme iron from plant-based sources.

Vitamin C can aid the absorption of non-heme iron, which is why dieticians often recommend consuming the two together. It has also led researchers to investigate whether supplementation can assist the treatment of iron deficiency anemia.

In a 2020 study, 440 iron-deficiency anemia patients took 100mg of iron at eight-hourly intervals each day. Half of the subjects also took 200mg of vitamin C alongside the iron. Perhaps somewhat surprisingly, the two groups displayed similar levels of recovery after three months.

Therefore, the study’s authors concluded that there was no additional benefit to taking vitamin C with iron supplementation. However, the link between ascorbic acid and iron is well-known, and there is likely still some benefit to combining them in meals. 

Does It Boost Immunity?

One of vitamin C’s most publicized benefits is boosting immunity. Proponents have recommended taking high doses for the prevention of colds since the 1970s.

Indeed, vitamin C does appear to benefit both innate and adaptive immunity.

It helps to maintain the function of cells that line our mucous membranes and airways. These act as our first-line defense against invading pathogens, such as bacteria and viruses.

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It also plays a crucial role in infection control by promoting activity in many different types of white blood cells.

Research suggests that taking 200mg of vitamin C each day could reduce the duration and severity of the common cold. It could also reduce the incidence of colds in people exposed to stressful conditions such as extreme exercise or low temperatures.

However, the results of clinical trials are inconsistent and more research is required to determine under what circumstances supplementation is warranted. 

Vitamin C Side Effects

Vitamin C has a relatively low risk of toxicity, and it is possible to take reasonably high doses without any ill effects.

The recommended upper daily limit is 2000mg for most adults. Doses higher than 3000mg could lead to adverse reactions in some cases.

The most common high-dose vitamin C side effects are abdominal cramps, nausea, and diarrhea. It could also increase the risk of kidney stones in some individuals.

The most common high-dose vitamin C side effects are abdominal cramps, nausea, and diarrhea.

Furthermore, some studies have shown that high-dose supplements could increase the risk of cardiovascular death in postmenopausal women with diabetes.

Other people who should exercise caution include those with hemochromatosis or who take other medicines or supplements.

Hemochromatosis is a condition that affects iron storage, leading to dangerously high levels in the organs. Since vitamin C affects iron absorption, individuals with this condition should consult a physician before taking supplements.

It can also affect the absorption of copper, vitamin B12, and certain medications. Therefore, anyone with a pre-existing condition should seek medical advice before taking additional vitamin C.

Bottom Line on Vitamin C Benefits

Vitamin C’s primary benefits include supporting protein synthesis, iron absorption, and immunity. It also has antioxidant properties, leading some individuals to believe it could prevent or delay the onset of chronic disease.

Further study is necessary before we fully understand how the nutrient influences specific conditions and when vitamin C supplements might be beneficial. What we know is that it has many vital functions, and it is essential to consume enough each day.

Most people can get ample vitamin C from their diets, and deficiencies are rare. Therefore, anyone considering long-term supplementation should seek professional guidance to ensure it is suitable for them.

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