Vitamin C - Ascorbic Acid

Vitamin C is a water-soluble nutrient essential for collagen synthesis, immune function, and antioxidant defence. It supports tissue repair, iron absorption, and neurotransmitter production while neutralising free radicals linked to chronic diseases like heart disease and cancer. Research suggests adequate intake may reduce oxidative stress and improve skin health, though high-dose supplementation’s benefits remain debated. Unlike most animals, humans cannot produce vitamin C internally, making dietary sources or supplements crucial.

Key Facts

  • Daily requirements: 90 mg for men and 75 mg for women, with smokers needing an additional 35 mg due to increased oxidative stress.
  • Found abundantly in citrus fruits, bell peppers, broccoli, and strawberries.
  • Enhances nonheme iron absorption from plant-based foods, aiding iron deficiency prevention.
  • Severe deficiency causes scurvy, which is marked by fatigue, bleeding gums, and poor wound healing.
  • Oral supplements are generally safe but may cause digestive discomfort at doses exceeding 2,000 mg/day.
  • Pharmacokinetic studies show plasma concentration plateaus at ~200 µmol/L, limiting benefits of mega-dosing.

What does the research say about vitamin C and its function in the body?

Vitamin C acts as a cofactor for enzymes involved in collagen production, carnitine synthesis, and neurotransmitter regulation. Studies highlight its antioxidant role in reducing oxidative damage, though evidence for disease prevention remains mixed. For example, trials like SU.VI.MAX showed modest cancer risk reduction in men with low baseline levels, while others found no cardiovascular benefits in well-nourished populations.

What are the primary food sources of vitamin C?

Citrus fruits (oranges, grapefruits), strawberries, kiwi, bell peppers, and dark leafy greens like spinach and kale are rich sources. Cooking can degrade vitamin C, so raw or lightly steamed preparations preserve the content best.

How can I supplement vitamin C?

Supplements come as tablets, chewables, or effervescent powders, typically containing ascorbic acid. Liposomal formulations and intravenous high-dose therapies are also used, though evidence for their superiority over oral routes is limited. Always consult a healthcare provider before starting high-dose regimens.

What are the main symptoms of vitamin C deficiency?

Early signs include fatigue and irritability, progressing to scurvy with symptoms like swollen gums, joint pain, and anaemia. Chronic deficiency weakens connective tissues, leading to bruising and slow wound healing.

Are there any known side effects of supplementing vitamin C?

Excess intake (over 2,000 mg/day) may cause diarrhoea, nausea, or abdominal cramps. Long-term high doses increase kidney stone risk in susceptible individuals and can interfere with blood glucose tests.

How long does it take to see the benefits of vitamin C supplementation?

Plasma levels saturate within 1–2 weeks of consistent intake, with scurvy symptoms resolving in similar timeframes. Antioxidant effects and immune support may become noticeable within days, though disease prevention benefits require long-term adherence.

What should consumers look for on the supplement label when supplementing vitamin C?

Opt for ascorbic acid or sodium ascorbate forms, and check for third-party certifications (e.g., USP, NSF). Avoid products with unnecessary additives or sugars. Dosages should align with recommended daily allowances unless medically advised.

Can vitamin C boost immunity during colds?

While regular supplementation may slightly reduce cold duration in active individuals or those under physical stress, it doesn’t prevent infections. Doses above 200 mg/day show diminishing returns due to absorption limits.

Does topical vitamin C benefit skin health?

Yes. Serums with L-ascorbic acid can reduce UV-induced damage and improve collagen synthesis, though stability and formulation affect efficacy. Pairing with vitamin E enhances antioxidant effects.

Are there drug interactions with vitamin C supplements?

High doses may reduce the effectiveness of chemotherapy drugs like bortezomib or statins. Conversely, they can increase aluminium absorption from antacids. Consult a doctor if taking warfarin or estrogen therapies.

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