Minerals

Nutrition and Food Science 3310 · CCEA AS Level · 10 min read · Updated: 1 Sept 2026

Welcome to Unit AS 1: Minerals

Welcome to your revision guide for Minerals in CCEA AS Level Nutrition and Food Science! Minerals are essential micronutrients that your body needs in varying amounts to function, grow, and stay healthy. While they do not provide energy directly like carbohydrates or fats, our bodies cannot function without them.

Don't worry if nutrition chemistry feels intimidating at first. We will break down every mineral step by step, look at how our bodies absorb them, explore real-world food sources, and understand what happens when we get too little or too much.

1. Classification of Dietary Minerals

In the CCEA specification, dietary minerals are classified into two main groups based on how much our body requires each day:

1. Macrominerals (Major Minerals):
These are minerals required in large amounts in the diet (measured in hundreds of milligrams to grams per day).
• Calcium (\(\text{Ca}\))
• Sodium (\(\text{Na}\))
• Potassium (\(\text{K}\))
• Phosphorus (\(\text{P}\))
• Magnesium (\(\text{Mg}\))

2. Microminerals (Trace Elements):
These are minerals needed only in very small amounts (measured in milligrams or micrograms per day), but they are just as vital for health.
• Iron (\(\text{Fe}\))
• Zinc (\(\text{Zn}\))
• Iodine (\(\text{I}\))
• Selenium (\(\text{Se}\))

Memory Trick: Think of Macro as "Massive amounts" (grams/milligrams) and Micro as "Miniature amounts" (milligrams/micrograms).

Key Takeaway: Macrominerals are needed in large daily quantities, whereas trace elements are needed in minute amounts. Both are essential for survival.

2. Calcium (\(\text{Ca}\))

Biological Functions

Calcium is the most abundant mineral in the human body. Its major roles include:
• Skeletal Structure: Works together with phosphorus to form hydroxyapatite crystals, providing hardness and strength to bones and teeth.
• Blood Clotting: Essential for normal blood coagulation mechanisms (activating clotting factors and converting prothrombin to thrombin).
• Muscle & Nerve Function: Enables muscle contraction (including the heart) and the transmission of nerve impulses.
• Cellular Regulation: Controls cell membrane permeability and activates key enzymes.

Dietary Sources

• Dairy Products: Milk, cheese, and yogurt (highly bioavailable).
• Canned Fish with Bones: Canned sardines and canned salmon (eating the soft bones provides concentrated calcium).
• Fortified Foods: Fortified plant milks, fortified breakfast cereals, and white flour (which is fortified by UK law with calcium carbonate).
• Plant Foods: Calcium-set tofu, kale, and broccoli.

Bioavailability: Enhancers vs Inhibitors

Not all calcium in food is absorbed by the digestive tract. Bioavailability depends on what else is in the digestive system:

Absorption Enhancers (Help absorption):
• Vitamin D (Calcitriol): Stimulates the synthesis of calcium-binding proteins in the small intestine.
• Lactose (milk sugar): Promotes passive absorption in the gut.
• Acidic Gut Environment: Increases the solubility of calcium salts.

Absorption Inhibitors (Hinder absorption):
• Phytates (Phytic Acid): Found in wholegrain cereals and pulses; binds with calcium to form insoluble compounds.
• Oxalates (Oxalic Acid): Found in spinach and rhubarb; binds tightly to calcium, preventing uptake.
• Unabsorbed Fatty Acids: Form insoluble "calcium soaps" in the gut.
• Excess Dietary Fibre: Speeds transit time and binds minerals.

Deficiency and Excess

• Deficiency in Children: Rickets — soft, weak bones that bend under body weight, leading to bowed legs.
• Deficiency in Adults: Osteomalacia (softening of the bones) and Osteoporosis (reduced bone mineral density leading to porous, fragile bones and high fracture risk).
• Excess / Toxicity: Hypercalcaemia (excess calcium in the blood), formation of kidney stones, and reduced absorption of other minerals like zinc and iron.

Key Takeaway: Calcium builds bone structure via hydroxyapatite and supports nerve and muscle function. Its absorption is boosted by Vitamin D and inhibited by phytates and oxalates.

3. Sodium (\(\text{Na}\)) and Potassium (\(\text{K}\))

Think of sodium and potassium as partners working on opposite sides of a cell membrane to maintain fluid balance and electrical signaling.

Sodium (\(\text{Na}\))

• Main Role: The major extracellular cation (positively charged ion outside cells). It regulates fluid volume, blood pressure, osmotic balance, and is essential for action potentials (nerve impulses) and active nutrient uptake (e.g., sodium-glucose cotransport).
• Dietary Sources: Table salt (sodium chloride), cured meats (bacon, ham), processed foods, ready meals, savoury snacks, and bread.
• Recommended Intake: Maximum of 6g of salt per day for adults (which equals approximately 2.4g of sodium).
• Health Risks of Excess: High blood pressure (hypertension), increased risk of stroke, coronary heart disease (CHD), and renal (kidney) strain.

Potassium (\(\text{K}\))

• Main Role: The major intracellular cation (positively charged ion inside cells). It works antagonistically (in balance) with sodium to maintain cellular fluid balance, control resting membrane potentials, ensure normal cardiac and skeletal muscle contraction, and help lower blood pressure.
• Dietary Sources: Fresh fruits (bananas, oranges), potatoes, leafy green vegetables, pulses, meat, and nuts.
• Deficiency: Hypokalaemia, causing muscle weakness, fatigue, and dangerous cardiac arrhythmias (irregular heartbeats).

Everyday Analogy: Think of sodium and potassium as a seesaw. If you consume too much sodium and too little potassium, your blood pressure tilts upwards!

Key Takeaway: Sodium controls extracellular fluid; potassium controls intracellular fluid. Adults should limit salt intake to 6g daily (2.4g sodium) to avoid hypertension.

4. Other Macrominerals: Magnesium (\(\text{Mg}\)) and Phosphorus (\(\text{P}\))

• Phosphorus (\(\text{P}\)): Works hand-in-hand with calcium in the formation of bone and tooth enamel (hydroxyapatite matrix). It is also a vital component of cell membranes (phospholipids) and cellular energy transfer (ATP — adenosine triphosphate).
• Magnesium (\(\text{Mg}\)): Acts as a cofactor for over 300 enzyme systems, supporting energy production, bone structure, and muscle relaxation.

5. Iron (\(\text{Fe}\))

Haem vs Non-Haem Iron

Iron exists in food in two distinct chemical forms. Understanding this difference is essential for scoring top marks in Unit AS 1 exams:

1. Haem Iron (\(\text{Fe}^{2+}\) - Ferrous Iron):
• Found exclusively in animal tissues (meat, liver, offal, poultry, seafood).
• Highly bioavailable (approximately \(15\text{--}35\%\) is absorbed).
• Absorbed easily because its ring structure protects it from dietary inhibitors in the intestine.

2. Non-Haem Iron (\(\text{Fe}^{3+}\) - Ferric Iron):
• Found in plant foods (pulses, lentils, beans, dark leafy greens, wholemeal flour, dried fruit) and fortified foods (breakfast cereals), as well as eggs.
• Lower bioavailability (approximately \(2\text{--}10\%\) is absorbed).
• Must be chemically reduced from the insoluble ferric form (\(\text{Fe}^{3+}\)) to the soluble ferrous form (\(\text{Fe}^{2+}\)) before absorption can occur.

Biological Functions

• Haemoglobin: Core component of haemoglobin in red blood cells, which carries oxygen from the lungs to all body tissues.
• Myoglobin: Component of myoglobin, which stores and supplies oxygen inside muscle cells.
• Energy Metabolism: Crucial cofactor in the mitochondrial electron transport chain (cytochromes) for producing cellular energy (ATP).

Absorption Factors for Non-Haem Iron

Enhancers:
• Vitamin C (Ascorbic Acid): Chemically reduces insoluble non-haem \(\text{Fe}^{3+}\) to soluble \(\text{Fe}^{2+}\) in the stomach and duodenum.
• Meat Protein Factor (MPF): Eating small amounts of animal meat alongside plant sources boosts non-haem absorption.
• Organic Acids: Citric acid and malic acid enhance uptake.

Inhibitors:
• Tannins & Polyphenols: Found in tea and coffee; bind to iron and block absorption.
• Phytates: Found in unrefined cereals and bran.
• Oxalates: Found in spinach.
• High Dietary Calcium: Competes with iron for intestinal transporters.

Deficiency: Iron Deficiency Anaemia (IDA)

When dietary iron stores are depleted, red blood cells become small and pale (microcytic, hypochromic). Symptoms include:
• Severe fatigue and lethargy
• Pale skin (pallor)
• Breathlessness and rapid heart rate during light activity
• Impaired cognitive performance and reduced immune defence

Vulnerable Groups across the Lifespan:
• Menstruating adolescent girls and women: Regular monthly blood and iron loss.
• Pregnant women: Greatly expanded blood volume and fetal growth requirements.
• Infants and young children: Rapid growth rates requiring high iron intake.
• Strict vegans/vegetarians: Rely entirely on non-haem plant iron with lower bioavailability.

Iron Excess / Overload

• Acute Toxicity: Accidental overdose of iron supplements, which is dangerous and potentially fatal in young children.
• Chronic Overload (Haemochromatosis): A genetic condition causing excessive iron absorption and dangerous accumulation in the liver, heart, and joints.

Key Takeaway: Haem iron (\(\text{Fe}^{2+}\)) from meat is readily absorbed; non-haem iron (\(\text{Fe}^{3+}\)) from plants requires Vitamin C for reduction to \(\text{Fe}^{2+}\). Deficiency causes Iron Deficiency Anaemia.

6. Trace Elements: Zinc (\(\text{Zn}\)), Iodine (\(\text{I}\)), and Selenium (\(\text{Se}\))

Zinc (\(\text{Zn}\))

• Key Functions: Serves as an essential cofactor for over 300 enzymes. Crucial for DNA and RNA synthesis, cell division, wound healing, healthy immune function, and normal sexual maturation.
• Dietary Sources: Lean red meat, shellfish (especially oysters), pumpkin seeds, nuts, and whole grains.
• Deficiency Signs: Delayed wound healing, stunted growth and delayed sexual development in children, hair loss (alopecia), loss of taste (hypogeusia), and increased vulnerability to infections.

Iodine (\(\text{I}\))

• Key Functions: Essential component for synthesizing thyroid hormones — thyroxine (\(\text{T}_4\)) and triiodothyronine (\(\text{T}_3\)). These hormones control the basal metabolic rate (BMR), energy metabolism, and the development of the brain and nervous system.
• Dietary Sources: Marine white fish, shellfish, dairy products (cows' milk contains iodine from feed supplements and dairy-cleaning iodophores), and iodised table salt.
• Deficiency Disorders:
1. Goitre: Swelling of the thyroid gland in the neck as it works overtime to capture iodine.
2. Hypothyroidism: Sluggish metabolism, weight gain, fatigue, and sensitivity to cold.
3. Cretinism: Severe, irreversible mental and physical growth impairment in babies born to mothers deficient in iodine during pregnancy.

Selenium (\(\text{Se}\))

• Key Functions: Works as a component of antioxidant enzymes (such as glutathione peroxidase) that protect cell membranes from free radical damage, and assists with thyroid hormone metabolism.
• Dietary Sources: Brazil nuts, seafood, meat, and grains grown in selenium-rich soils.

Key Takeaway: Zinc is the "growth and repair" trace mineral; Iodine is the "metabolism and thyroid" trace mineral; Selenium is a powerful cellular antioxidant.

7. Examiner Pitfalls & Revision Checklist

Watch out for these common mistakes highlighted in CCEA assessment reports:

• Common Mistake 1: Writing just "anaemia" instead of Iron Deficiency Anaemia (IDA). Always specify the type and explain the underlying mechanism: reduced haemoglobin means less oxygen is delivered to body tissues for cellular respiration.
• Common Mistake 2: Stating that Vitamin C enhances all iron absorption. Vitamin C only enhances non-haem iron by reducing \(\text{Fe}^{3+}\) to soluble \(\text{Fe}^{2+}\); haem iron absorption does not depend on Vitamin C.
• Common Mistake 3: Confusing bone health factors. Remember that bone density requires a combination of Calcium and Phosphorus (forming the mineral crystal matrix) alongside Vitamin D (for absorption) and Protein (for the collagen framework).
• Common Mistake 4: Ignoring meal context. If a question asks about improving an iron-deficient diet, don't just list spinach—explain that adding a glass of orange juice (Vitamin C) and avoiding tea/coffee (tannins) at the same meal maximizes absorption.

Quick Review Summary Table

Calcium (\(\text{Ca}\))
• Type: Macromineral
• Key Roles: Bones & teeth (hydroxyapatite), blood clotting, muscle contraction
• Key Sources: Milk, cheese, canned fish with bones, fortified white flour
• Deficiency: Rickets, osteomalacia, osteoporosis

Sodium (\(\text{Na}\))
• Type: Macromineral
• Key Roles: Extracellular fluid balance, nerve impulses; max 6g salt/day (2.4g sodium)
• Key Sources: Table salt, processed meats, ready meals, bread
• Excess: Hypertension, stroke, CHD

Potassium (\(\text{K}\))
• Type: Macromineral
• Key Roles: Intracellular fluid balance, resting membrane potentials, heart rhythm
• Key Sources: Bananas, potatoes, vegetables, pulses
• Deficiency: Hypokalaemia, muscle weakness, cardiac arrhythmias

Iron (\(\text{Fe}\))
• Type: Trace element
• Key Roles: Haemoglobin (oxygen transport), myoglobin, ATP synthesis
• Key Sources: Haem (red meat, offal), Non-haem (pulses, cereals, green leafy veg)
• Deficiency: Iron Deficiency Anaemia (IDA)

Zinc (\(\text{Zn}\))
• Type: Trace element
• Key Roles: Enzyme cofactor (300+ enzymes), wound healing, sexual maturation
• Key Sources: Lean meat, shellfish, pumpkin seeds, nuts
• Deficiency: Delayed wound healing, stunted growth, hypogeusia

Iodine (\(\text{I}\))
• Type: Trace element
• Key Roles: Synthesis of thyroid hormones (\(\text{T}_3\), \(\text{T}_4\)) regulating BMR
• Key Sources: White fish, seafood, dairy products, iodised salt
• Deficiency: Goitre, hypothyroidism, cretinism

Quick check

Can you answer these now?

Open each question to check the key ideas from this chapter.

How are dietary minerals classified in human nutrition?

Dietary minerals are classified into macrominerals (needed in large daily quantities, measured in milligrams to grams) and microminerals or trace elements (needed in minute amounts, measured in milligrams or micrograms).

What are the primary biological functions of calcium in the human body?

Calcium forms hydroxyapatite crystals with phosphorus to strengthen bones and teeth, activates blood clotting mechanisms, enables muscle contraction and nerve transmission, and regulates cell membrane permeability.

Which dietary factors enhance or inhibit the absorption of calcium in the gut?

Absorption is enhanced by Vitamin D (calcitriol), lactose, and an acidic gut environment, but inhibited by phytates, oxalates, unabsorbed fatty acids, and excess dietary fibre.

What conditions are caused by calcium deficiency across different age groups?

Calcium deficiency causes rickets (soft, bowed bones) in children, and osteomalacia (bone softening) or osteoporosis (reduced bone mineral density and porous, fragile bones) in adults.

How do sodium and potassium work together to maintain physiological balance, and what is the adult daily limit for salt?

Sodium acts as the primary extracellular cation and potassium as the major intracellular cation to regulate fluid balance and nerve impulses; adults should consume no more than 6g of salt (2.4g sodium) per day.

What are the primary physiological roles of phosphorus and magnesium?

Phosphorus builds bone and tooth matrix, cell membranes (phospholipids), and ATP, while magnesium acts as an essential cofactor for over 300 enzyme systems.

What are the fundamental differences between haem and non-haem iron?

Haem iron (\(\text{Fe}^{2+}\)) comes from animal tissues, is highly bioavailable (15–35%), and resists dietary inhibitors, whereas non-haem iron (\(\text{Fe}^{3+}\)) comes from plants/fortified foods, has lower bioavailability (2–10%), and requires reduction to \(\text{Fe}^{2+}\) for absorption.

How does Vitamin C enhance non-haem iron absorption, and which factors inhibit it?

Vitamin C chemically reduces non-haem \(\text{Fe}^{3+}\) to soluble \(\text{Fe}^{2+}\), while tannins, polyphenols, phytates, oxalates, and excess calcium inhibit its absorption.

What are the clinical characteristics and high-risk groups for Iron Deficiency Anaemia (IDA)?

IDA produces microcytic, hypochromic red blood cells leading to fatigue, pallor, and breathlessness; high-risk groups include menstruating females, pregnant women, growing children, and vegans.

What are the main biological functions and deficiency symptoms of Zinc?

Zinc is a cofactor for over 300 enzymes essential for cell division, immune function, and wound healing; deficiency leads to delayed wound healing, stunted growth, alopecia, and hypogeusia (loss of taste).

What role does Iodine play in the body, and what disorders arise from its deficiency?

Iodine is required to synthesize thyroid hormones (T3 and T4) that regulate basal metabolic rate; deficiency causes goitre, hypothyroidism, and cretinism.

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