Composition of Vitamins and Minerals: A Comprehensive Guide

The composition of vitamins and minerals includes water- and fat-soluble vitamins plus essential macro- and trace minerals. Together, they regulate metabolism, strengthen immunity, support bone health, and maintain cellular function critical for nutrition and nursing education.

Overview of Vitamins and Minerals

Vitamins and minerals are micronutrients—required in small amounts but indispensable for numerous bodily functions. Vitamins are organic compounds, while minerals are inorganic elements. Both act as co-factors, structural components, and regulators in myriad biochemical processes. Their absence or imbalance can lead to a range of clinical manifestations, from mild symptoms to severe, life-threatening conditions.

Vitamins:

Vitamins are organic substances, distinct from carbohydrates, proteins, and fats, required in minute quantities for normal metabolism, growth, and well-being. Unlike macronutrients, vitamins usually do not provide energy but facilitate energy-yielding reactions.

Classification of Vitamins

Vitamins are primarily classified based on their solubility:

1. Water-Soluble Vitamins: Dissolve in water, not stored in large amounts, require regular replenishment. Includes Vitamin C and the B-complex group.
2. Fat-Soluble Vitamins: Dissolve in fat, stored in body tissues, especially the liver and adipose tissue. Includes Vitamins A, D, E, and K.

General Functions of Vitamins

Vitamins serve as:

• Coenzymes in metabolic pathways (e.g., B vitamins in energy metabolism)
• Antioxidants (e.g., Vitamin C, E)
• Regulators of gene expression (e.g., Vitamin A, D)
• Essential factors in tissue repair and immunity

Water-Soluble Vitamins

Water-soluble vitamins are not stored in significant amounts; thus, a continuous dietary supply is essential. They are excreted in urine, and toxicity is rare but possible with excessive supplementation.

Chemical Structure and Classification

Water-soluble vitamins include:

• Vitamin C (Ascorbic Acid)
• B-Complex Group:
• B1 (Thiamine)
• B2 (Riboflavin)
• B3 (Niacin/Nicotinamide)
• B5 (Pantothenic Acid)
• B6 (Pyridoxine)
• B7 (Biotin)
• B9 (Folate/Folic Acid)
• B12 (Cobalamin)

Each vitamin has a unique chemical structure, generally containing nitrogen, oxygen, and carbon in complex arrangements.

1.Vitamin C (Ascorbic Acid)

• Chemical Structure: A six-carbon compound structurally related to glucose, with the formula C6H8O6.
• Sources: Citrus fruits, guava, amla (Indian gooseberry), strawberries, bell peppers, green leafy vegetables.
• Functions: Antioxidant, collagen synthesis, enhances iron absorption, immune support.
• Deficiency Symptoms: Scurvy (bleeding gums, delayed wound healing, anaemia), weakness, impaired immunity.

2.B-Complex Vitamins

The B-vitamins are chemically diverse but share the common feature of acting as coenzymes in metabolic pathways.

3.Vitamin B1 (Thiamine)

• Chemical Structure: Contains a thiazole and a pyrimidine ring.
• Sources: Whole grains, pulses, nuts, seeds, pork.
• Functions: Coenzyme in carbohydrate metabolism (as thiamine pyrophosphate).
• Deficiency: Beriberi (neurological and cardiac symptoms), Wernicke-Korsakoff syndrome (especially in alcoholics).

4.Vitamin B2 (Riboflavin)

• Chemical Structure: Isoalloxazine ring attached to a ribitol side chain.
• Sources: Milk, eggs, green vegetables, meat, fortified cereals.
• Functions: Coenzyme (FMN, FAD) in redox reactions.
• Deficiency: Cheilosis, glossitis, dermatitis, eye changes.

5.Vitamin B3 (Niacin/Nicotinamide)

• Chemical Structure: Pyridine ring.
• Sources: Meat, fish, peanuts, whole grains, synthesised from tryptophan.
• Functions: Coenzyme (NAD, NADP) in energy metabolism.
• Deficiency: Pellagra (dermatitis, diarrhoea, dementia, death).

6.Vitamin B5 (Pantothenic Acid)

• Chemical Structure: Pantoic acid and β-alanine.
• Sources: Eggs, liver, mushrooms, whole grains.
• Functions: Component of coenzyme A, essential for fatty acid metabolism.
• Deficiency: Rare; may cause fatigue, irritability, numbness.

7.Vitamin B6 (Pyridoxine)

• Chemical Structure: Pyridine derivative.
• Sources: Meat, fish, bananas, potatoes, nuts.
• Functions: Coenzyme in amino acid metabolism, neurotransmitter synthesis.
• Deficiency: Dermatitis, anaemia, neurological symptoms.

8.Vitamin B7 (Biotin)

• Chemical Structure: Imidazolidone ring fused with a tetrahydrothiophene ring.
• Sources: Eggs, nuts, soybeans, whole grains, synthesised by gut flora.
• Functions: Coenzyme in carboxylation reactions.
• Deficiency: Dermatitis, hair loss, neurological symptoms.

9.Vitamin B9 (Folate/Folic Acid)

• Chemical Structure: Pteridine ring, para-aminobenzoic acid, and glutamic acid.
• Sources: Green leafy vegetables, legumes, liver, oranges.
• Functions: DNA synthesis, cell division, red blood cell formation.
• Deficiency: Megaloblastic anaemia, neural tube defects in foetus.

10.Vitamin B12 (Cobalamin)

• Chemical Structure: Corrin ring with a central cobalt atom.
• Sources: Animal products only—meat, fish, eggs, dairy.
• Functions: DNA synthesis, nerve function, red blood cell formation.
• Deficiency: Pernicious anaemia, neurological disorders.

Fat-Soluble Vitamins

Fat-soluble vitamins are stored in the liver and adipose tissues. They are absorbed along with dietary fats and require bile for absorption. While deficiencies are less common, toxicities can occur with excessive intake.

Chemical Structure and Classification

Fat-soluble vitamins include:

• Vitamin A (Retinoids and Carotenoids)
• Vitamin D (Calciferols)
• Vitamin E (Tocopherols and Tocotrienols)
• Vitamin K (Phylloquinone, Menaquinone)

These vitamins are generally composed of large hydrocarbon chains or rings, making them soluble in fats but not water.

Vitamin A

• Chemical Structure: Retinol (alcohol form), retinal (aldehyde form), retinoic acid (acid form), and provitamin A carotenoids such as beta-carotene.
• Sources: Liver, fish oils, dairy products, orange and yellow vegetables (carrots, pumpkin), green leafy vegetables.
• Functions: Vision (component of rhodopsin), immune function, cell growth and differentiation.
• Deficiency: Night blindness, xerophthalmia, increased infection risk, keratinisation of epithelial tissues.

Vitamin D

• Chemical Structure: Steroid derivative; main forms are D2 (ergocalciferol) and D3 (cholecalciferol).
• Sources: Sunlight (skin synthesis), fortified foods, fish liver oils, egg yolk.
• Functions: Calcium and phosphorus metabolism, bone health, immune modulation.
• Deficiency: Rickets in children, osteomalacia in adults.

Vitamin E

• Chemical Structure: Tocopherols and tocotrienols; chromanol ring with a phytyl tail.
• Sources: Vegetable oils, nuts, seeds, green leafy vegetables.
• Functions: Antioxidant, protects cell membranes from oxidative damage.
• Deficiency: Rare; may cause neuromuscular problems, haemolytic anaemia.

Vitamin K

• Chemical Structure: Phylloquinone (plant form), menaquinone (bacterial form); naphthoquinone ring.
• Sources: Green leafy vegetables, cabbage, broccoli, synthesised by gut bacteria.
• Functions: Essential for synthesis of clotting factors (prothrombin), bone metabolism.
• Deficiency: Bleeding diathesis, prolonged clotting time, haemorrhagic disease of the newborn.

Minerals

Minerals are inorganic elements that play structural, catalytic, and regulatory roles in the body. Unlike vitamins, minerals are not synthesised by living organisms and must be obtained from the diet.

Classification of Minerals

Minerals are categorised based on the required daily amount:

1. Macrominerals: Required in amounts greater than 100 mg per day. Includes calcium, phosphorus, magnesium, sodium, potassium, chloride, and sulfur.
2. Microminerals (Trace Elements): Required in amounts less than 100 mg per day. Includes iron, zinc, copper, iodine, selenium, manganese, fluorine, chromium, and molybdenum.

General Functions of Minerals

• Structural components (bones, teeth)
• Electrolyte balance and osmoregulation
• Enzyme activation and cofactor roles
• Hormone synthesis and function

Macrominerals

Calcium

• Chemical Composition: Ca2+ ion.
• Sources: Milk, cheese, yoghurt, green leafy vegetables, ragi (finger millet), sesame seeds.
• Functions: Bone and teeth formation, muscle contraction, nerve transmission, blood clotting.
• Clinical Significance: Deficiency causes rickets, osteomalacia, tetany; excess leads to hypercalcaemia, kidney stones.

Phosphorus

• Chemical Composition: PO43- (phosphate ion).
• Sources: Meat, dairy, nuts, legumes, fish.
• Functions: Bone and teeth structure, energy metabolism (ATP), component of nucleic acids.
• Clinical Significance: Deficiency rare; may cause bone weakness, muscle dysfunction.

Magnesium

• Chemical Composition: Mg2+ ion.
• Sources: Whole grains, nuts, green vegetables, legumes.
• Functions: Enzyme cofactor, muscle and nerve function, bone health.
• Clinical Significance: Deficiency can cause muscle cramps, arrhythmias, neuromuscular irritability.

Sodium

• Chemical Composition: Na+ ion.
• Sources: Table salt, processed foods, cheese, pickles.
• Functions: Fluid and electrolyte balance, nerve impulse conduction, muscle contraction.
• Clinical Significance: Hyponatraemia, hypernatraemia; associated with blood pressure regulation.

Potassium

• Chemical Composition: K+ ion.
• Sources: Bananas, oranges, potatoes, beans, spinach.
• Functions: Intracellular fluid balance, nerve function, muscle contraction.
• Clinical Significance: Hypokalaemia, hyperkalaemia; affects heart rhythm and muscle function.

Chloride

• Chemical Composition: Cl- ion.
• Sources: Table salt, seaweed, tomatoes, celery.
• Functions: Acid-base balance, gastric acid (HCl) production, fluid balance.
• Clinical Significance: Disturbances may cause acid-base imbalances, dehydration.

Sulfur

• Chemical Composition: Component of amino acids (methionine, cysteine), vitamins (thiamine, biotin).
• Sources: Protein-rich foods—meat, eggs, legumes.
• Functions: Protein synthesis, detoxification, enzyme structure.
• Clinical Significance: Deficiency is rare; may impact protein metabolism.

Microminerals (Trace Elements)

Iron

• Chemical Composition: Fe2+ (ferrous), Fe3+ (ferric) ions.
• Sources: Red meat, liver, spinach, lentils, jaggery.
• Functions: Oxygen transport (haemoglobin, myoglobin), electron transport chain.
• Clinical Significance: Deficiency causes iron-deficiency anaemia; excess leads to haemochromatosis.

Zinc

• Chemical Composition: Zn2+ ion.
• Sources: Meat, shellfish, legumes, seeds, nuts.
• Functions: Enzyme cofactor, immune function, wound healing, DNA synthesis.
• Clinical Significance: Deficiency causes growth retardation, delayed wound healing, impaired immunity.

Copper

• Chemical Composition: Cu2+ ion.
• Sources: Shellfish, nuts, seeds, organ meats.
• Functions: Iron metabolism, antioxidant defence (superoxide dismutase), connective tissue formation.
• Clinical Significance: Deficiency causes anaemia, bone abnormalities; excess causes Wilson’s disease.

Iodine

• Chemical Composition: I- ion.
• Sources: Iodised salt, seafood, seaweed, dairy.
• Functions: Synthesis of thyroid hormones (T3, T4).
• Clinical Significance: Deficiency causes goitre, hypothyroidism, cretinism; excess can cause thyroid dysfunction.

Selenium

• Chemical Composition: Se2- ion.
• Sources: Brazil nuts, seafood, grains, eggs.
• Functions: Antioxidant (glutathione peroxidase), thyroid hormone metabolism.
• Clinical Significance: Deficiency causes Keshan disease (cardiomyopathy), impaired immunity.

Other Trace Elements

• Manganese: Bone formation, enzyme cofactor.
• Fluorine: Dental health, bone strength.
• Chromium: Glucose metabolism.
• Molybdenum: Enzyme cofactor.

Role of Vitamins and Minerals in Human Physiology

Vitamins and minerals collectively support:

• Metabolism: As coenzymes and cofactors, they facilitate biochemical reactions essential for energy production and nutrient utilisation.
• Immunity: Support immune cell function, antioxidant defence, and resistance to infections.
• Growth and Repair: Essential for cell division, DNA synthesis, tissue and bone formation, and healing processes.
• Neuromuscular Function: Regulate nerve impulse transmission, muscle contraction, and neurotransmitter synthesis.

For example, calcium and vitamin D are indispensable for bone health, while iron and vitamin B12 are crucial for oxygen transport and red blood cell formation.

Clinical Implications for Nurses

Nurses play a pivotal role in recognising, preventing, and managing micronutrient deficiencies and toxicities. Key responsibilities include:

• Assessment: Identifying clinical signs (e.g., anaemia, rickets, bleeding, neuropathy) and at-risk populations (children, pregnant women, elderly, chronically ill).
• Dietary Recommendations: Advising on balanced diets rich in fruits, vegetables, whole grains, lean proteins, and fortified foods.
• Supplementation: Recommending appropriate supplements when dietary intake is inadequate or during increased physiological demand (e.g., pregnancy, lactation, chronic illness).
• Monitoring: Observing for symptoms of both deficiency and toxicity, especially in patients receiving parenteral nutrition, on restrictive diets, or with malabsorption syndromes.
• Patient Education: Teaching patients about proper food choices, safe supplementation, and the importance of regular health check-ups.

REFERENCES

1. Harbans Lal, Textbook of Applied Biochemistry and Nutrition& Dietetics 2nd Edition ,November 2024, CBS Publishers and Distributors, ISBN: 978-9394525757
2. Suresh K Sharma, Textbook of Biochemistry and Biophysics for Nurses, 2nd Edition, September 2022, Jaypee Publishers, ISBN: 978-9354655760
3. Peter J Kennelly, Harpers Illustrated Biochemistry Standard Edition, September 2022, McGraw Hill Lange Publishers, ISBN: 978-1264795673
4. Denise R Ferrier, Ritu Singh, Lippincott Illustrated Reviews Biochemistry, Second Edition, June 2024, ISBN- 978-8197055973
5. Yadav, Tapeshwar & Bhadeshwar, Sushma. (2022). Essential Textbook of Biochemistry for Nursing.
6. Applied Sciences, Importance of Biochemistry for Nursing Practice, November 2, 2023, https://bns.institute/applied-sciences/importance-biochemistry-nursing-practice/

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