Types of Vitamins: Classification, Sources, Deficiencies

Vitamins are vital organic compounds that our body needs in small amounts to support growth, immune function, metabolism, and overall health. Unlike carbohydrates, proteins, and fats, vitamins do not provide energy but are essential for countless processes, including wound healing, bone strength, and nervous system function. A balanced intake of all types of vitamins prevents health issues like fatigue, weakened muscles, and poor digestion.

Types of Vitamins: Classification and Overview

There are two main categories of vitamins: fat-soluble and water-soluble. This classification is based on what substance the vitamin dissolves in:

• Fat-Soluble Vitamins: These dissolve in fats and are stored in the body's fatty tissues and liver. The four fat-soluble vitamins are: Vitamin A, Vitamin D, Vitamin E, and Vitamin K.
• Water-Soluble Vitamins: These dissolve in water and are not stored in the body. Excess amounts are excreted, so they need to be consumed more regularly. This group includes Vitamin C and the eight B-Complex vitamins.

The 13 Types of Essential Vitamins

Altogether, there are 13 essential vitamins. These include Vitamins A, C, D, E, K, and all eight B vitamins. Each has unique roles and sources, and deficiency in any can affect your health.

Vitamin	Function	Common Sources	Deficiency Signs
A (Retinol, Preformed and Provitamin)	Supports immune system, vision, and skin health	Carrots, sweet potato, leafy greens, dairy, liver	Poor immunity, night blindness, skin issues
B-Complex (B1 to B12)	Energy release, brain and nerve function, red blood cell formation	Whole grains, eggs, legumes, nuts, meat, leafy greens	Tiredness, nerve problems, anemia, pale skin, low mood
C (Ascorbic Acid)	Promotes healing, collagen formation, helps absorb iron, boosts immunity	Citrus fruits, strawberries, bell peppers, potatoes	Scurvy, weak immunity, slow wound healing
D (D2 & D3)	Helps absorb calcium, maintains bone and teeth health	Sunlight, oily fish, eggs, dairy, fortified foods	Weak bones, muscle pain, risk of rickets/osteomalacia
E (Tocopherol)	Antioxidant, supports immune system, protects cell membranes	Nuts, seeds, vegetable oils, spinach, broccoli	Rare, nerve and immune issues
K (K1 & K2)	Essential for blood clotting, bone and heart health	Leafy greens (K1), fermented foods, animal products (K2)	Bleeding disorders, weak bones

Detailed Breakdown: Major Vitamins and Their Roles

Vitamin A is crucial for supporting the immune system, eye health, and skin maintenance. Deficiency may result in poor immunity and vision problems. Sources include brightly colored vegetables, dairy, and liver.

B-Complex Vitamins (B1–Thiamine, B2–Riboflavin, B3–Niacin, B5–Pantothenic acid, B6–Pyridoxine, B7–Biotin, B9–Folic acid, and B12–Cobalamin) each support energy release, red blood cell production, and nerve function. Symptoms of deficiency range from tiredness, fatigue to anemia and low mood. Whole grains, eggs, legumes, nuts, and leafy greens are excellent sources.

Vitamin C is commonly found in citrus fruits and peppers. It acts as an antioxidant, supports the immune system, assists in wound healing, and improves iron absorption. Its deficiency causes scurvy, which shows as weak immunity and slow healing.

Vitamin D is produced in the skin when exposed to sunlight, and also found in oily fish, eggs, and fortified foods. It maintains bone health by helping absorb calcium. Not getting enough leads to weak bones and conditions like rickets.

Vitamin E acts as another antioxidant, protecting cells and supporting the immune system. Deficiency is rare but may affect nerves. Nuts, seeds, and vegetable oils are common dietary sources.

Vitamin K is key for blood clotting and strong bones. It is present in leafy greens (K1) and fermented foods/animal products (K2). Deficiency increases bleeding risk and affects bone health.

Fat-Soluble vs Water-Soluble Vitamins: At a Glance

Category	Vitamins	Key Features	Deficiency Impact
Fat-Soluble	A, D, E, K	Stored in fat tissues, can be retained for long	Deficiency develops gradually; risk of excess buildup
Water-Soluble	B-group, C	Not stored; excess excreted rapidly in urine	Deficiency appears quickly; daily intake needed

Key Points for Students: Why Regular Vitamin Intake Matters

• Maintain good nutrition for energy, focus, and immunity.
• If the diet misses any vitamin for long, you may develop symptoms like tiredness, mood changes, bleeding issues, or weak bones.
• Vitamins cannot be replaced by taking only supplements; diverse food sources remain important.

Practice Questions for Deeper Learning

1. List and differentiate between fat-soluble and water-soluble vitamins with examples.
2. What are common deficiency symptoms of Vitamin C? Name rich dietary sources.
3. Why is sunlight important for Vitamin D synthesis?

Explore more about vitamins in detail with these additional resources: Vitamins and Minerals Explained, Difference Between Fat-Soluble and Water-Soluble Vitamins, and Functions of Vitamins A, B, C, D, E. Practice more MCQs at Vitamins MCQs to solidify your concepts.