Vitamins are organic micronutrients that regulate essential body processes, including energy metabolism, tissue maintenance, immunity and blood formation. They do not directly provide energy, but deficiencies can impair health and sporting performance.
How vitamins function
Many vitamins act as coenzymes, helping enzymes catalyse metabolic reactions. For example, B-group vitamins support reactions involved in releasing energy from carbohydrates, fats and proteins; however, the vitamins themselves contain no usable energy.
Other vitamins have specialized functions. Vitamin A supports vision and epithelial tissue, vitamin C contributes to collagen formation and iron absorption, vitamin D promotes calcium absorption and bone mineralization, vitamin E acts as an antioxidant, and vitamin K is required for normal blood clotting.
| Vitamin group | Key characteristics and functions | Examples |
|---|---|---|
| Fat-soluble vitamins | Absorbed with dietary fat and stored in the liver or adipose tissue. Excessive intake can accumulate and cause toxicity. | A: vision; D: calcium absorption; E: antioxidant activity; K: blood clotting |
| Water-soluble vitamins | Generally stored only in limited amounts, so regular dietary intake is needed. Excess is usually excreted in urine. | B group: energy metabolism and red blood cell formation; C: collagen formation and iron absorption |
For athletes, adequate vitamin intake supports training and recovery indirectly. Vitamin D contributes to bone and muscle function, vitamin C supports connective tissue, and several B vitamins facilitate metabolic pathways used during exercise. A balanced diet normally provides sufficient vitamins; supplements do not automatically improve performance when no deficiency exists.
A common misconception is that vitamins “give you energy.” Energy is supplied by macronutrients, measured in kilojoules or kilocalories; vitamins enable the metabolic reactions that release and use that energy.
Exam technique
For IB SEHS subtopic A.2.2 Fuelling for health and performance, distinguish between energy-providing nutrients and micronutrients. If asked to explain a vitamin’s importance, identify its physiological function, connect deficiency to health or performance, and avoid claiming that supplementation benefits an athlete who already has an adequate intake.