Introduction

Vitamins are organic micronutrients required in small amounts for normal physiological function. Humans require 13 essential vitamins that must be obtained from food or supplements. This concise overview summarizes those vitamins, their classification, primary roles, common dietary sources, and signs of deficiency. For a more detailed explanation and context, see this comprehensive guide to the 13 essential vitamins.

Fat-soluble vs. Water-soluble

Vitamins are categorized by solubility, which affects absorption and storage. Fat-soluble vitamins (A, D, E, K) dissolve in fats and can be stored in adipose tissue and liver; they are absorbed more effectively with dietary fat. Water-soluble vitamins (vitamin C and the B-complex: B1, B2, B3, B5, B6, B7, B9, B12) dissolve in water, are not stored to a large extent, and excess is excreted in urine. This distinction informs dietary planning and supplement formulation.

The 13 Essential Vitamins

• Fat-soluble: A, D, E, K
• Water-soluble: Vitamin C; B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B7 (biotin), B9 (folate), B12 (cobalamin)

Key Functions at a Glance

Each vitamin serves specific biochemical roles, often as enzyme cofactors or precursors. Examples include:

• Vitamin A: vision, epithelial integrity, immune support.
• Vitamin D: calcium homeostasis and bone mineralization.
• Vitamin E: lipid antioxidant protecting cell membranes.
• Vitamin K: blood clotting and bone protein activation.
• Vitamin C: collagen synthesis, antioxidant activity, enhanced iron absorption.
• B vitamins: central in energy metabolism, neurotransmitter synthesis, red blood cell formation, and DNA synthesis (notably folate and B12).

Deficiency Patterns and Risk Groups

Deficiencies produce characteristic clinical signs: vitamin A deficiency can impair night vision; insufficient vitamin D contributes to bone pain and increased fracture risk; lack of vitamin C leads to impaired wound healing and scurvy in severe cases; B12 deficiency causes megaloblastic anemia and neurologic symptoms. Risk groups include older adults with reduced absorption, people with malabsorptive disorders, strict vegans (B12 risk), those with limited sun exposure (vitamin D risk), and individuals with restrictive diets.

Dietary Sources and Practical Notes

Whole foods remain the primary source for most vitamins: leafy greens, legumes, whole grains, nuts and seeds, dairy, eggs, liver, and oily fish supply many of the essentials. Fortified foods can help address shortfalls. For information on ingredient transparency and label assessment, consult this supplement label guide. For comparative information on natural vitamin products, see this Natures Plus overview and a related summary on Telegraph.

Balancing food sources with informed use of fortified products or supplements can help maintain adequate status, particularly where diet or physiology limits intake. For general reference, visit Topvitamine.

Conclusion

Understanding the 13 essential vitamins—their classification, functions, and dietary sources—supports evidence-based choices for nutrition and health. Regular dietary assessment and, when appropriate, clinical testing can help identify deficiencies and guide targeted nutritional strategies.