What is vitamin C?
Vitamin C, also known as L-ascorbic acid, is a water-soluble vitamin that is naturally present in some foods, added to others, and available as a dietary supplement. Humans, unlike most animals, are unable to synthesize vitamin C endogenously, so it is an essential dietary component.
Vitamin C is required for the biosynthesis of collagen, L-carnitine, and certain neurotransmitters; vitamin C is also involved in protein metabolism. Collagen is an essential component of connective tissue, which plays a vital role in wound healing. Vitamin C is also an important physiological antioxidant and has been shown to regenerate other antioxidants within the body, including alpha-tocopherol (vitamin E). Ongoing research is examining whether vitamin C, by limiting the damaging effects of free radicals through its antioxidant activity, might help prevent or delay the development of certain cancers, cardiovascular disease, and other diseases in which oxidative stress plays a causal role. In addition to its biosynthetic and antioxidant functions, vitamin C plays an important role in immune function and improves the absorption of nonheme iron, the form of iron present in plant-based foods. Insufficient vitamin C intake causes scurvy, which is characterized by fatigue or lassitude, widespread connective tissue weakness, and capillary fragility.
The intestinal absorption of vitamin C is regulated by at least one specific dose-dependent, active transporter. Cells accumulate vitamin C via a second specific transport protein. In vitro studies have found that oxidized vitamin C, or dehydroascorbic acid, enters cells via some facilitated glucose transporters and is then reduced internally to ascorbic acid. The physiologic importance of dehydroascorbic acid uptake and its contribution to overall vitamin C economy is unknown.
Oral vitamin C produces tissue and plasma concentrations that the body tightly controls. Approximately 70%–90% of vitamin C is absorbed at moderate intakes of 30–180 mg/day. However, at doses above 1 g/day, absorption falls to less than 50% and absorbed, unmetabolized ascorbic acid is excreted in the urine. Results from pharmacokinetic studies indicate that oral doses of 1.25 g/day ascorbic acid produce mean peak plasma vitamin C concentrations of 135 micromol/L, which are about two times higher than those produced by consuming 200–300 mg/day ascorbic acid from vitamin C-rich foods. Pharmacokinetic modeling predicts that even doses as high as 3 g ascorbic acid taken every 4 hours would produce peak plasma concentrations of only 220 micromol/L.
The total body content of vitamin C ranges from 300 mg (at near scurvy) to about 2 g. High levels of vitamin C (millimolar concentrations) are maintained in cells and tissues, and are highest in leukocytes (white blood cells), eyes, adrenal glands, pituitary gland, and brain. Relatively low levels of vitamin C (micromolar concentrations) are found in extracellular fluids, such as plasma, red blood cells, and saliva.
The following doses have been studied in scientific research:
By mouth -
By mouth -
- General: The daily recommended dietary allowances (RDAs) are: 90 mg for men and 75 mg for women; Pregnancy and Lactation: age 18 or younger, 115 mg; ages 19 to 50 years 120 mg. People who use tobacco should take an additional 35 mg per day. Do not take more than the following amounts of vitamin C: 1800 mg per day for adolescents and pregnant and breast-feeding women 14 to 18 years, and 2000 mg per day for adults and pregnant and lactating women.
- For vitamin C deficiency: 100-250 mg once or twice daily for several days for scurvy.
- For improving iron absorption: 200 mg of vitamin C per 30 mg of iron.
- For age-related vision loss (age-related macular degeneration; AMD): 500 mg of vitamin C, 400 IU of vitamin E, and 15 mg of beta-carotene, with or without 80 mg of zinc, per day for up to 10 years.
- For treating the common cold: 1-3 grams daily.
- For preventing a chronic pain condition called complex regional pain syndrome: 500 mg of vitamin C each day for 50 days starting right after the injury.
- For increased protein in the urine (albuminuria): 1250 mg of vitamin C with 680 IU of vitamin E per day for 4 weeks has been used.
- For irregular heartbeat (atrial fibrillation): 1-2 grams of vitamin C per day for 1-3 days before heart surgery followed by 1-2 grams in two divided doses daily for 4-5 days after heart surgery has been used.
- For upper airway infections caused by heavy exercise: 600 mg to 1 gram of vitamin C per day for 3-8 weeks before heavy exercise has been used.
- For stomach inflammation (gastritis).: 1200 mg of vitamin C daily along with omeprazole has been used.
- For abnormal breakdown of red blood cells (hemolytic anemia): 200-300 mg of vitamin C three times per week for 3-6 months has been used.
- For high blood pressure: 500 mg of vitamin C per day along with blood pressure-lowering medication has been used.
- For helping medicines used for chest pain work longer: 3-6 grams of vitamin C daily has been used.
- For osteoarthritis: 1 gram of vitamin C in the form of calcium ascorbate daily for 2 weeks has been used.
- For preventing sunburn: 2 grams of vitamin C along with 1000 IU vitamin E taken before sun exposure has been used.
- For high cholesterol: 500 mg vitamin C each day for at least 4 weeks.
Applied to skin:
- For skin redness/rash: A formulation containing 10% vitamin C, 2% zinc sulfate, and 0.5% tyrosine applied daily for 8 weeks has been used.
- For wrinkled skin: Most topical preparations used for aged or wrinkled skin are applied daily. Studies have used creams containing 3% to 10% vitamin C. In one study a specific vitamin C formulation (Cellex-C High Potency Serum) used 3 drops applied daily to areas of facial skin. Don't apply vitamin C preparations to the eye or eyelids. Also avoid contact with hair or clothes. It can cause discoloration.
Here are some proven benefits of taking the vitamin C supplement.
Strong Antioxidant That May Reduce the Risk of Chronic Diseases
- Vitamin C is a strong 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
May Help Battle High Blood Pressure
Studies have shown that vitamin C may help lower blood pressure in those both 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, on average, reduced systolic blood pressure (upper value) by 3.84 mmHg and diastolic blood pressure (lower value) by 1.48 mmHg in healthy adults.
In adults with existing high blood pressure, vitamin C supplements reduced systolic blood pressure by 4.85 mmHg and diastolic blood pressure by 1.67 mmHg, on average. While these results are promising, it’s not clear if the effects on blood pressure are long-term. Moreover, people with high blood pressure should not rely on vitamin C alone for treatment.
Prevent and Treat the Common Cold
It is a common practice to increase vitamin C intake during the winter months to prevent the common cold and flu.
Helps prevent anemia
Vitamin C can enhance iron absorption to help prevent iron-deficiency anemia. In fact, a study published in the American Journal of Clinical Nutrition found that taking vitamin C with a meal was able to increase iron absorption by up to 67 percent. For best results, combine a serving of iron-rich foods with some foods with vitamin C to bump up your iron intake.
Could Reduce Blood Uric Acid Levels and Help Prevent Gout Attacks
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 of 1,387 men found that people 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 see if vitamin C intake was linked to developing gout. Interestingly, people who took a vitamin C supplement had a 44% lower gout risk. Additionally, an analysis of 13 clinical studies found that taking a vitamin C supplement over 30 days significantly reduced blood uric acid, compared to a placebo. While there appears to be a strong link between vitamin C intake and uric acid levels, more studies on the impact of vitamin C on gout are needed.
Boosts Immunity by Helping White Blood Cells Function Better
One of the main reasons people take vitamin C supplements is to boost their immunity. 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 infections.
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 is actively transported to the skin where it can act as an antioxidant and help strengthen the skin’s barriers
Improves Heart Health
Your heart is absolutely essential to overall health. As one of the most important organs in your body, your heart works tirelessly to supply your cells with oxygen and nutrients by pumping blood through your veins.
Incorporating more vitamin C foods into your diet may help protect the health of your heart and prevent heart disease. A review from the National University of Health Sciences made up of 13 studies showed that supplementing with 500 milligrams of vitamin C daily significantly reduced levels of LDL cholesterol and triglycerides. Similarly, another human study from the University of Southampton found that a higher intake of vitamin C was associated with a lower risk of death from stroke or coronary heart disease.
Promotes Glowing Skin
Ascorbic acid, or vitamin C, is a common ingredient found in a wide assortment of skin care products and cosmetics alike. Thanks to its antioxidant content, vitamin C benefits skin health through several different mechanisms.
Because it’s involved in the synthesis of collagen, vitamin C is believed to help reverse skin aging and can also protect against skin damage and free radical formation caused by ultraviolet exposure. Plus, there may also be some vitamin C benefits for skin lightening and hyperpigmentation; studies have shown that vitamin C may help suppress melanin production to prevent dark spots and patches.
Effective for Vitamin C deficiency
Taking vitamin C by mouth or injecting as a shot prevents and treats vitamin C deficiency, including scurvy. Also, taking vitamin C can reverse problems associated with scurvy.
Taking Vitamin C is also possibly effective for:
- Age-related vision loss (age-related macular degeneration; AMD)
- Increasing protein in the urine (albuminuria)
- Irregular heartbeat (atrial fibrillation)
- For emptying the colon before a colonoscopy
- A chronic pain condition called complex regional pain syndrome
- Redness (erythema) after cosmetic skin procedures.
- Upper airway infections caused by heavy exercise.
- Stomach inflammation (gastritis).
- Abnormal breakdown of red blood cells (hemolytic anemia)
- High blood pressure
- High cholesterol
- Lead poisoning
- Helping medicines used for chest pain work longer
- Physical performance
- Wrinkled skin