- Vitamin C: Sources & Benefits
- Sources of vitamin C
- Deficiency and Dosage
- 20 best foods for vitamin C: Nutrition, benefits, and recipes
- Boosting heart health
- Strengthening the immune system
- Lowering the risk of some cancers
- 7 Impressive Ways Vitamin C Benefits Your Body
- Vitamin C Benefits | Vitamin C Foods | Andrew Weil, M.D
- What does vitamin C do?
- What are the signs of a vitamin C deficiency?
- How much, and what kind, does an adult need?
- How much does a child need?
- How do you get enough vitamin C from foods?
- Are there any risks associated with too much vitamin C?
- Are there any other special considerations?
- 29+ Foods High in Vitamin C & Deficiency Symptoms
- Assessing Deficiency (Vitamin C Levels)
- Vitamin C
- Dietary Recommendations
- Food Sources
- Clinical Uses
- Recent Research
Vitamin C: Sources & Benefits
Vitamin C, also called ascorbic acid, is important to many functions in the body. For example, it is needed to grow and repair tissues throughout the body. Vitamin C is a popular remedy for the common cold, but research is mixed on whether it helps or prevents the sniffles.
Sources of vitamin C
Dietary sources of vitamin C include many fruits and vegetables.
Sources with the most vitamin C are fresh, raw cantaloupes, citrus fruits, kiwis, mangos, papayas, pineapples, strawberries, raspberries, blueberries, watermelon and cranberries, according to National Institutes of Health (NIH).
Red and green peppers, spinach, cabbage, cauliflower, turnip greens and other leafy greens, tomatoes, potatoes, broccoli, winter squash and Brussels sprouts are other good sources of vitamin C.
The body uses vitamin C in many different ways. Vitamin C is needed by the body to form collagen. According to the NIH, the body also uses vitamin C to make skin, tendons, ligaments and blood vessels. It also uses this vitamin to repair and maintain cartilage, bones and teeth, to heal wounds and to form scar tissue.
Vitamin C may also prevent cancer by blocking the damage made by free radicals.
“Vitamin C is a vital antioxidant that helps protect cells from damage caused by free radicals that we are exposed to in the environment such as air pollution, cigarette smoke and ultraviolet light from the sun,” said Dr. Sherry Ross, OB/GYN and Women’s Health Expert at Providence Saint John’s Health Center in Santa Monica, California.
Many people tout vitamin C as a cure-all for a wide range of diseases. Many of these have not been proven. “Health benefits of vitamin C that have been proposed but not scientifically proven include a lower risk of certain cancers, cardiovascular disease, diabetes, age-related macular degeneration and cataracts,” said Ross.
A study by the National Eye Institute, however, did find that an intake of 500 mg per day of vitamin C, along with beta-carotene, vitamin E and zinc supplements, slowed the progression of advanced age-related macular degeneration by about 25 percent. It also helped slow visual acuity loss by 19 percent for those who are already at high risk of developing the disease. The vitamins did not have significant effect on the development or progression of cataracts, though.
The medical community is split over the benefits of vitamin C on the heart. Some studies suggest that vitamin C may prevent heart attacks by slowing down hardening of the arteries by preventing LDL (“bad”) cholesterol.
Other studies show that vitamin C does not prevent heart attacks.
A study by Johns Hopkins found that vitamin C has a “modest” effect on lowering high blood pressure and does not currently suggest supplements as a treatment option.
Vitamin C is often taken to prevent or cure the common cold. Research shows that most people taking high doses of Vitamin C still get the common cold just as often as those who don’t take high doses. It may shorten the amount of time a person is sick, though, and may also lessen the symptoms. [Related: Does Vitamin C Really Help Colds?]
Deficiency and Dosage
Vitamin C deficiency is fairly common. Smoking cigarettes can lower the amount of vitamin C in the body, so smokers are more prone to a deficiency, according to the University of Maryland Medical Center. Often, doctors will suggest a vitamin C supplement to smokers to prevent or cure a deficiency.
Not getting enough of this vitamin can cause easy bruising, gingivitis and bleeding gums, dry and splitting hair, rough, dry, scaly skin, a decreased wound-healing rate, nosebleeds and a decreased ability to ward off infection, according to the University of Maryland Medical Center.
An extreme lack of vitamin C for long periods of time can cause scurvy. Symptoms of scurvy are skin that bruises easily, bleeding gums, joint pain and poor wound healing.
“An estimated 40 percent of men and 38 percent of women are getting insufficient amounts of vitamin C. If you’re not eating your fruits and veggies, it’s a good idea to supplement,” said Dr. Brian Dixon, an expert in molecular and cellular biology and executive director of Health and Science Education at USANA Health Sciences.
The recommended daily allowance (RDA) for vitamin C varies, depending on age, gender and other factors. Typically, the RDA is 75mg for women and 90mg for men, according to Oregon State University. Pregnant and nursing women should take 80mg to 120 mg, depending on age.
Most of the population can take substantially more than the RDA without any side effects since vitamin C is water soluble. This means that it is not stored by the body.
It is filtered out and leaves the body in urine, according to the NIH. “However, some people taking more than 2,000 mg could experience some gastrointestinal upset.
And those who are prone to form kidney stones should get clearance from their doctor before taking high doses of Vitamin C,” said Dixon.
Dr. Kristine Arthur, internist at Orange Coast Memorial Medical Center in Fountain Valley, California told Live Science, “You can take too much. (It) may lead to kidney stones, irregular heart beat and diarrhea.”
20 best foods for vitamin C: Nutrition, benefits, and recipes
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Fruits and vegetables are the best food sources of vitamin C. Eating a variety of these healthful foods will help people meet their daily requirements.
Vitamin C, also called ascorbic acid, plays many important roles in the body. In particular, it is key to the immune system, helping prevent infections and fight disease.
The human body does not store vitamin C, so people need to get this nutrient from their diet every day. It dissolves in water, and any excess leaves the body in urine.
This article looks at the foods richest in vitamin C and how to include them in the diet. It also discusses the vitamin’s function and health benefits.
Share on PinterestVitamin C is important for a person’s immune system.
According to the Office of Dietary Supplements (ODS), the recommended daily allowance of vitamin C for adults is:
- 90 milligrams (mg) for males
- 75 mg for females
- 85 mg when pregnant
- 120 mg when breastfeeding
- an additional 35 mg for people who smoke
Some experts believe that people should consume much more than the recommended daily allowance for good health. One scientific editorial suggests that 200 mg per day is an optimal amount for most adults.
One serving of any of the foods below contains more than 20 percent of the recommended daily value of vitamin C. This makes these foods “excellent” sources of the vitamin, according to the Food and Drug Administration (FDA).
The following 20 foods are among the richest sources of vitamin C:
|Food||Serving size||Milligrams (mg) per serving||Percent of 90 mg daily value (DV)|
|1||Guava, raw||1 cup, raw||377||419%|
|2||Sweet red pepper, raw||1 cup, raw||190||211%|
|3||Tomato juice||1 cup, canned||170||188.9%|
|4||Orange juice||1 cup||124||137.8%|
|5||Sweet green pepper||1 cup, raw||120||133%|
|6||Hot green chili pepper, raw||1 pepper, raw||109||121%|
|7||Oranges||1 large fruit||97.5||108.8%|
|8||Strawberries||1 cup, sliced||97.6||108%|
|9||Papaya||1 small fruit||95.6||106.2%|
|10||Pink grapefruit juice||1 cup||93.9||104.3%|
|11||Broccoli||1 cup, raw||81.2||90.2%|
|12||Pineapple chunks||1 cup, raw||78.9||87.7%|
|13||Potato||1 large vegetable||72.7||80.8%|
|14||Brussels sprouts||1 cup, raw||74.8||79.8%|
|16||Mango||1 cup, raw||60.1||66.7%|
|18||Cauliflower||1 cup, raw||51.6||57.3%|
|20||White grapefruit||½ medium fruit||39||43.3%|
Cooking may reduce the amount of the vitamin in fruits and vegetables. To lose the least vitamin C, the ODS recommend steaming or microwaving these foods.
To get the most vitamin C, eat a variety of raw fruits and vegetables every day.
Vitamin C is an antioxidant. It protects the body’s cells from damage caused by free radicals. Free radicals can cause changes in cells and DNA that can lead to illnesses, including cancer.
This vitamin also plays a key role in almost all of the body’s tissues. Without vitamin C, the body cannot make collagen, a protein that is necessary for building and maintaining:
- healthy bones
- digestive tract tissues
Vitamin C is an important part of the immune system, which defends against viruses, bacteria, and other pathogens. Studies show that low levels of vitamin C lead to problems with the immune system and other illnesses.
Vitamin C deficiency can result in a condition called scurvy. This deficiency is relatively rare in the United States.
A vitamin C deficiency, or scurvy, may cause:
The following sections discuss some of the most important benefits of vitamin C.
Boosting heart health
Some evidence suggests that vitamin C may help lower the risk of heart disease or its complications.
One study indicates that people who consume more vitamin C have a lower risk of death from cardiovascular disease.
Other researchers are not convinced that vitamin C alone improves heart health. However, it is clear that eating more fruits and vegetables can help boost the health of the heart by providing a range of vitamins, minerals, antioxidants, and fiber.
Strengthening the immune system
Vitamin C has an immune-boosting effect that can help the body fight off illnesses, such as the common cold.
One study found that vitamin C helped prevent pneumonia and supported tetanus treatment. Also, findings of an animal study suggest that vitamin C plays a role in reducing lung inflammation that results from the flu.
Lowering the risk of some cancers
Vitamin C is an antioxidant, so it can prevent damage caused by free radicals. This may help prevent diseases such as cancer.
Investigations into whether vitamin C effectively prevents cancer have yielded mixed findings. However, the results of a few studies have been positive:
Vitamin C-rich foods can be a part of nearly any meal. The following breakfast, lunch, and dinner ideas can help a person meet their daily requirement.
Many people have a glass of orange juice with breakfast, but this is high in sugar. In fact, some brands of orange juice contain as much sugar as a soda.
Instead, load up on vitamin C in the morning with some of these breakfast options:
A healthful lunch can help prevent afternoon fatigue and keep energy levels up until dinner. Some ideas for a vitamin C-infused midday meal include:
Dinner can be a rich source of vitamin C when a person tops vegetables or meats with freshly squeezed lemon juice.
When vitamin C accompanies iron-rich plant foods, the body absorbs the iron more efficiently.
Some dinner ideas include:
Share on PinterestA person who smokes may need more vitamin C.
Some people may need higher amounts of vitamin C than others. People who smoke or are exposed to secondhand smoke, for example, may require more vitamin C to reduce the damage of the free radicals that the smoke releases.
Other groups who may benefit from a higher vitamin C intake include:
- people who do not eat enough fruits and vegetables or who have a very restricted diet
- people who are unable to fully absorb vitamins and nutrients
- people with certain health conditions, such as kidney disease or cancer
If someone cannot get enough vitamin C in their diet, they can take supplements. Many brands are available in drug stores and online.
Vitamin C is necessary for good health. Because it is abundant in many plant foods, eating a healthful diet that includes a variety of fruits and vegetables usually provides a person with all the vitamin C that they need.
People who wish to boost their vitamin C intake can do so by eating rich sources of the vitamin each day.
7 Impressive Ways Vitamin C Benefits Your Body
By Ryan Raman, MS, RD
Vitamin C is an essential vitamin, meaning your body can't produce it. Yet, it has many roles and has been linked to impressive health benefits.
It's water-soluble and found in many fruits and vegetables, including oranges, strawberries, kiwi fruit, bell peppers, broccoli, kale, and spinach.
The recommended daily intake for vitamin C is 75 mg for women and 90 mg for men.
While it's commonly advised to get your vitamin C intake from foods, many people turn to supplements to meet their needs.
Here are 7 scientifically proven benefits of taking a vitamin C supplement.
Vitamin C is a powerful antioxidant that can strengthen your body's natural defenses.
Antioxidants are molecules that boost the immune system. They do so by protecting cells from harmful molecules called free radicals.
When free radicals accumulate, they can promote a state known as oxidative stress, which has been linked to many chronic diseases.
Studies show that consuming more vitamin C can increase your blood antioxidant levels by up to 30%. This helps the body's natural defenses fight inflammation.
Vitamin C is a strong antioxidant that can boost your blood antioxidant levels. This may help reduce the risk of chronic diseases heart disease.
Approximately one-third of American adults have high blood pressure.
High blood pressure puts you at risk of heart disease, the leading cause of death globally.
Studies have shown that vitamin C may help lower blood pressure in both those with and without high blood pressure.
An animal study found that taking a vitamin C supplement helped relax the blood vessels that carry blood from the heart, which helped reduce blood pressure levels.
Moreover, an analysis of 29 human studies found that taking a vitamin C supplement reduced systolic blood pressure (the upper value) by 3.8 mmHg and diastolic blood pressure (the lower value) by 1.5 mmHg, on average, in healthy adults.
In adults with high blood pressure, vitamin C supplements reduced systolic blood pressure by 4.9 mmHg and diastolic blood pressure by 1.7 mmHg, on average.
While these results are promising, it's not clear whether the effects on blood pressure are long term. Moreover, people with high blood pressure should not rely on vitamin C alone for treatment.
Vitamin C supplements have been found to lower blood pressure in both healthy adults and those with high blood pressure.
Heart disease is the leading cause of death worldwide.
Many factors increase the risk of heart disease, including high blood pressure, high triglyceride or LDL (bad) cholesterol levels, and low levels of HDL (good) cholesterol.
Vitamin C may help reduce these risk factors, which may reduce heart disease risk.
For example, an analysis of 9 studies with a combined 293,172 participants found that after 10 years, people who took at least 700 mg of vitamin C daily had a 25% lower risk of heart disease than those who did not take a vitamin C supplement.
Interestingly, another analysis of 15 studies found that consuming vitamin C from foods — not supplements — was linked to a lower risk of heart disease.
However, scientists were unsure whether people who consumed vitamin-C-rich foods also followed a healthier lifestyle than people who took a supplement. Thus, it remains unclear whether the differences were due to vitamin C or other aspects of their diet.
Another analysis of 13 studies looked at the effects of taking at least 500 mg of vitamin C daily on risk factors for heart disease, such as blood cholesterol and triglyceride levels.
The analysis found that taking a vitamin C supplement significantly reduced LDL (bad) cholesterol by approximately 7.9 mg/dL and blood triglycerides by 20.1 mg/dL.
In short, it seems that taking or consuming at least 500 mg of vitamin C daily may reduce the risk of heart disease. However, if you already consume a vitamin-C-rich diet, then supplements may not provide additional heart health benefits.
Vitamin C supplements have been linked to a reduced risk of heart disease. These supplements may lower heart disease risk factors, including high blood levels of LDL (bad) cholesterol and triglycerides.
Gout is a type of arthritis that affects approximately 4% of American adults.
It's incredibly painful and involves inflammation of the joints, especially those of the big toes. People with gout experience swelling and sudden, severe attacks of pain.
Gout symptoms appear when there is too much uric acid in the blood. Uric acid is a waste product produced by the body. At high levels, it may crystallize and deposit in the joints.
Interestingly, several studies have shown that vitamin C may help reduce uric acid in the blood and, as a result, protect against gout attacks.
For example, a study including 1,387 men found that those who consumed the most vitamin C had significantly lower blood levels of uric acid than those who consumed the least.
Another study followed 46,994 healthy men over 20 years to determine whether vitamin C intake was linked to developing gout. It found that people who took a vitamin C supplement had a 44% lower gout risk.
Additionally, an analysis of 13 studies found that taking a vitamin C supplement over 30 days significantly reduced blood uric acid, compared with a placebo.
While there appears to be a strong link between vitamin C intake and uric acid levels, more studies on the effects of vitamin C on gout are needed.
Vitamin-C-rich foods and supplements have been linked to reduced blood uric acid levels and lower risk of gout.
Iron is an important nutrient that has a variety of functions in the body. It's essential for making red blood cells and transporting oxygen throughout the body.
Vitamin C supplements can help improve the absorption of iron from the diet. Vitamin C assists in converting iron that is poorly absorbed, such as plant-based sources of iron, into a form that is easier to absorb.
This is especially useful for people on a meat-free diet, as meat is a major source of iron.
In fact, simply consuming 100 mg of vitamin C may improve iron absorption by 67%.
As a result, vitamin C may help reduce the risk of anemia among people prone to iron deficiency.
In one study, 65 children with mild iron deficiency anemia were given a vitamin C supplement. Researchers found that the supplement alone helped control their anemia.
If you suffer from low iron levels, consuming more vitamin-C-rich foods or taking a vitamin C supplement may help improve your blood iron levels.
Vitamin C can improve the absorption of iron that is poorly absorbed, such as iron from meat-free sources. It may also reduce the risk of iron deficiency.
One of the main reasons people take vitamin C supplements is to boost their immunity, as vitamin C is involved in many parts of the immune system.
First, vitamin C helps encourage the production of white blood cells known as lymphocytes and phagocytes, which help protect the body against infection.
Second, vitamin C helps these white blood cells function more effectively while protecting them from damage by potentially harmful molecules, such as free radicals.
Third, vitamin C is an essential part of the skin's defense system. It's actively transported to the skin, where it can act as an antioxidant and help strengthen the skin's barriers.
Studies have also shown that taking vitamin C may shorten wound healing time.
What's more, low vitamin C levels have been linked to poor health outcomes.
For example, people who suffer from pneumonia tend to have lower vitamin C levels, and vitamin C supplements have been shown to shorten the recovery time.
Vitamin C may boost immunity by helping white blood cells function more effectively, strengthening your skin's defense system, and helping wounds heal faster.
Dementia is a broad term used to describe symptoms of poor thinking and memory.
It affects over 35 million people worldwide and typically occurs among older adults.
Studies suggest that oxidative stress and inflammation near the brain, spine, and nerves (altogether known as the central nervous system) can increase the risk of dementia.
Vitamin C is a strong antioxidant. Low levels of this vitamin have been linked to an impaired ability to think and remember.
Moreover, several studies have shown that people with dementia may have lower blood levels of vitamin C.
Furthermore, high vitamin C intake from food or supplements has been shown to have a protective effect on thinking and memory as you age.
Vitamin C supplements may aid against conditions dementia if you don't get enough vitamin C from your diet. However, additional human studies are needed to understand the effects of vitamin C supplements on nervous system health.
Low vitamin C levels have been linked to an increased risk of memory and thinking disorders dementia, while a high intake of vitamin C from foods and supplements has been shown to have a protective effect.
While vitamin C has many scientifically proven benefits, it also has many unfounded claims supported by either weak evidence or no evidence at all.
Here are some unproven claims about vitamin C:
- Prevents the common cold. While vitamin C appears to reduce the severity of colds and recovery time by 8% in adults and 14% in children, it does not prevent them.
- Reduces cancer risk. A handful of studies have linked vitamin C intake to a lower risk of several cancers. However, most studies have found that vitamin C does not affect the risk of developing cancer.
- Protects against eye disease. Vitamin C has been linked to reduced risks of eye diseases cataracts and age-related macular degeneration. However, vitamin C supplements have no effect or may even cause harm.
- May treat lead toxicity. Although people with lead toxicity appear to have low vitamin C levels, there is no strong evidence from human studies that show vitamin C can treat lead toxicity.
Although vitamin C has many proven benefits, it has not been shown to prevent the common cold, reduce cancer risk, protect against eye diseases, or treat lead toxicity.
Vitamin C is a water-soluble vitamin that must be obtained from the diet or supplements.
It has been linked to many impressive health benefits, such as boosting antioxidant levels, lowering blood pressure, protecting against gout attacks, improving iron absorption, boosting immunity, and reducing heart disease and dementia risk.
Overall, vitamin C supplements are a great and simple way to boost your vitamin C intake if you struggle to get enough from your diet.
Reposted with permission from Healthline. For detailed source information, please view the original article on Healthline.
Vitamin C Benefits | Vitamin C Foods | Andrew Weil, M.D
- Vitamins, Supplements & Herbs
Vitamin C (also known as ascorbic acid) is abundant in vegetables and fruits. A water-soluble vitamin and powerful antioxidant, it helps the body form and maintain connective tissue, including bones, blood vessels, and skin.
What does vitamin C do?
Vitamin C helps to repair and regenerate tissues, protect against heart disease, aid in the absorption of iron, prevent scurvy, and decrease total and LDL (“bad”) cholesterol and triglycerides.
Research indicates that vitamin C may help protect against a variety of cancers by combating free radicals, and helping neutralize the effects of nitrites (preservatives found in some packaged foods that may raise the risk of certain forms of cancer).
Supplemental vitamin C may also lessen the duration and symptoms of a common cold, help delay or prevent cataracts, and support healthy immune function.
What are the signs of a vitamin C deficiency?
Deficiency symptoms include fatigue, muscle weakness, joint and muscle aches, bleeding gums, and leg rashes. Prolonged deficiency can cause scurvy, a rare but potentially severe illness.
How much, and what kind, does an adult need?
According to the National Institutes of Health (NIH), the recommended vitamin C daily allowance (RDA) for adults over age 19 is:
- Men, 90 mg per day
- Women, 75 mg per day
- Pregnant women, 85 mg per day
- Breastfeeding women, 120 mg per day.
Smokers may benefit from a higher intake. Dr. Weil recommends taking 250 mg of vitamin C each day.
How much does a child need?
NIH recommends Adequate Intakes (AIs):
- Infants 0-6 months old, 40 mg per day
- Infants 7-12 months old, 50 mg per day.
The RDAs of vitamin C for teens and children are:
- Toddlers 1-3 years old, 15 mg per day
- Children 4-8 years old, 25 mg per day
- Children 9-13 years old, 45 mg per day
- Male teens 14-18 years old, 75 mg per day
- Female teens 14-18 years old, 65 mg per day
How do you get enough vitamin C from foods?
Vitamin C is easy to get through foods, as many fruits and vegetables contain vitamin C.
Good sources include: apples, asparagus, berries, broccoli, cabbage, melon (cantaloupe, honeydew, watermelon), cauliflower, citrus fruits (lemons, limes, oranges), kiwi, fortified foods (breads, grains, cereal), dark leafy greens (kale, spinach), peppers (especially red bell peppers, which have among the highest per-serving vitamin C content), potatoes, and tomatoes.
Are there any risks associated with too much vitamin C?
When obtained from food sources and supplements in the recommended dosages, vitamin C is generally regarded as safe. Side effects are rarely reported, but include diarrhea, nausea, abdominal cramps, and other gastrointestinal symptoms.
For most healthy individuals, the body can only hold and use about 200-250 mg of vitamin C a day, and any excess is lost though urine. At times of illness, during recovery from injury, or under conditions of increased oxidative stress (including smoking), the body can use greater amounts.
High doses of vitamin C (greater than 2,000 mg/day) may contribute to the formation of kidney stones, as well as cause severe diarrhea, nausea, and gastritis.
Are there any other special considerations?
Adverse affects may occur between vitamin C and anticoagulant drugs such as warfarin (Coumadin), decreasing their action. Nicotine products, oral contraceptives/estrogens, tetracyclines, barbiturates, and aspirin may decrease levels of vitamin C.
Vitamin C may increase absorption of iron and lutein. Although some evidence suggests that large doses of supplemental vitamin C may interfere with the absorption and metabolism of vitamin B12 found in food, other studies have shown no such effects.
Updated by: Andrew Weil, M.D., and Brian Becker, M.D., on Oct. 29th, 2012
Reviewed by Benjamin S. Gonzalez, M.D., May, 2016.
29+ Foods High in Vitamin C & Deficiency Symptoms
Vitamin C is a powerful antioxidant that’s found in many foods, but some exotic fruits contain it in exceptionally high amounts. Vitamin C deficiency is rare, but it can have serious health consequences. Read about the top dietary sources of vitamin C and which symptoms might signal deficiency in this post.
Early indications of Vitamin C deficiency are fatigue, malaise, depression, and they may manifest as a reduced desire to be physically active .
Scurvy (pathological Vitamin C deficiency) leads to blood vessel fragility resulting in hemorrhage, as well as connective tissue damage due to failure in collagen production, often leading to loss of teeth and tendon rupture. At worse, scurvy can lead to death [2, 3].
Other signs and symptoms of severe vitamin C deficiency include :
- Poor wound healing
- Weight loss
- Gum inflammation and bleeding
- Petechiae (tiny purple, red, or brown spots on the skin), ecchymosis (a type of bruise), and purpura (purple-colored spots on the skin)
- Joint pain
- Dry eyes and dry mouth
- Corkscrew hair
Clinical scurvy can be avoided by intaking as little as 10 mg of Vitamin C per day. Scurvy is extremely rare in developed countries .
However, mild Vitamin C depletion has been observed in 10-30 % of the presumed healthy population [5, 6].
Causes shown here are commonly associated with vitamin C deficiency. Work with your doctor or other health care professional for an accurate diagnosis.
One of the major causes of low vitamin C levels is eating a poor diet lacking in fresh fruits and vegetables. This is commonly seen in:
- Low-income individuals 
- Elderly individuals who eat a tea-and-toast diet 
- Alcoholics and drug users 
- People who follow fad diets 
- Anorexics 
- People with mental illness 
People with malabsorption issues caused by certain gut conditions (i.e., Crohn’s disease, celiac disease) are also at risk for vitamin C deficiency .
Low vitamin C levels can also be caused by:
- Heavy metal toxicity 
- Viral illnesses 
- Overactive thyroid gland (hyperthyroidism) 
- Kidney disease/failure 
- Cancer 
Certain drugs can lower vitamin C levels:
- Antibiotics 
- Painkillers 
Assessing Deficiency (Vitamin C Levels)
Vitamin C levels can be measured with a blood test.
Generally, blood Vitamin C concentration of:
- 40 μM is optimal 
Some researchers believe that up to 22% of the U.S. may have below adequate Vitamin C status (blood concentrations < 28 µmol/L), and about 6% of the adult population is classified as Vitamin C deficient (
Vitamin C (ascorbic acid) is a simple low-molecular-weight carbohydrate with an ene-diol structure that has made it a ubiquitous and essential water-soluble electron donor in nature. It is synthesized by all species except for higher-order primates, guinea pigs, and some bat, fish, and bird species.
In all of the latter, the gene encoding for i-gulonolactone oxidase—the enzyme catalyzing the final step in the biosynthesis of ascorbic acid—has evolved into a nonfunctional state due to accumulation of mutations and/or deletions; consequently, these species rely on an adequate supply of vitamin C from their diet.
In all its known biologic functions, vitamin C acts as a reductant, i.e., it donates an electron to a substrate while itself being oxidized to an ascorbyl radical, a relatively stable free radical.
Two molecules of ascorbyl free radical can dismutate into 1 molecule of ascorbate and 1 molecule of dehydroascorbic acid, the fully reduced and oxidized forms of vitamin C, respectively.
To minimize the loss of vitamin C through metabolism and excretion, efficient retaining mechanisms have evolved, including ascorbate recycling, in which dehydroascorbic acid is rapidly reduced to ascorbate intracellularly by glutathione (another cellular reductant) or the selenoenzyme, thioredoxin reductase, and active renal reabsorption by the sodium-dependent vitamin C transporter (SVCT)2 1. Vitamin C absorption, tissue distribution, and excretion are tightly controlled by tissue-specific, active transport through SVCT1 and SVCT2. If vitamin C intake in humans is in excess of ∼400 mg/d, a homeostatic state is reached with maximal plasma steady-state concentrations of ∼60 to 90 μmol/L and intracellular concentrations ranging from 0.5 to 10 mmol/L, depending on the tissue. The highest concentrations of vitamin C are found in the brain, eye, and adrenal gland.
The biologic role of vitamin C is related to its reduced form, ascorbate, and can be separated into enzymatic and nonenzymatic functions.
The best-known enzymatic function of vitamin C is probably as cofactor for the ferrous [Fe(II)] and 2-oxoglutarate dependent dioxygenases in collagen synthesis.
These enzymes catalyze the hydroxylation of lysine and proline residues in unfolded procollagen chains, which are the building blocks of the triple-helical structure of mature, functional collagen.
Ascorbate also serves as an electron donor for various enzymes catalyzing carnitine and norepinephrine biosynthesis, peptide hormone amidation, and tyrosine metabolism. Ascorbate-mediated hydroxylation of hypoxia inducible factor 1α (HIF-1α) regulates the transcription of several genes encoding proteins involved in iron homeostasis, angiogenesis, and cell proliferation.
More recently, several studies have shown that vitamin C plays an important role in vascular function. Ascorbate modulates vasorelaxation by increasing NO synthesis or bioavailability in a number of ways (1).
Endothelial NO synthase (eNOS) generates NO, which diffuses to the smooth muscle cell layer of the vascular wall and mediates dilation through its interaction with soluble guanylyl cyclase.
Tetrahydrobiopterin is a cofactor for eNOS activity, and vitamin C appears to recycle tetrahydrobiopterin from its oxidized form(s), thereby sustaining the enzyme's activity.
Moreover, vitamin C may affect NO bioavailability through ascorbate-mediated denitrosylation and phosphorylation of eNOS. Other roles of vitamin C in vascular function include modulating the endothelial cell barrier and regulating the activity of NADPH oxidases (NOXs) involved in inflammatory gene response.
In addition to its roles in the above enzymatic processes, ascorbate is a powerful antioxidant with the ability to reduce or “scavenge” many (patho)physiologically relevant free radicals and reactive oxygen species.
In addition, vitamin C can regenerate vitamin E (α-tocopherol) from its oxidized form (α-tocopheroxyl radical), allowing vitamin C to indirectly inhibit lipid peroxidation.
Ascorbate can also reduce urate and glutathione radicals as part of the antioxidant network in cells and extracellular fluids.
Although the clinical importance of ascorbate's antioxidant action is difficult to assess, a considerable experimental literature has shown that vitamin C effectively protects biologic macromolecules from oxidative damage that might otherwise causally contribute to the initiation and progression of several chronic and acute diseases (2).
The clinical hallmark of severe and prolonged vitamin C deficiency is scurvy, which is fatal if left untreated.
The symptoms of impaired wound healing, gingivitis, perifollicular hemorrhages, ecchymoses, and petechiae have been known for centuries and are largely related to impaired collagen biosynthesis and perhaps HIF-1α hydroxylation.
Other symptoms of severe vitamin C deficiency are malaise and fatigue or lethargy, which may be difficult to diagnose clinically.
These symptoms can be explained by impaired carnitine biosynthesis resulting in decreased fatty acid transport and subsequent β-oxidation in mitochondria required for ATP production and decreased synthesis of the neurotransmitter norepinephrine.
The enzymatic synthesis of both carnitine and norepinephrine involves hydroxylation steps that depend on vitamin C for full enzyme activity (2). Whereas vitamin C deficiency is mainly caused by poor diet, several additional risk factors have been identified, including smoking, pregnancy, low socioeconomic status, genetic predisposition, old or young age, strenuous exercise, and clinical conditions associated with metabolic syndrome, such as hypertension, diabetes, and obesity.
the vitamin C intake required to achieve near-saturation of plasma and leukocytes with minimal urinary excretion, and adjusted for body mass, an RDA of 75 and 90 mg/d for women and men, respectively, was established by the U.S. Institute of Medicine (IOM) in 2000.
In addition, the RDA for pregnant and breastfeeding women (≥19 y) was set at 85 and 120 mg/d, respectively. No RDA was established for infants; instead, the Adequate Intake of vitamin C was set at 40 mg/d for infants up to 6 mo of age, and 50 mg/d for infants up to 12 mo.
For older children, the recommendation is estimated body mass in relation to an adult: 15 mg/d for children up to 3 y of age, 25 mg/d for children up to 8 y, and 45 mg/d for children up to 13 y.
The RDA for teenagers is gender: 75 and 65 mg/d for boys and girls 13–17 y of age, respectively (3).
It has long been recognized that smokers and individuals exposed to environmental tobacco smoke (“passive” smokers) have a lower vitamin C status than nonsmokers.
This is believed to be partly due to poor dietary habits but also due to the oxidizing properties of tobacco smoke per se, resulting in an increased turnover of vitamin C. Consequently, the IOM recommends that smokers get an additional 35 mg/d of vitamin C.
No increased RDA has been established for passive smokers, but they are strongly encouraged to ensure that they meet the standard RDA.
Recent data suggest that the current RDA for vitamin C set by the IOM for men and women may be too low.
On the basis of a comprehensive review of the scientific evidence from human metabolic, pharmacokinetic, and observational studies as well as phase 2 randomized controlled trials, it was concluded that 200 mg/d is the optimum intake of vitamin C for the majority of the adult population to maximize the vitamin's potential health benefits with the least risk of inadequacy or adverse health effects (4).
Fruit and vegetables are good sources of vitamin C, and ~90% of the daily intake in the general population comes from these sources. The content varies between species, but citrus fruit, kiwi, mango, and vegetables such as broccoli, tomatoes, and peppers are all rich sources of vitamin C.
Because vitamin C degrades when heated and during storage, the processing and preparation procedures should be considered when estimating dietary intake of vitamin C. A total of 5–9 servings of fresh, minimally processed, or frozen fruit and vegetables per day is estimated to equal ~200 mg of vitamin C.
The presence of vitamin C in dietary products other than fruit and vegetables is typically due to its addition as a preservative to processed foods to protect against oxidation.
In areas where vegetation is sparse, such as the arctic regions, people have traditionally relied on alternative sources of vitamin C, such as medicinal herbs (herbal teas and tinctures from rose hips, pine needles, and tree barks) and animal organs, such as raw liver and whale skin.
The current RDA for vitamin C largely exceeds the amount necessary to prevent scurvy (~10 mg/d). However, given the possible severity of events associated with scurvy, urgent replacement therapy is suggested when clinical signs or symptoms of vitamin C deficiency are identified.
Oral supplementation with 500 mg/d will be adequate in milder cases, but parenteral therapy may be required in severe cases and in cases of impaired intestinal function or lack of compliance. Subclinical vitamin C deficiency is difficult to detect because the typical symptoms, fatigue and lassitude, are nonspecific.
Overt vitamin C deficiency can be seen in malnourished populations, including those with chronic conditions, poor dietary habits, malabsorption, or chemical dependencies.
A considerable epidemiologic literature has found associations between poor vitamin C status and increased risk of developing cardiovascular diseases (CVDs), including coronary heart disease, ischemic stroke, and hypertension (5).
Those with near-saturated plasma vitamin C concentrations appear to have the lowest CVD risk, suggesting that intakes greater than the RDA are required to achieve these health benefits.
However, properly designed randomized controlled trials have not yet been conducted to either confirm or reject a causal link between vitamin C status and CVD. Thus, prophylactic supplementation of high-risk individuals is not currently recommended by the medical community.
In contrast, a considerable number of large intervention studies have confirmed that supplementation of already well-nourished individuals has no additional health benefits.
Another clinical use of vitamin C is to increase nonheme-iron absorption. In the small intestine, vitamin C reduces dietary iron and allows for efficient transport across the intestinal epithelium. Food sources of vitamin C or supplements, when consumed with iron, may lead to increased hemoglobin production in anemic patients.
Recent work at the NIH and the University of Iowa has suggested that gram-doses of intravenously administered vitamin C may have merit in cancer therapy in conjunction with standard chemotherapy.
This beneficial effect of intravenous vitamin C may be due to ascorbate autooxidation and the generation of hydrogen peroxide, which is selectively toxic to cancer cells.
Vitamin C is generally safe and well tolerated, even in large doses. The IOM set the Tolerable Upper Intake Level for oral vitamin C ingestion at 2 g daily for adults gastrointestinal disturbances observed in some individuals at higher doses.
High amounts of vitamin C intake have been associated with an increased risk of kidney stones, although the evidence is mixed and inconsistent. The current recommendation is to avoid vitamin C supplementation in those susceptible to kidney stone formation.
Vitamin C consumed with iron could increase the risk of iron overload in susceptible individuals. Patients with these conditions should not avoid eating fruit and vegetables but limit their intake of iron instead.
Vitamin C has been reported to cause hemolysis in individuals with glucose-6-phosphate dehydrogenase deficiency, but these reports have not been substantiated.
The so-called antioxidant hypothesis of the 1980s promising a long and healthy life from an abundant intake of antioxidants, including vitamin C, has long been replaced by the view that the health benefits of vitamin C are derived from its role in a number of key reactions within immune function, metabolism, and other enzymatic and nonenzymatic reactions (see above). Thus, emerging evidence indicates that even marginal vitamin C deficiency may impair normal perinatal neurogenesis, affect fetal programming of adult disease risk, and increase the risk of cardiovascular and all-cause mortality. Several genetic variants have been identified in SVCTs, haptoglobin, and glutathione S-transferases that may influence plasma vitamin C status or uptake into tissues. More recent studies have investigated how these polymorphisms may interact with low dietary vitamin C concentrations to increase chronic disease risk (6).
hypoxia inducible factor 1α
sodium-dependent vitamin C transporter
Author disclosures: J. Lykkesfeldt, A. J. Michels, and B. Frei, no conflicts of interest. Nutrient Information Nutrient Information