Six Different Forms of Vitamin C and Their Uses

This article covers:

• How common is vitamin C deficiency?

• How to measure vitamin C levels in the body

• Ascorbic acid

• Ascorbic acid and vitamin C metabolites (Ester-C®)

• Vitamin C with bioflavonoids

• Liposomal vitamin C

• Ascorbyl palmitate

• Rosehip vitamin C

• Is vitamin C safe?

Vitamin C, also known as ascorbic acid, is one of the most researched vitamins over the past 50 years. A search of scientific literature shows that there have been over 65,000 studies on vitamin C in the past century.

Many scientists believe that humans once had the ability to produce vitamin C, but due to a genetic mutation (in the L-gulonolactone oxidase gene), we have lost this ability over time. Essentially, all animals, including most mammals, can produce vitamin C, except for humans, monkeys, guinea pigs, and some bats, birds, and fish. Therefore, humans must obtain vitamin C through their diet.

Currently, the recommended daily allowance (RDA) for vitamin C is 90 mg/day for men and 75 mg/day for women. Smokers are 400% more likely to be deficient in vitamin C due to excessive oxidation caused by cigarettes, and they require more vitamin C to maintain healthy levels. The concentration of vitamin C in the brain and adrenal glands is particularly high, being 15 to 50 times greater than that in the blood. Vitamin C has antioxidant properties and serves as a cofactor for at least eight important biochemical reactions.

While the standard RDA is sufficient to prevent severe vitamin C deficiency diseases like scurvy, it is inadequate to achieve other presumed health benefits, including promoting a stronger immune system and cardiovascular, brain, and skin health. Some suggest that this ultra-low intake of vitamin C should be at least 200 mg per day to optimize all the benefits of vitamin C.

How common is vitamin C deficiency?

According to a 2004 study of Americans, 14% of men and 10% of women have vitamin C deficiency. Additionally, up to 6% of children aged 12 to 17 do not have enough vitamin C. Among the population aged 25 to 64, 17% of men and 12% of women have insufficient vitamin C levels in their blood. A 1999 study in the UK found that 33% of individuals aged 65 and older had inadequate vitamin C intake.

A 2009 study published in the American Journal of Clinical Nutrition found that over 7% of participants aged 6 and older were vitamin C deficient after blood tests. More than half of the participants consumed too few vitamin C-rich foods.

I have also observed this in my clinic. Over the past five years, I have diagnosed three patients with scurvy; in the past, British sailors who had limited access to fresh fruits were often diagnosed with this disease. My first scurvy patient was a 40-year-old smoking woman (smokers have lower vitamin C levels) with poor dietary habits. She was concerned about bleeding gums and easy bruising. After her dentist confirmed she did not have gum disease, I had her blood tested, which confirmed vitamin C deficiency, leading to a diagnosis of scurvy. After taking vitamin C supplements for several weeks, her symptoms of bleeding gums and bruising improved. The initial symptoms of the other three patients were also noticeable bruising and bleeding gums.

How to measure vitamin C levels in the body

There are two main methods for measuring vitamin C levels in the body. The first is serum concentration. The normal range for women is 0.3-2.7 mg/dL, while for men, it is 0.2-2.1 mg/dL. The second method is to check the vitamin C content in white blood cells. Reference ranges depend on the laboratory.

Risk factors for vitamin C deficiency

• Poor dietary habits, including insufficient intake of fruits and vegetables

• Smoking (each cigarette oxidizes about 60 mg of vitamin C)

• Exposure to air pollutants

• Exposure to heavy metals (lead, mercury)

Symptoms of vitamin C deficiency

• Bruising

• Fatigue

• Depression

• Bleeding gums

• Joint pain

• Bone pain

• Muscle pain

• Swelling

Fruits that provide vitamin C

• Acerola cherries

• Avocado

• Guava

• Papaya

• Mango

• Orange

• Pineapple

• Cantaloupe

• Kiwi

• Strawberry

Vegetables that provide vitamin C

• Bell peppers

• Cabbage

• Broccoli

• Cauliflower

• Kale

• Brussels sprouts

• Potato

Health benefits of vitamin C

• Increases iron absorption, helping to treat anemia

• Collagen and skin health

• Heart health

• Immune system health

• Maintains memory

• Helps prevent periodontal disease

• Helps prevent upper respiratory infections/colds

• Helps prevent seizures

• Helps prevent sepsis (blood infection)

In addition to the above benefits, vitamin C appears to be beneficial for hospitalized patients, especially those in intensive care units. A 2019 meta-analysis of nutrients studied over 18 studies and more than 2,000 patients, showing that hospitalized patients receiving vitamin C had an 8% to 18% reduction in ICU stay compared to those not receiving vitamin C.

There are various formulations available for consumers.

1. Ascorbic acid

Ascorbic acid is the most commonly used and inexpensive form of vitamin C. However, its mildly acidic nature can cause digestive issues for some individuals, especially those with stomach acid problems. Many studies have used this form of vitamin C. Although ascorbic acid is synthetic, it is identical to the form found in nature. Research shows that only 30% of the dose is actually absorbed, prompting researchers to seek other formulations that may be better absorbed in the gastrointestinal tract. Ascorbic acid can be made into tablets, capsules, or powders. Below are mineral ascorbate salts.

• Calcium ascorbate – This formulation contains calcium (100 mg) and ascorbic acid (900 mg), aiming to optimize bone health and is recommended for those at risk of osteoporosis. According to a 2018 study, one of its advantages is that it is less irritating to the stomach while maintaining the same antioxidant capacity as ascorbic acid.

• Magnesium ascorbate – This formulation contains magnesium (50 to 100 mg) and 900 mg of ascorbic acid. It is a good choice for those taking magnesium-depleting medications (i.e., acid reducers and diuretics), patients with chronic headaches, or those who frequently experience leg cramps. Since magnesium deficiency can also increase the risk of palpitations or arrhythmias, vitamin C magnesium may be considered for those at risk.

• Sodium ascorbate – This formulation contains sodium (~100 mg) and 900 mg of ascorbic acid. Those on a low-salt diet should avoid this formulation. While most low-salt dieters should keep their total daily intake below 2,000 mg, even small amounts of salt can accumulate over time.

2. Ascorbic acid and vitamin C metabolites (Ester-C®)

Ascorbic acid and vitamin C metabolites (Ester-C®) is a patented formulation of calcium ascorbate discovered in the 1980s. It contains small amounts of vitamin C metabolites such as calcium threonate, calcium malate, lyxonate, and dehydroascorbic acid. Manufacturers claim that it helps improve absorption and leads to higher levels of vitamin C in the blood compared to regular ascorbic acid.

A 2008 study evaluated serum and white blood cell levels after taking calcium ascorbate and regular ascorbic acid. Both groups had the same serum ascorbic acid levels. However, patients taking the calcium ascorbate formulation had higher vitamin C levels in their white blood cells.

3. Vitamin C with bioflavonoids

Vitamin C is also combined with antioxidants known as bioflavonoids. Supporters of this formulation are attracted by the fact that vitamin C with bioflavonoids may be better absorbed. A 1988 study indicated that this might be the case. The study showed that the absorption rate of vitamin C with bioflavonoids was 35% higher than that of regular ascorbic acid formulations. This is also a better choice for those who may experience gastrointestinal symptoms from ascorbic acid.

4. Liposomal vitamin C

Liposomal vitamin C is a formulation that appears to optimize bioavailability or absorption characteristics. To enhance absorption, scientists have developed liposomal vitamin C, a fat-soluble coating that helps ascorbic acid molecules pass more easily through the digestive tract. Data shows that orally administered liposomal-encapsulated vitamin C results in higher blood concentrations than unencapsulated oral formulations like ascorbic acid, but lower than intravenous administration.

Additionally, a 2020 study showed that liposomal vitamin C could lower blood pressure in laboratory rats at lower doses.

5. Ascorbyl palmitate

This formulation converts the typically water-soluble vitamin C into a fat-soluble form. It is often added to topical vitamin C formulations so that it can be absorbed by the skin. It is also used as a suppository and food preservative. It is sometimes marketed as vitamin C ester but should not be confused with Ester-C.

6. Rosehip vitamin C

Vitamin C formulations containing rosehip typically include regular ascorbic acid. Rosehip is the fruit of the rose plant and contains a high amount of vitamin C that is well absorbed. Rosehip also contains many antioxidants, including lycopene, phenolics, flavonoids, tannins, and vitamin E.

Is vitamin C safe?

Vitamin C is considered safe across all formulations. The general dosage is up to 2000 mg per day, which is well tolerated. Unless taken in excess of 3000 mg daily, diarrhea or loose stools should not occur. However, if taken in large doses spread throughout the day, taking up to three times daily, digestive issues are less likely to occur.

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