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Can High Doses of Vitamin C Cause Diarrhea? Exploring the Connection

Consuming foods rich in vitamin C does not cause health problems, but taking excessive vitamin C supplements can have adverse side effects. When taking large doses of vitamin C supplements, you may experience acute diarrhea; however, this usually goes away as you reduce the dosage. 

Anyone interested in maintaining a healthy lifestyle, including those who may be considering supplementation, should be aware of the link between high dosages of vitamin C and diarrhea. 

This article will examine the symptoms of excessive vitamin C intake, explain the science underlying the relationship, and offer advice on consuming vitamin C in moderation. 

Why do high doses of vitamin C cause diarrhea?

Water-soluble vitamin C, sometimes referred to as ascorbic acid, is essential for many physiological functions in the human body, such as collagen production, immunological response, and antioxidant defense. Although vitamin C is often available in fruits and vegetables, many take supplements to ensure sufficient intake.

Even though vitamin C is typically considered safe and healthful, taking too much of it might have some adverse effects, such as diarrhea. 

Using high-dose supplements can lead to excessive consumption of these nutrients, which can overburden the digestive system and cause gastrointestinal problems, including diarrhea.

The osmotic action of vitamin C in the intestines is the mechanism underlying diarrhea. Excess unabsorbed vitamin C draws water into the intestines through high dosages, increasing loose stools and bowel movements. The osmotic effect is more likely to happen when the body absorbs and uses more vitamin C than it can.

There are differences in vitamin C tolerance among individuals; some may be more prone to diarrhea than others. Age, general health, and gastrointestinal disorders before treatment can all impact the body's response to high doses of vitamin C. 

What are other symptoms of a high dose of vitamin C?

Close-up of some vitamin C capsules.

Overconsumption of vitamin C can lead to additional adverse effects, such as:

Iron overload

Vitamin C enhances iron absorption.

Plant-based diets contain non-heme iron, which it can bond to. Heme iron is the form of iron in animal products; it is absorbed by the body more easily than non-heme iron.

Your body absorbs non-heme iron considerably more readily when vitamin C binds to it. This plays a crucial role, particularly for people whose primary source of iron comes from plant-based diets.

A study found that taking 100 mg of vitamin C with a meal increased participants' iron absorption by 67%.

On the other hand, people with diseases like hemochromatosis, which raises the danger of iron buildup in the body, must use vitamin C supplements with caution.

In some instances, consuming too much vitamin C could result in iron overload, which can seriously harm your central nervous system, liver, pancreas, heart, and thyroid.

However, if you do not have a medical condition promoting iron absorption, the likelihood of iron overload is very low. Iron overload is also more likely to happen if you take too much iron in supplement form.

Development of kidney stones

Excess vitamin C is eliminated by your body as oxalate, a waste product. Usually, oxalate leaves your body through urine. Kidney stones may develop due to oxalate's ability to bind to minerals and form crystals in specific situations.

Excessive vitamin C consumption may raise the oxalate content of your urine, which may raise your risk of kidney stones. In one study, the amount of oxalate excreted by adults increased by 20% when they received a 1,000 mg vitamin C supplement twice daily for six days.

Increased urinary oxalate levels are connected to high vitamin C intake, which is also linked to kidney stone production, particularly if the daily dose exceeds 2,000 mg.

Patients who have consumed more than 2,000 mg of oral vitamin C supplements in a single day have also been known to experience renal failure. But this is very uncommon, particularly in otherwise healthy individuals.

Disruption of the balance of nutrients

Overconsumption of vitamin C can reduce the body's natural equilibrium of other vital vitamins and minerals. It might obstruct the use or absorption of specific nutrients, resulting in imbalances. 

Possible interactions between medications

An excess of vitamin C in the body can cause unanticipated adverse effects or interfere with the effectiveness of some drugs. Aluminum is present in certain medications, such as phosphate binders. 

It is possible to improve your absorption of aluminum by taking more than 2,000 mg in supplement form. However, this may be dangerous for those with kidney issues.

Taking too much vitamin C in supplement form can raise your estrogen levels if you're on hormone replacement treatment or an oral contraceptive. Consult your physician if you are receiving chemotherapy. 

This is because, when receiving chemotherapy, taking antioxidants like vitamin C may lessen the effects of the medication. Consult your doctor beforehand, as there are differing views regarding antioxidants and how they affect chemotherapy.

Additionally, supplemental vitamin C taken orally may lessen the effects of protease inhibitors. It may also lessen the effects of prescription drugs like niacin, Warfarin, Coumadin, or Jantoven on your body.

Emergence of conditional scurvy

Ascorbic acid, the active component of vitamin C, has been shown to cause conditional scurvy when taken in excess over an extended period of time. 

The theory behind this illness's mechanism of action is that long-term high ascorbic acid dosages prepare the patient's body for ascorbic acid to be cleared quickly, which causes scurvy. 

Ascorbic acid levels in the plasma stay within normal bounds. It's still debatable whether conditional scurvy exists. Fewer people have experienced flank pain as a side effect. There have also been reports of conditional scurvy.

Formation of bone spurs

According to the Arthritis Foundation, having very high amounts of vitamin C in the body raises the risk of painful bone spurs

Nonetheless, the Foundation also referenced a study that discovered a link between low vitamin C levels and an increased risk of rheumatoid arthritis, a severe inflammatory joint disease.

These results highlight the importance of taking the right vitamin C supplements—neither too little nor too much.

Reduction in the effectiveness of niacin-simvastatin

Research indicates that consuming vitamin C supplements could impair the capacity of the body to raise high-density lipoprotein (HDL) cholesterol in patients receiving niacin-simvastatin combo medication. 

This medication, used to treat high cholesterol, combines statin simvastatin (Zocor) with vitamin niacin.

Physicians refer to HDL cholesterol as "good" cholesterol because it reduces blood levels of harmful cholesterol.

If a person takes niacin-simvastatin and vitamin C pills, they should discuss with their physician how to increase their effectiveness. 

Physicians are unsure if vitamin C also impacts the functionality of other medications comparable to Zocor.

Development of dental problems

It is important to remember that there may not be an immediate connection between vitamin C and dental issues. However, excessive use of vitamin C can erode dental enamel, the layer that covers your teeth and provides protection. Your teeth are more vulnerable to harm and decay as a result.

Since vitamin C is naturally acidic, taking too much of it could erode the enamel on your teeth. This erosion can eventually result in cavities and heightened tooth sensitivity, among other dental issues.

A person's entire health is closely related to their dental health. While vitamin C is essential for many aspects of health, maintaining good dental hygiene requires finding the correct balance.

How do I flush out high doses of Vitamin C from my system?

Orange slices and vitamin C tablets in a wooden spoon on a black background.

If you are healthy, an overabundance of vitamin C cannot possibly be fatal. However, if you have any underlying medical conditions, taking too many vitamin C supplements may be harmful. 

Some over-the-counter medications may also be helpful if you're suffering from symptoms like headaches, cramps, or nausea.

If you are taking prescription medication or have a medical condition and you think you might be taking too much vitamin C, consult your physician. 

Additionally, get in touch with your doctor if the diseases worsen or if you're suffering from dangerous side effects, including breathing problems or kidney stones.

After evaluating the situation, your doctor can decide what steps to take to relieve your symptoms and stop them from worsening, like ordering tests and procedures or giving you medication.

If you're taking too many vitamin C supplements, stop taking them. However, reducing your daily consumption or quitting the supplement is the simplest and most effective strategy to deal with vitamin C overdose. 

This does not imply that you should give up on vitamin C-rich fruits and vegetables.

Lowering or removing vitamin C in supplement form should, in most circumstances, be sufficient to remove most or all overdose symptoms. Increasing your water intake should also aid in detoxification and overdose recovery.

However, keep an eye on how much water you drink. Drinking a lot of water too soon or in excess can drastically lower your salt levels, which can be fatal.

What is the function of Vitamin C in the body?

Here are some functions of vitamin C in the body: 

Lowers your chance of developing chronic illness

Strong antioxidants like vitamin C can bolster your body's defenses naturally. Molecules called antioxidants strengthen the immune system. They accomplish this by shielding cells from dangerous substances known as free radicals.

Free radicals have been linked to several chronic illnesses because they increase oxidative stress and contribute to it.  

Studies show that consuming excess vitamin C can lead to an increase in blood antioxidant levels by up to 30%. This aids in the body's defensive mechanisms' battle against inflammation.

Manages high blood pressure

According to a study, people with and without high blood pressure may benefit from vitamin C's ability to lower blood pressure. Taking a vitamin C supplement assists in lowering blood pressure by relaxing the blood capillaries that convey blood from the heart.

The review that involved 29 human trials found that vitamin C supplements lowered healthy adults' average systolic blood pressure by 3.8 mmHg. 

It also decreased blood pressure in adults with high blood pressure by an average of 1.7 mmHg in the diastolic and 4.9 mmHg in the systolic range.

Reduces your chance of developing heart disease

Heart disease is among the leading causes of death worldwide. Numerous factors, including high blood pressure, excessive triglycerides or LDL (bad) cholesterol, and low HDL (good) cholesterol levels, can contribute to heart disease.

Vit C may help reduce the risk of heart disease by lowering these risk factors. 

After analyzing nine different trials and studying 293,172 participants over a period of ten years, researchers have found that individuals who consume a minimum of 700 mg of vitamin C on a daily basis have a 25% lower risk of heart disease compared to those who don't take any supplement. 

Helps prevent iron deficiency

Iron is a vital mineral that the body uses for many different purposes. The body must produce red blood cells and carry oxygen throughout.

Supplementing with vitamin C can enhance the body's ability to absorb iron from food. Iron from plant-based sources, for example, is poorly absorbed; vitamin C helps to transform it into a form that is easier to absorb.

Those following a plant-based diet will find this especially helpful, as meat is a significant source of iron. Vitamin C alone can boost iron absorption by 67% in just 100 mg. 

Therefore, for individuals susceptible to iron shortages, vitamin C may help lower the occurrence of anemia.

Boosts immunity

Enhancing immunity is one of the primary reasons people take vitamin supplements because vitamin C is involved in many immune-related processes. 

First, two types of white blood cells that support the body's defense against infection—lymphocytes and phagocytes—are developed with the help of vitamin C.

Second, vitamin C shields these white blood cells from dangerous substances like free radicals and enhances their ability to perform their intended functions. Third, the skin's defensive mechanism depends heavily on vitamin C. 

It is actively delivered to the skin, where it can fortify the skin's defenses and function as an antioxidant. Research has also indicated that vitamin C supplementation may accelerate the healing of wounds.

You may also like: 4 Great Benefits of Vitamin C.

What are the signs and symptoms of vitamin C deficiency?

Orange background with pills and glasses of orange juice.

Although it may take months for severe vitamin C deficiency symptoms to appear, there are some subtle warning signs to be aware of. 

Here are some of the most typical indications that you may be deficient in vitamin C:

Uneven, bumpy skin

Collagen is a protein in large quantities in connective tissues such as skin, hair, joints, bones, and blood vessels. Collagen formation requires the presence of vitamin C. Low vitamin C levels can cause the skin condition keratosis pilaris.

This disorder results in the development of bumpy skin due to an accumulation of keratin protein inside the pores. 

When there is a vitamin C deficiency, keratosis pilaris usually develops three to five months after insufficient intake and goes away with supplements.

Nevertheless, keratosis pilaris has numerous other possible causes. Therefore, a deficiency cannot be diagnosed based solely on the condition's appearance.

Corkscrew-shaped body hair

Inadequate levels of vitamin C can also lead to structural flaws in the protein structure of hair, which can result in bent or coiled hair as it grows. When you take enough vitamin C, hair irregularities often disappear after a month of treatment.

Fingernails in the shape of a spoon with red dots or lines

Concave nails, often spoon-shaped, are often thin and brittle. They have been connected to vitamin C insufficiency but are more frequently tied to iron deficiency anemia.

A vitamin C deficit can also cause splinter hemorrhage, characterized by red patches or vertical lines in the nail bed that break readily due to weakening blood vessels.

Easy bruising

Blood seeps into the surrounding areas as blood vessels beneath the skin burst, resulting in bruises. Easy bruising is frequently indicative of a vitamin C deficiency because weak blood vessels are caused by low collagen synthesis.

Bruises caused by deficiencies can be little purple dots under the skin or cover vast portions of the body. Easy bruising should be investigated further to determine vitamin C levels because it is often one of the first noticeable signs of a shortage.

Iron deficiency anemia that persists

Iron deficiency anemia and vitamin C deficiencies often coexist. Paleness, exhaustion, and spoon-shaped fingernails are symptoms of iron deficiency anemia.

Because low vitamin C levels impair iron metabolism and reduce the amount of iron absorbed from plant-based diets, they may be linked to iron deficiency anemia. 

Anemia may result from heavy bleeding, which is another risk factor for vitamin C deficiency.

Frail bones

Lack of vitamin C can also affect bone health. Low consumption has actually been connected to a higher risk of osteoporosis and fractures. A vitamin C shortage can accelerate the rate of bone loss because research has shown that this vitamin is essential for producing new bone.

Since children's skeletons are still growing and developing, vitamin C deficiencies may negatively impact them.

How much vitamin C is recommended?

Fifty years of age and older should take 75 to 90 mg of vitamin C, with a daily maximum of 2,000 mg. In general, as we age, this recommended intake does not rise.

There exists a possibility that some demographics are more susceptible to inadequate consumption of vitamin C. This includes people who have a restricted diet and people who have certain chronic illnesses or medical disorders that prevent the body from absorbing vitamin C.

It is important to know that most older adults who follow a healthy, balanced diet obtain enough vitamin C. Multivitamins or standalone vitamin C supplements may benefit older adults, who may be more likely to experience inadequate vitamin C intake.

Which foods are high in vitamin C?

Fruits and vegetables are rich in vitamin C. Suitable sources consist of:

  • Citrus fruits, including orange juice and oranges
  • Chillies
  • Strawberries
  • Potatoes
  • Broccoli
  • Brussels sprouts
  • Blackcurrants

To learn more, read: What Foods Contain Vitamin C?

Takeaway: Vitamin C moderation is key

There is ample evidence in the scientific research linking high dosages of vitamin C to diarrhea. 

Therefore, moderation is essential, as evidenced by the possible hazards associated with over-supplementation. If you are considering vitamin supplementation, it's important to note that not all supplements are created equal. 

While some products flood the market, we pride ourselves on offering what dietary supplements should be: 100% natural. 

At Why Not Natural, we understand the significance of providing high-quality supplements that align with your health goals. Learn about the Why Not Natural line of nutritional supplements to improve your health and energy levels.

Don't forget to subscribe to our newsletter to learn which supplements to take, how to combine them for maximum benefit, and other health tips to boost your energy and vitality. Plus, discover natural strategies to reduce hormonal imbalances, stress, and anxiety. Click here to get started!

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