A 69-year-old woman was rushed to the emergency room after experiencing a rapid weight loss of 20 pounds, widespread bruises, and muscle pain in her legs. She also suffered from weakness and small bleeding spots around hair follicles.

Before it was identified, this vitamin was designated “C” to signify its anti-scurvy properties. Vitamin C was later discovered in 1932 to be ascorbic acid, with ascorbic meaning “anti-scurvy.”

Our bodies require vitamin C to produce collagen, which is crucial for connective tissues, wound healing, and certain brain chemicals. Vitamin C also acts as an antioxidant and can regenerate other antioxidants, such as vitamin E.

Inadequate levels of vitamin C have been linked to osteoporosis, diabetes, cancer, and schizophrenia. Supplementation with vitamin C can potentially reduce glucose concentrations, high blood pressure, and cholesterol. A 2017 meta-analysis found that vitamin C administration led to a significant decrease in glucose levels in patients with diabetes and older individuals. When administered intravenously, it can also be effective in treating cancer and serve as a potent adjuvant cancer treatment, enhancing the effects of various standard therapies, including chemotherapy. It can also act to reduce the toxic side effects associated with chemotherapy.

Unfortunately, vitamin C deficiency may be more prevalent than we previously thought.

Vitamin C offers us a plethora of health benefits, the full extent of which researchers are still actively exploring. Some of the major ones include the following.

1. Aids in Liver Detoxification

Vitamin C is essential for your liver because it helps regenerate a key detoxification tripeptide called glutathione. Glutathione plays a crucial role in reducing the toxic load in your body by improving the liver’s ability to convert and eliminate toxins, such as mercury and persistent organic pollutants.

Some toxins are fat-soluble. The liver transforms those toxins into water-soluble forms that can be excreted through urine or sweat. Glutathione is essential for this detoxification process, and vitamin C helps replenish it.

It’s worth noting that taking acetaminophen (Tylenol) can decrease glutathione levels and lead to lower vitamin C levels. Glutathione can also regenerate oxidized vitamin C.

2. Maintains Healthy Skin, Bones, and Connective Tissue

Vitamin C helps make a crucial protein called collagen, essential for skin, bones, muscles, and even blood vessels. Without enough vitamin C, your body struggles to heal wounds, maintain strong bones and teeth, and absorb iron properly. Vitamin C is the director that tells the amino acids (building blocks for collagen) glycine, proline, and lysine how to synthesize collagen, ensuring your body can build and repair itself effectively.

3. Regulates Immunity

Vitamin C helps the immune system by regulating its activity, which can be especially beneficial for autoimmune conditions and contributes to its immune defense. Specifically, vitamin C supports both the innate and adaptive immune systems. It also helps maintain the skin’s protective barrier by shielding it against harmful molecules called reactive oxygen species (ROS). Vitamin C also helps remove cellular debris and plays a role in the growth and function of critical immune cells, such as B- and T-lymphocytes, which produce antibodies for fighting infections.

4. Converts Fat Into Energy

When the body uses fat for energy, it goes through a process inside tiny energy-producing units called mitochondria. Fats use a special shuttle called carnitine to enter mitochondria. Your body produces carnitine with the help of vitamin C. If you don’t have enough vitamin C, your body might struggle to break down fats for energy. If you’re following a ketogenic diet, which relies heavily on fat for fuel, your need for vitamin C may increase.

Meat contains some carnitine, and while the topic remains debated, some research suggests that a ketogenic diet may lower the body’s vitamin C requirement by enhancing mitochondrial function and boosting antioxidant levels through increased glutathione synthesis. However, if you are following a ketogenic diet and experience fatigue, it may be due to your body’s insufficient production of carnitine.

5. Reduces Heavy Metal Accumulation

The accumulation of heavy metals such as mercury and chromium can severely damage various organs and systems, such as the respiratory, nervous, and reproductive systems. Vitamin C can reduce heavy metal accumulation, possibly by scavenging free radicals generated by heavy metals, thus inhibiting their genotoxic effects, and by reactivating repair mechanisms that heavy metals have inactivated.

6. Regulates Cholesterol

One systematic review found that vitamin C could decrease total cholesterol in people under 52 years old, and another study showed that taking at least 500 milligrams of vitamin C daily for at least four weeks could notably reduce serum low-density lipoprotein (LDL) cholesterol and triglyceride levels. However, while the systematic review also found vitamin C supplementation capable of significantly increasing high-density lipoprotein (HDL) cholesterol levels, the second study didn’t find a significant increase in serum HDL.

7. Fights Atherosclerosis

Atherosclerosis is characterized by the thickening or hardening of the arteries due to plaque accumulation in their inner lining. This plaque buildup restricts blood flow and can lead to various cardiovascular problems. Vitamin C helps protect against atherosclerosis by reducing the stickiness of white blood cells to artery walls, improving blood vessel function, and preventing the death of cells in blood vessel walls. This helps keep plaques in arteries stable and reduces the risk of blockages.

8. Improves Mental Health

In addition to affecting mood, thinking, memory, and sleep, serotonin also helps control appetite, nutrient absorption, and gut movement. It is linked to various mental disorders, including depression, anxiety, attention-deficit/hyperactivity disorder (ADHD), sleep disorders, and schizophrenia. Vitamin C plays a crucial role in synthesizing serotonin. High levels of vitamin C are linked to better moods in male college students, and the vitamin can also improve the mood of hospitalized patients.

Because vitamin C supplements work quickly, have low toxicity, and are well-tolerated, they are currently considered a promising option for treating stress-related disorders such as depression and anxiety, especially when other treatments don’t work.

There is also a link between schizophrenia and low vitamin C levels. It is theorized that some individuals cannot properly metabolize adrenochrome, a byproduct of adrenaline, due to insufficient vitamin C levels. Research on glutathione S-transferase, an enzyme related to vitamin C that helps detoxify adrenochrome, supports this idea in some cases. However, not everyone with schizophrenia suffers from vitamin C deficiency.

9. Helps Adrenal Glands Generate Essential Hormones

The adrenal glands assist in the production of adrenaline, cortisol, and progesterone. Vitamin C contributes to the formation of these hormones in the following ways:

• Epinephrine (aka adrenaline) and noradrenaline: Vitamin C is crucial for producing and metabolizing adrenaline properly. Sometimes, people can produce adrenaline but cannot properly metabolize it. Without enough vitamin C, adrenaline levels can remain elevated, which can lead to increased anxiety and an exaggerated fight-or-flight response. This chronic fight-or-flight state can inhibit digestion, make it difficult to adapt to stress, impair healing, and lead to “hamster thinking,” where the mind is stuck in a loop of persistent worry.
• Cortisol: As a “stress hormone,” cortisol temporarily reduces inflammation, and vitamin C can enhance cortisol production.
• Progesterone: Vitamin C can help the adrenal glands produce more progesterone.

10. Boosts Iron Absorption

Vitamin C enhances the absorption of nonheme iron, which is present in plant-based foods such as leafy greens. Therefore, adding a vitamin C-rich food or drinking a glass of freshly squeezed 100 percent orange juice with meals containing nonheme iron sources may increase iron absorption. Freshly squeezed orange juice is reported to contain higher levels of vitamin C than commercial orange juices.

11. Prevents and Targets Cancers

Certain types of cancer exhibit inverse associations with vitamin C intake or concentration. In one 1999 study, premenopausal women with a family history of breast cancer had a 53 percent to 63 percent lower risk of developing the disease when consuming an average of 205 milligrams a day of vitamin C from food compared to those consuming an average of 70 milligrams per day.

One 2006 study showed that people with higher plasma vitamin C levels (≥ 51 micromoles per liter) had a 45 percent lower risk of developing gastric cancer compared to those with lower levels (< 29 micromoles per liter). In a 2017 study, vitamin C demonstrated roughly 10-fold greater effectiveness than an experimental drug targeting cancer stem-like cells.

12. Improves Endothelial Dysfunction

Endothelial dysfunction occurs in the early stages of vascular disorders, which can contribute to complications such as stroke, heart attack, diabetes, and metabolic syndromes. A 2014 meta-analysis found that short-term vitamin C supplementation reduced endothelial dysfunction in individuals with heart failure, atherosclerosis, or diabetes. Therefore, vitamin C supplementation may help reduce the risk of cardiovascular disease.

13. Regulates Folate Metabolism

Folate metabolism involves how our bodies use folate, a type of vitamin B, which is crucial for many processes. One critical process is methylation, vital for synthesizing DNA, regulating gene expression, producing neurotransmitters, and detoxifying ourselves from harmful substances. Vitamin C helps with folate methylation and boosts folate levels. Plus, it might lower levels of a compound called homocysteine, linked to heart disease risk.

14. Slows Age-Related Macular Degeneration

Research indicates that combining vitamin C with other nutrients can potentially slow the progression of age-related macular degeneration (AMD). A 2001 study involving 3,640 individuals aged 55 to 80 years with AMD, who were at high risk of advanced AMD, found that those who took a daily dietary supplement containing 500 milligrams of vitamin C, 80 milligrams of zinc, 400 international units (IUs) of vitamin E, 15 milligrams of beta carotene, and 2 milligrams of copper for approximately six years had a reduced likelihood of developing advanced AMD. They also experienced less vision loss than those who did not take the supplement.

The 2005–2016 NHANES survey reported that 46 percent of U.S. adults had an “inadequate” vitamin C intake. Furthermore, daily intake dropped 17.5 percent between 2002 and 2020.

Scurvy still occurs today in developed countries. According to a 2013 clinical case report, “In developed countries, scurvy is still endemic, and evidence is growing that vitamin C deficiency might affect up to 30 percent of the population.”

Cases of scurvy have been reported as recently as 2022, including a 12-year-old in Canada and a 53-year-old male in Philadelphia.

A 5-year-old girl with a rash and pain in both legs was found to have a vitamin C deficiency and scurvy after several misdiagnoses. She was started on vitamin C and admitted to an intensive feeding program, which successfully increased the number of new foods in her diet. After one year, all symptoms related to vitamin C deficiency resolved.

Unfortunately, many doctors do not investigate vitamin C deficiency as a potential cause of symptoms, thus leading to misdiagnosis. For instance, symptoms of Crohn’s disease can overlap with those of scurvy, making vitamin C deficiency less commonly diagnosed. However, the consequences may be deadly.

The risk of deficiency increases with conditions that increase the body’s vitamin C needs, such as pregnancy, breastfeeding, high fever or inflammation, hyperthyroidism, prolonged diarrhea, surgery, Type 1 diabetes, burns, stress, and smoking.

Other risk factors of vitamin C deficiency include:

• Excessive alcohol intake
• Infant feeding practices: Choosing cow’s milk over breast milk or fortified formula for infants can increase the risk of vitamin C deficiency due to insufficient vitamin C content in cow’s milk.
• Malabsorptive disorders: Conditions such as inflammatory bowel disease (IBD) and cystic fibrosis can impede the body’s vitamin C absorption.
• Bariatric surgery: People who have had bariatric surgery face reduced absorption capacity.
• Iron-overload conditions: Conditions characterized by excess iron accumulation and renal loss of vitamin C can contribute to vitamin C deficiency as the body may struggle to retain and utilize this vitamin effectively.
• Food allergies: Allergies to certain foods can restrict dietary choices, potentially limiting the intake of vitamin C-rich foods.
• Developmental disabilities and mental illness: These medical conditions may influence food preferences, potentially leading to inadequate consumption of vitamin C-rich foods.

Symptoms of vitamin C deficiency develop after weeks to months of vitamin C depletion. They may vary depending on the patient’s age.

In adults, early symptoms include:

• Fatigue
• Weakness
• Irritability
• Weight loss
• Vague muscle pain
• Joint pain

Other symptoms and signs include:

• Femoral neuropathy due to bleeding into femoral sheaths (the sleeve-like structure encasing the femoral artery and vein)
• Swelling in the lower extremities
• Painful bleeding
• Abnormal accumulation of fluid inside a joint cavity
• Dry and splitting hair
• Gingivitis (inflammation of the gums) or bleeding gums
• Rough, dry, and scaly skin
• Slow wound healing
• Easy bruising
• Nosebleeds
• Subcutaneous bleeding
• Potential weight gain due to a decrease in metabolic rate
• Varicose veins: The development of varicose veins may occur due to the lack of collagen caused by vitamin C deficiency, as collagen plays a role in shaping the vascular system. Insufficient vitamin C levels can lead to vein ruptures or bulging, resulting in varicose veins.
• Heavy metal toxicity: Vitamin C plays a crucial role in protecting against certain heavy metals, so low levels could contribute to increased levels of heavy metals in the body.
• Estrogen dominance: Vitamin C can boost progesterone production. Low progesterone levels can cause estrogen dominance, which may contribute to thyroid issues.

In infants and children, signs and symptoms include:

• Irritability
• Painful movement
• Anorexia
• Slowed growth
• Impaired bone growth
• Bleeding
• Anemia

Symptoms of scurvy include:

• Persistent fatigue and weakness
• Chronic irritability and sadness
• Pain in joints, muscles, or legs
• Swollen and bleeding gums (with a risk of tooth loss)
• Red or blue spots on the skin, often on the lower extremities (might be less visible on darker skin tones)
• Easily bruised skin

Humans cannot synthesize or store vitamin C, unlike some other species, so we must obtain this nutrient through our diet. When enjoying food, remember that it contains different types of nutrients that interact with each other in complex ways.

Fruits rich in vitamin C (content per 100 grams), with content listed in milligrams (mg), include:

• Guavas (228 mg)
• Red bell peppers (142 mg)
• Kiwifruit (92.7 mg)
• Persimmons (66 mg)
• Papayas (60.9 mg)
• Strawberries (58.8 mg)
• Lemons (53 mg)
• Pineapples (47.8 mg)
• Oranges (45 mg)
• Cantaloupes (36.7 mg)
• Mangos (36.4 mg)
• Cooked ripe red tomatoes (22.8 mg)

Vegetables rich in vitamin C

• Kale (93.4 mg)
• Broccoli (89.2 mg)
• Brussels sprouts (85 mg)
• Mustard greens (70 mg)
• Turnip greens (60 mg)
• Red cabbage (57 mg)
• Cauliflower (48.2 mg)
• Bok choy (45 mg)
• Green peas (40 mg)
• Swiss chard (30 mg)
• Spinach (28.1 mg)

Some types of meat and organs also contain vitamin C, such as:

• Cooked beef spleen (50.3 mg)
• Cooked veal thymus (39.4 mg)
• Cooked beef lungs (32.7 mg)
• Cooked fish roe (16.4 mg)

In-season fruits and vegetables are good dietary options for vitamin C, as those grown under optimal conditions have the highest levels of vitamins, nutrients, and antioxidants. For instance, broccoli harvested in the fall can have nearly double the vitamin C compared to broccoli grown in the spring.

Growing your own produce or buying locally can also lead to elevated vitamin C levels. Local farmers often pick when the produce is ripe and prioritize freshness and flavor over shelf life, thus reducing or eliminating the need for anti-ripening agents.

Even if you eat enough vitamin C-rich foods, your absorption of the vitamin may still be insufficient due to factors such as cooking methods and dietary habits. What can we do to enhance vitamin C intake and absorption?

• Avoid prolonged storage and cooking when possible: Long-term storage and cooking can diminish the vitamin C content in food since ascorbic acid, being water-soluble, breaks down with heat. Luckily, many top vitamin C sources, such as fresh fruits and vegetables, are commonly eaten raw. You can also turn them into smoothies and salads.
• Choose the proper food preparation method: Steaming or microwaving is better than high-heat cooking to minimize vitamin C loss. Cooking quickly or using minimal water, such as stir-frying or blanching, also helps retain the vitamin since vitamin C may end up in the liquid after cooking.
• Eat raw foods at peak ripeness: Fruits and vegetables at peak ripeness contain the most vitamin C.

Vitamins C and E are antioxidants that can work synergistically to protect cells from oxidative stress. In a 2012 trial involving 23 Alzheimer’s disease patients, researchers combined vitamin C (1,000 milligrams a day) and vitamin E (400 IU per day) supplementation with a cholinesterase inhibitor. After a year, this combination significantly increased antioxidant levels and reduced lipoprotein oxidation in the cerebrospinal fluid.

Bioflavonoids are a group of plant compounds with antioxidant properties found in fruits, vegetables, grains, tea, and wine. Bioflavonoids are often included in dietary supplements due to their potential health benefits, including anti-inflammatory and immune-boosting effects.

Research suggests that bioflavonoids can enhance vitamin C absorption while collaborating with it to combat free radicals, regulate inflammation, and support immune responses.

L-ascorbic acid exists in nature and foods. It is an active form of vitamin C readily absorbed by the body.

Some examples of synthetic vitamin C include:

• Synthetic l-ascorbic acid: This type of vitamin C is a white to pale-yellow powder with a sharp, acidic taste, and almost no smell. This form helps enzymes work properly, acts as an antioxidant in food, helps plants grow, and protects against aging. Natural and synthetic l-ascorbic acids are chemically identical, with no known differences in their biological activity or how well they are absorbed and used by the body.
• Sodium ascorbate: Sodium ascorbate is an organic sodium salt. It’s considered a “buffered” form of vitamin C because it is less acidic than ascorbic acid. It is often used in supplements and is gentler on the stomach.
• Calcium ascorbate: Sodium ascorbate and calcium ascorbate are the most common buffered forms of vitamin C. It’s less acidic and easier on the digestive system.
• Ascorbyl palmitate: Ascorbyl palmitate is a fat-soluble form of vitamin C easily absorbed by the body. It has all the same benefits as the water-soluble vitamin C forms. It is also a powerful antioxidant that protects fats in the body from damage and fights free radicals. It is widely used in skin care products.

Supplements

Vitamin C supplements come in various forms, including tablets, capsules, chewables, gummies, dissolving powders, liquid forms, and liposomal options. These include unencapsulated versions, traditional without added fats, and encapsulated forms such as liposomal. A liposome is a fatty, spherical vessel that transports microscopic particles in the body.

The efficacy of liposomal vitamin C absorption in terms of synthetic sources is also contested. A 2021 study concluded that liposomal vitamin C was 1.77 times more bioavailable than non-liposomal vitamin C. Some health authorities continue to recommend traditional vitamin C supplementation. In addition, the absorption rate of oral vitamin C is comparatively low.

When opting for a synthetically derived traditional form of vitamin C, make sure it is buffered with minerals, such as calcium and magnesium. Buffering helps prevent potential irritation in the gastrointestinal tract caused by acidity. Moreover, it should be fully reduced to avoid oxidation. Synthetic vitamin C production necessitates a nitrogen blanket (nitrogen gas) to prevent oxidation, ensuring that the supplement remains fully reduced and retains its efficacy.

Synthetic forms of vitamin C are commonly derived from corn, including liposomal vitamin C. Therefore, if you have allergies or sensitivities to corn or gluten, verify the source of the vitamin. Furthermore, if you wish to steer clear of genetically modified organisms (GMOs), carefully check the origin of the synthetic vitamin C used in the supplement since corn is often genetically modified.

Contraindications

Vitamin C supplementation also has contraindications. Supplementation is not recommended for individuals with certain blood disorders such as thalassemia, G6PD deficiency, sickle cell disease, and hemochromatosis. It’s also advised to avoid taking vitamin C supplements around the time of angioplasty procedures.

It’s also advisable to avoid high doses of vitamin C supplements during pregnancy, as they may result in vitamin C deficiency in the newborn following birth.

Intravenous Supplementation

Vitamin C can be administered intravenously (IV) in medically supervised settings to achieve higher levels in the bloodstream. This approach can improve the quality of life in people with advanced-stage cancers.

The gastrointestinal (GI) tract obtains most of its nutrition from oral intake. Therefore, IV vitamin C, which bypasses the GI tract, can begin to weaken. Thus, IV vitamin C isn’t a long-term solution, but it may be helpful in acute situations.

Vitamin C is also available in topical skin care products, such as serums, creams, and transdermal patches. Such products are popular due to the naturally high levels of vitamin C in healthy skin.

Vitamin C stimulates collagen production and shields against UV damage. In a 2015 study, participants who used a vitamin C-loaded dissolving microneedle patch with an anti-wrinkle effect for three months showed a significant improvement in skin texture and appearance without experiencing cumulative skin irritation or sensitization. The researchers believed that this patch could be effectively used in anti-wrinkle cosmetics.

Yet research indicates that topical vitamin C products, in general, may offer limited advantages since only a small amount can permeate the skin, providing no extra benefits if one already gets sufficient vitamin C from their diet or supplements. Also, since sunlight reduces vitamin C in your skin, it’s better to apply topical vitamin C after sun exposure rather than before.

The dietary reference intakes (DRIs) from the Food and Nutrition Board (FNB) at the Institute of Medicine provide intake recommendations for vitamin C and other nutrients.

The recommended dietary allowances (RDAs) for vitamin C are based on the amount of vitamin C believed to provide antioxidant protection, with the understanding that there are “wide uncertainties in the data utilized to estimate the vitamin C requirements.”

A 2012 study’s researchers concluded that 200 milligrams per day is the optimal dietary intake of vitamin C for most adults. This will maximize health benefits and lower the risk of heart disease, cancer, eye diseases, and neurodegenerative conditions. Eating five servings of fruits and vegetables daily can supply over 200 milligrams of vitamin C.

No definitive test consistently and reliably detects vitamin C deficiency, which is one reason it is underdiagnosed.

Vitamin C levels differ between serum, plasma, and body tissues. In the bloodstream, vitamin C levels typically range from 0.4 to 1.7 milligrams per deciliter, but concentrations in tissues can vary widely and are usually higher. Red blood cells can contain vitamin C levels approximately 80 times greater than those found in the blood. However, lymphocytes offer the most accurate assessment, as lymphocytic vitamin C levels remain relatively stable, unaffected by daily rhythms or diet changes.

Doctors can use plasma tests and leukocyte vitamin C assays to measure vitamin C levels. Doctors often recommend these tests to check for vitamin C deficiency and begin treatment if symptoms are present. The tests provide insight into cardiovascular, immune, and nutritional health. Measuring leukocyte vitamin C concentration might offer more precise indications of tissue vitamin C levels than plasma tests.

While plasma vitamin C concentration reflects recent dietary intake, the vitamin C level in leukocytes (white blood cells) is a better indicator of the body’s vitamin C stores. The leukocyte vitamin C assay is designed to determine the concentration of vitamin C inside white blood cells. It involves isolating leukocytes from a blood sample, treating them with a reducing agent to release intracellular vitamin C, and then quantifying the vitamin C concentration, typically using colorimetric or fluorometric methods.

As a water-soluble vitamin, vitamin C is generally safe at high doses with low toxicity. The main side effects of vitamin C excess (aka, toxicity) include diarrhea, nausea, abdominal cramps, and other digestive issues.

The upper limits for vitamin C intake are the same for both sexes and are as follows:

• Birth to 12 months: unestablished
• 1 to 3 years: 400 milligrams
• 4 to 8 years: 650 milligrams
• 9 to 13 years: 1,200 milligrams
• 14 to 18 years: 1,800 milligrams
• 14 to 18 years (pregnancy): 1,800 milligrams
• 14 to 18 years (lactation): 1,800 milligrams
• Over 19 years: 2,000 milligrams
• Over 19 years (pregnancy): 2,000 milligrams
• Over 19 years (lactation): 2,000 milligrams

These ULs don’t apply to individuals receiving vitamin C for medical treatment.

Before taking vitamin C supplements, inform your doctor of all your current medications and dietary supplements. At least 30 medications reportedly interact with vitamin C. Some examples include:

• Aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs): These medicines can decrease the amount of vitamin C in your body by increasing its loss through urine. Conversely, high doses of vitamin C can lead to higher levels of these drugs in your bloodstream.
• Oral contraceptives and hormone replacement therapy (HRT): When taken with birth control pills and HRT, vitamin C can cause an increase in estrogen levels.
• Acetaminophen: High doses of vitamin C can reduce the amount of acetaminophen excreted in urine, potentially increasing the levels of this drug in your bloodstream.
• Certain antibiotics: Taking vitamin C with antibiotics tetracycline, minocycline, and doxycycline might increase their levels in the body. However, they can also reduce the effectiveness of vitamin C.
• Barbiturates: Barbiturates such as phenobarbital, pentobarbital, and seconobarbital can reduce vitamin C’s effectiveness.
• Aluminum-containing antacids: Vitamin C can enhance the absorption of aluminum from these medications, potentially intensifying their side effects.
• Warfarin: Vitamin C has occasionally been reported to interfere with the effectiveness of the blood-thinning medication warfarin.