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Vitamin C Guide

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Vitamin C Guide

What is Vitamin C?

Vitamin C, also known as ascorbic acid, is a water-soluble vitamin that plays a vital role in numerous body functions. It's required for the synthesis of collagen, certain neurotransmitters, and protein metabolism. Vitamin C is also a powerful antioxidant that protects your cells against damage from free radicals.

Biochemistry of Vitamin C

Vitamin C exists in two forms: L-ascorbic acid (reduced form) and L-dehydroascorbic acid (oxidized form). Both are biologically active and easily absorbed by the body. Unlike most animals, humans cannot synthesize vitamin C, making dietary intake essential.

Recommended Daily Intake

The recommended daily allowance (RDA) for vitamin C:

  • Infants (0-12 months): 40-50 mg
  • Children (1-13 years): 15-45 mg
  • Adolescents (14-18 years): 65-75 mg
  • Adults (19+ years): 75-90 mg
  • Pregnant women: 85 mg
  • Breastfeeding women: 120 mg
  • Smokers: Add 35 mg to above values

Key Benefits

  • Supports immune system function and helps fight infections
  • Essential for collagen production, promoting skin health and wound healing
  • Powerful antioxidant that protects cells from free radical damage
  • Improves iron absorption from plant-based foods
  • May reduce risk of chronic diseases like heart disease
  • Supports healthy gums and teeth
  • Helps maintain cartilage, bones, and blood vessels
  • Involved in protein metabolism and neurotransmitter production

Deficiency Symptoms

Vitamin C deficiency can lead to a condition called scurvy. Early symptoms include:

  • Fatigue and weakness
  • Muscle and joint pain
  • Easy bruising and bleeding gums
  • Dry, rough skin and poor wound healing
  • Swollen, bleeding gums and loose teeth
  • Corkscrew hairs (hair that grows in a spiral pattern)
  • Iron deficiency anemia (due to reduced iron absorption)
  • Weakened immune system and frequent infections

Risk Factors for Deficiency

Certain groups are at higher risk of vitamin C deficiency:

  • Smokers and those exposed to secondhand smoke (require more vitamin C)
  • People with malabsorption disorders (Crohn's disease, ulcerative colitis)
  • Those with limited food variety or poor diets
  • People with certain types of cancer and undergoing treatments
  • Heavy alcohol users
  • Elderly people with limited diet variety

Food Sources

  • Citrus Fruits:
    • Orange (1 medium): 70 mg
    • Grapefruit (1/2 fruit): 39 mg
    • Lemon (1 fruit): 31 mg
    • Lime (1 fruit): 20 mg
    • Mandarin (1 fruit): 26 mg
  • Berries:
    • Strawberries (1 cup): 85 mg
    • Raspberries (1 cup): 32 mg
    • Blueberries (1 cup): 14 mg
    • Blackberries (1 cup): 30 mg
    • Cranberries (1 cup): 14 mg
  • Tropical Fruits:
    • Guava (1 fruit): 126 mg
    • Papaya (1 cup): 88 mg
    • Pineapple (1 cup): 79 mg
    • Mango (1 cup): 60 mg
    • Kiwi (1 medium): 64 mg
  • Vegetables:
    • Bell peppers, red (1 cup): 190 mg
    • Broccoli, raw (1 cup): 81 mg
    • Brussels sprouts (1 cup): 75 mg
    • Cauliflower (1 cup): 52 mg
    • Sweet potato (1 medium): 22 mg
  • Leafy Greens:
    • Kale (1 cup): 80 mg
    • Spinach (1 cup): 14 mg
    • Mustard greens (1 cup): 39 mg
    • Swiss chard (1 cup): 31 mg
    • Watercress (1 cup): 14 mg
  • Herbs and Spices:
    • Thyme (1 tbsp): 3.8 mg
    • Parsley (1 cup): 79 mg
    • Basil (1 cup): 8 mg
    • Cilantro (1 cup): 27 mg
  • Other Sources:
    • Tomatoes (1 medium): 17 mg
    • Green peas (1 cup): 40 mg
    • Fortified juices: 60-120 mg per cup
    • Fortified cereals: 20-40 mg per serving
Note: The recommended daily intake is 65-90 mg for adults. Values listed are approximate and may vary based on ripeness and preparation method.

Stability & Storage

Vitamin C is one of the least stable vitamins:

  • Sensitive to heat (cooking can destroy up to 60%)
  • Degrades with exposure to oxygen (cut fruits lose vitamin C quickly)
  • Water-soluble (leaches into cooking water)
  • Damaged by prolonged storage and alkaline environments
Tip: To maximize vitamin C content, consume fruits and vegetables fresh, store them properly, and use minimal water and cooking time when preparing them.

Supplement Information

Vitamin C supplements are available as:

  • Ascorbic acid (most common and economical form)
  • Sodium ascorbate (less acidic, gentler on the stomach)
  • Calcium ascorbate (often marketed as "buffered" vitamin C)
  • Time-released vitamin C
  • Vitamin C with bioflavonoids
Upper Limit: The tolerable upper intake level for adults is 2,000 mg per day. Higher doses may cause digestive issues, including diarrhea and stomach cramps.

Special Considerations

Vitamin C and the Common Cold

While vitamin C cannot prevent colds, research suggests it may reduce the duration and severity of symptoms by about 8% in adults and 14% in children. Regular supplementation seems more effective than taking vitamin C after cold symptoms begin.

Vitamin C and Iron Absorption

Vitamin C significantly enhances the absorption of non-heme iron (found in plant foods). Consuming vitamin C-rich foods alongside iron-rich plant foods can help vegetarians and vegans meet their iron needs.

Interactions and Contraindications

Be cautious with vitamin C if you have:

  • Hemochromatosis or other iron overload disorders
  • History of kidney stones (high-dose vitamin C may increase risk)
  • G6PD deficiency (high-dose supplements may cause hemolysis)

Vitamin C may interact with certain medications, including chemotherapy drugs, blood thinners, estrogen, and certain antibiotics.

Take Our Vitamin Test

Concerned about a possible vitamin C deficiency? Our comprehensive vitamin deficiency test can help identify potential nutritional gaps based on your symptoms.

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Benefits of Vitamin C

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Recommended Daily Intake

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