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Water-Soluble Vitamins:

Vitamin C (Ascorbic Acid):

Function: Boosts the immune system, aids in collagen synthesis (important for skin, bones, and tissues), and acts as an antioxidant.

Sources: Citrus fruits, strawberries, bell peppers, broccoli

RDA: Men: 90 mg/day. Women: 75 mg/day. Pregnancy: 85 mg/day. Lactation: 120 mg/day.

Deficiency (Scurvy): Adults: 100–300 mg daily until symptoms resolve (usually within weeks).

Therapeutic Uses: High doses (e.g., up to 2 g/day) are sometimes used in oxidative stress conditions but should be monitored to avoid gastrointestinal side effects.

Vitamin B1 (Thiamine):

Function: Supports energy production and the nervous system.

Sources: Whole grains, nuts, seeds, pork.

RDA: 1.2 mg/day for men; 1.1 mg/day for women.

Deficiency or Wernicke’s encephalopathy: 100–500 mg IV or IM daily for several days.

Vitamin B2 (Riboflavin):

Function: Helps convert food into energy and supports healthy skin and eyes.

Sources: Dairy products, eggs, leafy green vegetables.

RDA: 3 mg/day for men; 1.1 mg/day for women.

Vitamin B3 (Niacin):

Function: Supports digestion, skin health, and the nervous system.

Sources: Poultry, fish, peanuts, mushrooms.

RDA: 16 mg/day for men; 14 mg/day for women3.

Vitamin B5 (Pantothenic Acid):

Function: Helps with the production of hormones and cholesterol.

Sources: Avocados, sweet potatoes, whole grains.

Vitamin B6 (Pyridoxine):

Function: Vital for brain development, immune function, and red blood cell production.

Sources: Bananas, chickpeas, potatoes, poultry.

RDA: 1.3 mg/day for adults; increases to 1.9–2.0 mg/day during pregnancy and lactation.

Deficiency: 50–100 mg daily.

Peripheral neuropathy etc up to 200 mg/day.

Vitamin B7 (Biotin):

Function: Supports healthy hair, skin, and nails; aids in energy metabolism.

Sources: Eggs, almonds, spinach.

Vitamin B9 (Folate/Folic Acid):

Function: Crucial for DNA synthesis and cell division, especially during pregnancy.

Sources: Leafy greens, beans, fortified cereals.

RDA:: 400 mcg/day; increases to 600 mcg/day during pregnancy.

Deficiency or pregnancy: 400–1,000 mcg daily.

Vitamin B12 (Cobalamin):

Function: Essential for red blood cell formation, DNA synthesis, and nerve function.

Sources: Meat, fish, dairy, fortified plant-based alternatives.

RDA: 2.4 mcg/day; increases to 2.6–2.8 mcg/day during pregnancy and lactation.

Deficiency or pernicious anemia: 1,000 mcg IM daily for a week, then weekly for a month, followed by monthly maintenance.

Fat-Soluble Vitamins:

Vitamin A:

Function: Supports vision, immune health, and skin cell production.

Sources: Carrots, sweet potatoes, spinach, fish liver oil.

RDA: 900 mcg/day for men; 700 mcg/day for women. Pregnant Women: 770 mcg/day. Lactating Women: 1,300 mcg/day.

Deficiency Treatment: Adults: 200,000 IU orally for 2 consecutive days, followed by 200,000 IU after 2 weeks. Children: Doses are weight-based, typically ranging from 50,000 IU to 200,000 IU.

Toxicity Risk: Chronic intake above 10,000 IU/day can lead to hypervitaminosis A.

Vitamin D:

Function: Helps the body absorb calcium and phosphorus for bone health; supports the immune system.

Sources: Sunlight, fortified dairy, salmon, eggs.

RDA: Adults: 15 mcg (600 IU)/day; increases to 20 mcg (800 IU)/day for adults over age 70.

Deficiency Treatment: Adults with severe deficiency (<12 ng/mL): High-dose therapy: 50,000 IU weekly for 6–12 weeks or equivalent daily dosing (e.g., ~7,000 IU/day). Maintenance dose: 800–2,000 IU/day depending on levels and risk factors.

Special Populations: patients with malabsorption or obesity may require higher doses (up to 10,000 IU/day).

Children: Severe deficiency: Up to 2,000–4,000 IU/day depending on age1.

Vitamin E:

Function: Acts as an antioxidant to protect cells from damage.

Sources: Nuts, seeds, vegetable oils, spinach.

RDA: Adults: 15 mg (22.4 IU)/day. Upper limit from supplements or fortified foods: 1,000 mg (1,500 IU)/day.

Deficiency treatment: Adults: Typically treated with alpha-tocopherol at doses of 400–800 IU/day.

Therapeutic Uses: Neurological disorders or oxidative stress conditions may require higher doses but should not exceed the upper limit of ~1,500 IU/day due to bleeding risks.

Vitamin K:

Function: Important for blood clotting and bone metabolism.

Sources: Kale, broccoli, Brussels sprouts.

RDA: Men (19+ years): 120 mcg/day. Women (19+ years): 90 mcg/day. Adequate Intake levels vary by age and sex, starting from 2 mcg/day in infants to higher levels in adults.

Deficiency or Bleeding Disorders: Adults: Phytonadione (Vitamin K1) is given at doses of 1–10 mg orally or subcutaneously depending on severity.

Warfarin Reversal: emergency reversal may require higher doses (e.g., up to 10 mg IV).

Newborns: standard prophylaxis is a single injection of Vitamin K1 (0.5–1 mg IM) at birth.

Comments

Each vitamin plays a unique role, and a balanced diet can help ensure getting the right amounts.

RDA’s are US ‘recommended daily allowances’ intended to meet the needs of nearly all healthy individuals and may vary based on age, sex, and life stage.

Therapeutic doses should always be individualized based on specific conditions and monitored by healthcare professionals.

Excessive supplementation can lead to toxicity; therefore, adherence to guidelines is crucial.