Vitamin C, also known as L-ascorbic acid, is a water-soluble vitamin naturally present in foods, particularly in fresh fruits and vegetables. It is also added to foods as a nutritional supplement. Unlike most animals, humans cannot synthesize vitamin C on their own, making it an essential vitamin for the human body. Vitamin C is a common supplement during periods of colds and inflammation. In the past two years, amid the COVID-19 pandemic, vitamin C has become an essential health product for many families as a preventive measure and dietary supplement.
Health Effects of Vitamin C Deficiency
Vitamin C participates in numerous biochemical metabolic processes within the body, possesses antioxidant capabilities, and contributes to the normal functioning of the immune system[1].
In certain population groups, higher vitamin C consumption is required due to specific health conditions, and deficiency can occur. These conditions may include smoking, gastrointestinal diseases, cancer, and an unbalanced diet.
Vitamin C deficiency can lead to scurvy, characterized by symptoms such as anemia, gum bleeding, bruising, and poor wound healing[2].
During the current pandemic, many studies have explored the use of vitamin C in helping to treat COVID-19 patients, especially in cases involving inflammation and vascular damage[3].
Benefits of Vitamin C
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Boosting the Immune System
Due to its excellent antioxidant capabilities, vitamin C also plays a significant role in immune function. Research has shown that vitamin C can help prevent the onset of certain diseases, such as the common cold. Vitamin C can regulate B cells and T cells, has antibacterial and antiviral effects, and helps maintain the integrity of epithelial cells, which resist pathogens[4].
In a clinical study, subjects including marathon runners, skiers, and soldiers exposed to extreme physical exercise or cold environments were given additional vitamin C supplements ranging from 250 mg to 1000 mg daily. The study found that this reduced the incidence of colds by 50%[5]. Other research also indicates that vitamin C supplementation can shorten the duration of colds and alleviate symptoms[6].
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Cancer Prevention
Many studies have observed a negative correlation between dietary vitamin C intake and the risk of lung, breast, colon, stomach, oral, pharyngeal, and esophageal cancers, indicating the potential cancer-preventive properties of vitamin C[7][8].
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Cardiovascular Protection
Epidemiological studies have found that a high intake of fruits and vegetables is associated with a reduced risk of cardiovascular diseases, linked to antioxidant nutrients. In addition to its antioxidant properties, vitamin C can improve nitric oxide production, leading to vasodilation and reducing the death of vascular smooth muscle cells, thereby preventing atherosclerosis[9][10].
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Assisting Collagen Production
Vitamin C can stimulate the production of collagen, primarily types I and III collagen, whose synthesis decreases with age. Vitamin C can also inhibit melanin production and aid in wound healing[11][12].
When Is the Best Time to Take Vitamin C?
Vitamin C is best taken after meals as it helps with the absorption of iron. Additionally, vitamin C and Q10 both participate in collagen synthesis together, so taking it after a meal enhances the absorption of other nutrients.
Some individuals with sensitive stomachs may experience stomach pain and diarrhea when taking high-dose vitamin C on an empty stomach. For such people, it is advisable to avoid effervescent or chewable tablets and opt for time-release vitamin C, which extends the release and absorption time, preventing excessively high vitamin C levels in the gastrointestinal tract.
Are Vitamin C Effervescent Tablets Good?
While vitamin C effervescent tablets are convenient and tasty, they contain alkaline carbonates like sodium bicarbonate, potassium hydrogen carbonate, and baking soda to dissolve and create effervescence. The stomach’s digestive environment is acidic, so consuming alkaline effervescent drinks can neutralize stomach acid and affect the gastrointestinal tract, which may hinder digestion and absorption. If you are already prone to indigestion or have reduced digestive acid secretion, especially among the elderly population, gastrointestinal discomfort is more likely to occur.
Furthermore, the carbonated components in vitamin C effervescent tablets can contribute to tooth erosion. If you have periodontal or dental issues, it is advisable to choose alternative forms of vitamin C supplementation.
Which Fruits Are High in Vitamin C?
Vitamin C is abundant in natural fruits, and consuming at least one serving of fruit per day is an effective way to intake and supplement this essential nutrient. Below is the vitamin C content in each serving of fruits (measured per 100g):
- Guava: 130-220 mg
- Custard Apple: 100 mg
- Longan: 90-100 mg
- Jujube: 90-100 mg
- Kiwi: 70-90 mg
- Papaya: 70-80 mg
- Orange: 70-80 mg
- Strawberry: 70 mg
- Grapefruit: 50-60 mg
- Lemon: 30-40 mg
Three Key Points for Choosing Vitamin C
Choose High-Dosage Units
According to the Ministry of Health and Welfare’s recommendations, the daily recommended intake of vitamin C for an average adult is 100 mg, with an upper limit of 2000 mg. There are many high-dosage vitamin C supplements available on the market.
Most studies indicate that supplementing with high doses of 1000-4000 mg of vitamin C is very safe[13]. The regulatory standard for vitamin C added to capsule tablet products is 1000 mg daily, so when choosing products, you can opt for products with 1000 mg of vitamin C per serving[14].
Some studies have found that giving high doses of vitamin C can be helpful in cancer prevention and treatment[15]. Clinical research has shown that supplementing COVID-19 patients with high-dose vitamin C reduces the risk of death and improves oxygen levels in the body without adverse effects[16].
Therefore, it is recommended to choose high-dosage vitamin C products to maintain good health.
Choose Time-Release Formulas
When selecting high-dose vitamin C products, consider choosing time-release formulas. These provide slow and steady release of vitamin C in the body, reducing the risk of gastrointestinal irritation and diarrhea associated with high-dose vitamin C intake, and maintaining an effective concentration of vitamin C in the body[17].
Third-Party Testing
When selecting vitamin C products, make sure the brand has third-party testing reports, such as heavy metals, plasticizers, etc., to ensure that the product’s raw materials and production processes are not contaminated, guaranteeing good quality and providing peace of mind when choosing a product.
Top 5 Vitamin C Supplements in 2023
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Daiken Vitamin C
- Per Vitamin C Tablet: 500 milligrams
- Form: Slow-Time-release
- Quantity: 60 tablets
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Blackmores Vitamin C 1000
- Per Vitamin C Tablet: 1000 milligrams
- Form: Coated tablets
- Quantity: 60 tablets
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DHC Vitamin C
- Per Vitamin C Capsule: 500 milligrams
- Form: Hard capsules
- Quantity: 30 capsules
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Centrum Vitamin C
- Per Vitamin C Tablet: 500 milligrams
- Form: Chewable tablets
- Quantity: 30 tablets
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AjiouVitamin C High-Dose
- Per Vitamin C Tablet: 500 milligrams
- Form: Effervescent tablets
- Quantity: 60 tablets
Comparison Table for the Top 5 Vitamin C Supplements in 2023
| Brand | Daiken Vitamin C | Blackmores Vitamin C 1000 | DHC Vitamin C | Centrum Vitamin C | AjiouVitamin C High-Dose |
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| Per Vitamin C Tablet | 500 milligrams | 1000 milligrams | 500 milligrams | 500 milligrams | 500 milligrams |
| Form | Slow-release tablets | Coated tablets | Hard capsules | Chewable tablets | Effervescent tablets |
| Quantity | 60 tablets | 60 tablets | 30 capsules | 30 tablets | 60 tablets |
Most people find it challenging to get sufficient vitamin C from their regular diet, and in high-stress environments, vitamin C is depleted more rapidly. Vitamin C deficiency is a possibility for everyone, especially those with chronic diseases and unhealthy lifestyles. Therefore, it is recommended to use the information provided above to help you choose the right vitamin C supplement to meet your health needs.
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