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Nutritional Physiology > Minerals > Flashcards

Minerals Flashcards

1
Q

Classification of Minerals

A

Major Minerals:
* larger amounts required
* present in the body in larger amounts than trace minerals

Minor (or trace) minerals:
* smaller amounts required

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2
Q

Are minerals organic or inorganic

A

Minerals are inorganic elements
* they do not contain carbon
* do not combine to form other molecules in the body
* they are stable - cannot be destroyed by heat, air, aid or mixing
* minerals can only be lost from food during cooking through water

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3
Q

Mineral interaction?

A

Minerals interact with each other
* Similar with vitamins, presence or absence of one mineral can affect another
* Can be problematic when mineral supplements are taken in excess

Plays varied roles in the body
* Sodium, chloride, potassium – body’s fluid balance
* Calcium, phosphorus, magnesium - bone growth and health

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4
Q

Calcium

Distribution of Calcium in the body

A
  • most abundant mineral in the body (1.9% of body weight)
  • 99% of calcium exists in the bones
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5
Q

Calcium

Roles of Calcium in the body

A

1. Bone structure and Strength
* calcium salts (hydroxyapatite)
* embedded in collagen fibres

2. Blood clotting
* participates in several steps of the clotting process (prothrombin -> thrombin)

3. nerve transmission
* action potential at a synapse stimulates calcium influx -> releases neurotransmitter

4. Body Fluids

5. Muscle Contraction

6. Hormonal Signals - many hormones act via calmodulin

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6
Q

Calcium

Blood calcium Levels

A
  • Calcitonin helps decrease blood calcium levels
  • Calcitriol helps increase blood calcium levels

Bones aids as a storage bank when blood calcium is high and as a source of calcium when blood calcium is low

  • Blood calcium above normal = calcium rigor
  • Blood calcium below normal = calcium tetany
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7
Q

Calcium

Osteoclasts

A

Break down bone and release calcium into blood

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8
Q

Calcium

Osteoblasts

A

Build new bone using calcium from blood

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9
Q

Calcium

Role of Vitamin D (calcitriol) in calcium balance/regulation

A
  1. increases calcium gut absorption
  2. increases calcium release from bones
  3. increases kidney reabsorption (decreases losses from body)
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10
Q

Calcium

Calcium Regulation by PTH

A

Parathyroid hormone (PTH): principle regulator of extracellular calcium

Low Blood calcium = Increases PTH = Increases osteoclast activity

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11
Q

Calcium

Low calcium intake

A

Low dietary intake → no effect on plasma levels, but may result in bone loss
In children, stunted growth (deficiency)

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12
Q

Calcium

Low calcium intake - osteoporosis

A

Osteoporosis
* ↓bone density through life leading to bone fractures (risk ↑ with age)
* Loss of bone accelerates around menopause in women
* Protection by ensuring highest peak bone mass (PBM) in late adolescence
* PBM strongly influenced by genetics

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13
Q

Calcium

Food Sources of Calcium

A

60% of dietary intake from dairy products
* milk, yoghurt, cheddar cheese, cottage/ricotta
* salmon (+bones), broccoli, spinach

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14
Q

Major Minerals - Phosphorus

Phosphorus

A
  • second most abundant mineral in the body after calcium
  • mainly found in bones and teeth (85%), but also in bodily fluids
  • absorption improved by vitamin D and presence of calcium
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15
Q

Major Minerals - Phosphorus

Roles of Phosphorus

A
  • Essential for bone health (part of hydroxyapatite)
  • DNA and RNA
  • Involved in virtually all biochemical reactions via ATP (energy metabolism)

Phospholipids in cell membrane:
* Major component of cell membranes – control movements and transportation of nutrients

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16
Q

Major Minerals - Phosphorus

Food Sources of Phosphorus

A
  • Dairy products (half of intake)
  • Meat
  • Dried fruit
  • Eggs
  • Cereals
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17
Q

Major Minerals - Phosphorus

Phosphate Toxicity

A

Toxicity (hyperphosphataemia):
Caused by renal disease, hypoparathyroidism,
acute muscle breakdown
* results in Ca-P precipitates, calcification of non-skeletal tissues and organ damage

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18
Q

Major Minerals - Phosphorus

Phosphate Deficiency

A

Deficiency (hypophosphatemia):
▪ Results in rickets/osteomalacia, bone pain, muscle weakness, anorexia, cardiac arrhythmias and even death

19
Q

Major Minerals - Magnesium

Role of Magnesium

A
  • Cofactor in over 300 enzymes in the body
  • Cofactor in the formation and transfer of high-energy phosphate groups (catalyst)
  • Muscle contraction
  • ** supports bone mineralisation**

▪ Interplay between calcium and phosphate in muscle contraction
▪ Regulates heart function, blood pressure and lung function
* Supports immune system

20
Q

Major Minerals - Magnesium

Dietary Sources of Magnesium

A

Vegetables, legumes, seeds and nuts, cereals, seafood
Dairy not a rich source (unlike calcium and phosphorus)
Chocolate, cocoa
water (hard water)

21
Q

Major Minerals - Sulphate

Sulphate

A

Oxidised form of sulphur
* Found in food and water

Roles in stabilising protein structure:
* helps determine the shape of protein molecule and protein structure

Easily found in a variety of foods, therefore, no known deficiency symptoms
* Unless deficiency in protein

22
Q

What minerals are involved with bone health?

A

Calcium, phosphorus and magnesium

23
Q

Trace Minerals

Iron

A
  • iron is an essential nutrient
  • found in small amounts in every cell
24
Q

Trace Minerals

Haem Iron vs Non-haem Iron

A

Haem (haemoglobin and myoglobin) iron vs Non-haem iron
▪ Haem iron found in animal foods is better absorbed than non-haem

25
Q

Trace Minerals

What are two states of Iron in the body?

A

Ferrous iron (Fe2+) vs Ferric iron (Fe3+)
▪ Ferrous is better absorbed (ferric is virtually insoluble)

* Vitamin C enhances absorption by converting ferric Fe to ferrous Fe (vitamin C is thus ‘oxidised’)

26
Q

Trace Minerals

Functions of Iron - Haemoglobin

A

Haemoglobin in red blood cells
▪ Transport oxygen and carbon dioxide

27
Q

Trace Minerals

Functions of Iron - Myoglobin

A

Myoglobin in muscle cells (acts as an oxygen reservoir)
* Electron transport chain: iron acts as an electron carrier
* Immune function

28
Q

Trace Minerals

Iron Absorption Factors - What decreases absorption?

A
  • Phytates (cereals, legumes, nuts)
  • Oxalate (in leafy vegetable)
  • Excess in Zn, Ca, Mn
  • High Iron stores
  • Polyphenols (tea, coffee, red wine)
29
Q

Trace Minerals

Storage of Iron

A

Transferrin - major blood transporter of iron

Ferritin in the intestinal cells and tissues (mostly liver) for short-term storage

Haemosiderin - insoluble iron-storage protein in the liver (to deal with iron overload)
* As iron stores increases, transferrin is saturated and iron absorption decreases

30
Q

Trace Minerals

Storage of Iron continued.

A

Storage: 70% in RBCs and myoglobin (in muscle) and the rest in liver, bone marrow, and spleen
* No method for excretion except for blood loss, gut losses, and in pregnancy

31
Q

Trace Minerals

Iron-deficiency: Anaemia

A

Anaemia:
decreased levels of haemoglobin leads to reduced production of RBCs and oxygen capcaity

Symptoms:
* paleness
* brittle nails
* fatigue
* difficulty breathing
* poor growth
* impaired cognition
* reduced immune function

32
Q

Trace Minerals

Causes of Iron deficiency

A

Dietary factors:
* low iron, haem iron
* low vitamin C
* excess phytate
* excess tea/coffee
* Fad diets

33
Q

Trace Minerals

Stages of Iron Deficiency

A
  1. Iron stores diminish (decrease in ferritin-bound iron)
  2. transport iron decreases
  3. haemoglobin production decreases
34
Q

Trace Minerals

Treatment of Iron deficiency

A
  • medicinal forms of iron supplements e.g., ferrous sulphate
  • well balanced diet
  • possivle intravenous or intra-muscular iron of oral iron is porrly absorbed.
35
Q

Trace Minerals

Food Sources of Iron

A

Haem iron:
* red meat
* chicken
* fish

  • enriched grains
  • fortified cereal
  • green, leafy vegeatables

Milk is a poor source

36
Q

Trace Minerals

Toxicity of Iron

A

Haemochromatosis:
▪ Over-absorb iron: iron deposits which can lead to organ damage, diabetes, heart disease, and arthritis
▪ Treatment by frequent ‘bleeding’

General Toxicity:
* can be serious, especially for children
* diarrhoea, constipation, nausea, abdominal pain

37
Q

Trace Minerals - Zinc

Zinc Role

A

Cofactor to many enzymes – more than 100 enzymes
Zinc plays many different roles in the body:
* Synthesis of nucleic acids
* transport of Vitamin A
* pancreatic digestive enzymes synthesis
* Wound healing
* immune function (WBC production)
* Blood clotting
* Insulin function
* sense of smell and taste

38
Q

Trace Minerals - Zinc

Absorption of Zinc

A

Absorption monitored by metallothionein
* Binds and regulates the release of zinc in intestinal cells

  • Presence of phytates (and fibre) decrease absorption
  • Calcium supplements decrease zinc absorption
  • Transported in blood by protein albumin and transferrin
39
Q

Trace Minerals - Zinc

Deficiency of Zinc

A
  • Poor growth – children
  • Reduced sense of smell and taste
  • Delayed wound healing
  • Hair loss
  • Lack of appetite
  • Impaired pancreatic function*
40
Q

Trace Minerals - Zinc

Toxicity of Zinc

A
  • Inhibits copper absorption ( metallothionein – binds more copper)
  • decreases HDL, increases LDL - increases risk of heart disease
  • Diarrhoea, cramps, nausea, vomiting
  • Depressed immune function
41
Q

Trace Minerals

Food Sources of Zinc

A
  • meat and poultry
  • shell fish - e.g., oyster and crab
  • dairy foods
  • legumes
42
Q

Trace Minerals - Iodine

Iodine Role

A

Plays key role in thyroid hormones
▪ Basal metabolic rate
▪ Production of body heat energy
▪ Growth
▪ Reproduction
▪ Nerve and muscle function

43
Q

Trace Minerals - Iodine

Deficiency of Iodine

A
  • Growth of the thyroid gland (goitre)
  • Drop in metabolic rate
  • Harmful during pregnancy (results in mental retardation)
  • Consumption of goitrogens (raw turnips, cabbage, Brussels sprouts, cauliflower, broccoli) inhibits iodide metabolism – inactivated by heat
44
Q

Trace Minerals - Iodine

Food Sources of Iodine

A
  • Iodised salt – In Aus/NZ food labels indicates whether salt are iodised
  • Saltwater fish, seafood, seaweed

Nutritional Physiology (5 decks)

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