When to take Vitamin C | PlanYourVitamins.com

What is vitamin C good for?

Short answer: Vitamin C has potential benefits for antioxidants, the immune system, cardiovascular health, brain health, wound healing, collagen production, blood pressure and iron absorption.

Vitamin C is an essential nutrient that is involved in several fundamental aspects of our health, such as wound healing, tissue repair, skin health, collagen formation, blood pressure regulation, brain health and neurotransmitter production, as well as enhancing our immune system through its antioxidant properties.

It achieves this by assisting in the production and function of specialized immune cells, and protecting them from oxidative damage. Research shows that vitamin C supplementation can increase the level of antioxidants in your blood by a massive 30%.

While most mammals are able to synthesize or even recycle their own vitamin C, humans cannot do this due to a mutation in a particular gene, so we must obtain it from our diet alone. You are probably already well aware that the best sources of vitamin C are from citrus fruits, berries, cabbage, and other similar fruits and vegetables.

Incorporating fruit into your diet is a fantastic way of meeting your body's vitamin C requirements.

That said, achieving a decent daily intake of vitamin C with our modern lifestyles is easier said than done, so many people resort to vitamin C supplementation, either to ensure that the daily recommended amount is met, or otherwise to periodically reinforce and replenish their vitamin C levels during times of physical stress and illness.

Role in the immune system

In fact, research has demonstrated that vitamin C supplementation helps treat both mild and severe infections, including sepsis, COVID-19 and pneumonia.

There has been much discussion over the years regarding vitamin C's role in how our body deals with the flu or the common cold, and while studies show that vitamin C does not seem to possess preventative properties in this regard, it significantly reduces the overall duration of infection, especially when vitamin C supplementation begins within the first 24 hours of infection, giving your immune system the boost it needs early on in the battle before it becomes overwhelmed.

Furthermore, mucous membranes are one of the fundamental components of our immune system, providing protection in the respiratory tract, digestive tract, and many other parts of our body from pathogens, and vitamin C plays a key role in mucous production. Intake of vitamin C has been proven to elevate levels of mucous secretion, and also help loosen any existing mucous that could be obstructing pathways, as is the case in bronchitis for example.

Benefits for skin health

Vitamin C is also very popular within the context of skincare, which is due to a number of factors. Not only do vitamin C's antioxidant properties contribute to a reduction in skin inflammation and help protect the skin against damage from sun exposure, but vitamin C is also involved in wound healing and in the production of collagen, which is the most abundant protein in your body, and forms the structural building block of our skin, bones, tendons, and other connective tissues.

This means that healthy vitamin C intake is associated with healthy, flexible and hydrated skin.

Role in brain health

While the benefits of vitamin C for our immune system and skin are relatively well known, a lesser known but no less important benefit of vitamin C is its role in the healthy functioning of our brain. Specifically, vitamin C deficiency has been associated with impaired memory and cognitive ability, and it has been demonstrated that people who suffer from dementia have lower blood levels of vitamin C.

Conversely, high levels of vitamin C, achieved through either diet or supplementation, are linked with improved memory and cognitive ability, something that becomes increasingly important to preserve as we age.

Role in cardiovascular health

Vitamin C's benefits for regulating blood pressure are also of increasing interest. High blood pressure is a major driver of heart disease globally, and approximately one in three adults in the US currently has high blood pressure levels.

Research shows that vitamin C intake not only helps to prevent blood pressure from becoming too elevated, but also helps to reduce blood pressure levels in those that already have high blood pressure. It is thought to achieve this by causing the blood vessels to relax.

Vitamin C has several benefits for cardiovascular health, including its ability to help lower blood pressure through the relaxaion of blood vessels.

Role in iron absorption

The absorption of iron is directly affected by the presence of vitamin C, as it assists in converting iron that has low bioavailability, such as plant-based sources of iron, into a form of iron that is easier for the body to absorb. Even a relatively small dose of 100mg of vitamin C has been shown to increase iron absorption by up to 67%.

This makes it especially valuable for people who follow diets that are naturally poor in iron, such as vegetarian or vegan diets, as meat accounts for a large amount of the iron that we obtain naturally.

Excessive iron absorption

However, it is important to emphasize that vitamin C supplementation is appropriate for enhancing the absorption of iron that is found in food naturally.

Combining a vitamin C supplement with an iron supplement could result in a potentially excessive (and therefore dangerous) intake of iron, so it is recommended to take these supplements separately in order to avoid this, and instead combine iron supplements with something that is naturally rich in vitamin C, such as fresh orange juice, if at all necessary.

When should I take vitamin C?

Short answer: Vitamin C is best taken on an empty stomach, at least 2 hours since the last meal and at least 30 minutes before the next meal.

Vitamin C is a water-soluble vitamin, which means that you don't need to take vitamin C supplements with a meal in order for them to be absorbed, and it is thought taking vitamin C on an empty stomach could maximize its absorption.

That said, it's easy to forget that vitamin C is actually an acid, technically speaking (ascorbic acid, to be precise), so you may prefer to take it with a meal if you experience any gastrointestinal side effects due to its acidity. While this may slightly reduce its bioavailability compared to taking it on an empty stomach, being able to take your supplements without having to deal with stomach upset is definitely the priority!

What does vitamin C combine well with?

Short answer: Vitamin C has been shown to work well together with astaxanthin, beta-glucan, bromelain, collagen, fish oil, krill oil, L-arginine, L-carnitine, L-glutathione, L-lysine, L-proline, MSM, omega-3, pine bark extract, quercetin, resveratrol, selenium, vitamin E and zinc.

Vitamin C with zinc, for respiratory infection

While vitamin C's efficacy in treating the common cold and flu is well documented, this effect has been shown to be enhanced even further when vitamin C is combined with zinc. Studies show that this combination is able to significantly reduce the duration of infection.

Vitamin C with L-arginine, for cardiovascular health

On this topic, when it comes to COVID-19 specifically, two particular issues associated with infection are oxidative stress and endothelial dysfunction, the latter meaning a reduction in the function of the inner lining of our blood vessels, which is needless to say of vital importance to our well-being.

Studies found that a combination of vitamin C supplementation and L-arginine supplementation was able to both reduce oxidative stress and improve endothelial function significantly when compared to patients who took alternative yet similar combinations, making vitamin C and L-arginine a potent duo.

Vitamin C with collagen, for collagen synthesis

Vitamin C's is also able to promote collagen synthesis, so taking vitamin C together with collagen will ensure that you get the most out of your collagen supplement.

Vitamin C with L-carnitine, for stomach repair

If you have issues with your stomach lining, you may be interested in knowing that a combination of vitamin C and L-carnitine was found to help treat damage to the mucous that protects the stomach lining in animal studies, while the same supplements did not result in the same mucous healing effect when taken separately, proving the combination to show great potential.

L-carnitine has already been documented to achieve similar results when paired with zinc, for example.

Vitamin C with quercetin, for increased absorption

Vitamin C is also known to enhance the bioavailability of quercetin, which by itself is notoriously difficult for our bodies to absorb. For this same reason, you will often see quercetin paired with the enzyme bromelain, but vitamin C also serves this purpose, so you may want to combine quercetin with vitamin C in your schedule in order to get the most out of your quercetin.

Bromelain with vitamin C, for inflammation

On a related note, bromelain itself has also been shown to combine well with vitamin C, as both compounds exhibits potent anti-inflammatory and antioxidant effects.

Vitamin C with selenium, for increased absorption

Likewise, the absorption of selenium is directly dependent on the presence of vitamin C, so taking vitamin C is a great way to ensure that you are getting the most out of any selenium supplements you may be taking.

Vitamin C with MSM, for joint health

You will also often see MSM supplemented together with vitamin C for the same reason, as vitamin C improves the bioavailability of MSM, while both vitamin C and MSM also share a lot of the same benefits when it comes to promoting collagen production and reinforcing the immune system through their antioxidant properties.

Studies have been able to confirm that the combination of MSM and vitamin C is more effective and with more pronounced effects than when the supplements are taken separately.

Vitamin C with glutathione, for antioxidant activity

Combining vitamin C with glutathione is known to reduce oxidative stress and inflammation, which are main drivers of many health conditions and diseases. Glutathione and vitamin C have been shown to replenish and recycle one another, working in a synergistic manner.

Several studies have found that taking between 500mg and 1,000mg of vitamin C together with glutathione increases levels of red blood cells by a massive 18% and 47% respectively. That said, higher doses of vitamin C could actually reduce the effectiveness of glutathione, so it is recommended to combine the two supplements in moderation.

Vitamin C with astaxanthin, for antioxidant activity

Vitamin C's potent antioxidant properties have been shown to have an additive effect when combined with those of astaxanthin, a red-orange pigment that is found in certain aquatic animals such as salmon and lobster.

The combination of vitamin C and astaxanthin was shown to reduce oxidative stress markers and increase the function of white blood cells, which are an essential component of our immune system, with the antioxidant effects shown to be greater when vitamin C and astaxanthin were combined, than when they were taken separately.

Vitamin C with resveratrol & beta-glucan, for cancer prevention

Vitamin C's anticancer properties are also being studied, with one study in particular that combined vitamin C with resveratrol and beta-glucan finding that the combination of all three had a much greater anticancer effect, including in the promotion of cancer cell death and the reduction of cancer cell spread, than when the individual components were taken by themselves.

Vitamin C with vitamin E

Vitamin C also shows promise when combined with vitamin E, specifically by lowering the risk of developing diseases such as macular degeneration, cataracts, Alzheimer's disease, and ischemic heart disease, as well as several types of cancer.

Vitamin C with pine bark extract, for migraines

Research has found that vitamin C combines well with pine bark extract supplementation for dealing with migraines. Daily supplementation of vitamin C and pine bark extract over the course of three months was shown to reduce both the severity of migraines and the likelihood of developing a migraine.

Vitamin C with omega-3, for reducing inflammation

Omega-3 fatty acids, such as those found in fish oil and krill oil, are known to combine well with vitamin C, exhibiting potent antioxidant and anti-inflammatory properties when combined that enhance protection against inflammation and oxidative stress.

Vitamin C with L-lysine and L-proline, for cardiovascular health

The great Linus Pauling promoted an artery-cleaning protocol that involved taking large amounts of L-lysine, L-proline and vitamin C in order to clear arteries of atherosclerotic plaque buildup, the leading cause of heart disease worldwide.

Specifically, L-lysine has the ability to bind to the lipoproteins from which these plaques are formed, and helps to effectively "melt" them away, while the combination of all three supplements supports the formation of new collagen for the regeneration of artery walls once the plaque has been cleared.

In this context, Vitamin C also ensures that the artery walls are smooth and free of lesions, which is what lipoproteins usually adhere to, forming plaque in the first place. Linus proposed the idea that plaque formation is an evolutionary defense mechanism for artery repair, as we are one of the few animals that does not produce its own vitamin C. To put it into perspective, animals that do produce their own vitamin C do so in an equivalent to human dosage of around 10g per day.

Interestingly, only animals that do not produce their own vitamin C develop atherosclerosis, which certainly raises more questions than what it appears the cardiovascular academic establishment is willing to look into, considering that heart disease is the single leading cause of death for our species across the globe.

What should I avoid taking vitamin C with?

Short answer: Avoid taking vitamin C supplements at the same time as B-complex, copper, grape seed extract, iron, vitamin B12, blood thinners, chemotherapy drugs or estrogen.

Avoid with vitamin B12

Taking vitamin C supplements could potentially affect the available amount of vitamin B12 in your body, as well as your body's ability to absorb vitamin B12 from food, so it is recommended to take these two supplements separately, at least two hours apart, in order to avoid this.

Avoid with copper

Similarly, copper absorption is also affected by the presence of vitamin C, so be sure to take your copper supplement and vitamin C supplement separately also, at least two hours apart.

Avoid with grape seed extract

Although vitamin C is known for its ability to lower blood pressure, this can actually have a reversed effect when vitamin C is combined with grape seed extract.

It is recommended to avoid taking a combination of vitamin C and grape seed extract at the same time if your blood pressure is already high, and you may as well avoid taking this combination regardless of whether you take them separately or not, just to be on the safe side.

Avoid with iron

Also, as discussed above, vitamin C can enhance the amount of iron that your body absorbs. While this is considered a positive in terms of diet and nutrition, when it comes to supplementation, combining vitamin C supplements with iron supplements can lead to excess levels of iron in the body, and consequently increase the risk of iron toxicity.

So, if you are taking both in supplemental form, you should take them at least three hours apart.

Avoid with blood-thinning medication, chemo drugs or estrogen

Vitamin C is known to interact with certain medications, such as chemotherapy drugs, estrogen supplements and blood thinners.

It is advised that you check with your doctor or pharmacist before taking vitamin C supplements to ensure that there are no potential side effects from any such medication.

Who should avoid taking vitamin C supplements?

Short answer: People under the following conditions should check with a trusted doctor before taking vitamin C supplements: Iron overload, chronic kidney disease, kidney stones, cancer treatment.

People with iron overload

As mentioned above, vitamin C can significantly increase the amount of iron that the body is capable of absorbing. This means that anyone who is already suffering from an excessive intake of iron should avoid vitamin C supplementation altogether.

People with kidney problems

High doses of vitamin C can increase the formation of oxalates, a type of crystal that can in turn contribute towards the formation kidney stones if left unchecked.

This means that anyone that suffers from chronic kidney disease, or anyone who is susceptible to kidney stone formation, should consult with their trusted doctor first before taking any vitamin C supplementation, in order to ensure that there is no risk.

People undergoing cancer treatment

The same applies to anyone who is currently undergoing cancer treatment, due to the way in which vitamin C can potentially interact with certain cancer therapies and medications.

What are natural sources of vitamin C?

If you are interested in achieving your daily vitamin C intake through your diet, rich sources of vitamin C include:

Citrus fruits
Berries
Bell peppers
Chili peppers
Cabbage
Broccoli
Potatoes
Tomatoes
Cantaloupes
Kale
Parsley
Papayas

Vitamin C is predominantly found in citrus fruits, such as oranges, lemons and limes; and also kiwi fruit, mango, strawberries, blueberries and other types of berry. Certain vegetables, such as bell peppers, cabbage, potatoes, turnips, brussel sprouts, radishes, cauliflowers, broccoli and tomatoes are also rich in vitamin C.

One more thing regarding vitamin C

Prolonged vitamin C supplementation

If you have been taking high doses of vitamin C supplements for a prolonged period, you shouldn't cease supplementation suddenly, but instead taper off supplementation by gradually reducing the dose over the course of a few weeks, so that your body becomes gradually less dependent on vitamin C supplementation.

Vitamin C dosage for smokers

Also, the recommended dietary allowance for vitamin C is actually higher if you are a smoker. For example, the National Institutes of Health in the US advises anyone that smokes to increase their daily vitamin C intake by an additional 35mg.

Vitamin C data sources & further reading

Last updated by Asklepios on 30th January, 2025