The Essential Guide to Vitamins: A, B, C, D, E, F, and K

Vitamins are vital nutrients that support various bodily functions, from maintaining eyesight to strengthening the immune system. In this comprehensive overview, we explore the key vitamins, their sources, roles, and how to ensure adequate intake for optimal health.

Vitamin A — Also called retinol, Vitamin A is found in foods like eggs, oily fish, and dairy products. It is essential for healthy skin and immune function. Its most famous role is supporting vision; it aids in light perception by interacting with the light-sensitive pigments in your retina. Deficiency, though rare in developed countries, can cause severe vision problems and blindness. Beta-carotene, present in colorful fruits and vegetables such as carrots, spinach, peppers, and pumpkin, is a precursor to Vitamin A, as your body converts it into the active form.

B Vitamins — This family includes eight distinct nutrients, each supporting critical functions like energy production and red blood cell formation. B1 (thiamine) helps nerve health and digestion, with deficiencies risking neurological issues like Wernicke-Korsakoff syndrome, especially in chronic alcohol users. B2 (riboflavin) and B3 (niacin) aid energy metabolism, while B9 (folate) and B12 (cobalamin) are crucial for red blood cell production and pregnancy health, preventing neural tube defects. Rich sources include beans, legumes, meats, fish, and dairy.

Vitamin C — Renowned for its role in immune support and tissue repair, Vitamin C, or ascorbic acid, is abundant in citrus fruits, strawberries, and vegetables like bell peppers. It promotes wound healing and maintains healthy blood vessels and bones. A deficiency leads to scurvy, characterized by fatigue, bruising, and gum disease.

Vitamin D — Essential for strong bones and teeth, Vitamin D is synthesized in the skin through sunlight exposure and obtained from foods like oily fish, eggs, and meats. Insufficient levels can result in soft, weak bones—rickets in children and osteomalacia in adults—leading to bone pain and deformities.

Vitamin E — An antioxidant that protects cells, supports vision, and boosts immunity, Vitamin E is found in nuts, seeds, and plant oils. It is generally easy to obtain through a varied diet.

Vitamin F (Omega Fatty Acids) — Not true vitamins, Omega-3 and Omega-6 fatty acids (like ALA and LA) are essential fats supporting brain function, reducing inflammation, and maintaining healthy skin and cell membranes.

Vitamin K — Critical for blood clotting, Vitamin K is found in leafy greens and grains. Deficiency is more common in children and can cause bleeding issues. Most adults meet their needs through a balanced diet.

The Food Powerhouse: Liver — Among various foods, liver stands out as the richest source of multiple vitamins, especially A, B, D, and K. However, it should be eaten in moderation to avoid Vitamin A toxicity, especially in pregnancy.

Maintaining a balanced diet with a variety of nutrient-rich foods is the best way to ensure sufficient vitamin intake. While supplements can help in deficiency cases, most people can meet their needs through everyday foods, fostering overall health and well-being.

Source: https://medicalxpress.com/news/2025-07-vitamins.html