Vitamins are organic compounds essential as micronutrients for numerous metabolic processes. They act as coenzymes, converting food to energy, building tissues, and maintaining organ function. A balanced diet rich in various whole foods is key to obtaining these vitamins.
Vitamins are categorized by their solubility: fat-soluble and water-soluble. This impacts their absorption, storage, and use by the body.
Fat-Soluble Vitamins
These vitamins (A, D, E, and K) dissolve in fat and are stored in body fat and the liver. Due to storage, excessive intake can be toxic.
Vitamin A
- Functions: Important for vision, immune function, reproduction, and cell growth.
- Food Sources: Sweet potatoes, carrots, spinach, beef liver.
- Deficiency: Can cause night blindness and increased infection risk.
Vitamin D
- Functions: Essential for calcium absorption, promoting bone health, and supporting the immune system.
- Food Sources: Sunlight exposure is the main source; also found in fatty fish, egg yolks, and fortified foods.
- Deficiency: Can lead to rickets in children and osteomalacia in adults.
Vitamin E
- Functions: Acts as an antioxidant, protects cells, and supports immune function and red blood cell formation.
- Food Sources: Nuts, seeds, vegetable oils, and leafy green vegetables.
- Deficiency: Rare, may cause nerve and muscle damage.
Vitamin K
- Functions: Necessary for blood clotting and bone health.
- Food Sources: Leafy green vegetables like kale and spinach.
- Deficiency: Can lead to easy bruising and excessive bleeding.
Water-Soluble Vitamins
These vitamins (C and the eight B-complex vitamins) dissolve in water and are not stored. Excess is excreted, requiring regular intake.
Vitamin C (Ascorbic Acid)
- Functions: An antioxidant vital for collagen production, wound healing, immune support, and iron absorption.
- Food Sources: Citrus fruits, bell peppers, strawberries, broccoli.
- Deficiency: Scurvy.
Vitamin B1 (Thiamine)
- Functions: Converts carbohydrates to energy and is important for nerve and heart function.
- Food Sources: Whole grains, pork, legumes.
- Deficiency: Beriberi.
Vitamin B2 (Riboflavin)
- Functions: Essential for energy production, cell growth, and red blood cell formation.
- Food Sources: Dairy products, eggs, lean meat.
- Deficiency: Can cause skin disorders and sore throat.
Vitamin B3 (Niacin)
- Functions: Helps convert food to energy and maintain healthy skin and nerves.
- Food Sources: Meat, poultry, fish, mushrooms.
- Deficiency: Pellagra.
Vitamin B5 (Pantothenic Acid)
- Functions: Metabolizes food and produces hormones.
- Food Sources: Meat, dairy, eggs, avocados.
- Deficiency: Rare, can cause fatigue and intestinal issues.
Vitamin B6 (Pyridoxine)
- Functions: Aids protein metabolism, red blood cell production, and brain function.
- Food Sources: Chickpeas, fish, poultry, bananas.
- Deficiency: Anemia and nerve damage.
Vitamin B7 (Biotin)
- Functions: Metabolizes fats, carbs, and proteins; supports hair, skin, and nail health.
- Food Sources: Egg yolk, liver, nuts.
- Deficiency: Can cause hair loss and skin problems.
Vitamin B9 (Folate/Folic Acid)
- Functions: Crucial for DNA/RNA synthesis and red blood cell formation; important in pregnancy.
- Food Sources: Leafy green vegetables, legumes, fortified grains.
- Deficiency: Anemia and birth defects.
Vitamin B12 (Cobalamin)
- Functions: Essential for nerve function, red blood cell production, and metabolism.
- Food Sources: Animal products and fortified foods.
- Deficiency: Anemia, nerve damage. Vegans and older adults are at higher risk.
Water-Soluble vs. Fat-Soluble Vitamins
| Feature | Water-Soluble Vitamins | Fat-Soluble Vitamins |
|---|---|---|
| Absorption | Dissolve and absorb readily in water. | Absorbed with dietary fats. |
| Storage | Not stored long; excess excreted in urine. | Stored in fatty tissue and liver. |
| Replenishment | Requires regular dietary intake. | Daily intake not strictly required. |
| Toxicity Risk | Low risk; excess is flushed out. | Higher risk due to accumulation. |
Conclusion: A Diverse Diet is Key
Each of the 13 essential vitamins plays a critical role in health. While supplements can help in specific cases like deficiency or pregnancy, a balanced diet is the best way to get all needed nutrients. Consuming a variety of whole foods supports body functions and protects against health issues. For dietary recommendations, consult sources like the NIH Office of Dietary Supplements.
